Dr. Derek Mahony
Registered Specialist in Orthodontics
BDS(Syd) MScOrth(Lon) DOrth RCS(Edin) MDOrth RCSP(Glas) MOrth RCS(Eng)
MOrth RCS(Edin) FRCD(Can) FICD FICCDE FACD FADFE GradDipDentalSleepMedicine (WA)
49 Botany Street, Randwick NSW 2031, Sydney, Australia

Aim

Edward H. Angle dominated orthodontic armamentarium, diagnosis and treatment planning for almost a half century until Charles Tweed successfully challenged his mentor’s nonextraction mantra.  The ensuing diagnostic regimen used by Tweed, however, proved to have serious limitations and clearly resulted in the extraction of too many teeth. This caused a subsequent deterioration of soft tissue appearances of patients that neither they nor their doctors liked.  This article will describe and illustrate how new expansion techniques differ qualitatively from those of Angle, and how these techniques offer patients and doctors less invasive and more comfortable therapies which do not jeopardize facial appearances.

Introduction

For the first third of this past century, orthodontics found itself dominated by one man, Edward H. Angle, with the resultant intellectual stagnation that arises from such monomaniacal control.  This recognition in no way detracts from Angle’s contributions – notably his clear and simple classification system along with the edgewise bracket.  Both of these inventions have endured for a century, and that is no mean achievement in any scientific discipline.  Nevertheless, orthodontists’ unquestioning acceptance of his limited diagnostic and treatment planning regimens hindered the advancement of this discipline more than it helped, and the last half of this past century was spent trying to overcome the stupor of the first half.

Angle’s influence continued until an apostate student of his, Charles H. Tweed,[1] had enough courage and objectivity to challenge Angle’s non-extraction scheme.  It wasn’t a tremendous leap of intellectual power.  Tweed simply and honestly recognized that when 100% of your patients relapsed, there might be something wrong with the diagnosis and/or treatment planning.

Dr. Tweed acted appropriately in the face of this challenge – quite unlike the ancient dentist who chided a young colleague who was describing his meticulous technique of endodontic filling to the monthly assembly of dentists.  The old man explained his own technique that used a simple matchstick sharpened with a pocketknife and then jammed into the canal.  When the young dentist asked if a lot of these root canal fillings didn’t subsequently fail, the older man replied, “Every damn time!”

Dr. Tweed tired of those orthodontic abscesses and, unlike his peers, sought to correct the deficiencies he saw in Angle’s philosophy.  Some would say that he overcorrected, but that said, we must pay homage to anyone who has the skill and temerity to successfully challenge a mentor and his minions.  Tweed’s success brings to mind the remark of C.S. Lewis, who said, “No genius is so fortunate as he who has the skill and ability to do well that which others have been doing poorly.”

Nevertheless, I don’t think that Tweed would have ever been able to deliver his paper describing his extraction technique had Dr. Angle still been alive.  Angles influence over the society that bore his name was too immense to permit such hubris from a young upstart.  But as Samuelson, the MIT economist, once noted: “Science progresses slowly – funeral by funeral.”  And so it was and is in orthodontics.

Nonextraction Philosophy

Aside from the edgewise bracket and the classification system, Angle’s most enduring legacy has been his belief in nonextraction therapy.  Angle had unsuccessfully experimented with premolar extractions while using his ribbon arch appliance, but he never solved the problem of paralleling the roots to prevent the extraction spaces from opening.  If he couldn’t do it, then, ergo, no one else could, and this resulted in a virulent opposition to any extractions and an insistence upon enlarging the arches to accommodate all of the teeth.

This dogma stayed dominant for several decades until Tweed advocated the extraction of premolars based on his diagnostic triangle, which was the first systematic treatment planning stratagem orthodontists had.  Tweed received corroboration simultaneously from another former Angle protégé in Australia, Raymond Begg,[2]  who had studied aborigines and concluded that nature intended for enamel to wear.  He decided that orthodontists could mimic nature by extracting teeth prior to orthodontic therapy.   The Tweed and Begg Extraction Philosophies eventually prevailed and remained uncontested for some time.

Several years past before Holdaway[3, 4] published his articles that suggested the soft tissue as the determining feature of diagnosis.  This disputed Tweed’s narrow diagnostic regimen that focused on the mandibular incisor and totally neglected the soft tissue. Tweed’s triangle set in motion a trend that emphasized more prudence in the extraction of teeth.  Soon others added their discoveries regarding soft tissue and the maxillary incisors as main determinants of diagnosis and treatment planning.[5-7]

From the inception of this specialty, with Dr. Angle, diagnosis never had too much importance because everyone received the same nonextraction treatment with the same expansive appliance.  The marvel of it all is that the collection of orthodontic records never became important.  A few months ago an orthodontist boasted that since invoking a different treatment regimen, he was treating 98% of his patient’s nonextraction.  One was tempted to ask if he still took records because with diagnostic certainty such as that, records are clearly redundant.  Orthodontists shouldn’t waste patients’ time and money taking impressions, cephalometric X-rays or doing treatment simulations if all treatment plans are essentially the same.  One doesn’t need orthodontic records to come to such a preconceived conclusion.

Obviously, this one-size-fits-all treatment planning didn’t benefit patients a hundred years ago, and it doesn’t in our own age.  But such simplicity continues to hold enormous appeal for many orthodontists.  Orthodontists pride themselves in being scientists, and without doubt they receive good training in the scientific method; but it takes very little anecdotal information to eclipse the scientific judgment of many in the profession.  Albert Szent-Györgyi was probably more right than he knew when he said, “The brain is not an organ of thinking but an organ of survival like a claw and fang.  It is made is such a way as to make us accept as truth that which is only advantage.”

No matter how spectacularly orthodontic therapy changes, it will benefit our patients minimally if we do not have a concomitant improvement in our diagnostic and prognostic knowledge.  This remains the number one imperative for those who practice orthodontics.  Orthodontists should view any new therapy unaccompanied by equally sophisticated diagnostic knowledge suspiciously.  Patients have already received far too much orthodontic treatment and far too little diagnosis.

Instrumentation

The first attempts to correct malocclusions used simple large arch wires ligated to the malposed teeth.  Pierre Fauchard of France developed the precursor of the modern appliance – expansion arch (Figure 1).

Figure 1: Fauchard’s expansion arch

This arrangement gave only tipping control, in one dimension, and soon proved inadequate for controlling rotations.  In 1887 Edward H. Angle introduced the E arch, i.e. expansion arch that used a labial wire supported by clamp bands on the molar teeth which ligated to the other teeth (Figure 2).

Figure 2: Angle’s E Arch

Metallurgical developments by the early 20^th Century allowed clinicians to encase all of the teeth with bands and solder attachments that could control the horizontal rotations.  Angle developed a popular attachment known as the pin and tube attachment in 1911 (Figure 3), and it satisfied many of the requirements of clinicians; but this demanded unusual dexterity, patience and skill, so dental clinicians evolved to a ribbon arch bracket (Figure 4), which Angle introduced in 1916. It provided good control in two dimensions and became popular quickly.  The ribbon arch attachment also marked the first time orthodontic attachments gained the name bracket.[8]

Figure 3: Pin and tube appliance

Figure 4: Ribbon arch

When Angle launched the ribbon arch bracket, he had already started work on the edgewise bracket primarily as a supplement to his ribbon arch appliance.  Nevertheless, the edgewise bracket did not suddenly spring full-grown from Angle’s fertile mind, but slowly evolved with several iterations (Figure 5).  When Angle realized that this bracket could deliver three-dimensional control of the teeth with horizontal, one directional placement and simultaneous engagement of all the teeth, he changed the bracket several times until he achieved the #447 (Figure 6) in 1928.  It received early and enthusiastic endorsement from dental clinicians throughout the United States and eventually eclipsed other useful orthodontic appliances such as the McCoy open tube appliance, the Atkinson universal appliance and the Johnson twin wire attachment.

Figure 5: Angle’s many iterations of the edgewise bracket

Figure 6: Angle’s 447 edgewise bracket, “the latest and best in orthodontic mechanisms.”

The universal application and durability of the edgewise bracket confirmed Angle’s immodest claim that it offered the “latest and best in orthodontic mechanisms”.[9]  Innovators have added minor but practical trimmings such as rotating wings, twin brackets, different dimensions, preadjusted appliances, lingual applications, etc., but the essence has remained edgewise.  For any instrument, particularly in the health sciences, to remain virtually unchanged (and almost as useful for close to a century) approaches unbelievability.  In the automobile industry, this would be equivalent to the Model T Ford remaining as the epitome of motoring sophistication.

Other than adding wings and doubling the bracket to make the popular twin edgewise bracket, Angle’s invention has remained basically unchanged.  Holdaway[10] suggested angulations for brackets to help set anchorage, parallel roots and artistically position teeth, while Lee[11] had built some anterior brackets with the ability to torque incisors. But it was Andrews that was to develop an appliance that would apply 1^st, 2^nd and 3^rd order movements to the teeth without making changes in the wire – hence the Straight Wire Appliance.[12]

Preadjusted orthodontic appliances have dominated the profession for the past 30 years, and the belief in them shows little sign of abating even though many have questioned the one-size-fits-all idea.[13-18]

And Back Again

The publication of Frankel’s[19] work with functional appliances illustrated significant enlargement of dental arches and reawakened an interest in nonextraction therapy.  Nevertheless, Frankel mechanics required the use of removable appliances, and that didn’t resonate well with many orthodontists or their patients.  After a brief flurry of interest in the United States, few clinicians continued to use the Frankel appliance on a regular basis.

Nevertheless, the successful use of orthopedic appliances alerted orthodontists to the possibility of increasing arch widths and arch perimeters with minimum forces.  Although mandibular canines offer significant resistance to expansion, mandibular premolars and first molars often demonstrate substantial and stable expansion. Brader[20] hinted at this with his work on the tri-focal ellipse arch form, but he didn’t follow through about how this might give wider and more accommodating arch forms.

Low-force titanium coil expanders have shown their ability to develop arches laterally,[21] and recently Damon[22] has suggested that low arch wire forces, coupled with a passive tube and a small wire-to-lumen ratio, enable teeth and their accompanying dentoalveoli to expand in all planes of space.  Damon feels that using small, low-force wires such as those of Copper Ni-Ti™ (Ormco Corporation, Orange, CA) achieves the ideal biological forces proposed long ago by several investigators.[23] [24, 25]

Self-ligating brackets that essentially form a tube developed several decades ago with the Ormco Edgelok[26] being the first, closely followed by the Speed bracket[27]. Both of these early self-ligating systems suffered from the fact that the Straight-Wire Appliance phenomenon debuted at the approximately the same time, plus a lack of appreciation for what the newer titanium wires could achieve.

Damon has persisted since 1995 with his version of a self-ligating bracket (Figure 8) and has fundamentally changed the types of arch wires and the sequence in which clinicians use them.  His experience has shown that with many patients he can often eliminate distalisation of molars, extractions (excluding those needed to reduce bimaxillary protrusions) and rapid palatal expansion.  He offers compelling clinical evidence of doing this with consistency. [22]

The Damon bracket is essentially a tube designed with the right dimensions to  foster sliding mechanics where needed and enough  play in the system for torque and rotational control using the larger cross section wires. Damon starts  cases with a large lumen arch wire slot and .014 or smaller diameter hi-technology arch wires. Starting cases with a large dimension passive arch wire slot and small diameter wires diminishes the divergence of the angles of the slots.  This lowers the applied force and binding friction. (figure 7)

Fig 7a: Binding

Fig 7b: Divergence

Figure 8: Damon 3 bracket opened and closed

The most logical questions readers could propose would be why has Damon shown successful expansion whereas Angle did not?  The quantity of expansion probably differs little, but the quality of expansion offers a quantum change.  Mollenhauer[28] has suggested as much with his appeal for light forces.  Even though Angle used a ribbon arch, (which suggests a thin, delicate wire) the actual size of the wire had the dimension of .036 x .022 inches. Ligating to this wire would overwhelm the periodontium and prevent the development of a supporting dentoalveolus.  Rather than forming new bone, the supporting dentoalveolus would simply bend and upon completion of treatment quickly return.  Astute clinicians often see this with molar distalization from headgear use and over treat such movement in order to compensate for this regressive bone bending.

Schwartz [25] stated that it takes 20 to 26 g/cm² of force to collapse the capillaries in the Periodontal Ligament. With RPEs and headgears this force sometimes exceeds 10 pounds!

