Mapping Tooth Surface Loss with a Fixed-Base Stereo Camera

Change detection of tooth surface loss in the cervical region of a tooth replica has been performed using a fixed-base stereoscopic camera, consisting of two SLR digital cameras with lenses of fixed focal length. Commercial digital photogrammetric and calibration software was used to perform a convergent multi-station calibration with an artefact comprising a transilluminated planar array and a tiered object exhibiting optical texture. Digital surface models of a tiered test object and a tooth surface containing a non-carious cervical lesion were generated from stereo-imagery. The accuracy of automatic mass point measurement of a planar surface was 4 ± 13 ìm in Z. The sensitivity of change detection on mapped tooth replicas was 0·03 mm with change ranging from 0·03 to 0·07 mm per annum. Different rates of change were clearly evident in different areas at different times. 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.