New regression formula to estimate the prenatal crown formation time of human deciduous central incisors derived from a Roman Imperial sample (Velia, Salerno, Italy, I-II cent. CE)

Abstract

The characterization and quantification of human dental enamel microstructure, in both permanent and deciduous teeth, allows us to document crucial growth parameters and to identify stressful events, thus contributing to the reconstruction of the past life history of an individual. Most studies to date have focused on the more accessible post-natal portion of the deciduous dental enamel, even though the analysis of prenatal enamel is pivotal in understanding fetal growth, and reveals information about the mother’s health status during pregnancy. This contribution reports new data describing the prenatal enamel development of 18 central deciduous incisors from the Imperial Roman necropolis of Velia (I-II century CE, Salerno, Italy). Histomorphometrical analysis was performed to collect data on prenatal crown formation times, daily secretion rates and enamel extension rates. Results for the Velia sample allowed us to derive a new regression formula, using a robust statistical approach, that describes the average rates of deciduous enamel formation. This can now be used as a reference for pre-industrial populations. The same regression formula, even when daily incremental markings are difficult to visualize, may provide a clue to predicting the proportion of infants born full term and pre-term in an archaeological series.

Effects of maternal, gestational, and perinatal variables on neonatal line width observed in a modern UK birth cohort

“…Early life history can be investigated using light microscopy of histological ground sections of deciduous teeth using evidence from the regular structure of enamel growth (Birch & Dean, , ; Nava et al, ). Disruptions to the regular incremental pattern of enamel formation can be used to identify and reconstruct a sequential chronology of events that affected the growth and development of an individual in the past (Hillson, ).…”

Virtual histological assessment of the prenatal life history and age at death of the Upper Paleolithic fetus from Ostuni (Italy)

“…Table 1 reports the measurements along the enamel prisms from the Enamel Dentine Junction (EDJ) to the ALs, the estimated time represented by each distance in days and weeks, and the total Crown Formation Time (CFT). These estimates were created using the regression formula developed by Nava and coworkers 31 . The time interval between AL 1 and AL 3 is identical and sums to 46 days in both crowns.…”

“…3 , together with the CFTs and EDJ lengths reported by Nava et al . 31 for the Roman imperial series of Velia 33 (Campania, Italy), which includes a number of preterm individuals. The CFTs and EDJ lengths profiles of Os1b fall within the range of variation observed for Velia and follow the same trajectories.…”

“…Same data reported by Nava et al . 31 for the Roman imperial series of Velia (grey circles and red squares). Each profile was calculated with a locally weighted polynomial regression fit.…”

“…The observed 80% of EDJ surface already formed at death apparently contradicts these results. However, given the expected deceleration of the enamel extension rate in the cervical region 31 , the remaining 20% of EDJ surface to complete the crown would correspond to a larger proportion of the total CFT. Data collected via virtual histology suggest a 95% confidence interval of Os1b age at death between 30.7 and 34.3 gestational weeks (see Table 1 and Supplementary Table S2 ).…”