Profitt [29] states that that optimal force levels for orthodontic tooth movement should be just high enough to stimulate cellular activity without completely occluding blood vessels in the  periodontal ligament.

True Biomechanics is staying in the Optimal Force Zone i.e. keeping forces below capillary blood pressure. Conventional ties (o-rings and stainless steel ligatures and spring clips) make staying in the Optimal Force Zone nearly impossible due to the increased binding and friction.

The most important caveat Damon offers clinicians is not to use their ordinary mechanics with his system, and I could not agree more.  When I first began to use the Damon system, I continued to use the regular sequence of arch wires and saw little advantage to these new, more expensive brackets.  Nevertheless, as I began to use the brackets according to Dr. Damon’s advice, I started seeing phenomenonal changes.  The following patient illustrates typical responses to the biomechanics offered by the Damon System:

Summary

The paradigm shift in our current thought processes is the belief that alveolar bone can be altered  and re-shaped with low clinical forces. Using low force, low friction orthodontics, the alveolar bone allows the bodily movement of teeth in all directions.

The architecture of alveolar bone appears to improve over time following low force orthodontics so clinicians should be very creative on how to maintain the appropriate biologic forces during  all phases of treatment.

Orthodontists are currently witnessing an interest in qualitatively different expansive biomechanics that offer patients the possibility of obviating the use of distalizers, rapid palatal expanders and many needless extractions.  The bracket systems that make this possible should command the utmost respect and clinicians should use them as recommended with light forces.

I am witnessing  shorter treatment in most of my Damon cases with less discomfort to my patients. The playing field seems to be leveled between adults and children. These changes I am seeing are more than enough reasons for me to question my previous force systems.

1. Tweed, C.H., The Frankfort mandibular incisor angle (FMIA) in orthodontic diagnosis, treatment planning and prognosis. Angle Orthod, 1954. 24: p. 121-169.
2. Begg, R., Begg orthodontic theory and technique. 3rd ed. 1977, Philadelphia: W.B. Saunders Co.
3. Holdaway, R.H., op. cit., A soft tissue cephalometric analysis and its use in orthodontic treatment planning, Part II. Am. J. Orthod., 1984. 85(4): p. 279-293.
4. Holdaway, R.H., A soft tissue cephalometric analysis and its use in orthodontic treatment planning, Part I. Am. J. Orthod., 1983. 84(1): p. 1-28.
5. Alvarez, A., The A Line: A New Guide for Diagnosis and Treatment Planning. J. Clin. Orthod, 2001. 35(9): p. 556-569.
6. Creekmore, T.M., Where teeth belong and how to get them there, J. Clin. Orthod, 1997. 30(9): p. 586-608.
7. Sarver, D.M., Profitt, W.R., Special Considerations in Diagnosis and Treatment Planning. 4th ed. Orthodontics – Current Principles and Techniques, ed. Tom Graber. 2005, St. Louis, MO: Elsevier Mosby. 1213.
8. Renfroe, E.W., Technique Training in Orthodontics. 1st ed. 1960, Ann Arbor, MI: Edwards Brothers Inc. 230.
9. Angle, E.H., The latest and best in orthodontic mechanism. Dental Cosmos, 1929. 71: p. 164-174, 260-270, 409-421.
10. Holdaway, R.A., Bracket angulation as applied to the edgewise appliance. Angle Orthod, 1952. 22: p. 227-236.
11. Lee, I.F.
12. Andrews, L.F., Straight Wire, the Concept and Appliance. 1989, San Diego, CA: L.A. Wells Company.
13. Andreiko, C., JCO interviews Craig Andreiko, DDS, MS, on the Elan and Orthos Systems. J. Clin. Orthod, 1994. 28(August): p. 459-472.
14. Sachdeva, R., SureSmile technology in a patient-centered orthodontic practice. J. Clin. Orthod., 2001. 35(April): p. 245-253.
15. Melsen, B.F., Giorgio, Biomechanics in Orthodontics, Libra Ortodonzia.
16. Creekmore, T.C., R., Straight Wire: The Next Generation. Am J.Orthod & Dentofacial Orthop, 1983. 104(July): p. 8-20.
17. Dellinger, E.L., A scientific assessment of the straight-wire appliance. Am J Orthod, 1978. 73: p. 290-299.
18. McGann, B.D., Individual patient (IP) appliances. World J. Orthod, 2005. 6(2): p. 189-192.
19. Frankel, R., The Frankel Appliance (The Function Corrector(Removable Orthodontic Appliances, ed. T.G. Neumann. 1977, Philadelphia, Pa: W. B. Saunders Company.
20. Brader, Dental arch form related with intraoral forces: PR=C. Am. J. Orthod., 1972. 61(June): p. 541-561.
21. Williams, M.O., White, L.W., A Rationale for Expansion. World J. Orthod, Pending Publication.
22. Damon, D.H., Treatment of the face with biocompatible orthodontics. 4th ed. Orthodontics – Current Principles and Techniques, ed. Tom Graber. 2005, St. Louis, MO: Elsevier Mosby. 1213.
23. Reitan, K., Tissue behavior during orthodontic tooth movement. Am J Orthod, 1960. 46: p. 881-900.
24. Rygh, P., Elimination of hyalinized periodontal tissues associated with orthodontic tooth movement. Scand J Dent Res, 1973. 81: p. 467-480.
25. Schwartz, A.M., Tissue changes incidental to orthodontic tooth movement. Int J Orthod Oral Surg Radiography, 1932. 18: p. 331.
26. Wildman, A.J., Lee, I.F., Hice, T.L., Lang, H.M., Strauch, E.C. Jr., The Edgelok Bracket. J Clin Orthod, 1972. 6(11): p. 613-633.
27. Hanson, H., Dr. G. Herbert Hanson on the Speed Bracket. J. Clin. Orthod., 1986. 20(3): p. 183-189.
28. Mollenhauer, B., Ultralight forces for simultaneous orthodontics and orthopedics: part III. dentofacial orthopedics. World J. Orthod, 2000. 1: p. 195-201.
29. Proffit and Fields, Contemporary Orthodontics, Second edition, Mosby 1993

Impression techniques used for single-unit crowns: findings from the National Dental Practice-Based Research Network

Dr. Michael McCracken, Professor, Department of Clinical & Community Sciences, UAB School of Dentistry, SDB Room 111,1530 Third Avenue South, Birmingham, AL 35294-0007. E-mail: mikemc@uab.edu.

Purpose

To: (1) determine which impression and gingival displacement techniques practitioners use for single-unit crowns on natural teeth; and (2) test whether certain dentist and practice characteristics are significantly associated with the use of these techniques.

Materials and Methods

Dentists participating in the National Dental Practice-Based Research Network were eligible for this survey study. The study used a questionnaire developed by clinicians, statisticians, laboratory technicians, and survey experts. The questionnaire was pretested via cognitive interviewing with a regionally diverse group of practitioners. The survey included questions regarding gingival displacement and impression techniques. Survey responses were compared by dentist and practice characteristics using ANOVA.

Results

The response rate was 1777 of 2132 eligible dentists (83%). Regarding gingival displacement, most clinicians reported using either a single cord (35%) or dual cord (35%) technique. About 16% of respondents preferred an injectable retraction technique. For making impressions, the most frequently used techniques and materials are: poly(vinyl siloxane), 77%; polyether, 12%; optical/digital, 9%. A dental auxiliary or assistant made the final impression 2% of the time. Regarding dual-arch impression trays, 23% of practitioners report they typically use a metal frame tray, 60% use a plastic frame, and 16% do not use a dual-arch tray. Clinicians using optical impression techniques were more likely to be private practice owners or associates.

Conclusions

This study documents current techniques for gingival displacement and making impressions for crowns. Certain dentist and practice characteristics are significantly associated with these techniques.

Clinicians frequently offer crowns to patients as a treatment option. Whether to protect a tooth from fracture, improve esthetics, or restore decayed surfaces, crowns provide a solution for a variety of restorative needs. Although crowns are a common factor in daily practice, little is known about the prevalence of different techniques used to make crown impressions, or variations in techniques that may exist regionally or by practice/dentist characteristics.

Steps associated with making a crown include gingival displacement, impression of the prepared tooth, obtaining a jaw relationship record, and registration of the opposing dentition. The first step, gingival retraction or displacement, often uses a mechanical element placed into the gingival sulcus, such as a cord or paste. A general goal is to create a gap of about 0.2 mm or more around the finish line of the preparation.  Cordless and cord techniques can both provide this level of retraction. One recent survey reported that 92% of dentists use retraction cord. Often a chemical agent is added to induce hemostasis, or the gingival tissues might be removed surgically with a rotary instrument, laser, or heated electrode. In some studies, the techniques using retraction cord provided more displacement, but cordless techniques (paste) may have advantages in patient comfort and fewer inflammatory markers. The use of compression caps and lasers has also been reported.

A multitude of techniques exist for making impressions for single-unit crowns, with variations in impression materials, techniques, and tray types. Many clinicians use poly(vinyl siloxane) (PVS) polymeric impression materials. Even within this category, clinicians must pick a particular technique. For example, some authors advocate a putty-wash technique, during which the tray is filled with a high-viscosity PVS material, and a lower-viscosity material is injected around the prepared tooth. Other studies demonstrate that a two-stage technique is superior. In this technique, a preliminary impression is made before tooth preparation, sometimes using a spacer to provide relief in the impression. After tooth preparation, a second impression is made using a lower viscosity material. Clinicians also commonly use other combinations of viscosity materials both to load the impression tray and to syringe around a prepared tooth.

Similarly, variation exists in the type of tray used to capture the impression. One study examined 1403 impressions submitted to a commercial laboratory in the United States: a majority of the trays used were plastic (62%), and most were dual-arch (73%).In a U.K. survey of dentists, 61% used a full-arch plastic tray for crown impressions. Another U.K. survey reports 65% of impressions used a flexible tray. While some studies suggest that custom trays or rigid metal trays produce superior impressions, other authors conclude that plastic dual-arch trays, even though less rigid, provide acceptable clinical results. It is possible that higher-viscosity materials may distort more when using a dual-arch tray system.

Advances in technology offer additional options for impressions, including the use of optical (digital) techniques for making crowns. One study examined 50 crowns made with optical impressions in a general practice and documented a median marginal gap of 46 μm. Several studies compared digital and polymeric impression techniques by making multiple impressions and crowns for the same tooth and comparing the fit of these crowns. In these studies, the fit of the digitally produced crown was similar to or better than conventional techniques. In vitro work also supports the use of digital impression techniques, claiming clinically acceptable marginal fit and internal adaptation. Some data suggest that the optical impression may be faster or offer higher patient satisfaction. Optical impressions crowns may also boast fewer chairside adjustments.

The results presented in this study used questionnaire data from clinicians describing the techniques they commonly (or regularly or routinely) use to achieve gingival displacement and obtain impressions. Additionally, we identify dentist and practice characteristics significantly associated with use of these techniques. In circumstances for which clinical scientific evidence is equivocal, clinicians may gain valuable insight by observing colleagues and knowing what techniques are reported by other dentists as effective. While every dentist learns these techniques in dental school, technology and materials change rapidly, so it is helpful to identify current techniques widely used in general clinical practice.

Materials and methods

This study is based on two surveys completed by dentists in the National Dental Practice-Based Research Network (PBRN; “network”). This included the Enrollment Questionnaire, and the Clinical Techniques Questionnaire. The network is a consortium of dental practices and dental organizations focused on improving the scientific basis for clinical decision-making. Detailed information about the network is available at its website. The network’s applicable Institutional Review Boards approved the study. All participants provided informed consent after receiving a full explanation of the procedures.

Results

For this study, 2299 dentists were selected to participate. Of these, 101 were deemed ineligible before beginning the questionnaire (no longer in active practice, deceased, specialists who do not do single-unit permanent crowns). An additional 66 were deemed ineligible once completing at least part of the questionnaire (do not do at least one crown each month). This left a total of 2132 eligible clinicians, of whom 1777 responded, for a response rate of 83%. Among the 47 test/retest participants, the mean (SD) time between test and retest was 15.5 (3.0) days. For categorical variables, agreement between time 1 and time 2 showed a mean weighted kappa of 0.62 (IQR: 0.46, 0.79). Mean test-retest reliability for numeric variables was 0.75.

The majority of respondents were male, and many had been in practice for over 20 years. Most of the respondents, 73%, were practice owners. Respondents were distributed fairly evenly across regions, and the majority work full time (86%). Only 3% of respondents were specialists, including 32 prosthodontists.

