Dentin, Cementum, and Age Determination in Bats: A Critical Evaluation

Secondary dentin and cementum were studied histologically in 17 known-age (2–8 years) specimens of Myotis lucifugus and M. velifer and in 30 adult specimens of unknown age representing Pteronotus parnellii, Leptonycteris nivalis, Artibeus jamaicensis, Sturnira ludovici , and Desmodus rotundus . Incremental lines in secondary dentin and cementum were highly variable (both between and within individuals) and did not correspond exactly to age although there generally was a loose correlation between number of lines and age. Difficulties in using such histologically recognizable characteristics to determine age are discussed and previous studies of age determination in bats are reviewed. Incremental lines in secondary dentin were associated with changes in direction and shape of dentinal tubules. Chemical and structural alterations in collagenous matrix and ground substance also were implicated in the formation of incremental lines. Incremental changes in cement were related to stress, consequent dental drift, and eruption.