Mathematical shape matching as a tool in tooth wear assessment - development and conduct

The quantitative assessment of restoration and tooth wear usually requires fixed reference points from which measurements are made. in longitudinal pa tient follow-up the loss or erosion of such points may preclude measurement and an alternative approach is to seek regions of coincidence and conflict in digital models of before and after wear surfaces, with a continuous ref inement of the parameters of the coordinate transformations, until the clos est correspondence between them is found. A computer program has been writt en to implement the algorithm and assess the technique's capacity to find t he match between surfaces both artificially generated and from tooth replic as recorded from patients at different epochs. The program was able to achi eve the desired ends, demonstrating the utility of the technique in tooth w ear assessment but identifying the need to refine the program further to en hance both its difference detection capabilities and level of automation. E xamination of the theory and practical experience highlighted certain situa tions when user understanding is invaluable to ensure a satisfactory soluti on. This strengthened the investigators' resolve against reliance upon comm ercially based surface fitting programs whose basis may not be fully unders tood. Notwithstanding this surface matching is a powerful, tool in the inve stigation of dental wear.