Donald J. Rinchuse

An Evaluation of Functional Occlusal Interferences in Orthodontically Treated and Untreated Subjects

Centric occlusion-generated functional bite registrations failed to show a difference in the number, location or severity of nonworking (balancing) or protrusive functional occlusion contacts between 49 post-orthodontically treated subjects and 27 non-orthodontically treated subjects with ideal static occlusion. Nonworking (balancing) side functional occlusion contacts were present in 85% of the non-orthodontic subjects and 97% of the post-orthodontic subjects. At least within the parameters of this investigation, the lateral and protrusive occlusions of post-orthodontic subjects and comparable non-orthodontic subjects were equivalent. It is important to note that this is a study of incidence. It does not address the meaning or importance of such contacts.

Reliability of three methods of occlusion classification.

Four orthodontic faculty at one dental school classified 25 dental casts according to the classification systems of Angle, Katz, and the British Incisor Classification. The dental casts were selected from a pool of 350 pretreatment graduate orthodontic cases and were those deemed the most atypical. The results demonstrated that Katzs classification was more reliable than both Angle and the British. Angles classification was the least reliable of the three methods.

Myths of orthodontic gnathology

D r Beverly McCollum established the Gnathologic Society in 1926. Gnathology is defined as ‘‘the science that treats the biology of the masticatory mechanism as a whole: that is, the morphology, anatomy, histology, physiology, and the therapeutics of the jaws or masticatory system and the teeth as they relate to the health of the whole body, including applicable diagnostic, therapeutic, and rehabilitation procedures.’’ Many gnathologic research endeavors have added much to our knowledge and understanding of the stomatognathic system, particularly those involving chewing (masticatory) kinematics and the early intraoral telemetry studies (to cite only a few). Although originally founded on scientific principles, the application of the valid gnathologic research to clinical practice has moved away from these founding tenets. Modern clinical gnathology (vs university-based gnathologic research) has become, for the most part, a pseudo-science based on mechanistic, perfunctory procedures, and instrumentation. There are many contemporary occlusal institutes that clearly have perverse views on gnathology that are not evidence-based. Dr Lysle Johnston sarcastically stated that ‘‘gnathology is the science of how articulators chew.’’ In the 1970s, Roth formally introduced the classic principles of clinical gnathology to orthodontics (orthodontic gnathology). The notions and considerations of modern orthodontic gnathology are not based on principles of science and do not correspond to contemporary evidence-based thinking. There might not be a unified orthodontic gnathologic view, but it seems that the one established by Roth is by far the most notable.

The craniofacial morphology of bruxers versus nonbruxers.

The purpose of this investigation was to test for an association between the craniofacial morphologies of bruxers and nonbruxers. The sample for this retrospective descriptive comparative study consisted of 28 Caucasian dental school subjects. Sixteen were bruxers and 12 were nonbruxers. The determination of bruxism was based on a six-item questionnaire as well as objective measures of the severity of tooth wear as analyzed from dental casts. Craniofacial morphology was determined directly using anthropometric spreading calipers. Craniofacial measurements included glabella-opiscranion, euryon-euryon, nasion-gnathion, zygoma-zygoma, and gonion-gonion. From these measurements, the following indices were calculated: cephalic (Gla-Op/Eu-Eu), facial (Na-Gla/Zy-Zy), gonial (Zy-Zy/Go-Go), and gonial height (Na-Gla/Go-Go). This study found no differences in the craniofacial morphologies of bruxers and nonbruxers, nor was there a difference in overbite. There was, however, a statistically significant difference in the bizygomatic (Zy-Zy) and cranial (Eu-Eu) widths of bruxers compared with nonbruxers.

The impact of the American Dental Association's guidelines for the examination, diagnosis, and management of temporomandibular disorders on orthodontic practice

Abstract There appears to be no simple diagnosis and treatment plan for the management of TM disorder patients. A differential diagnosis of TM disorders should be based upon a logical classification that incorporates a number of variables, such as masticatory disorders, problems involving derangement of the TMJ, problems that result from extrinsic trauma, degenerative joint diseases, inflammatory joint disorders, chronic mandibular hypomobility, and growth disorders of the joint. In the absence of definitive scientific research pertaining to TM disorders, the ADA has established guidelines for the examination, diagnosis, and management of TM disorders. Most often, treatment of TM disorders has been anecdotal and directed at allaying the symptoms and not particularly directed at the cause. The general recommendation of the ADA guidelines regarding TM disorder treatment is that it be conservative, reversible, and based upon scientific data whenever possible. These general recommendations, although nebulous, point to the fact that we simply have not progressed far enough to develop a consensus plan concerning the most appropriate treatment for each and every patient with TM disorders. The problems in the patient population are too complex and varied for an outline or “cookbook” type of treatment plan. Since orthodontists have become more involved in the treatment of TM disorders, some may re-evaluate their thinking in light of the ADA TM disorder guidelines. The orthodontist may also have to resolve conflicts that arise over differing opinions regarding the major issues involved in TM disorder examination, diagnosis, and treatment. Too often simplistic models of natural phenomena may be misleading and inaccurate, as is true of some existing models which explain TM disorders. It is time that we, as members of the great profession of dentistry, critically evaluate current literature in order that we may responsibly justify our diagnoses and treatment modalities. In light of the fact that the more knowledge we accumulate, the more we should realize how much we do not know, it might be wise for us to reflect upon the following quotation from Shakespeare: The fool doth think he is wise, but the wise man knows himself to be a fool.

