Surface form analysis on complex freeform organic structures – measuring erosive wear on human teeth in vitro

Abstract Natural human enamel (NHE) is a complex freeform surface which has presented significant difficulties in measuring form change using non-contacting laser profilometry (NCLP). Measuring on NHE metrology proxy for dental tooth structure loss, and characterising this non-ISO parameters (volume, area, normalised lesion depth) been seldom studied due complexity undetermined measurement errors. This study determines NCLP errors (instrument repeatability method reproducibility) parameters, characterises following dietary pH-cycling model. (n = 1) was scanned consecutively twenty-times with/without sample replacement producing consecutive profile data. Residual data created after subtracting filtered (80 ? m, Gaussian filter), mean (SD) volume, depth determined within 1.5 mm circular region of interest (ROI). Volume error (expressed as height variation across ROI area) 0.022 m repeatability) 0.149 (method reproducibility), whilst area percentage the deviation entire 0.034% (repeatability error) 0.081% (reproducibility error). Sixty-four natural surfaces taped with polyvinyl-chloride tape leaving exposed underwent erosion cycling (three 5-min cycles, 0.3% citric acid w/v, pH 3.2) generating artificial lesions. Samples were before/after each cycle, scans microtexture, after-erosion subtracted from before-erosion scans. results show depth, 3D step-height eroded increased significantly no difference calcium phosphate release cycle. We demonstrate robust valid model analysis workflow to measure NCLP, improving understanding surfaces.