Using bearing area parameters to quantify early erosive tooth surface changes in enamel: A pilot study

Objectives

Most in vitro studies investigate the erosive process using relatively simple roughness parameters such as roughness average (R_a). In isolation, R_a may misrepresent the surface features. Further, few studies report baseline surface characteristics after sample preparation. This study aimed to test the hypothesis that measuring the bearing area parameters in addition to R_a may be useful when qualifying the surface of enamel at baseline and after an erosive challenge. The null hypothesis for this study was that the bearing area parameters provide no more useful information than R_a alone, when qualifying the surface of enamel at baseline and after an erosive challenge.

Methods

Enamel slabs (n = 20) were prepared from human (n = 2) and bovine (n = 4) incisor teeth and polished with 0.05 μm paste. Roughness average (R_a) and bearing parameters (MR1, MR2, R_pk, R_k, R_vk) were used to record baseline characteristics. Specimens were subjected to erosion with 1% citric acid solution for 1 min. Profilometric characteristics were recorded post-erosion, along with the maximum height changes within the profile. T-tests were carried out in order to compare baseline surface characteristics between tissue types. Post-erosion, analysis of variance (ANOVA) was used to test the effects of tissue type (bovine or human).

Results

There was no significant difference in R_a between human and bovine incisor enamel at baseline (human 0.11 μm, bovine 0.12 μm P > 0.05), and no significant difference was observed post-erosion (human 0.23 μm, bovine 0.20 μm P > 0.05). There were significant differences in bearing parameters at baseline and post-erosion that were not identified by the R_a measurement alone.

Conclusions

The results suggest that if R_a alone is measured, important differences in surface characteristics may be missed. The null hypothesis is rejected, and the recommendation is made that bearing parameters are included within profile measurements in order to further triangulate the results of surface analysis studies.

Clinical relevance

In isolation, R_a may misrepresent the surface features of a profile. These results have shown that the bearing parameters are an important and informative set of measurements. The recommendation is made that bearing parameters are included within profile measurements at baseline and post-erosion, in order to further triangulate the results of surface analysis studies.