Dentists indicated their most commonly used method of gingival retraction. Possible responses included: none, dual cord, single cord, injectable retraction material (e.g., Expasyl), dual impression (wash) technique, gingival troughing (e.g., electrical or laser tissue removal), and other. Only two clinicians reported using a dual impression (wash) technique, and four reported gingival troughing; for the purposes of reporting in these were combined with the “Other” category. Most clinicians used either a single cord (35%) or dual cord (35%) technique. About 16% of respondents preferred an injectable retraction technique. These preferences correlated significantly with dentist and practice characteristics.

Dentists reported using chemical agents to control hemostasis on 57 ± 38% of impressions. Some 37% of respondents use these agents more than 90% of the time, and 22% use them less than 10% of the time.

When making crown impressions, dentists were asked to indicate the percentage of time they use the following techniques: PVS, polyether, optical (digital or CAD/CAM), hydrocolloid, or other. While some clinicians might use 100% PVS, as an example, other clinicians might use multiple techniques in varying percentages. The average (±SD) responses overall for each technique were: PVS, 77% (39); polyether, 12% (30); optical, 9% (26); hydrocolloid, 1% (10); other, 1% (9).

The dentist who prepared the tooth made the impression 98% of the time, and an assistant made the final impression 2% of the time. The dentist who prepared the tooth made the provisional 49% of the time, and an assistant made the provisional 50% of the time. The remaining responses included offices that do not make provisionals, or make them with a combination of efforts between the dentist and auxiliary.

Discussion

The use of optical scanners is perhaps reaching a tipping point, with dentists reporting they use optical impressions about 9% of the time to make single-unit crown impressions. This trend is expected to continue, as more clinicians choose to make crown impressions digitally, and apply this technology to other aspects of dentistry, such as fabricating removable prostheses. However, there is little documentation of the prevalence of these techniques in private practice, or which practitioner characteristics correlate with their use. Three factors were significantly correlated with the use of digital scanners among clinicians who used digital impressions more than 90% of the time for single-unit crown impressions: race, type of practice, and practice busyness. While the use of advanced technology is often associated with younger people, that was not the case in this sample, with no difference among users who had graduated from dental school recently, compared to those who had been in practice longer. It appears that the use of digital scanners has appeal across all generations of dentists.

By practice type, the clinicians who used digital impressions were more likely practice owners or associates, while clinicians in large group practices did not report widespread use of digital impression technology. This is somewhat surprising, as a larger office may have greater financial resources for the use of an optical scanner. The association may reflect a more nimble decision structure present in a smaller private practice, or a desire to standardize techniques and materials within a larger group structure, pushing the group toward more conventional materials. Also, with a larger group, more people must agree on an expensive capital investment, and in particular the brand or type of technology to purchase. This may delay the decision in some cases.

Practices that were not overly busy were more likely to use digital technology. This may be associated with having adequate time to implement a new impression technique into practice. Also, clinicians burdened with their clinical load may be less likely to invest time into new technology, particularly when its use has not reached a point of majority use within the industry. Finally, clinicians of different races reported different levels of digital impression utilization, with clinicians reporting their race as white or other using digital impressions more than clinicians who reported their race as black or Asian. It is unclear why these differences exist.

The most popular overall impression material for single-unit crowns was polymeric impression materials, especially PVS materials. These numbers were slightly lower than a U.K. dentist survey, which reported about 90% use of silicone materials (addition and condensation) and 9% of dentists using polyether materials. That same study, published in 2005, reported that 1% of restorations were made using CAD/CAM technology, far lower than the results presented here, over a decade later. A similar study, published in 2012 by the same author, found that addition silicone was used 71% of the time, and polyether materials 17%, numbers similar to our findings. They also noted that female clinicians were less likely to use polyether impression materials.

The polymeric material viscosity used to fill the impression tray varied statistically by most parameters reported in this study. Overall, approximately one-third of practitioners use medium body in the tray, and two-thirds use putty in the tray. This occurs despite some evidence that suggests that higher-viscosity materials distort impressions more when using disposable trays. Clinicians who graduated more than 15 years ago reported less use of heavy-body materials in the tray, but a higher use of putty. Clinicians in larger group practices reported frequent use of medium-body materials in the impression trays, at 49% and 46% for HealthPartners and Permanente Dental Associates clinicians, respectively. This may be due to an effort to standardize material choice by using a medium-viscosity material to appeal to various dentist preferences in a large group setting.

The overall use of dual-arch trays in this survey was similar to that reported by Mitchell et al, who observed that about 60% of dual-arch trays used are plastic. Of the impressions examined in that study, 73% were dual-arch; however, this also included impressions for implant crowns, inlays, onlays, and veneers, which were types of restorations not considered in this survey. The results were echoed by Storey and Coward, with 65% of impressions made with flexible trays. While some controversy exists regarding the use of a dual-arch impression tray, clearly it is popular in practice. The use of the dual-arch impression tray is supported in the literature. Considering practice characteristics, several factors were associated with tray choice. Black and Asian clinicians used more plastic frame dual-arch trays, while white clinicians were more likely not to use a dual-arch technique. Clinicians who had been in practice more than 15 years were less likely to use a dual-arch technique, which may reflect a change in views over time regarding this technique. Clinicians in the HealthPartners group were much more likely to use a metal frame dual-arch tray than a plastic one, reflecting a possible group preference for this technique. It is unclear why practitioners from different parts of the country would use different tray types, but regional differences are notable. This may reflect differences in philosophies at dental schools located in these regions or differences in regional key opinion leaders, or perhaps vendor marketing and opinion in a particular area.

Interest is growing in expanded duty dental assistant functions. It was noted in this survey that 2% of final crown impressions, and 50% of provisionals, are made by dental auxiliaries. Future analyses from this study will evaluate the fit of crowns clinically. If differences exist between dentist impressions and auxiliary impressions regarding clinical crown acceptability, these may become evident. This data will contribute to the discussion of expanded duty functions.

Conclusion

By understanding the wide variety of techniques used to make impressions for single-unit crowns, clinicians may modify their own techniques and approaches to optimize impression and gingival retraction techniques. Clinicians learn from other clinicians. Great variability exists regarding the type of techniques used for gingival displacement and impression making, and these variations are significantly associated with dentist and practice characteristics.

Identification of gum disease genes may speed quest for compounds to treat severe periodontitis

Identification of the genes represents a vital step toward developing compounds that can be used in targeted, individualized treatment of severe periodontitis, before loss of teeth and supportive bone occurs.

Findings of the study were published recently in the Journal of Dental Research.

In gene expression studies, investigators find those genes that are most commonly expressed in either healthy or diseased tissue. But such studies cannot identify a causal link between these genes and the disease, and often miss genes that affect a larger number of genetic pathways, which may have a large impact on the disease process.

In this study, a team led by Panos N. Papapanou, DDS, PhD, professor and chair of oral, diagnostic and rehabilitation sciences at the College of Dental Medicine at CUMC, “reverse-engineered” the gene expression data to build a map of the genetic interactions that lead to periodontitis and identify individual genes that appear to have the most influence on the disease. “Our approach narrows down the list of potentially interesting regulatory genes involved in periodontitis,” says Dr. Papapanou. “This allows us to focus on the handful of genes that represent the most important players in the process rather than the whole transcriptome.”

To identify the genes, Dr. Papapanou partnered with CUMC investigators including Ryan Demmer, PhD, assistant professor of epidemiology, at the Mailman School of Public Health, and researchers in Systems Biology who had previously developed algorithms to identify regulatory genes that fuel cancer growth. The researchers examined RNA from healthy and diseased gum tissues of 120 patients with periodontitis. They applied one algorithm to study the interactions among the genes and used another algorithm to identify genes that disrupt healthy tissue and drive the disease process.

Many of the genes identified by Dr. Papapanou and his team are implicated in immune and inflammatory pathways, confirming laboratory and clinical observations of the development of periodontal disease.

Identification of the master regulator genes will allow investigators to test compounds that interrupt their action, creating treatments that stop periodontal disease at its source. “Now it’s important to do the downstream work of validating these master regulators in the lab before we can test these genes in experimental models,” says Dr. Papapanou.

Jaw-dropping research explains mouth formation during embryonic development

By Nicole Giese Rura

“All biological holes—openings—that form in the embryo are fascinating because they would become a catastrophic wound if they do not form precisely,” says Whitehead Member Hazel Sive, who is also a professor of biology at MIT. “We call these ‘scheduled holes’ and the mouth is a crucially important example.  Mouth formation involves many steps that ensure the opening happens at the right time and at the right place— when the cells are connected with the correct junctions to be exposed to the outside and where the opening connects to a prepared region, in the case of the mouth to the digestive system. But I was so surprised when we found that this process is initiated in frogs several days before the mouth actually opens.”

The Sive lab has studied mouth formation during embryonic development in Xenopus frogs for many years. Because mouth formation occurs early in embryonic development and is highly conserved across species, model organisms, such as frogs and fish, provide fundamental insights into key developmental events that are difficult to observe and study in humans.

In the most recent work Sive lab researchers led by Laura Jacox, then a graduate student pursuing a dual DMD-PhD degree through the Harvard School of Dental Medicine and the Harvard-MIT Health Sciences and Technology program, monitored a region of the embryo known as the Extreme Anterior Domain (EAD). Within the EAD, which the Sive group has identified as the earliest element of facial development, they noted that a group of cells reorganizes to form a “pre-mouth array” that indicates where the mouth opening will later form.

The pre-mouth array begins as a square, eight cells wide and high, and morphs into a two-cell wide by twenty tall column. This transformation is a process called convergent extension, a crucial embryonic mechanism of cell reorganization. As the larvae prepares to begin feeding, the two rows of cells unzip down the middle to surround the oral opening that connects the digestive system to the outside.

The team observed that pre-mouth array formation occurs as ‘neural crest’ cells (that later form bones and muscles of the face) come to lie on either side of the EAD. They proposed that these cells send a signal to EAD cells instructing them to reorganize and form the pre-mouth array. Supporting this proposal, they showed that the neural crest and the Wnt/PCP signaling pathway, specifically a Wnt11 signal, triggers pre-mouth array formation.

Jacox acknowledges that this research clarifies a piece of a highly complex, carefully orchestrated process.

“There’s a lot of craniofacial development that we don’t understand,” says Jacox, a co-author of the Cell Reports paper who will soon become a resident in orthodontics at the University of North Carolina Chapel Hill. “If we hope to understand why craniofacial anomalies happen in humans and how to treat them at an earlier point to avoid years of surgery and orthodontics, we need to obtain a better handle on what’s going on. Recognizing what is required to form a mouth and the face and how it’s regulated is a step toward understanding how these processes can be disrupted.”

This work on mouth formation during embryonic development was supported by the National Institute of Dental and Craniofacial Research (NIDCR 1R01 DE021109-01 and F30DE022989) and Harvard University’s Herschel Smith Graduate Fellowship.

* * *

Hazel Sive’s primary affiliation is with Whitehead Institute for Biomedical Research, where her laboratory is located and all her research is conducted. She is also a professor of biology at Massachusetts Institute of Technology.

* * *

Full Citation:

“Formation of a ‘‘pre-mouth array’’ from the extreme anterior domain is directed by neural crest and Wnt/PCP signaling“

Cell Reports, August 2, 2016.

Laura Jacox (1,2,3,4,5), Justin Chen (1,2), Alyssa Rothman (1,2). Hillary Lathrop-Marshall (1,3) and Hazel Sive (1,2).

1. Whitehead Institute for Biomedical Research, 9 Cambridge Center, Cambridge, MA 02142, USA
2. Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
3. Harvard School of Dental Medicine, 188 Longwood Avenue, Boston, MA 02115, USA
4. Harvard-MIT Health Sciences and Technology Program, Harvard Medical School, 250 Longwood Avenue, Boston, MA 02115, USA
5. Biological Sciences in Dental Medicine Program, Harvard Graduate School of Arts and Sciences, 1350 Massachusetts Avenue, Holyoke Center 350, Cambridge, MA 02138, USA

Researchers find byproducts from gum disease incite deadly oral cancer growth

Researchers from Case Western Reserve University have discovered how byproducts in the form of small fatty acids from two bacteria prevalent in gum disease incite deadly oral cancer growth (the growth of deadly Kaposi’s sarcoma-related (KS) lesions and tumors in the mouth).

