Enamel growth rate variation of inner, mid, and outer enamel regions between select permanent tooth types across five temporally distinct British samples.

Objective: This study explored differences in the regional daily growth rates of human enamel between tooth types across a temporal transect in Britain.

Methods: Upper permanent central incisors (n = 81), upper permanent canines (n = 69), and upper and lower permanent first molars (n = 115) from Roman, Pre-Medieval, Medieval, and Modern day populations were analysed using histological methods. Daily secretion rates (DSRs) were collected for inner, mid, and outer regions of cuspal and lateral enamel for each tooth type and temporal sample. Variation in DSRs between the tooth types, within each population, was sought using Welch's tests.

Results: Numerous significant differences were observed in DSRs between equivalent enamel regions of different tooth types. The majority of differences were observed between molars and the anterior teeth, but there were no obvious trends as to which typically grew faster/slower, nor was there any consistency across the temporal samples. In contrast, comparisons between incisors and canines yielded minimal differences and variation, when significant, was found to be enamel area- and sample-specific.

Conclusions: This study presents evidence for a high level of variation in DSRs between anterior teeth and first molars of the permanent dentition. This variation appears sporadic with no clear trend outside of anterior tooth comparisons, where analyses of the Late Pre-Medieval and Modern-day populations highlight how DSRs within cuspal and lateral enamel can vary independently.