Variation in modern human enamel formation times

Area of Science:

• Paleoanthropology
• Developmental Biology
• Dental Anthropology

Background:

• Radiographic studies are the primary source for human enamel formation timing.
• Previous research often relies on indirect methods, potentially overestimating variations.

Purpose of the Study:

• To present new longitudinal data on human enamel formation timing using histological analysis.
• To compare enamel formation times between southern African and northern European populations.
• To investigate variations in enamel development across different tooth types.

Main Methods:

• Histological analysis of 326 molars and 352 anterior teeth from diverse geographic and temporal samples.
• Utilized polarized light microscopy and daily enamel cross striations to determine formation times.
• Calculated enamel formation times for deciles of crown length using long-period striae periodicity.

Main Results:

• Mean cuspal enamel formation times were similar for anterior teeth but varied in some molar cusps between samples.
• Southern African anterior teeth generally completed enamel formation earlier than northern European counterparts.
• Molar teeth exhibited minimal differences in enamel completion times, with most falling between 3.0 and 3.45 years.

Conclusions:

• Histological data suggest less variation in human enamel formation times globally compared to radiographic studies.
• The findings offer a more accurate representation of worldwide variation in tooth enamel development.
• This research refines our understanding of developmental timing in human populations.