Evaluation for the fully automatic inlay reconstruction by means of the biogeneric tooth model

Length measurements and descriptive characterizations were previously the sole reference points for describing the morphology of the occlusal surface. For computerized methods in dentistry, this is not sufficient for producing a data record. So far, the literature has reported no solutions. With the aid of a tooth library containing three-dimensionally measured occlusal surfaces free of caries and abrasion, a mathematical model was produced to describe a certain type of tooth by reference to a few parameters, taking account of functional and biologically relevant structures. This biogeneric tooth model was tested on 27 different inlay situations. The results show that fully automatic reconstruction was possible in all cases. The deviations of the reconstructions from the original tooth surface were on average around 150 microm. Furthermore, the influence of different parameters on the mathematical model was examined. Here, combinations that guarantee the best possible reconstruction for many situations could be found. The visual evaluation and the metric comparison of the reconstructions among one another illustrate the great flexibility of the biogeneric tooth model. With the aid of the biogeneric tooth model, there is the possibility of reconstructing the occlusal surfaces of dental restorations by CAD/CAM processes fully automatically, taking account of morphological and functional criteria. Further studies are needed to show to what extent the inclusion of degree of abrasion, antagonist and adjacent teeth delivers the desired results in the whole spectrum of clinical cases.