Comparison between a profilometer and a measuring microscope for measurement of enamel erosion.

The aim of this study was to measure the difference in the erosion depth of enamel measured by profilometry (PM) and a measuring microscope (MM). Sixty enamel specimens were divided into ten groups. Each specimen group was exposed to 50 ml of a carbonated drink with pH 2.38 or orange juice with pH 3.67 for 15, 30, 60, 120, and 180 minutes. Depths of eroded areas were measured with a profilometer and a measuring microscope. Data of average enamel loss were measured by PM and MM for all erosion times and were scatter plotted on a graph with regression fit. Correlations between the enamel loss measured by PM and MM were analyzed with a paired sample t-test to compare the discriminatory abilities of the two methods of analysis for all erosion times. The regression fit in all study cases showed a high linear relationship (R(2) = 0.90) between measurements by PM and MM, but in cases where the erosion depth was lower than the depth of focus (DOF) of the MM objective lens, there were weak correlation coefficients (-0.007 - 0.303) for comparison between the two measurement methods.