Abstract
Morphological changes in temporomandibular joint with increasing age have been reported.
These changes could affect mandibular movements ; however, changes of mandibular movements have been never clarified. We measured mandibular movements of elderly subjects in three-dimensions to investigate changes with aging.
Ten subjects ranging from 60 to 79 years of age (old group) and 11 young subjects ranging from 19 to 24 years of age (young group) were selected. The dentition of both group subjects was either complete or nearly so, and their intercuspal positions were firm.
We investigated the paths of protrusive movement and lateral excursion at representative points; the incisal point and the condylar centers. The parameters analyzed with protrusive movement were: the sagittal inclination of the incisal path, the sagittal inclination of the condylar path, and the sagittal curvature of the condylar path. The parameters with lateral excursion were: the path length of the working side condyle, the horizontal inclination of the incisal path, the horizontal inclination of the non-working side condylar path, the horizontal curvature of the non-working side condylar path, and the sagittal inclination of the nonworking side condylar path.
The results were as follows:
1) In parameters with incisal paths, no statistical difference between the old group and the young group could be found.
2) The sagittal inclination of the condylar path during protrusive movement and that of the non-working side condylar path were gentler in the old group than in the young group.The sagittal curvature of the condylar path during protrusive movement tended to be bigger in the old group than in the young group.It is considered that these results are due to theflattening of the anterior slope of the mandibular fossa which occurs withaging.
3) In the path length of the working side condyle, the sagittal inclination and curvature of the non-working side codylar path, there was no statistical difference between two groups. These parameters are considered to relate to the condition of the lateral ligament of the temporomandibular joint. Therefore these results shows that the lateral ligament does not change even in elderly subjects, if their intercuspal positions are firm.
