Age-related changes in reducible crosslinks of human dental pulp collagen

Coronal pulp of human third molars from patients ranging in age from 16 to 40 yr was analysed for collagen, protein, calcium and reducible crosslink content. Dihydroxylsinonorleucine (DHLNL) was the major crosslink; it decreased with age. Hydroxylsinonorleucine (HLNL) and lysinonorleucine (LNL) appeared in insignificant amounts. Calcium content increased with age. Based on the premise that collagen synthesis is characterized by the presence of reducible crosslinks, the study showed that coronal pulp collagen synthesis decreases with age; this is accompanied by a decrease in collagen concentration in terms of dry weight and total protein between 16 and 30 hr of age.