A Comparison of Surface Measurement Methods for Enamel Erosion Studies

Objectives: To compare contact and non-contact surface measurement equipment used in determining mean material loss in enamel erosion studies.

Methods: Ninety eroded human enamel specimens were taken from two randomised clinical erosion trials. All samples were read at baseline and endpoint on three types of profilometer: (1) Proscan Non-Contact Profilometer (2) Mitutoyo Surftest Contact Profilometer (3) Planer Contact Profilometer. Mean enamel loss in the Z axis was measured along a trace in the X axis. Two single traces were read for 45 samples on the Proscan and Planer, and the average calculated, compared and correlated. Mean enamel loss of a second data set of the other 45 samples was also calculated on the Proscan using z-values from the entire sample surface for comparison as well as single trace on the Planer and Mitutoyo.

Results: In terms of mean material loss at endpoint, single trace measurement comparisons showed the Planer recorded the lowest erosion (1.733µm), and the Proscan the greatest (3.784µm). The second data set measured at baseline compared mean peak height relative to flatness. The Planer reading indicated the flattest surface (0.016µm) and the Proscan the least flat (2.144µm). This second data set also showed a strong correlation of 0.933 indicating very similar reading trends despite the difference in magnitude of the raw data.

Conclusion: Both contact and non-contact profilometry identify the same trends in patterns of erosion. Non-contact profilometry has greater accuracy in terms of reproducibility of trace and specimen location, with its 3D topography facilitating study of erosion patterns and distribution. Non-Contact profilometry utilities approximately 100 fold more points than contact profilometry and further eliminates surface damage caused by the stylus of contact profilometry. Though there are merits of both systems, these are largely determined by the software that accompanies them, and by the experience of the operator.