Computer modeling of occlusal surfaces of posterior teeth with the CICERO CAD/CAM system

Statement of problem. Static and dynamic occlusal interference frequently n eeds to be corrected by selective grinding of the occlusal surface of conve ntional cast and ceramic-fused-to-metal restorations. CAD/CAM techniques al low control of the dimensional contours of these restorations. However, par ameters responsible for the occlusal form need to be determined. In most ar ticulators, these parameters are set as default values. Which technique is best for minimizing the introduction of occlusal interference in restoratio ns has not been determined. Purpose. This study investigated differences in crown structure of a crown designed in static occlusion (STA) with designs adapted for dynamic occlusa l interferences. Therefore, values from an optoelectronic registration syst em (String-Condylocomp, KAVO), an occlusal generated path (OGP) technique a nd default settings (DEF) were used in the CICERO CAD/CAM system. Material and methods. Morphology of CON, DEF, and OGP crowns was compared w ith that of the STA crown with respect to differences in a buccolingual sec tion and frequency of occlusal distances in an interocclusal range of 1 mm, measured from the occlusal surface of the crown. Results,;UI crown types f ulfilled the esthetic and morphologic criteria for restorations in clinical dentistry. Difference in the morphology of the OGP crown, compared with th at of the STA crown, was greater than that fur the CON and DEF crowns. Thes e differences were seen especially in the distobuccal part of the occlusal surface; however, the number of occlusal contacts was considered sufficient to stabilize occlusion. Conclusion, Functional occlusion, adapted to dynamic occlusion in a CICERO crown for the first mandibular molar, can be obtained using data acquired w ith the String-Condylocomp registration system. The OGP technique nas prefe rred to other techniques because of the simplicity of the technique for eli minating potential problems with opposing teeth during motion. However, thi s is achieved at the cost uf fewer points of contact during occlusion than with the CON crown.