Nature of occlusion during eccentric mandibular movements in young adults

The aim of this study was to find out the nature of occlusion and tooth contact during various eccentric mandibular movements in young adults with class I occlusion.

The sample consisted of 100 young adults with class I occlusion with full complement of teeth. Anterior disclusion in centric occlusion was demonstrated using a shim stock interposed between the upper and lower anteriors. Disclusion of posteriors was ascertained during 1.5 mm straight protusion and in edge-to-edge protrusion, visually as well as using a silk floss method. Posterior disclusion was also verified during lateroprotrusion and crossover. Besides these occlusal wear of teeth also were observed.

The results of this study showed that the anterior disclusion is seen only in one-fourth of the subjects compared to almost three-fourth showing posterior disclusion. Mutually protected occlusion was also seen only in one-fourth of the subjects. Canine protective mechanism is seen in a relatively large number of subjects, but it was not overwhelmingly predominant. No correlation could be established between cuspid wear and the type of occlusion. A relatively high percentage of subjects showed wear on posterior teeth when there was no posterior disclusion.

From the above study it is seen that posterior disclusion is acknowledged as a common factor except when a bilateral balance is present. Since bilateral balance is harmful, the ideal occlusal relationship in eccentric movements is in favor of posterior disclusion. Posterior disclusion is easily obtainable when restorations are planned.

From the findings and results it has been possible to make some contributions on the nature of tooth contacts and disclusion during various eccentric movements and compare it with the requirements of ideal occlusion.