Methods
erosion, enamel loss
EROSION, PVC
The primary measurement outcome between groups was wear in the form of step height, which is widely recognised as the gold standard in quantifying bulk enamel loss [The method workflow is summarised in Outlines the study's workflow. (A) presents 500x co-axial microscopy images of enamel samples before preparation, ensuring that natural samples started the study with an aprismatic layer of enamel. (B) is a flowchart summarising the methodological sequence. (C) illustrates the ISO-5436–1 standard and a simplified diagram of its application to a natural surface, following the superimposition/subtraction workflow. (D) shows both polished and natural samples at a macro level to provide context for the curvature present in the natural surface.Baseline measurements were taken using a 655 nm white light confocal profilometer (WLCP) mounted on an automatic motion system (XYRIS 2000CL, Taicaan, Southampton, UK) Reference zones were created on the polished and natural enamel samples using PVC tape (3 M, UK), the reference zones followed a previously used by Mylonas et al. investigating both polished and natural surfaces Scans were imported into a software (Geomagic Inc, North Carolina, USA) as x, y, z point clouds, wrapped to create a mesh and a process of superimposition/surface registration was performed using an iterative closest point (ICP) for best fit alignment [The visual characteristics of both the natural and polished enamel exposed to erosion and erosion/abrasion was further explored using imaging via a scanning electron microscopy (SEM) [Data from the scans were analysed in SPSS (IBM Corporation, Armonck, USA) and tested for normality using Shapiro-Wilks test and visually using histograms and boxplots and found not to be normal and were log transformed. A repeated measures MANOVA was performed using substrate (polished enamel and natural enamel) and wear challenge (erosion, abrasion, erosion/abrasion) as the independent variables for each time point. As significant differences between the substrate and challenge were observed (