Characteristics of dentine wear: an in vitro study

Previous studies have described the nature of wear in enamel and various restorative materials under conditions simulating attrition and erosion. Objective: The aim of this study was to investigate the pattern of dentine wear under various loads and with different lubricants. Methods: 53 human third molar teeth were sectioned longitudinally in a mesio-distal direction. After removing enamel from one half of the teeth, dentine surfaces were worn against enamel in a purpose-built electromechanical tooth wear machine at different loads (3.2, 6.2 and 9.95 kg), and with different lubricants (water at pH 7.0 and hydrochloric acid solutions at pH 1.2 and 3.0). Tooth wear was quantified by measuring reduction in dentine volume over time using Dr PICZA 3D Scanner (PIX-4) and MATLAB software package (version 6, The Mathwork Inc, Natick MA, USA). Qualitative assessment was also carried out using Scanning Electron Microscopy (SEM). Results: Dentine wear increased with increasing loads at each pH level (p<0.05). Dentine wear rate was greatest at pH 1.2 (p<0.05) and there was a trend for the wear rate at pH 3.0 to be less than that at pH 7.0 under all loads. Dentine was noted to wear more slowly than enamel at loads of 3.2 kg and 9.95 kg at pH 1.2 (p<0.05). SEM analyses showed extensive surface destruction of dentine wear facets due to erosion at pH 1.2, whereas dentine wear facets were smoother at pH 3.0 compared with pH 7.0. Conclusions: This study provides evidence of different wear mechanisms in dentine under different experimental conditions. Dentine wear rate is linear with load but its relationship with pH is more complicated. This project was supported by the National Health and Medical Research Council of Australia (Grant no: 207803).