Brief communication: The timing of linear hypoplasias on human anterior teeth

One hundred and fifteen unworn anterior teeth were sectioned longitudinally with a diamond saw and prepared for histological examination by polarized light microscopy. Incremental markings in the enamel of each tooth were use d to estimate the average total crown formation times of each tooth type, T he total time taken to form the crowns of each tooth type was apportioned b y 1) cuspal enamel formation and 2) each tenth percentile of total tooth he ight. Based on these data, and on histological estimates for the time of in itiation of mineralization in each anterior tooth, the following conclusion s can be drawn. Little if any visible surface enamel is likely to form befo re the end of the first year after birth in any anterior tooth type. No rel ation exists between tooth crown height and the total time taken to form en amel. Anterior crown formation is nonlinear and slows towards the cervix in all teeth. The estimated mean chronological age at crown completion ranged in this study from between around 4 years for lower central incisors to ar ound 6 years for lower canines, We suggest that these combined findings wil l be useful for devising more reliable ways to estimate the timing of linea r enamel hypoplasias than some methods currently in use. (C) 2000 Wiley-Lis s, Inc.