CAD-designing of occlusal surfaces fulfilling all functional aspects still remain a work- and time-consuming task. Objectives: The aim of this study was to calculate automatically the coordinates of possible occlusal contact points solely from the information of static and functional (FGP) registrations. Methods: Casts of 39 various clinical inlay preparations were placed into an articulator. For each case, static and functional bite registrations (Regisil PB, UV Band) were produced. The cavities and the registrations were scanned three-dimensionally (etkon prototype) and registered by software positioning (Match3D). First, the real contact points on the cast were marked with an articulating film and photographs were taken. Second, difference images between the static bite registration and the tooth (process A) and difference images between the static and functional bite registrations (process B) were calculated and analyzed. Areas with differences less than 75 µm were selected as contact regions. These regions were compared with the real contact points shown in the photographs. Results: The accuracy of the registering process was 13µm (+/- 3µm). With process A, 34 out of 43 real occlusal contact points were detected by calculating the difference image (79%), 9 (21%) were not detected (false negative) and 8 (19%) did not coincide with the real contact points (false positive). Concerning process B, 32 calculated contact points coincide with the real 42 contact points (74%), 11 (26%) were false negative and 16 (37%) false positive. The number of false positive locations plus correct contact points can be interpreted as possible contact points. Conclusion: Only with the 3D-information of static and functional bite registrations the possible locations of contact points can be detected and integrated into an automatic occlusal reconstruction process of CAD/CAM-restorations f.e. using the biogeneric tooth model.

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