Study on the Condyle Shapes and Protrusive Mandibular Movements in Edentulous Patients.

Complete denture wearers rarely complain about TMJ disorders. However, there aremany morphological differences of the condyle in complete denture wearers. The purpose of this study was to clarify the relationship between morphological factors of condyles and the path of protrusive mandibular movements in complete denture wearers. The subjects consisted of 107 complete denture wearers (42 males, 65females, mean age 69.7 years) without symptoms involving the TMJ. The shape, theabnormal bone changes and the size of the right and left condyles were examined by panoramic radiography. Horizontal mandibular movements were recorded for lateral deviation during protrusive movement by gothic arch tracing.The resultswere as follows:1. The shapes of the condyle were classified in four types.Type I (round) was 111 condyles (51.9%), Type II (flat anterior portion) was 34 condyles (16.2%), Type III (flat top portion) was 31 condyles (14.5%) and Type IV (flat posterior portion) was 38 condyles (17.7%).2. The abnormal bone changes of condyle were found in 56 cases (77 joints, 36.0%). The bone changes of condyle were Erosion, Osteophyte, Flattening, Concavity, Deformity, Irregular surface and Eburnation.3. A difference of the size of the right and left condyles was found in 32 cases (29.9%).4. The average lateral deviation during protrusive mandibular movement was 1.0±0.6 mm (male 0.8mm, female 1.1 mm)5. In case of less lateral deviation, the Type I tended to increase, but in case of much lateral deviation, the Type III tended to increase.6. Much lateral deviation during protrusive movement in patients appeared in a high ratio in relation to the difference of the size of condyle, abnormal bone changes of condyles and morphological changes of condyle shape.