Does tooth loss cause tempomandibular disorders?

Relationship between tooth loss and temporomandibular disorders (TMD) is one of the most controversial subjects in dentistry. Objectives: The objective of this study was to evaluate this relationship by comparing condylar tracings of different edentulous cases during mandibular movements. Methods: Effect of tooth loss on TMD was evaluated by means of the tracings of condylar movements obtained from computerized axiography data (Condylocomp LR3, DENTRON GmBh, Hoechberg, Germany) during opening-closing, protrusion-retrusion, right and left lateral movements. Five groups (each n=10), with no etiologic factors that cause TMD other than tooth loss, were selected for the study: fully dentate (Group1), unilateral tooth loss maintaining molar support (Group2), bilateral tooth loss maintaining molar support (Group3), unilateral tooth loss without molar support (Group4), bilateral tooth loss without molar support (Group5). For each tracing, total length and lengths in x-y-z directions were evaluated and results were compared with Kruskal-Wallis Test and then Bonferroni adjusted Mann Whitney U Test. Results: Differences were statistically significant between group 3 vs. 1 for condylar movement of right condyle in anteroposterior direction during left lateral excursion (p=0.04), between group 3 vs. 1 and group 3 vs. 4 for total condylar movement of left condyle during right lateral excursion (p=0.04, p=0.03 respectively). There was no statistically significant difference for any direction between groups during other movements. Additionally, dentate subjects did not show longer or more accurate condylar pathways when compared with groups with tooth loss. Conclusion: Although the effect of tooth loss is statistically significant for two tracings of group3, lengths of all tracings of all groups in all directions, including the statistically significant ones, are clinically in physiological limits indicated as ‘healthy' in the literature. Tooth loss may affect condylar movements but it is not strong enough to cause pathology if there is no other etiologic factor creating TMD.