Methods: Measurements of the distance between von Ebner lines were taken using a transmitted polarising Olympus BX51 light microscope and Improvision Openlab 5.0.2 image analysis software from the sections of the deciduous teeth and DSR calculated. Using these DSRs, chronological ages were assigned to the segments on a transect starting at the enamel dentine junction (EDJ) to the dentine-pulp cavity (DPC). Using the neonatal line as a reference point, measurements of 10 sets of von Ebner lines allowed us to generate mean DSRs for each line segment and estimate the age sampled for the corresponding ablation pit. Lead concentration and isotopic ratio were obtained using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS).
Results: DSRs gradually decrease upon approaching the pulp chamber, interestingly with considerable oscillation for all four teeth, and lead concentration was seen to increase with age. The isotopic ratio changed in both teeth at around 200 days postnatally, indicating a change in source at about six months in both children.
Conclusion: We have provided sufficient evidence to apply this novel dental histology approach into assigning chronological ages to isotopic ablation pits in dentine using growth incremental lines in deciduous teeth. Further research is required to explain the extent of oscillation in the mean DSRs present in all teeth.