A histologic study of age changes in the adult human periodontal joint (ligament).

This study evaluated the histological age changes in 80 periodontal joints from 24 human cadavers ranging in age from 20 to 90 years. The limitations of such a descriptive study were reviewed to prevent overextrapolation of the findings to whole populations. In the young speciments, the bone surface of the tooth socket was smooth and regular with the insertion of Sharpey's fibers evenly distributed in the woven bone. Interstitial lamellae were found between secondary osteons in the alveolar bone. Copious periodontal fibers passed around small vascularized interstitial spaces to insert evenly into the cementum as Sharpey's fibers. Numerous cells, probably fibroblasts, were present within and between the fiber bundles. Like the bone surface, the cemental surface was smooth and regular. Both cellular and acellular cementum were present. Cemental splits were found both intracementally and at the cemento-dentinal junction. In the older specimens, the periodontal surface of the alveolar bone was jagged and uneven with Sharpey's fibers inserting irregularly into the woven bone. Subjectively an increased amount of internal remodeling was seen in the periodontal bone. A relative decrease in both suspensory fibers and cellular content was noted in the periodontal ligaments of the older specimens. Large vascularized interstitial spaces encroached upon areas formerly occupied by periodontal fibers and bone. Fat cells also were observed replacing the suspensory fibers. The cementum showed an irregular surface into which Sharpey's fibers were unevenly inserted. Both cellular and acellular cementum were present, and cemental splits were seen with the same frequency as in the young specimens. There was a tendency for greater cemental apposition, particularly in the apical region of the tooth. In many respects the aging periodontal joint showed atrophic and degenerative changes similar to those in cranio-facial sutures. However, these changes did not include either bony ankylosis or osteoporosis related to increasing age. In summary, the periodontal joints of the younger specimens were well organized while those of the older specimens showed a more irregular structure and a decrease in fiber and cellular content. Intermediate changes were seen in the intermediate age groups.