Histomorphometry of age and sex changes in mandibular condyles of young human adults.

Changes in cartilage, subchondral bone and their interface were studied using sagittal (6-8 micron thick) sections from the lateral, central, and medial parts of 21 condyles (11 males and 10 females; aged 18-36 years). The presence of undifferentiated mesenchymal (UM) cells in the proliferative zone of the cartilage was noted. Five condyles were judged to be immature because they had hypertrophic cartilage, cartilage resorption and bone formation at the cartilage-bone interface, no compact bone in their anterior and the superior regions, and the many cartilage rests in subchondral bone. Four of these immature specimens were from males. Immature specimens had quantitatively thicker cartilage (p less than 0.01), thinner subchondral bone (p less than 0.005), and less bone, more vascular spaces and more cartilage rests, both at the cartilage-bone interface and in the subchondral bone (p less than 0.001). Of the 16 mature condyles, the older had fewer UM cells in the proliferative layer, thicker compact bone (p less than 0.05), less vascular spaces at the cartilage-bone interface (p less than 0.05) and more bone and less vascular spaces in the compact bone (p less than 0.05 and p less than 0.01 respectively). No significant differences were found between mature condyles of males and females, but females had more UM cells, less hyperplastic cartilage and fewer irregularities at the cartilage-bone interface.