The discovery could lead to early saliva testing for the bacteria, which, if found, could be treated and monitored for signs of cancer before it develops into a malignancy, researchers say.

“These new findings provide one of the first looks at how the periodontal bacteria create a unique microenvironment in the oral cavity that contributes to the replication the Kaposi’s sarcoma Herpesvirus (KSHV) and development of KS,” said Fengchun Ye, the study’s lead investigator from Case Western Reserve School of Dental Medicine’s Department of Biological Sciences.

The discovery is described in The Journal of Virology article, “Short Chain Fatty Acids from Periodontal Pathogens Suppress HDACs, EZH2, and SUV39H1 to Promote Kaposi’s Sarcoma-Associated Herpesvirus Replication.”

The research focuses on how the bacteria, Porphyromonas gingivalis (Pg) and Fusobacterium nucleatum (Fn), which are associated with gum disease, contribute to cancer formation.

Ye said high levels of these bacteria are found in the saliva of people with periodontal disease, and at lower levels in those with good oral health—further evidence of the link between oral and overall physical health.

The deadly oral cancer growth KS impacts a significant number of people with HIV, whose immune systems lack the ability to fight off the herpesvirus and other infections, he said.

“These individuals are susceptible to the cancer,” Ye said.

Deadly oral cancer growth KS first appears as lesions on the surface of the mouth that, if not removed, can grow into malignant tumors. Survival rates are higher when detected and treated early in the lesion state than when a malignancy develops.

Also at risk are people with compromised immune systems: those on medications to suppress rejection of transplants, cancer patients on chemotherapies and the elderly population whose immune systems naturally weaken with age.

The researchers wanted to learn why most people never develop this form of cancer and what it is that protects them.

The researchers recruited 21 patients, dividing them into two groups. All participants were given standard gum-disease tests.

The first group of 11 participants had an average age of 50 and had severe chronic gum disease. The second group of 10 participants, whose average age was about 26, had healthy gums, practiced good oral health and showed no signs of bleeding or tooth loss from periodontal disease.

The researchers also studied a saliva sample from each. Part of the saliva sample was separated into its components using a spinning centrifuge. The remaining saliva was used for DNA testing to track and identify bacteria present, and at what levels.

The researchers were interested in Pg’s and Fn’s byproducts of lipopolysaccharide, fimbriae, proteinases and at least five different short-chain fatty acids (SCFA): butyric acid, isobutryic acid, isovaleric acid, propionic acid and acetic acid.

After initially testing the byproducts, the researchers suspected that the fatty acids were involved in replicating KSHV. The researchers cleansed the fatty acids and then introduced them to cells with quiescent KSHV virus in a petri dish for monitoring the virus’s reaction.

After introducing SCFA, the virus began to replicate. But the researchers saw that, while the fatty acids allowed the virus to multiple, the process also set in motion a cascade of actions that also inhibited molecules in the body’s immune system from stopping the growth of KSHV.

“The most important thing to come out of this study is that we believe periodontal disease is a risk factor for Kaposi sarcoma tumor in HIV patients,” Ye said.

With that knowledge, Ye said those with HIV must be informed about the importance of good oral health and the possible consequences of overlooking that area.

The research was supported by a career development grant at Center for AIDS Research at Case Western Reserve University, and a National Institute of Dental and Craniofacial Research grant.

Contributing to the study were Case Western Reserve University researchers Abdel-Malek Shahir and Nabil Bissada, from the Department of Periodontics; Xiaolan Yu, Jingfeng Sha, Zhimin Feng, Betty Eapen, Stanley Nithianantham, and Aaron Weinberg, from the dental school’s Department of Biological Sciences; and Biswajit Das and Jonathan Karn, from the Department of Molecular Biology & Microbiology at the School of Medicine.

© 2017 Case Western Reserve University
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Dr. Derek Mahony
Registered Specialist in Orthodontics
BDS(Syd) MScOrth(Lon) DOrth RCS(Edin) MDOrth RCSP(Glas) MOrth RCS(Eng)
MOrth RCS(Edin) FRCD(Can) FICD FICCDE FACD FADFE GradDipDentalSleepMedicine (WA)

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Introduction

The term neuromuscular occlusion has become associated with certain limited methodologies that are used to obtain a muscle-compatible occlusal relationship.  In reality, there are several different approaches that can be used to determine a “neuromuscular” maxillo-mandibular relationship, even with a fully edentulous case. Within each method, however, the common basis for all muscle-oriented approaches involves first determining the resting length of the masticatory muscles.

Historically, opening the bite has been considered hazardous and/or foolhardy by many dentists and with good reason.  Arbitrary opening of the bite, especially when accomplished strictly on an articulator, can result in a difficult, uncomfortable and unappreciative patient.  Some dentists have recommended against ever opening a bite, perhaps after an especially troublesome experience with a patient.

In spite of the risks, there are some advantages associated with opening an over-closed bite. The identification can be traced back at least 70 years to an ENT physician, Dr. J. B. Costen.^1-3  Dr. Costen discovered, perhaps quite by accident after referring many of his symptomatic, edentulous patients to a local dentist for new dentures, that many returned with their head and ear pain symptoms greatly relieved.  His publications were positively received at the time and, in fact, what we refer to today as temporomandibular disorders (TMDs) were originally referred to as “Costen’s Syndrome.”  While we know today that many TMD patients are not over-closed, over-closed patients do often exhibit some of the signs and symptoms commonly associated with TMD.  Thus, although over-closure in and of itself is not pathognomonic of TMD, it should be considered as a risk factor.

The use of the patient’s own muscles to determine the vertical dimension of occlusion was already being explored in the 1940s by people like orthodontist John R. Thompson.⁴   Sears⁵ introduced the concept of the “Pivot Appliance” in the 1950s, which was designed to open the bite enough to allow the patient’s muscles to reposition the mandible.  Following their lead, others^6-28 have subsequently evolved the current array of neuromuscular registration methods presently in use.  At the same time several studies^29-32 have demonstrated that a muscle-determined position, although similar, is not identical to centric relation. 

Common signs and symptoms of over-closure

When asked, over-closed patients often report symptoms such as frequent headaches, dull pain of the elevator muscles and pain or stiffness in their neck muscles.  Ear stuffiness, tinnitus and/or vertigo are also commonly reported.  A more subtle symptom, less often reported, is frequent gastrointestinal distress in various forms that has no clear, identifiable cause.  This may also be accompanied by a report of difficulty in chewing and/or swallowing.  An overclosed patient will usually report several, but not all, of the following symptoms.

1. Frequent headaches with no identifiable cause
2. Ear stuffiness with no indication of ear pathology
3. Difficulty in chewing tough foods
4. Difficulty or discomfort in swallowing
5. Frequent gastrointestinal distress
6. Vertigo
7. Tinnitus
8. Persistent dull pain in masticatory elevator muscles
9. Neck pain or stiffness
10. Possible increased wear of incisor teeth

Under examination, a number of signs indicating over-closure may appear.  These include; 1) a measured freeway space greater than 3 mm, 2) EMG or visual identification of a tongue-thrust swallow, 3) the appearance of less than fully erupted molars, 4) a deep curve of Spee, 5) one or more posterior edentulous spaces, 6) lingually tipped mandibular molars, 7) EMG identification of elevator muscle hyperactivity at rest of more than 2.0 microvolts average (or 2.2 microvolts RMS), 8) worn and shortened teeth (there is no scientific evidence that human teeth “grow out” in response to wear in the way that elephant’s teeth do), 9) horizontal skin creasing and saliva weeping at the corners of the mouth, 10) a so-called “Shimbashi” measurement (in centric occlusion) of less than 16 mm from the cemento-enamel junction of the maxillary central incisor to the cemento-enamel junction of its opposing mandibular tooth and 11) long-term chronic internal derangement of the TM Joint(s).  However, patients rarely seek dental treatment for any of these objective signs.  Instead, they are more likely to seek rehabilitative treatment for headache, jaw-ache, ear-ache, difficulty in chewing/swallowing or for purely esthetic reasons.  In other cases they are unaware of their condition, apparently due to their excellent adaptability.  In the over-closed patient the “reason” for treatment, either cosmetic or functional, is often dependent more on his/her individual adaptability than on the dental conditions present.  While some signs simply indicate the “progress of the destruction” that a pathological maxillo-mandibular relationship fosters, other signs may indicate a successful adaptation.

1. Freeway space > 3 mm [if pain level is low, it is an adaptation, otherwise it is not]
2. Tongue thrust swallow [if full arch tongue thrust, usually a successful compensation]
3. The appearance of less than fully erupted molars [tongue inhibition of natural eruption]
4. A deep curve of Spee [often associated with one or more missing molars or a deep anterior overbite with retroclined upper incisors]
5. One or more posterior edentulous spaces [leads to deep curve of Spee]
6. Lingually tipped posterior teeth [tongue thrust during swallow, restricted maxillary arch]
7. Hyperactivity of elevator muscles at “rest.” [an adaptation, successful if no elevator muscle pain]
8. Worn/short teeth, abfractions (ground off) [not a successful adaptation]
9. Skin creasing at corners of mouth [may appear as aesthetic problem only, not an adaptation]
10. Saliva weeping at corners of mouth [an esthetic and functional problem, not an adaptation]
11. CEJ (cemento-enamel junction) to CEJ in C.O. < 16 mm. [less than the normal adaptive range]
12. Internal derangement(s) of the TMJ [if no degeneration, may be a successful adaptation]

Maxillo-mandibular bite relationships

Centric occlusion (CO = habitual)

The maxillo-mandibular position of maximum intercuspation is most often the dental treatment position, primarily by default.  This is of necessity whenever single tooth preparations or small restorations are involved, since they must fit within the patients existing occlusal scheme.  It is only at times of major reconstructive, orthodontic and/or surgical treatments that the option of opening a bite or establishing a new maxillo-mandibular relation may present itself.  However, many clinicians still prefer to “play it safe” and retain the existing habitual (CO) maxillo-mandibular relationship, even during major rehabilitative procedures.  By definition, the use of centric occlusion as a treatment position excludes re-establishing a proper vertical dimension in an over-closed patient.  However, if the patients condition is actively deteriorating this may not be a safe option at all, as the continued physiologic breakdown may lead to failed dentistry and/or a flair up of craniofacial pain.

Centric relation (CR)

The concept of centric relation has a very long history and was originally devised, at least in part, to accommodate the use of articulators during prosthodontic treatment.  Although we now know that the jaw doesn’t function like a hinge, originally it was convenient to make that assumption when using articulators to make prostheses.  Today, one clear difference between centric relation procedures and strictly muscle-oriented methodologies is the priority given by CR methods to evaluating the function of the temporomandibular joints.  Typically, centric relation operators give first priority to establishing stable joint function, while muscle-oriented (neuromuscular) approaches tend to focus almost exclusively on muscle comfort.

Muscle-related centric (MC)

Fig. 1.  BioJVA* testing for normal TM joints

In general, muscle-oriented approaches consider joint position and/or stability secondary to muscle function.  In the extreme, it is simply assumed that creating “happy muscles” will automatically provide good or at least adequate joint function.  In a more practical view, both joint function and muscle function are seriously evaluated and, when indicated, a compromise is sought to provide both joint and muscle compatibility.  This represents an approach that bridges the gap between strict CR and rigid MC approaches.  Consequently, a variety of methods have evolved to capture and establish a muscle-related centric position, while maintaining favorable joint function.

The requirements of proper neuromuscular occlusion (NMO)

Fig. 2.   Bio-TENS,* a ULF-TENS unit used for muscle relaxation

The first step in all approaches to NMO requires inducing relaxation in the masticatory musculature, however, there is no rational excuse for not evaluating TM joint function prior to beginning the process.  This can be accomplished quickly and easily with Joint Vibration Analysis (JVA see figure 1.), or with more expensive and invasive imaging such as MRI.  Muscle relaxation can be aided by Ultra-Low Frequency TENS (ULF-TENS, see Figure 2.), an Aqualizer, soft music or any other technique that reduces the resting hyperactivity of the masticatory muscles.  Surface electromyography (see figure 3.) is useful for making a quantitative determination whether relaxation has occurred or whether resting muscle hyperactivity still exists.  Needles and/or fine wire electrodes not only make relaxation less likely, they record a more localized signal that is less representative of overall muscle activity.  However, needle EMG electrodes are required when one is seeking to differentiate a myopathy from a neuropathy.  Using the relaxed rest position of the mandible, with respect to the maxilla as a reference, a clinician can select a vertical dimension that allows adequate freeway space, yet avoids over-closing the bite.  There are several methods currently used for selecting the treatment vertical.  Each has its own rationale and advantages, but all of them benefit from objective diagnostic aids to ensure the best compromise between optimum joint, muscle, and tooth function.

