International Journal of Computerized Dentistry, 02/2006

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.1 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 µm. 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. Keywords: CAD/CAM, occlusion, morphology

To date, CAD/CAM technology has made no noteworthy inroads into removable dentures. We want to present a new area of application for this in our study. Models of the maxilla and edentulous mandible were 3D scanned. The software detects and automatically reconstructs the reference structures that are anatomically important for the set-up of artificial teeth, such as the alveolar ridge centerlines and the interalveolar relations between the alveolar ridges. In a further step, the occlusal plane is semiautomatically defined and the front dental arch is designed. After these design features have been determined, artificial teeth are selected from a database and set up automatically. The dental technician can assess the esthetics and function of the suggested dental set-up on the computer screen and make slight corrections if necessary. Summarizing: The interplay of hardware and software components within an integrated solution including conversion of the "virtual" into a real positioning of prosthetic teeth is presented. Keywords: complete dental prosthetics, tooth set-up, computerized, simulation, virtual, occlusion

The adjustment of the static occlusion can be automated in computer-based systems. The Cerec 3D software makes it possible to take preformed occlusal surfaces from a database and adapt them to the antagonist. In this adaptation (settling), the CAD occlusal surface "settles" as whole or each cusp individually into the occlusal surface of the antagonist until stable occlusion is reached. Two occlusal surface shapes were compared: Vita Physiodens and Lee Culp. An index was formed from the number, quality, and position of the occlusal contacts for 35 model cases (25 molars, 10 premolars). With regard to the settling of the total occlusal surfaces, there were no differences between the two occlusal surface shapes. In "cusp settling" of the molars, Vita Physiodens® performed significantly better. In the comparison of the 1st with the 3rd settling process, significant improvements occurred the 3rd time in many cases when settling individual cusps, but in clearly fewer cases in the settling process of the total occlusal surface. The Lee Culp tooth occlusion improved especially after the 3rd settling process of individual cusps. It is therefore expedient to combine both settling versions with one another. Keywords: Cerec 3D, chairside, settling, occlusal surface

Purpose: The objective of this study was to compare resulting contact point patterns in the context of crown production with the Cerec 3D system. The contact surface patterns of full-ceramic crowns milled with the Cerec 3D system were examined for agreement with the corresponding virtually produced crowns. Materials and Methods: The agreement was determined with regard to the parameters number, size, position, and shape. Twenty-eight models were mounted centrally in a mechanical articulator. In these model cases, at least one second premolar and one first molar in the maxilla and mandible had to be prepared for crown production (preparation). A total of 50 teeth was prepared. Crowns were then designed with the aid of the Cerec 3D system. The crown designs were milled and integrated in the model. Silicone bite registrations, the contact point patterns of which were compared with the virtually designed crowns, were produced in static occlusion in the region of the crowns. Different evaluation methods were used for the comparison. Results: There was an agreement of 78% with regard to number, 76% in terms of localization, 65% regarding size, and 65% in terms of shape. Conclusion: It was thus confirmed that very good, highly reproducible results can be achieved with the Cerec 3D system. Keywords: CAD/CAM, Cerec 3D, fulceramic crowns, occlusal settling GEDAS - Greifswald Digital analyzing System

The clinical display of the occlusal contact points is an essential part of the quality control of restorative work. Normally, articulating paper of different colors, occlusion foil or special waxes are used for this. A possible digital method has to date been to display the contact points and their distribution using a pressure sensor foil (T-Scan system). Occlusion bites in a silicone material are also possible alternatives. The Greifswald Digital Analyzing System (GEDAS) displays the strength, extent and localization of static contacts in intercuspation (IP) based on digitized silicone registrations. In 10 completely dentulous test persons (age 23 to 29 years), with 3 different examiners as well as 2 examination times spaced 14 days apart, the intraindividual reproducibility of the contact relations resulted in kappa values of 0.92, 0.96 and 0.99, and the interindividual reproducibility was between 0.90 and 1.00. Different versions of the GEDAS software are presented, including explanation and discussion of the possibilities of use.

Individual masticatory patterns are similar to chaotic tangles of tortuous paths and are characterized by variability. The analysis of such masticatory patterns is therefore difficult. The new GEMAS software - Greifswald Movement Analyzing System - with which the variability of the masticatory function can be examined, is presented. Intersecting planes are placed through the orbit of the chewing cycles with which it is possible to wander from the intercuspal position up to the maximum mouth-opening position of the masticatory pattern. The opening and closing points are displayed in different colors. Zones where masticatory paths converge or diverge can be determined, including the fan or funnel-shaped entering and exiting movements close to the centric position and the extent of their spread. A special diagram visualizes the rhythmic sequence of entering and subsequent exiting movement. The relation between restricted variability or monotony and forms of disease of the masticatory system is indicated by reference to case examples. The more monotonous or stereotyped the chewing cycles are, the higher is the risk of permanent wear of anatomical structures. Attention should therefore also be paid to variability in the individual occlusal surface design of dental restorations. Keywords: Chewing patterns, masticatory movement, occlusion