Timing of Development of the Permanent Mandibular Dentition: New Reference Values from the Fels Longitudinal Study.

Estimating chronological age or assessing the rate of maturation in immature individuals is an important task in biological anthropology and clinical practice. One of the most reliable ways of doing this is by evaluating one's dental development, specifically tooth mineralization. However, few chronologies include reference values for very young children, and few provide an extensive documentation of the range of variation surrounding the reported reference values. We present a new chronology of development of permanent mandibular canine and postcanine teeth from birth through age 28 years, based on over 6,000 radiographs of 590 participants of the Fels Longitudinal Study, recorded between 1940 and 1982. Tooth mineralization was scored following the 14-stage system of Moorrees, Fanning, and Hunt (Moorrees et al., 1963a) with an additional crypt stage. We calculated ages of attainment, as well as average age in stage, using transition analysis. We find that variation increases throughout ontogeny for all teeth, though it is generally comparable between girls and boys. The tempo of dental development tends to be faster in girls. Compared to the classic chronology of Moorrees et al. (1963a), partly based on Fels radiographs, in our sample the development of crowns tends to occur at earlier, and development of roots at increasingly later ages. Our results are more similar to chronologies based on more recent, clinical samples (Liversidge, 2009), though the development of tooth roots in our sample occurs at older ages. Anat Rec, 302:1733-1753, 2019. © 2019 American Association for Anatomy.