Qualifying the lapped enamel surface: a profilometric, electron microscopic and microhardness study using human,...

When enamel specimens are prepared for erosion and abrasion studies, the assumption is often made that specimens prepared in the same way will have the same baseline surface characteristics. This study aimed to test the null hypothesis that there are no significant differences in baseline surface characteristics of human, ovine and bovine enamel specimens prepared using the same method.

Twenty enamel slabs were prepared from bovine, human and ovine incisor crowns and polished with 3μm aluminium oxide paste. Roughness average (Ra), bearing parameters (MR1, MR2, Rpk, Rk, Rvk), surface microhardness and scanning electron microscopy (SEM) were used to compare the different tissues. One way Analysis of Variance (ANOVA) was used to quantitatively compare surface characteristics between tissue types.

Human, bovine and ovine enamel roughness and microhardness were significantly different to one another at baseline (P<0.001); ovine enamel was the roughest and softest, and bovine enamel was the smoothest and hardest. SEM allowed a visual comparison to be made between tissue types, confirming the quantitative data.

Enamel from human, bovine and ovine specimens showed significantly different surface characteristics after lapping and polishing. The null hypothesis is rejected, recognising that the same preparation techniques will not necessarily result in consistent baseline roughness or surface characteristics between tissue types. Surface studies should lap and polish samples with a standardised approach, whilst ensuring that baseline data are recorded for comparison.