Mapping a non-carious cervical lesion using stereo-imagery and dental casts incorporating optical texture

Objectives: Recent advances in digital photogrammetry have enabled a new approach to high resolution mapping of tooth surfaces. The aim of this study was to assess the accuracy and the precision of a new system using automatic digital stereo-photogrammetry combined with an experimental casting material and to measure tooth surface loss in a noncarious cervical lesion. Methods: A test object and tooth replicas incorporating optical texture obtained at baseline, one and 2 years were imaged with a pre-calibrated stereocamera. The stereoimagery was then processed with digital photogrammetric software to automatically generate digital surface models. Test object models were analysed for accuracy and precision and tooth surface models were aligned with point cloud analysis software and tooth surface loss determined. Results: Replicas were mapped to an accuracy of (6 :i:: 13) !-I,m. The sensiLivity of change detection on tooth replicas was 10 lJ.m with change ranging from 40 to 70 lJ.m per annum in a discrete part of the lesion. Conclusions: In the case examined, the change detection data were of sufficient accuracy and resolution to draw meaningful conclusions about the spatial distribution and quantum of tooth hard tissue loss. The results of this investigation suggest that annual change detection studies will provide a clearer picture of the pattern of tooth surface loss and, in combination with other analytical techniques, a more detailed explanation of the natural history of these lesions.