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Manfred Wichmann

Publications and source records attributed to Manfred Wichmann.

20 records · Page 2Linked to original sources

Articulator-related registration--a simple concept for minimizing eccentric occlusal errors in the articulator.

PURPOSE: The purpose of this study was to develop an easy-to-use procedure for individual registration and to test its accuracy. Unlike common principles, the method should be based on a transfer of the articulator geometry to the patient. MATERIALS AND METHODS: The system consists of an articulator holding a bite plate in a standard position. The bite plate connects to an electronic recording system, which transfers the articulator's condylar points virtually to the patient's mandible by a centric relation record. The trajectories of the transferred points are recorded during mandibular protrusions and laterotrusions. From the trajectories, sagittal condylar and Bennett angles are measured and are adjusted at the articulator after mounting of the casts via the bite plate. Using a mechanical testing device, the accuracy of the measured angles was examined by comparison with preset values varying from 10 to 60 degrees (condylar angle) and from 0 to 40 degrees (Bennett angle) in 10-degree increments. RESULTS: The mean deviations of measured condylar angles from preset values ranged between 1.5 and 0 degrees. The mean deviations of the Bennett angles ranged from -0.5 to -1.3 degrees. CONCLUSION: The transfer of articulator geometry to the patient reduces the number of individual parameters necessary to imitate jaw motion to the condylar and Bennett angles. This leads to a significant simplification in registration and cast transfer. Since the required parameters are recorded with high accuracy, the method could be an alternative to traditional sophisticated instrumental registration.

Centric Relation↗

A comparative study of two CEREC software systems in evaluating manufacturing time and accuracy of restorations.

This study compared the manufacturing times and the accuracy of proximal and occlusal contacts on restorations produced by two different versions of CEREC 3 software, COS and 3D. Fourteen casts containing pre-existing inlay and onlay preparations of premolars and molars were mounted on articulators. A bite registration was made in maximum intercuspation. Optical impressions of the preparation and the bite registration were made. The Wilcoxon signed rank test was applied for a statistical analysis of time expended in the different design and manufacturing steps of both software versions. The chi-square test was applied for the statistical analysis of proximal and occlusal contacts.

Ceramics↗