Longitudinal Monitoring of Early Dentine Erosion with Surface Roughness

Objectives: Step height has been the most frequently used outcome measure for assessment of advanced dentine erosion with profilometry. However step height cannot be applied for measurement of early dentine erosion. The objective is to assess the potential of surface roughness in detection and monitoring of early dentine erosion. Methods : 20 polished dentine samples were prepared from external surfaces of 10 human permanent premolar roots. A window was created on the surface of each sample. Half of the window was covered with tape creating a control and an exposed area. Baseline images were obtained with a non-contact Profilometer. Samples were then immersed in 0.003M citric acid for 10 minutes, three times a day in a cycling model for 3 days. In between erosive challenges, the samples were stored in a remineralisation solution for up to 3 hours followed by overnight storage in similar remineralisation solution. Images were taken at the beginning of each cycling day. 5x100µm measurements were drawn on each image and an average value of surface roughness (Ra) was calculated for both the control and eroded areas. The outcome measure used was the fractional difference of surface roughness between baseline and each time point (ΔRa). Statistical analysis was performed with SPSS 12.0. Multiple linear regression analyses were performed to ascertain whether time related changes were detected with Profilometry. When a significant time-related change was found for ΔR, paired t-test was performed to identify the detection sensitivity. Results: Multiple regression analysis showed that ΔRa for the eroded area detected significant erosion-interval related increase in roughness while ΔRa for the control area did not. Paired t-test revealed that ΔRa for the eroded area showed significant difference between baseline and Day 3 ( p-value <0.05). Conclusion: Surface roughness can be used for monitoring of early dentine erosion after 3 days of cycling erosion challenge.