J Prosthet Dent 1999;82:410-415.
Julian Kahn, DDS a • Ross H. Tallents, DDS b
No association between working and non working occulsion and temporomandibular disorders. Orthodontists generally attempt to produce a finished occlusion that has maximum intercuspation with canine disclusion and no cross-arch or balancing interferences. However, in some patients, these goals are not entirely achievable. If patents lack proper working and nonworking occlusion, will they be predisposed to temporomandibular dysfunction (TMD)? That question was explored in a study that was published in the Journal of Prosthetic
Dentistry (82:410–415). The purpose of this investigation was to compare the prevalence of molar relationship, occlusal guidance, and balancing side contacts in both
symptomatic patients with TMD and asymptomatic volunteers. The sample consisted of 250 symptomatic patients who had been seen consecutively at a major TMJ clinic. They
were compared to 80 asymptomatic volunteers. The occlusion, including the type of lateral contacts on both working and nonworking sides was evaluated. The authors
wanted to determine if canine guidance or group function were predominant in either sample. In addition, the authors divided their sample into asymptomatic and
symptomatic patients who had displaced disks and normal condyle-to-disk relationships. The results showed:
1. Higher incidence of canine guidance in patients whose temporomandibular joints were symptomatic.
2. The most common type of relationships in asymptomatic patients were group functions with a high incidence of nonworking or balancing interferences.
3. Based upon the results of this study the authors conclude that the presence of group function and balancing interferences does not predispose an individual to temporomandibular joint problems.
Only a fraction of temporomandibular disorders are due to occlusal problems. The relationship between malocclusion and temporomandibular disorders is controversial. Some clinicians believe that occlusal disharmony causes dysfunction of the temporomandibular joint (TMJ). However, there is little evidence to confirm this association. A study published in the Journal of Prosthetic Dentistry (2000;83:66–75) evaluated the predictive value of specific occlusal variables for producing temporomandibular disorders. The sample consisted of 350 individuals who had intracapsular temporomandibular disorders. They were differentiated into 2 groups: those with disk displacement and those with osteoarthrosis with inflammation of the joint. Then these samples were compared with asymptomatic controls. In evaluating the samples, these authors also tried to correlate occlusal variables such as overjet, overbite, open bite,
posterior crossbite, and centric slides with the incidence of intracapsular disorders. On the basis of careful analysis of all of the variables, the authors found that the predictive
value of malocclusion for temporomandibular disorders was somewhere between 5% and 27%.
Therefore, 73% to 95% of the time, other nonocclusal factors are necessary to explain disorders of the TMJ.