 Fig. 3.  BioEMG II* for monitoring rest position and testing muscle function against the new bite

 Several muscle-oriented bite registration techniques

The wax swallow bite registration

A physiologic, muscle-oriented, vertical dimension can be obtained by means of the swallowing reflex technique originally proposed by the late Dr. Willie May.  Currently, the wax swallow bite technique, developed by James Carlson, is a simple, direct close approximation of a muscle-related bite registration.  Small pillars of soft wax are placed on the first molars, then the patient is instructed to swallow several times.  Subsequently, fast-curing impression material is injected around the arch to firmly establish the maxillo-mandibular relationship.  Since humans swallow thousands of times per day, it has been proposed that the swallow position should be compatible with the musculature.  This technique is recommended only after verification of good TM joint function with Joint Vibration Analysis or MRI.

The ULF-TENS bite registration                                                                          

Ultra-low Frequency TENS, originally conceived by Bernard Jankelson, is often used to relax the masticatory muscles.  It can also be used to determine a bite registration position, sometimes referred to as myo-centric.  After a patient has been “pulsed” for relaxation, usually for about 40 minutes, bite registration material (a quick-cure acrylic) is placed over the mandibular occlusal surfaces and the ULF-TENS is re-applied to “close” the mandible about 1 – 2 mm above the rest position.  During this procedure the vertical dimension is usually monitored with a mechanic’s inside calipers between marks on the chin and nose.  There is a definite “technique sensitivity” to this procedure such that different operators tend to produce slightly to greatly different results.  However, once the skill is developed, an operator may produce good consistency.  These classic TENS bites ignored the TM joints function in the past, but this should no longer be the case. A final outcome with healthy TMJ’s and muscles is our goal today.

The phonetic bite registration

As with the previously described muscle-oriented methods, this one begins with muscle relaxation.  Then the patient is instructed to speak specific sounds while the anterior teeth are observed by the clinician.  Based on the positions assumed by the teeth with specific phonetics, the clinician recognizes the vertical and antero-posterior requirements and records the position, typically also with impression material.  Admittedly, this technique requires subjective clinical judgment and the development of a skill without any objective support.

The EMG bite registration

To enhance the precision with which one can determine the optimum muscle-related position, some practitioners recommend monitoring the activity of the masseter, temporalis and anterior digastric muscles electromyographically.  Since the electrical muscle output levels involved are just a few microvolts, this measurement requires a high common mode noise rejection amplifier.  After relaxation has been verified electromyographically, the patient is instructed to open very gradually until the digastrics show a slight increase in activity (e.g. 0.5 microvolts average).  This establishes the limit to which opening the bite is permissible and is typically used as a position for constructing removable orthodontic appliances.  Similar tests are done for closing or repositioning the bite antero-posteriorly while monitoring the elevator muscles.  The concept is to find the superior, inferior, anterior and posterior limits of muscle resting.  Then the new bite position is selected within these limits.  The exact relation chosen may be dependent on many factors, such as clinical findings and the clinician’s best judgment.  With this technique it is also possible to evaluate functional activity of the musculature with the bite registration in place to further evaluate the appropriateness of the new maxillo-mandibular relation.

Fig. 4. JT-3D* Jaw Tracker used together with EMG to monitor a bite registration

The instrument monitored bite registration

To maximize the precision with which one can determine the bite registration position, clinicians can actively monitor the position of the mandible using a magnetic jaw tracker while simultaneously recording EMG activity.  After the muscles are relaxed, a recording is made of the movement from rest to centric occlusion, light tapping in CO and protrusive guidance.  Next, the registration position is selected and targeted on the computer screen.  The treatment position chosen can reflect all of the information available regarding the patient’s current condition.  Finally, the registration material is placed in the mouth and the patient is instructed to close into it while the position of the mandible and the muscle activities are monitored on the computer screen.  (Figure 5).  This allows the clinician to immediately see the three dimensional relationship between the old centric occlusal position and the new bite position.  The saved recording can be recalled later and utilized to evaluate an appliance, provisional restorations or the prosthesis at try-in.

Figure 5.  The position of the bite registration and the levels of muscle activity, are simultaneously visible in this combined EMG and jaw tracking recording.  The vertical dimension is increased      2.5 millimeters, the freeway space is reduced from 4.1 mm to 1.6 mm.

Figure 5.  The position of the bite registration and the levels of muscle activity, are simultaneously visible in this combined EMG and jaw tracking recording. The vertical dimension is increased 2.5 millimeters, the freeway space is reduced from 4.1 mm to 1.6 mm.

Figure 6. Example of a patient with an overclosed vertical dimension, due to previous loss of teeth, that has been successfully treated using Neuromuscular Principles.

Predicting a patient’s response to correcting overclosure

The question is often asked, “How quickly will a patient adapt to a new bite registration?”  Even though the object is to “correct” a mal-relationship of the mandible to the maxilla, the patient’s current relationship still has familiarity.  The new relationship, no matter how “perfectly” established, will seem strange to the patient at first.  There are many factors that influence a patient’s adaptation to a new maxillo-mandibular relation.  It is possible to estimate a patient’s response by considering the following factors:

1. The age of the patient [younger = more adaptive, older = less adaptive]
2. The amount of the change [a big change is more difficult to adapt to than a small change]
3. The duration of the overclosed condition [a long-standing condition will be more difficult to “de-program” than one of short duration]
4. The quality of bilateral TM joint function [good joint function makes adaptation easier]
5. An overclosed bite, due to developmental abnormalities (if caught early) can be corrected easily and with rapid adaptation by the patient [children are much more adaptive]
6. Overclosure resulting from parafunction typically coincides with a strong, healthy musculature. Strong, healthy muscles make adaptation easier, but require a treatment plan to protect the restored occlusion from destructive parafunctional forces.
7. An overclosed bite due to caries, loss of teeth, etc. without evidence of parafunction, typically coincides with a weak musculature, making adaptation difficult. This is very often the case with complete removable prosthetics.

Summary

Overclosure is a common condition among patients seeking restorative and/or orthodontic rehabilitation.  By evaluating the patient for common signs and symptoms associated with overclosure, one can determine the need for re-establishing a physiologic vertical dimension.  Opening of the bite can be accomplished in a number of ways by following specific guidelines.  The use of objective diagnostic aids are extremely helpful by allowing the clinician to optimize TMJ and craniofacial muscle function at the new VDO.  The correction of the vertical dimension during a rehabilitative procedure should result in enhanced comfort and improved function in the finished case.

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Katherine Unger Baillie has found that protein drugs, which derive from biological sources, represent some of the most important and effective biopharmaceuticals on the market. Some, like insulin, have been used for decades, while many more based on cloned genes are coming to market and are valued for their precise and powerful functions. Plant-made Antimicrobial Peptide Targets Dental Plaque and Gum Tissues.

Yet the field of dental medicine has very few such drugs due to their high costs, and the ones that are used are delivered invasively, often through surgical procedures, to gum tissues.

Now, a report by University of Pennsylvania School of Dental Medicine scientists in the journal Biomaterials suggests a new approach for delivering a protein drug to treat and prevent oral diseases, including dental caries, commonly known as cavities. Using plants to produce antimicrobial peptides, the researchers were able to rapidly kill tooth-decay-causing bacteria and thwart their ability to form biofilms on a tooth-like surface with a single topical treatment. The peptides were even more effective when combined with an enzyme that degrades the matrix, which surrounds and protects bacteria residing inside biofilms.

In addition, the researchers demonstrated that these peptides, produced in a cost-effective manner in plants, could be taken up by periodontal and gingival cells, indicating that this novel delivery method could be useful in treating diseases that affect the gum tissues, perhaps by promoting wound healing or bone regeneration.

The platform is low-cost compared to the current means of producing biopharmaceuticals and presents a unique opportunity to develop an affordable therapeutic approach that simultaneously attacks disease-causing plaque and promotes gum health, the researchers said.

“As scientists we have many opportunities to develop breakthrough treatments but cost is a huge obstacle,” said Hyun (Michel) Koo, co-corresponding author on the study and professor in the Department of Orthodontics and divisions of Pediatric Dentistry and Community Oral Health in Penn Dental Medicine. “What makes this approach so exciting is not only the science but, because the production costs are low, the feasibility of getting the therapy to the population who truly needs yet can’t afford it.”

The work arose from a partnership between Koo and co-corresponding author Henry Daniell, director of translational research and professor in Penn Dental Medicine’s Department of Biochemistry. Koo was aware of Daniell’s groundbreaking plant-produced therapeutics for a number of important human infectious and inherited diseases. And Daniell learned that Koo had done extensive work on caries-causing biofilms, including searching for alternative approaches to degrade them or prevent them altogether.

“It was a synergism,” Daniell said. “Bringing our research together led to this new concept of a topical protein drug made in plants that can both kill bacteria and break down the oral biofilm.”

Dental caries predominantly affect children and adults of lower socioeconomic status and are responsible for more than $40 billion in health-care spending annually.

In the past, researchers have identified antimicrobial peptides that are potent killers of caries-causing bacteria. But these agents are expensive to make and have had limited success at killing bacteria protected by the extracellular matrix, as is found in dental plaque.

Meanwhile, other groups have investigated enzymes that can break down the biofilm matrix, and these, too, have had limited success at preventing dental caries by themselves.

In the new study, Koo, Daniell and colleagues tried a new approach, combining the antimicrobial peptides with the matrix-degrading enzyme.

To address the prohibitive cost of antimicrobial peptide production, the researchers turned to Daniell’s plant-based protein drug production platform. The process entails bombarding a plant leaf with gold particles coated in a cloned gene in order to reprogram the chloroplasts to synthesize the associated protein. In this case, the researchers coaxed plants to produce two different antimicrobial peptides, retrocyclin and protegrin. Both peptides have complex secondary structures, making them expensive to produce in the lab by traditional means. But the researchers found they could literally grow them in Daniell’s greenhouse and faithfully replicate their unique secondary structures in the plant’s leaves.

They then tested whether the plant-made agents could prevent creation of a biofilm. They exposed a saliva-coated tooth-like surface to the plant-made protegrin for 30 minutes, then exposed the surface to S. mutans cells along with sugar and found that it significantly impaired the ability of the bacterium to form a biofilm compared to an untreated surface.

To see whether the antimicrobials could act not just preventively but therapeutically, the researchers next exposed a pre-formed biofilm on the tooth-mimicking surface to either protegrin alone or a combination of protegrin and a matrix-degrading enzyme. The enzyme alone had no effect on the biofilm, and while the antimicrobial alone was able to kill some bacteria, the combination was powerful, able to degrade 60 percent of the matrix and killing even more bacteria.

“A single topical treatment was capable of disrupting the biofilm,” Koo said. “It’s effectiveness was comparable to chlorhexidine, which is considered the ‘gold standard’ for oral antimicrobial therapy.”

Beyond topical-drug delivery, Daniell’s lab has been investigating molecular “tags” to route protein drugs to human cells to treat several diseases. In this context, delivering growth hormones or other such drugs to gum tissues for wound healing or bone regeneration is of paramount importance to enhance oral health. Their study found that the plant-made antimicrobial peptides could be taken up by human cells in the oral cavity.

“This was unexpected,” Daniell said. “The antimicrobials didn’t harm any of the human cells in gum tissues but had an unusual ability to go across the cell membranes of periodontal and gingival cells. This opens up a completely new field for drug delivery with a topical agent.”

A collaboration with Johnson & Johnson Consumer Inc. will enable Koo and Daniell to continue optimizing their antimicrobial-enzyme production system. One possibility, they note, is to create a chewing gum laced with antimicrobial peptides that could be slowly released as one chews. Alternatively, for Asian cultures where betel leaf chewing is common, the researchers may investigate the possibility of growing these peptides in that plant to promote oral health.

Additional coauthors on the study included co-first authors Yuan Liu and Aditya C. Kamesh and Yuhong Xiao, Victor Sun and Michael Hayes, all of Penn Dental Medicine.

The work was supported by the National Institutes of Health and the Bill & Melinda Gates Foundation.

