Gary C. Anderson

Variation in tooth wear in young adults over a two-year period

STATEMENT OF PROBLEM Although all the processes of loss of hard tissue are important, attrition on the occlusal surfaces commands our attention. PURPOSE OF STUDY The enamel wear rate of 18 young adults over 2 consecutive years was measured independently by volume loss and mean depth loss. Any significant differences in tooth wear resulting from gender and a clinical diagnosis of bruxism were identified. MATERIAL AND METHODS A strict protocol for dental impressions provided epoxy models, which were digitized with a null point contact stylus. AnSur software provided a complete morphologic description of changes in the wear facets. RESULTS The mean loss for all teeth measured was 0.04 mm3 by volume and 10.7 microns by depth for the first year. CONCLUSIONS These numbers were approximately doubled at 2 years of cumulative wear.

Comparative study of two treatment methods for internal derangement of the temporomandibular joint

Orthopedic mandibular repositioning and flat plane occlusal splint therapy were compared in the treatment of 20 patients with internal TMJ derangement with reduction. The following conclusions can be drawn. Mandibular repositioning treatment produces significant subjective and objective improvement in the dysfunction of patients with internal joint derangements with reduction. Flat plane occlusal splint treatment produces no significant change in the dysfunction level of patients with internal joint derangements with reduction. Mandibular repositioning treatment may eliminate the reciprocal click of internal joint derangement with reduction. To realize improvement in dysfunction of internal joint derangement, it appears that the reciprocal click must be eliminated. Mandibular repositioning treatment produces a significant improvement in muscle pain associated with internal joint derangement.

Dimensional stability of injection and conventional processing of denture base acrylic resin

C omplete denture fabrication is fraught with both extrinsic and intrinsic potential error. The greater part of this error can be controlled with careful clinical and laboratory technique. ’ Woelfel and Paffenbarge9 outlined the inaccuracies inherent to the use of poly(methy1 methacrylate) as a denture base material. Dimensional change during processing is one such source of error. The processing shrinkage of poly(methy1 methacrylate) resin is well documented.*” Injection processing of poly(methy1 methacrylate) denture bases was introduced by Pryor in an attempt to reduce processing shrinkage. More recently a continuous-pressure injection technique has been developed (SR-Ivocap, Ivoclar AG, Schaan, Liechtenstein). As discussed by Schmidt9 the process claims to deliver reduced processing error and increased resin density through layered curing of the resin and no processing flash. Trituration of the liquidpowder system is mechanically performed in prepackaged capsules in an attempt to produce a more even mix resulting in a homogeneous denture base. The mixed resin is injected into the flask under continuous pressure during the processing.” This study determined the dimensional changes of heat-cured poly(methy1 methacrylate) resin processed by the injection processing system compared with that processed by a conventional compression packing technique.

Influence of headache frequency on clinical signs and symptoms of TMD in subjects with temple headache and TMD pain

&NA; The relationship of the frequency of temple headache to signs and symptoms of temporomandibular joint (TMJ) disorders (TMD) was investigated in a subset of a larger convenience sample of community TMD cases. The study sample included 86 painful TMD, nonheadache subjects; 309 painful TMD subjects with varied frequency of temple headaches; and 149 subjects without painful TMD or headache for descriptive comparison. Painful TMD included Research Diagnostic Criteria for Temporomandibular Disorders diagnoses of myofascial pain, TMJ arthralgia, and TMJ osteoarthritis. Mild to moderate‐intensity temple headaches were classified by frequency using criteria based on the International Classification of Headache Disorder, 2nd edition, classification of tension‐type headache. Outcomes included TMD signs and symptoms (pain duration, pain intensity, number of painful masticatory sites on palpation, mandibular range of motion), pressure pain thresholds, and temple headache resulting from masticatory provocation tests. Trend analyses across the painful TMD groups showed a substantial trend for aggravation of all of the TMD signs and symptoms associated with increased frequency of the temple headaches. In addition, increased headache frequency showed significant trends associated with reduced PPTs and reported temple headache with masticatory provocation tests. In conclusion, these findings suggest that these headaches may be TMD related, as well as suggesting a possible role for peripheral and central sensitization in TMD patients. Subjects with painful temporomandibular disorders (TMD) showed significant trends for increased signs and symptoms of TMD associated with increased frequency of concurrent temple headaches.

Clinical vs. Arthrographic Diagnosis of TMJ Internal Derangement

Internal derangements of the temporomandibular joint (TMJ) have gained increased recognition as a potential source of pain and dysfunction of the masticatory system. The objective of this study was to evaluate the reliability of clinicians in predicting an arthrographic diagnosis of articular disc position in a typical patient population presenting for TMJ arthrographic evaluation. Two clinicians utilized a brief history, clinical examination (including evaluation of mandibular movement and TMJ auscultation), and tomographic TMJ imaging in evaluating 60 patients. The radiologist subsequently performed the arthrographic procedures on 102 TMJs (18 unilateral and 42 bilateral). Diagnostic agreement was determined for all possible diagnostic categories including: normal disc position, TMJ internal derangement with reduction, TMJ internal derangement without reduction/acute, TMJ internal derangement without reductionlchronic, and osteoarthrosis. The significance of the diagnostic agreement between the clinicians and arthrography was evaluated with a Kappa Statistical Test, which showed good reliability. For epidemiological studies, it was concluded that clinical and tomographic evaluation would provide sufficient reliability for determination of the presence and stage of TMJ internal derangement. However, in a specific clinical situation, a difficult diagnostic problem may require the use of arthrography, depending on the impact of the diagnosis on subsequent treatment decisions.

