Differences in the microstructure and fatigue properties of dentine between residents of North and South America

•We evaluate the microstructure of dentine from donor teeth obtained from patients of the US and Colombia.•We evaluate the fatigue crack growth resistance of dentine from these donor teeth and the spatial variations.•There are significant differences in the microstructure of coronal dentine by location.•There are significant differences in the microstructure between the dentine of donor teeth from the US and Colombia.•There are significant differences in the fatigue crack growth resistance of the peripheral dentine between the two groups.

Spatial variations in the microstructure of dentine contribute to its mechanical behaviour.ObjectiveThe objective of this investigation was to compare the microstructure and fatigue behaviour of dentine from donors of two different countries.MethodsCaries-free third molars were obtained from dental practices in Colombia, South America and the US to assemble two age-matched samples. The microstructure of the coronal dentine was evaluated at three characteristic depths (i.e. deep, middle and superficial dentine) using scanning electron microscopy and image processing techniques. The mechanical behaviour of dentine in these three regions was evaluated by the fatigue crack growth resistance. Cyclic crack growth was achieved in-plane with the dentine tubules and the fatigue crack growth behaviour was characterized in terms of the stress intensity threshold and the Paris Law parameters.ResultsThere was no difference in the tubule density between the dentine of patients from the two countries. However, there were significant differences (p ≤ 0.05) in the tubule lumen diameters between the two groups in the deep and peripheral regions. In regards to the fatigue resistance, there was a significant increase (p ≤ 0.05) in threshold stress intensity range, and a significant decrease in fatigue crack growth coefficient with increasing distance from the pulp in teeth from the US donors. In contrast, these properties were independent of location for the dentine of teeth from the Colombian donors.ConclusionsThe microstructure of dentine and its mechanical behaviour appear to be a function of patient background, which may include environmental factors and/or ethnicity.