Johns Hopkins researchers find that normal bacterial colonies in human body linked to presence of cancer of the mouth and throat

In a sample study, researchers at Johns Hopkins say they have found an association between the makeup of an individual’s normal bacterial colonies and head and neck cancer, a finding that potentially advances the quest for faster and more accurate cancer diagnosis and therapy.

In a report on the research published on May 30 in Oncotarget, the scientists say that populations of the human microbiome — the collection of normal bacteria inhabiting peoples’ bodies (normal bacterial colonies) — can help discriminate between patients with head and neck cancer and healthy individuals.

“One of the goals of our research is to better understand how the microbiome may influence the immune response to cancer and how the immune response affects the microbiome in turn,” says Rafael Guerrero-Preston, Dr. P.H., assistant professor of otolaryngology–head and neck surgery at the Johns Hopkins University School of Medicine and a member of its Kimmel Cancer Center. “Our findings suggest that we may one day use the composition of the microbiome to test for disease.”

Normal bacterial colonies contain trillions of microbes colonize the adult body. Changes in this community have already been tied to the risk and presence of arthritis, multiple sclerosis, irritable bowel syndrome and cancer. With more information on how these microbes are connected with cancer and cancer risk factors, such as genetic predispositions, smoking and other environmental factors, researchers hope to create individualized screening and treatment plans for cancer patients and for those at an increased cancer risk.

For this study, Guerrero-Preston and his colleagues extracted bacterial DNA from the saliva of 42 patients. Seventeen samples were drawn from people with head and neck squamous cell carcinoma, seven of which were positive for HPV and 10 of which were HPV-negative. Twenty-five noncancerous samples were used as a control.

The bacterial DNA found in the saliva was sequenced and sorted into groups of highly related populations. Through further DNA analysis, researchers were then able to determine the category, or genus, of bacteria to which each group belonged.

The researchers found differences in the bacterial populations present in cancerous versus noncancerous samples. Samples from patients with tumors, for example, showed increased populations of Streptococcus, Dialister and Veillonella genera, as well as decreased populations of Neisseria, Aggregatibacter, Haemophilus and Leptotrichia genera with respect to controls. Tumor samples also showed an increased prevalence of the Lactobacillus genus, which was present in 9.1 percent of tumor samples and in only 0.1 percent of the healthy controls. In addition, the researchers found correlations between the types of bacteria present and the patients’ HPV statuses. HPV-positive samples had increased abundances of Gemellaceae, Leuconostoc and Veillonella genera when compared to HPV-negative samples. Veillonella, for example, was present in 15 percent of HPV-positive tumor samples but was only present in 9.4 percent of HPV-negative tumor samples.

“We see some specific bacterial populations that are increased or lost in the presence of cancer when compared to healthy controls,” says Guerrero-Preston. This may mean that either the tumor is affecting the environment in the mouth by killing bacteria that would fight cancer or that the patients may be predisposed to cancer because they originally lacked bacteria that prevent tumor development.

Guerrero-Preston cautions that these findings do not establish a direct cause-and-effect link between any of the bacteria and head and neck cancer, stressing the preliminary nature of these assays. In particular, he says that future research needs to distinguish between the detection of bacterial DNA and the effects of the bacteria themselves. In order to determine how bacteria affect the oral environment, Guerrero-Preston’s team intends to look at which genes bacteria have turned on in saliva samples.

If the differences in the microbiome between cancerous and noncancerous/HPV-positive and HPV-negative tumors are confirmed in further studies with more patients, doctors may be able to use the same sequencing tools as Guerrero-Preston to quickly and accurately screen and diagnose patients based on the bacteria present in their mouths.

Guerrero-Preston says other research on the human microbiome has found that bacteria only present in the gut influence immunotherapies that utilize the body’s immune system to combat cancer in other tissues. With a greater understanding of how bacteria interact with a patient’s immune system, doctors may be better able to determine if immunotherapy will be effective and what side effects the patient may experience as a result of the treatment.

Other scientists who contributed to the study include Jessica Bondy, Fahcina Lawson, Oluwasina Folawiyo, Christina Michailidi, Tal Hadar, Maartje G. Noordhuis, Wayne Koch and David Sidransky  of the Johns Hopkins University School of Medicine; Filipa Godoy-Vitorino, Arnold Rodriguez and Herminio Gonzalez of the Inter American University of Puerto Rico; Anne Jedlicka and Amanda Dziedzic of the Johns Hopkins Bloomberg School of Public Health; and Rajagowthamee Thangavel of the Icahn School of Medicine at Mount Sinai.

Funding for the study was provided by National Cancer Institute grants (U01CA84986, K01CA164092, CA121113), National Institute of Dental and Craniofacial Research grants (P50DE019032, RC2DE20957).

Identification of immune cells in healthy mouth lays groundwork for understanding disease

Maintaining the body’s barrier defenses at sites such as the skin and mucosal surfaces is critical for health and survival. These barriers are continually exposed to foreign substances and infectious agents, and are home to a diverse array of commensal microbes—microorganisms that cause no harm and are part of the normal flora. Immune cells at barrier sites performs the remarkable task of keeping​ peace with commensal microbes while fighting off dangerous pathogens.

To gain a better understanding of how the immune system achieves this delicate balance, researchers led by Niki M. Moutsopoulos, D.D.S., Ph.D., chief of the Oral Immunity and Infection Unit​ at NIH’s National Institute of Dental and Craniofacial Research (NIDCR), in collaboration with Joanne E. Konkel, Ph.D., of the University of Manchester​, set out to identify the types of immune cells present in the gingiva (gums), a key barrier site. Their findings appeared in the journal Mucosal Immunology.

The gingiva that lines the teeth is especially susceptible to infection because it lies close to the bacterial biofilms that coat the surface of the teeth. The gingiva is an important barrier site because it is continually exposed to large communities of bacteria called biofilms, which adhere to the teeth. In addition, the inner covering of the gingiva lining the teeth is especially thin, providing ready access to the underlying tissue.

By examining gingival biopsies from 50 young, healthy volunteers, the researchers observed a predominance of immune cells called T cells and neutrophils, as well as a sophisticated network of antigen-presenting cells and a small population of innate lymphoid cells, a type of cell not previously known to inhabit human gingiva.

Nicolas Dutzan, the study’s first author, was able to make these determinations thanks to advances in a technique called multicolor flow cytometry, which scientists use to identify cellular components. Current methodologies enabled Dutzan and colleagues to define as many as 15 different molecules per cell, which allowed them to identify definitively each cell’s type and to gain insight into how the cells may be functioning.

Moutsopoulos’ team also found evidence that many of the immune cells in healthy mouths, such as T cells and innate lymphoid cells, are tissue-resident, continually patrolling the area like a local police force. This finding is consistent with data from other studies, which have shown that barrier sites often rely heavily on local populations of immune cells rather than calling in the systemic immune system for protection.

To see how the pattern of immune cells changes with disease, the scientists next examined gingival biopsies from a small group of people with periodontitis, a serious inflammatory disease that, if left untreated, results in tissue damage and erosion of the bones that support the teeth. The diseased gingiva had elevated numbers of neutrophils, a type of immune cell that helps quell infections by engulfing bacteria. The researchers also saw increased levels of a molecule called IL-17, which recruits neutrophils to the site of infection.

Healthy and periodontal disease gingival tissue taken from biopsies of study participants. Large numbers of immune cells are visible in the tissue damaged by periodontal disease. Courtesy of Niki M. Moutsopoulos, NIDCR.

While IL-17 is part of the host’s defense, if it is overproduced it may contribute to damaging inflammation. IL-17 is known to be associated with arthritis and other types of bone loss such as that seen in periodontitis, and inhibitors of the IL-7 pathway are used to treat psoriatic arthritis, a form of the disease associated with the skin condition, psoriasis. In future work, Dr. Moutsopoulos’ team aims to test the effectiveness of IL-17-like inhibitors in alleviating aggressive forms of periodontitis.

While landmark classical clinical studies have surveyed the major immune cell populations in the gingiva in certain inflammatory states, this study is the first to make use of current methodologies to perform an in-depth characterization of the immune cell network in healthy gingiva in humans.

“Our work is important because it provides a detailed picture of what the immune cell landscape looks like at this important barrier site under normal circumstances—before aging, infection or other problems arise,” said Moutsopoulos. “Knowing how these cells keep you healthy under ideal conditions sets the stage for our understanding of oral immunity and for being able to track changes that occur as disease begins and progresses. Ultimately, we expect to be able to use this information to identify novel drug targets and to develop new therapies for periodontitis and other diseases.”

Characterization of the human immune cell network at the gingival barrier. Dutzan N, Konkel JE, Greenwell-Wild T, Moutsopoulos NM. Mucosal Immunol. 2016 Jan 6. doi: 10.1038/mi.2015.136. [Epub ahead of print] PMID: 26732676​​​​​​​​

Unique site-specific factors control oral immunity

The body’s barrier sites, such as the skin, mouth and intestines, are continually exposed to potentially harmful foreign substances and infectious agents, and they are also home to a diverse array of harmless microbes called commensal microorganisms. Oral immunity is dependent on the immune system performing a remarkable balancing act at these sites by fighting off dangerous pathogens while tolerating the presence of the normal flora.

Multiple cell types are involved in protecting the body’s barriers, including immune cells called Th17 cells. These cells have been shown to help assist oral immunity and combat infections in the oral cavity—people with genetic defects in Th17 cell function experience frequent fungal infections of the mouth. Conversely, exaggerated Th17 cell responses have been linked to periodontal disease, underscoring the importance of precise control of the cells’ function. Previous research has shown that certain microbes regulate Th17 cells in the skin and intestines, but the factors that control them in the mouth have been less clear.

Niki M. Moutsopoulos, D.D.S., Ph.D., chief of the Oral Immunity and Infection Unit at the NIH’s National Institute of Dental and Craniofacial Research (NIDCR), wondered if, similar to other barrier sites, microbes control Th17 cell accumulation in the mouth.

Dr. Moutsopoulos has a longstanding interest in how microorganisms and the immune system interact to preserve the health of the oral cavity. Her research team focuses on the molecular pathways that lead to periodontal disease, with the ultimate goal being to identify therapeutic targets for this common condition.

In the current study, which was published in the journal, Immunity, and was carried out in collaboration with Joanne E. Konkel, Ph.D., of the University of Manchester, the researchers observed that Th17 cells appear in the oral cavity with age. There were few Th17 cells in young, 8-week-old mice but by 24 weeks, middle age for mice, Th17 cell numbers had increased dramatically. Based upon what was known about Th17 cells in the skin and intestines, the researchers suspected that the cells’ surge in middle age might involve shifts in microbial populations.

To their surprise, they found that the composition and levels of microbes in the oral cavity of 8-week-old mice were comparable to those of the 24-week-old mice. In addition, mice raised in a germ-free environment had similar oral Th17 cell levels as mice raised under normal, non-sterile conditions. These findings revealed that, in contrast to other barrier sites, the presence of Th17 cells in the mouth does not depend on microbes. The researchers concluded that factors that regulate Th17 cells must differ depending on the unique characteristics of each site.

Th17 cells are key mediators of immunity at barrier sites such as the oral cavity. The factors that control them differ depending on cues unique to each site’s local environment. Credit: Niki M. Moutsopoulos, D.D.S., Ph.D., NIDCR.

A clue as to what these factors might be in the oral cavity came from experiments showing that a signaling molecule called IL-6 is needed for Th17 cell accumulation—mice engineered to lack IL-6 produced far fewer Th17 cells compared to control mice that have the molecule. Dr. Moutsopoulos’s team next focused on identifying the factors that induce IL-6 and drive Th17 cell accumulation at this barrier. They hypothesized that “damage signals” caused by chewing could stimulate the local immune response.

Subsequent experiments validated this idea. The researchers found that mice raised on a soft food diet requiring minimal chewing had fewer Th17 cells by 24 weeks than mice fed a normal diet. In addition, Th17 cell numbers rose in the mouths of young mice when the researchers hardened the diet or induced damage by mechanical abrasion. This rise in Th17 cell levels did not occur in mice lacking IL-6, confirming the key role of this signaling molecule in promoting Th17 cell accumulation.

Together, these findings have uncovered a role for mechanical damage in triggering local immunity in the oral cavity, and have linked induction of Th17 cells to the stimulation of protective immune responses. However, exaggeration of these signals could be pathogenic and contribute to inflammation and periodontal bone loss.

“We know that Th17 cells are important for preserving the health of the oral cavity, but they also may contribute to periodontal disease, which is why we want to understand the factors that regulate them in this unique environment,” said Dr. Moutsopoulos.