Diagnostic criteria for headache attributed to temporomandibular disorders

Aims: We assessed and compared the diagnostic accuracy of two sets of diagnostic criteria for headache secondary to temporomandibular disorders (TMD). Methods: In 373 headache subjects with TMD, a TMD headache reference standard was defined as: self-reported temple headache, consensus diagnosis of painful TMD and replication of the temple headache using TMD-based provocation tests. Revised diagnostic criteria for Headache attributed to TMD were selected using the RPART (recursive partitioning and regression trees) procedure, and refined in half of the data set. Using the remaining half of the data, the diagnostic accuracy of the revised criteria was compared to that of the International Headache Society’s International Classification of Headache Diseases (ICHD)-II criteria A to C for Headache or facial pain attributed to temporomandibular joint (TMJ) disorder. Results: Relative to the TMD headache reference standard, ICHD-II criteria showed sensitivity of 84% and specificity of 33%. The revised criteria for Headache attributed to TMD had sensitivity of 89% with improved specificity of 87% (p < 0.001). These criteria are (1) temple area headache that is changed with jaw movement, function or parafunction and (2) provocation of that headache by temporalis muscle palpation or jaw movement. Conclusion: Having significantly better specificity than the ICHD-II criteria A to C, the revised criteria are recommended to diagnose headache secondary to TMD.

Reliability of the evaluation of occlusal contacts in the intercuspal position

Reliability of clinical measurement is essential to any clinical discipline. This investigation assessed intraexaminer and interexaminer reliability achieved in identifying contacting teeth in the intercuspal position. Shim stock and an articulating film were compared in the evaluation of occlusal contacts of 337 antagonist occlusal pairs in 24 young adults by two examiners. Results were compared by use of a simple proportion of agreement and, when possible, the Kappa statistical test that corrects for chance agreement. Shim stock displayed better reliability than articulating film and appeared suitable for clinical measurement of occlusal contacts in intercuspal position.

The relationship between level of mandibular pain and dysfunction and stage of temporomandibular joint internal derangement.

Temporomandibular joint internal derangement (TMJ ID) is the most common intra-articular TM disorder and can progress from TMJ ID with reduction to TMJ ID without reduction. It is not known whether this anatomical progression is associated with increasing levels of mandibular dysfunction. The objective of this study was to determine whether the level of clinically detectable mandibular dysfunction was related to the stage of TMJ ID. Two clinicians examined 42 subjects prior to bilateral TMJ arthrographic evaluation. The level of mandibular dysfunction was calculated by Helkimos Clinical Dysfunction Index (Di) and the Craniomandibular Index (CMI). Statistical analysis revealed that the level of mandibular dysfunction as determined by the Di and CMI was not related to the arthrographic presence or absence of TMJ ID. Therefore, the clinician cannot assume that the level of mandibular dysfunction is directly related to the absence or presence of TMJ ID. Epidemiologically, the CMI and Di can be used only for estimation of the degree of mandibular dysfunction, since they do not provide direct information on a specific TM disorder.

Cephalometric norms for craniofacial asymmetry using submental-vertical radiographs

The submental-vertical (S-V) radiograph has become popular in the assessment of craniofacial asymmetry because of ease in identifying reliable midline reference structures. To date, no standards of asymmetry that use the S-V projection have been reported. Submental-vertical radiographs were obtained on 44 adults. Subjects were excluded if previous orthodontic treatment or temporomandibular joint symptoms were reported. With the use of a system of asymmetry analysis developed by Ritucci and Burstone, asymmetry was reported for cranial base, zygomaxillary complex, and mandibular structures. Mean and standard deviations were used to report the asymmetry values across 23 pairs of anatomic landmarks. The data showed that asymmetry is present to some degree in all landmarks and patients. Further, strong asymmetry associations existed between landmarks within patients, with most high positive correlation coefficient values found between regionally or geometrically related points. A refined version of the asymmetric analysis was presented that included easily identified and clinically relevant points. This system is more feasible for the orthodontic clinician.

Digital assessment of occlusal wear patterns on occlusal stabilization splints: A pilot study

STATEMENT OF PROBLEM If masticatory load distribution is task-dependent, then the pattern of wear on an acrylic resin occlusal splint over time may affect clinical outcome. PURPOSE This pilot study quantitatively assessed posterior wear after 3 months on the occlusal surfaces of maxillary stabilization splints. MATERIAL AND METHODS Subjects with known history of nocturnal bruxism were given heat-cured full-arch acrylic resin occlusal stabilization splints to be worn nocturnally for 3 months. Splint occlusion was adjusted at appliance delivery and was refined at the baseline session 1 to 2 weeks later. No further adjustment of the splint surface was performed during the 3-month study period. Sequential impressions of the splint occlusal surface provided epoxy resin models that were digitized and analyzed through specialized software. Changes in the digitized splint surface from baseline to 3 months allowed comparison of wear facets between splint sides and among tooth locations. RESULTS Splint wear was asymmetric between sides and uneven between dental locations. CONCLUSIONS For full coverage occlusal splints, the appliance wear phenomenon can be site specific and, if left undisturbed, may yield two extremes of high wear and a zone of low wear in-between.