Central mediated pressor effect by prostaglandins in the rat

Extremely small concentrations (1 ng/kg/min) of prostaglandins E1, A1, and A2 elevated arterial blood pressure in the rat when infused into the carotid artery. Similar infusions into the femoral vein failed to demonstrate a pressor response. Higher concentrations of the same prostaglandins infused into the femoral vein resulted in a significant depression of blood pressure.

Assessment of buccal separators in the relief of bruxist activity associated with myofascial pain-dysfunction.

The purpose of this study was to evaluate the effectiveness of heavy (S2) Alastik separators in relieving bruxist activity as monitored through masseter muscle area EMG activity, muscle palpation, and self-reporting in 21 Caucasian subjects. The subjects, all of whom suffered from both bruxism and myofascial pain-dysfunction, were randomly assigned to one of three groups: experimental (separator group); placebo (separator placed and removed); and control groups (no separator). The findings from this study indicate that there were no observable differences in either subjective or objective responses to the pretreatment versus posttreatment questionnaire and clinical examination for tooth clenching or grinding, facial pain, and fatigue of the jaws. In addition, no statistical differences were found between pre and posttreatment data. The EMG data did not show any statistical differences between pretreatment and posttreatment evaluations or among the 3 groups.

The trend toward increased use of statistics in published orthodontic articles.

There has been an almost twofold increase in the use of statistical procedures in the articles appearing in the American Journal of Orthodontics from 1975 to 1985. That increase is due primarily to the increase in articles using inferential statistics. This trend toward increased use and complexity of statistical procedures in published orthodontic articles suggests a need for orthodontists to be fully familiar with statistical procedures.

Clinical pharmacology for the orthodontist

The practice of orthodontics encompasses all other aspects of dentistry, but at the same time it also is very different. Therefore, the pharmacologic agents that would be practical for orthodontic practice are much more limited than those used in other disciplines of dentistry. This, however, does not imply that a full understanding of pharmacologic drug action, side effects, and contraindications is unnecessary. Some common drugs, such as the antibiotics, anticholinergics, fluoride, antianxiety agents, and drugs for myofacial pain, are reviewed according to their application to orthodontic practice.

Scoping review of systematic review abstracts about temporomandibular disorders: Comparison of search years 2004 and 2017

Introduction: The purposes of this study were to determine how many systematic reviews and meta‐analyses relating to temporomandibular disorders (TMDs) had been published as of 2017 compared with those published as of 2004 and then to summarize the findings, based on an analysis of the abstracts from those studies. Methods: A PubMed search was initiated on May 1, 2017. There were 2 separate searches. The first search was for the topic, “temporomandibular disorders.” The second search was for “temporomandibular disorders and published in the Cochrane database.” The number and the topic category of reviews for 2017 were compared with those published as of 2004. Results: There were 120 relevant TMD systematic reviews found in search year 2017: 110 from the PubMed and 10 from the Cochrane searches. By comparison, there were only 8 TMD systematic reviews published in 2004. The abstracts for all 120 reviews indicated increased roles of genetics and psychosocial factors in the etiology of TMD. The future of TMD diagnoses appears to be toward various psychosocial and cellular tests, along with brain neuroimaging. The reviews on the topic of “treatment” supported conservative, noninvasive, reversible therapies, with a trend toward more targeted individual strategies. Conclusions: There were only 8 TMD systematic reviews published in 2004 compared with 110 in 2017. Overall, the trend has been in the direction of better diagnostic procedures, more scientific concepts of etiology, and more conservative treatments for TMD. HIGHLIGHTSA 2004 literature search found 8 systematic reviews on TMD.A 2017 search found 110 relevant systematic reviews in PubMed and 10 in Cochrane.In 2017, 58 of the PubMed listings and all 10 of the Cochrane listings reported on treatments.Conservative, noninvasive, and reversible TMD treatments are preferred.No evidence was found that orthodontic treatment causes, cures, or prevent TMDs.