More generally, the findings highlight the importance of evaluating the local environment for novel factors that may control immune responses at barrier sites.

This study was funded in part by the intramural program of NIDCR, the Biotechnology and Biological Sciences Research Council, the Wellcome Trust and the Manchester Collaborative Centre for Inflammation Research.

On-going mechanical damage from mastication drives homeostatic Th17 responses at the oral barrier. Dutzan N, Abusleme L, Bridgeman H, Greenwell-Wild T, Zangerle-Murray T, Fife ME, Bouladoux N, Linley H, Brenchley L, Wemyss K, Calderon G, Hong B, Break TJ, Bowdish DME, Lionakis MS, Jones SA, Trinchieri G, Diaz PI, Belkaid Y, Konkel JE, and Moutsopoulos NM. Immunity. 2017 Jan 6. doi: 10.1016/j.immuni.2016.12.010. [Epub ahead of print] PMID: 28087239

This article deals with practical oral care for people with intellectual disability. Providing oral care to people with intellectual disability requires adaptation of the skills you use every day. In fact, most people with mild or moderate intellectual disability can be treated successfully in the general practice setting. This article will help you make a difference in the lives of people who need professional oral care.

Intellectual disability is a disorder of mental and adaptive functioning, meaning that people who are affected are challenged by the skills they use in everyday life. Intellectual disability is not a disease or a mental illness; it is a developmental disability that varies in severity and is usually associated with physical problems. While one person with intellectual disability may have slight difficulty thinking and communicating, another may face major challenges with basic self-care and physical mobility.

Data indicate that people with intellectual disability have more untreated caries and a higher prevalence of gingivitis and other periodontal diseases than the general population.

Health challenges in intellectual disability and strategies for care

Many people with intellectual disability also have other conditions such as cerebral palsy, seizure or psychiatric disorders, attention deficit/hyperactivity disorder, or problems with vision, communication, and eating. Though language and communication problems are common in anyone with intellectual disability, motor skills are typically more affected when a person has coexisting conditions.

Before the appointment, obtain and review the patient’s medical history. Consultation with physicians, family, and caregivers is essential to assembling an accurate medical history. Also, determine who can legally provide informed consent for treatment.

Mental challenges

People with intellectual disability learn slowly and often with difficulty. Ordinary activities of daily living, such as brushing teeth and getting dressed, and understanding the behaviour of others as well as their own, can all present challenges to a person with intellectual disability.

• Set the stage for a successful visit by involving the entire dental team–from the receptionist’s friendly greeting to the caring attitude of the dental assistant in the operatory. All should be aware of your patient’s mental challenges.
• Reduce distractions in the operatory, such as unnecessary sights, sounds, or other stimuli, to compensate for the short attention spans commonly observed in people with intellectual disability.
• Talk with the parent or caregiver to determine your patient’s intellectual and functional abilities, then explain each procedure at a level the patient can understand. Allow extra time to explain oral health issues or instructions and demonstrate the instruments you will use.
• Address your patient directly and with respect to establish a rapport. Even if the caregiver is in the room, direct all questions and comments to your patient.
• Use simple, concrete instructions and repeat them often to compensate for any short-term memory problems. Speak slowly and give only one direction at a time.
• Be consistent in all aspects of oral care, since long-term memory is usually unaffected. Use the same staff and dental operatory each time to help sustain familiarity. The more consistency you provide for your patients, the more likely they will cooperate.
• Listen actively, since communicating clearly is often difficult for people with intellectual disability. Show your patient whether you understand. Be sensitive to the methods he or she uses to communicate, including gestures and verbal or nonverbal requests.

Behaviour challenges

While most people with intellectual disability do not pose significant behaviour problems that complicate oral care, anxiety about dental treatment occurs frequently. People unfamiliar with a dental office and its equipment and instruments may exhibit fear. Some react to fear with uncooperative behaviour, such as crying, wiggling, kicking, aggressive language, or anything that will help them avoid treatment. You can make oral health care a better experience by comforting your patients and acknowledging their anxiety.

• Talk to the caregiver or physician about techniques they have found to be effective in managing the patient’s behaviour.
• Schedule patients with intellectual disability early in the day if possible. Early appointments can help ensure that everyone is alert and attentive and that waiting time is reduced.
• Keep appointments short and postpone difficult procedures until after your patient is familiar with you and your staff.
• Allow extra time for your patients to get comfortable with you, your office, and the entire oral health care team. Invite patients and their families to visit your office before beginning treatment.
• Permit the parents or caregiver to come into the treatment setting to provide familiarity, help with communication, and offer a calming influence by holding your patient’s hand during treatment. Some patients’ behaviour may improve if they bring comfort items such as a stuffed animal or blanket.
• Reward cooperative behaviour with compliments throughout the appointment.
• Consider nitrous oxide/oxygen sedation to reduce anxiety and fear and improve cooperation. Obtain informed consent from the legal guardian before administering any kind of sedation.
• Use immobilization techniques only when absolutely necessary to protect the patient and staff during dental treatment–not as a convenience. There are no universal guidelines on immobilization that apply to all treatment settings. Before employing any kind of immobilization, it may help to consult available guidelines on federally funded care, your State department of mental health/disabilities, and your State Dental Practice Act. Guidelines on behaviour management published by the American Academy of Paediatric Dentistry may also be useful. Obtain consent from your patient’s legal guardian and choose the least restrictive technique that will allow you to provide care safely. Immobilization should not cause physical injury or undue discomfort.

People with intellectual disability often engage in perseveration, a continuous, meaningless repetition of words, phrases, or movements. Your patient may mimic the sound of the suction, for example, or repeat an instruction over and again. Avoid demonstrating dental equipment if it triggers perseveration, and note this in the patient’s record.

Physical challenges

Intellectual disability does not always include a specific physical trait, although many people have distinguishing features such as orofacial abnormalities, scoliosis, unsteady gait, or hypotonia due to coexisting conditions. Countering physical challenges requires attention to detail.

• Maintain clear paths for movement throughout the treatment setting. Keep instruments and equipment out of the patient’s way.
• Place and maintain your patient in the centre of the dental chair to minimize the risk of injury. Placing pillows on both sides of the patient can provide stability.
• If you need to transfer your patient from a wheelchair to the dental chair, ask the patient or caregiver about special preferences such as padding, pillows, or other things you can provide to ease the transition. The patient or caregiver can often explain how to make a smooth transfer.
• Some patients cannot be moved into the dental chair but instead must be treated in their wheelchairs. Some wheelchairs recline or are specially moulded to fit people’s bodies. Lock the wheels, then slip a sliding board (also called a transfer board) behind the patient’s back to provide support for the head and neck during care.

Cereal palsy occurs in one-fourth of those who have intellectual disability and tends to affect motor skills more than cognitive skills. Uncontrolled body movements and reflexes associated with cerebral palsy can make it difficult to provide care.

• Place and maintain your patient in the centre of the dental chair. Do not force arms and legs into unnatural positions, but allow your patient to settle into a position that is comfortable and will not interfere with dental treatment.
• Observe your patient’s movements and look for patterns to help you anticipate direction and intensity. Trying to stop these movements may only intensify the involuntary response. Try instead to anticipate the movements, blending your movements with those of your patient or working around them.
• Softly cradle your patient’s head during treatment. Be gentle and slow if you need to turn the patient’s head.
• Help minimize the gag reflex by placing your patient’s chin in a neutral or downward position.
• Stay alert and work efficiently in short appointments.
• Exert gentle but firm pressure on your patient’s arm or leg if it begins to shake.
• Take frequent breaks or consider prescribing muscle relaxants when long procedures are needed. People with cerebral palsy may need sedation, general anaesthesia, or hospitalization if extensive dental treatment is required.

Cardiovascular anomalies such as heart murmurs and damaged heart valves occur frequently in people with intellectual disability, especially those with Down syndrome or multiple disabilities. Consult the patient’s physician to determine if antibiotic prophylaxis is necessary for dental treatment.

Seizures are common in this population but can usually be controlled with anticonvulsant medications. The mouth is always at risk during a seizure: Patients may chip teeth or bite the tongue or cheeks. Persons with controlled seizure disorders can easily be treated in the general dental office.

• Consult your patient’s physician. Record information in the chart about the frequency of seizures and the medications used to control them. Determine before the appointment whether medications have been taken as directed. Know and avoid any factors that trigger your patient’s seizures.
• Be prepared to manage a seizure. If one occurs during oral care, remove any instruments from the mouth and clear the area around the dental chair. Attaching dental floss to rubber dam clamps and mouth props when treatment begins can help you remove them quickly. Do not attempt to insert any objects between the teeth during a seizure.
• Stay with your patient, turn him or her to one side, and monitor the airway to reduce the risk of aspiration.

Visual impairments, most commonly strabismus (crossed or misaligned eyes) and refractive errors, can be managed with careful planning.

• Determine the level of assistance your patient requires to move safely through the dental office.
• Use your patients’ other senses to connect with them, establish trust, and make treatment a good experience. Tactile feedback, such as a warm handshake, can make your patients feel comfortable.
• Face your patients when you speak and keep them apprised of each upcoming step, especially when water will be used. Rely on clear, descriptive language to explain procedures and demonstrate how equipment might feel and sound. Provide written instructions in large print (16 point or larger).

Hearing loss and deafness can also be accommodated with careful planning. Patients with a hearing problem may appear to be stubborn because of their seeming lack of response to a request.

• Patients may want to adjust their hearing aids or turn them off, since the sound of some instruments may cause auditory discomfort.
• If your patient reads lips, speak in a normal cadence and tone. If your patient uses a form of sign language, ask the interpreter to come to the appointment. Speak with this person in advance to discuss dental terms and your patient’s needs.
• Visual feedback is helpful. Maintain eye contact with your patient. Before talking, eliminate background noise (turn off the radio and the suction). Sometimes people with a hearing loss simply need you to speak clearly in a slightly louder voice than normal. Remember to remove your facemask first or wear a clear face shield.

Record in the patient’s chart strategies that were successful in providing care. Note your patient’s preferences and other unique details that will facilitate treatment, such as music, comfort items, and flavour choices

Oral health problems in intellectual disability and strategies for care

In general, people with intellectual disability have poorer oral health and oral hygiene than those without this condition. Data indicate that people who have intellectual disability have more untreated caries and a higher prevalence of gingivitis and other periodontal diseases than the general population.

Periodontal disease

Medications, malocclusion, multiple disabilities, and poor oral hygiene combine to increase the risk of periodontal disease in people with intellectual disability.

• Encourage independence in daily oral hygiene. Ask patients to show you how they brush, and follow up with specific recommendations on brushing methods or toothbrush adaptations. Involve your patients in hands-on demonstrations of brushing and flossing.
• Some patients cannot brush and floss independently due to impaired physical coordination or cognitive skills. Talk to their caregivers about daily oral hygiene. Do not assume that all caregivers know the basics; demonstrate proper brushing and flossing techniques. A power toothbrush or a floss holder can simplify oral care. Also, use your experiences with each patient to demonstrate sitting or standing positions for the caregiver. Emphasize that a consistent approach to oral hygiene is important–caregivers should try to use the same location, timing, and positioning.
• Some patients benefit from the daily use of an antimicrobial agent such as chlorhexidine. Recommend an appropriate delivery method based on your patient’s abilities. Rinsing, for example, may not work for a patient who has swallowing difficulties or one who cannot expectorate. Chlorhexidine applied using a spray bottle or toothbrush is equally efficacious.
• If use of particular medications has led to gingival hyperplasia, emphasize the importance of daily oral hygiene and frequent professional cleanings.

Dental caries

People with intellectual disability develop caries at the same rate as the general population. The prevalence of untreated dental caries, however, is higher among people with intellectual disability, particularly those living in noninstitutionalised settings.

• Emphasize non-cariogenic foods and beverages as snacks. Advise caregivers to avoid using sweets as incentives or rewards.
• Advise patients taking medicines that cause xerostomia to drink water often. Suggest sugar-free medicine if available and stress the importance of rinsing with water after dosing.
• Recommend preventive measures such as fluorides and sealants.

Malocclusion

The prevalence of malocclusion in people with intellectual disability is similar to that found in the general population, except for those with coexisting conditions such as cerebral palsy or Down syndrome. A developmental disability in and of itself should not be perceived as a barrier to orthodontic treatment. The ability of the patient or caregiver to maintain good daily oral hygiene is critical to the feasibility and success of treatment.

Missing permanent teeth, delayed eruption and enamel hypoplasia

Missing permanent teeth, delayed eruption and enamel hypoplasia are more common in people with intellectual disability and coexisting conditions than in people with intellectual disability alone.

• Examine a child by his or her first birthday and regularly thereafter to help identify unusual tooth formation and patterns of eruption.
• Consider using a panoramic radiograph to determine whether teeth are congenitally missing. Patients often find this technique less threatening than individual films.
• Take appropriate steps to reduce sensitivity and risk of caries in your patients with enamel hypoplasia

Damaging oral habits

Damaging oral habits are a problem for some people with intellectual disability. Common habits include bruxism; mouth breathing; tongue thrusting; self-injurious behaviour such as picking at the gingiva or biting the lips; and pica, eating objects and substances such as gravel, cigarette butts, or pens. If a mouth guard can be tolerated, prescribe one for patients who have problems with self-injurious behaviour or bruxism

Trauma and injury

Trauma and injury to the mouth from falls or accidents occur in people with intellectual disability. Suggest a tooth-saving kit for group homes. Emphasize to caregivers that traumas require immediate professional attention and explain the procedures to follow if a permanent tooth is knocked out. Also, instruct caregivers to locate any missing pieces of a fractured tooth, and explain that radiographs of the patient’s chest may be necessary to determine whether any fragments have been aspirated.

Physical abuse often presents as oral trauma. Abuse is reported more frequently in people with developmental disabilities than in the general population. If you suspect that a child is being abused or neglected, State laws require that you call your Child Protective Services agency.

Making a difference in the oral health of a person with intellectual disability may go slowly at first, but determination can bring positive results–and invaluable rewards. By adopting the strategies discussed in this booklet, you can have a significant impact not only on your patients’ oral health, but on their quality of life as well.

Reproduced February 2017 from NIH Publication No. 09-5194

Periodontal Disease background 

Oral plaque (biofilm) contains a complex of multiple bacterial species that can lead to periodontitis or inflammation and, in its more advanced stages, deterioration of gums and tissues that surround the teeth (Periodontal Disease). Dental scaling and root planing removes plaque and tartar; however, these bacterial biofilms have been documented to redevelop in as little as two days post-cleaning. Recent molecular explorations of oral biofilm formation have examined colony formation of several bacterial species in supragingival (above the gum line) and subgingival (below the gum line) locations. Assuming that the order of bacterial succession may be important to periodontal health, the authors of the present report conducted a large-scale biofilm formation study, examining the temporal bacterial species formation in subjects with healthy periodontium and subjects with chronic periodontitis at supragingival and subgingival locations.

Advance in Periodontal Disease

Supragingival and subgingival plaque samples were taken from 28 sites at 1, 2, 4, and 7 days post-cleaning in healthy and periodontitis subjects (post-full mouth scaling and root planing). Plaque samples were analyzed for changes in bacterial proportions for 41 species of bacteria.

Supragingival plaque redevelopment was similar in both healthy and periodontitis samples, but the subgingival profiles were different between these two groups. Both supragingival colony succession order as well as colony proportion were comparatively similar for healthy and periodontal subjects. Subgingival biofilm, however, exhibited changes in colony development order and timing. Healthy individuals had increases in S. oralis and S. constellatus by day 1. Periodontitis subjects exhibited significant increases in C. gracilis, A. oris, P. intermedia and S. noxia by day 7. Proportions of more ‘classic’ periodontal pathogens did not significantly increase in either group; and, in fact, E. nodatum, P. gingivalis, T. forsythia and T. denticola decreased in periodontitis subjects, which with other reports suggest that these complexes may take longer to establish in part because they may require the presence of appropriate conditions provided by earlier colonizers.

Periodontal Disease public impact statement and significance

Results from this NIDCR-supported study suggest that the supragingival microenvironment for plaque redevelopment is similar for healthy and periodontal patients, but that bacterial recolonization is different in periodontal disease when examining subgingival biofilms. Understanding the sequence of microbial colonization may lead to more targeted approaches for controlling periodontal disease.

Publication citation

The work, published in the Journal of Periodontal Research in February 2012, was conducted by Teles FR, Teles RP, Uzel NG, Song XQ, Torresyap G, Socransky SS, and Haffajee AD at the Forsyth Institute and Harvard School of Dental Medicine​.

Reproduced February 2017 from NIH Publication No. 16-6288 July 2016

Are you being treated with chemotherapy for cancer? If so, this article can help you. While chemotherapy helps treat cancer, it can also cause other things to happen in your body called side effects. Some of these problems affect the mouth and could cause you to delay or stop treatment. This article will tell you ways to help prevent mouth problems so you’ll get the most from your cancer treatment. To help prevent serious problems, see a dentist ideally 1 month before starting chemotherapy.

How does chemotherapy affect the mouth?

Chemotherapy is the use of drugs to treat cancer. These drugs kill cancer cells, but they may also harm normal cells, including cells in the mouth. Side effects include problems with your teeth and gums; the soft, moist lining of your mouth; and the glands that make saliva (spit).

It’s important to know that side effects in the mouth can be serious.

• The side effects can hurt and make it hard to eat, talk, and swallow.
• You are more likely to get an infection, which can be dangerous when you are receiving cancer treatment.
• If the side effects are bad, you may not be able to keep up with your cancer treatment. Your doctor may need to cut back on your cancer treatment or may even stop it.

What mouth problems does chemotherapy cause?

You may have certain side effects in your mouth from chemotherapy. Another person may have different problems. The problems depend on the chemotherapy drugs and how your body reacts to them. You may have these problems only during treatment or for a short time after treatment ends.

• Painful mouth and gums.
• Dry mouth.
• Burning, peeling, or swelling tongue.
• Infection
• Change in taste.

Why should I see a dentist?

You may be surprised that your dentist is important in your cancer treatment. If you go to the dentist before chemotherapy begins, you can help prevent serious mouth problems. Side effects often happen because a person’s mouth is not healthy before chemotherapy starts. Not all mouth problems can be avoided but the fewer side affects you have, the more likely you will stay on your cancer treatment schedule. It’s important for your dentist and cancer doctor to talk to each other about your cancer treatment. Be sure to give your dentist your cancer doctor’s phone number.

When should I see a dentist?

You need to see the dentist 1 month, if possible, before chemotherapy begins. If you have already started chemotherapy and didn’t go to a dentist, see one as soon as possible.

What will the dentist and dental hygienist do?

• Check and clean your teeth.
• Take x-rays.
• Take care of mouth problems.
• Show you how to take care of your mouth to prevent side effects.

What can I do to keep my mouth healthy?

You can do a lot to keep your mouth healthy during chemotherapy. The first step is to see a dentist before you start cancer treatment. Once your treatment starts, it’s important to look in your mouth every day for sores or other changes. These tips can help prevent and treat a sore mouth:

• Keep your mouth moist.
• Drink a lot of water.
• Suck ice chips.
• Use sugarless gum or sugar-free hard candy.
• Use a saliva substitute to help moisten your mouth.

Clean your mouth, tongue, and gums.

• Brush your teeth, gums, and tongue with an extra-soft toothbrush after every meal and at bedtime. If brushing hurts, soften the bristles in warm water.
• Use a fluoride toothpaste.
• Don’t use mouthwashes with alcohol in them.
• Floss your teeth gently every day. If your gums bleed and hurt, avoid the areas that are bleeding or sore, but keep flossing your other teeth.
• Rinse your mouth several times a day with a solution of ¼ teaspoon of salt or 1 teaspoon of baking soda in 1 cup (8 ounces) of warm water. Follow with a plain water rinse.
• Dentures that don’t fit well can cause problems. Talk to your cancer doctor or dentist about your dentures.

If your mouth is sore, watch what you eat and drink.

• Choose foods that are good for you and easy to chew and swallow.
• Take small bites of food, chew slowly, and sip liquids with your meals.
• Eat soft, moist foods such as cooked cereals, mashed potatoes, and scrambled eggs.
• If you have trouble swallowing, soften your food with gravy, sauces, broth, yogurt, or other liquids.

Call your doctor or nurse when your mouth hurts.

• Work with them to find medicines to help control the pain.
• If the pain continues, talk to your cancer doctor about stronger medicines.

Remember to stay away from

• Sharp, crunchy foods, like taco chips, that could scrape or cut your mouth.
• Foods that are hot, spicy, or high in acid, like citrus fruits and juices, which can irritate your mouth.
• Sugary foods, like candy or soda, that could cause cavities.
• Toothpicks, because they can cut your mouth.
• All tobacco products.
• Alcoholic drinks.

Do children get mouth problems too?

Chemotherapy causes other side effects in children, depending on the child’s age.

Problems with teeth are the most common. Permanent teeth may be slow to come in and may look different from normal teeth. Teeth may fall out. The dentist will check your child’s jaws for any growth problems. Before chemotherapy begins, take your child to a dentist. The dentist will check your child’s mouth carefully and pull loose teeth or those that may become loose during treatment. Ask the dentist or hygienist what you can do to help your child with mouth care.

• Visit your dentist beforeyour cancer treatment starts.
• Take good care of your mouth during
• Talk regularly with your cancer doctor and dentist about anymouth problems you have.

Reproduced February 2017 from NIH Publication No. 13-4361, August 2013

Key points for Burning Mouth Syndrome

• Burning Mouth Syndrome (BMS) is burning pain in the mouth that may occur every day for months or longer.
• Doctors and dentists do not have a specific test for BMS, which makes it hard to diagnose.
• No specific treatment works for all people. However, your doctor can prescribe medicine to help you manage mouth pain, dry mouth, or other symptoms.

Symptoms

The main symptom of Burning Mouth Syndrome (BMS) is pain in the mouth that is burning, scalding, or tingling. Or, the pain may be a feeling of numbness. Other symptoms include dry mouth or altered taste in the mouth.

BMS is a painful condition. Usually, the tongue is affected, but the pain may also be in the lips or roof of the mouth, or throughout the mouth.

BMS pain can last for months or years. Some people feel constant pain every day. For others, pain increases throughout the day. For many people, the pain is reduced when eating or drinking.

Diagnosis

BMS is hard to diagnose. One reason is that people with BMS often don’t have a mouth problem that the doctor or dentist can see during an exam. Your dentist or doctor may refer you to a specialist. Specialists who diagnose BMS include dentists who specialize in oral medicine or oral surgery. Other specialists include doctors who are ear, nose, and throat specialists; gastroenterologists; or dermatologists.

The dentist or doctor will review your medical history and examine your mouth. A lot of tests may be needed. Tests may include:

• Blood tests to check for certain medical problems
• Oral swab tests
• Allergy tests
• Salivary flow test
• Biopsy of tissue
• Imaging tests

Primary and secondary Burning Mouth Syndrome

Primary Burning Mouth Syndrome: If tests do not reveal an underlying medical problem, the diagnosis is primary Burning Mouth Syndrome. Experts believe that primary BMS is caused by damage to the nerves that control pain and taste.

Secondary Burning Mouth Syndrome: Certain medical conditions can cause Burning Mouth Syndrome. Treating the medical problem will cure the secondary Burning Mouth Syndrome. Common causes of secondary BMS include:

• Hormonal changes (such as from diabetes or thyroid problem)
• Allergies to dental products, dental materials (usually metals), or foods
• Dry mouth, which can be caused by certain disorders (such as Sjögren’s syndrome) and treatments (such as certain drugs and radiation therapy)
• Certain medicines, such as those that reduce blood pressure
• Nutritional deficiencies (such as a low level of vitamin B or iron)
• Infection in the mouth, such as a yeast infection
• Acid reflux

Treatment

Your doctor will help you get relief. Medicine can help control pain and relieve dry mouth.

Because BMS is a complex pain disorder, the treatment that works for one person may not work for another.

Symptoms of secondary BMS go away when the underlying medical condition, such as diabetes or yeast infection, is treated. If a drug is causing secondary Burning Mouth Syndrome, then your doctor may switch you to a new medicine.

Helpful tips

To help ease the pain of Burning Mouth Syndrome, sip a cold beverage, suck on ice chips, or chew sugarless gum. Avoid irritating substances, such as:

• Tobacco
• Hot, spicy foods
• Alcoholic beverages
• Mouthwashes that contain alcohol
• Products high in acid, such as citrus fruits and juices

Reproduced February 2017 from NIH Publication No. 16-6288 July 2016