PubMed ID (PMID): 21657122Pages 11-21, Language: English, GermanEnder, Andreas / Mehl, Albert
Die digitale intraorale Abformung ist inzwischen zu einem zentralen Bestandteil der CAD/CAM-Technik geworden. Ziel der vorliegenden Untersuchung war, die Genauigkeit (Richtigkeit und Präzision) von digitalen Abformungen des ganzen Kiefers mit der von konventionellen Abformungen am In-vitro-Modell zu vergleichen. Hierzu wurde ein Mastermodell mit einem neuen Referenzscan-Verfahren erfasst, dessen Messrichtigkeit bei ± 4,1 µm und Präzision bei ± 2,5 µm lag. Von diesem Mastermodell wurden zum einen konventionelle Abformungen und anschließend Gipsmodelle (n = 5), zum anderen digitale Abformungen mit der Cerec-AC-Bluecam und dem Lava- COS-System (je n = 5) erstellt. Die Gipsmodelle wurden ebenfalls mit dem Referenzscan-Verfahren vermessen. Die vorliegenden Datensätze wurden überlagert und die Differenzen bestimmt. Wie richtig die Abformmethode ist, definiert die Abweichung zum Mastermodell. Die Abweichungen der Modelle untereinander ergeben die Präzision der Methode. Die Richtigkeit der Abformungen lag in der Gruppe der konventionellen Abformung bei 55 ± 21,8 µm, für die digitale Abformung mit Cerec-Bluecam bei 49 ± 14,2 µm und bei der digitalen Abformung mit Lava-COS bei 40,3 ± 14,1 µm. Die Präzision lag bei 61,3 ± 17,9 µm für die konventionelle Abformung mit Impregum, bei 30,9 ± 7,1 µm für die digitale Abformung mit der Cerec-Bluecam und bei 60,1 ± 31,3 µm für die digitale Abformung mit Lava-COS. Die hier vorliegenden In-vitro-Ergebnisse zeigen, dass die digitale Abformung ähnlich genau wie die konventionelle ist. Diese Resultate müssen in weiteren klinischen Untersuchungen bestätigt werden.
Keywords: digitale Abformung, CAD/CAM, Genauigkeit, Präzision, Richtigkeit, Cerec-Bluecam, Lava-COS
PubMed ID (PMID): 21657123Pages 23-31, Language: English, GermanEllerbrock, Christof / Kordaß, Bernd
CAD/CAM methods are also being used ever more frequently to produce fully anatomical restorations. These automated, computer-assisted methods play an outstanding role in generating occlusal surfaces. This study examines whether such computer generated occlusal surfaces are comparable with those which an experienced dental technician functionally waxes-up in the individually controlled articulator. A comparison of the occlusal surfaces in twelve posterior teeth of eleven functionally healthy patients showed differences ranging from 380 to 530 µm related to the mean difference in volume between both types of occlusal surface. Furthermore, a mean pixel deviation of the superimposed occlusal surfaces of 5.12 ± 1.951 µm (min: 2.49 µm, max: 9.16 µm) was observed. These deviations were found for both functionless surfaces and occlusal surface areas of the functional occlusion. Thus, comparable occlusal surfaces can be achieved with computer generated methods, but they do not quite achieve the result of functionally waxed-up occlusal surfaces in the individually programmed articulator.
Keywords: functional occlusion, dynamic occlusion, occlusal surface design, computer generated occlusal surfaces, CAD/CAM method, CAD/CAM occlusion
PubMed ID (PMID): 21657124Pages 33-45, Language: English, GermanWiedhahn, Klaus
Two new developments extend the spectrum of the Cerec applications: Cerec-Connect: The entire mandible and maxilla can be scanned, as well as their relationship to one another, with the intraoral scanner. Multilayer technique for up to four-unit fixed dental prostheses (FDPs): the CAD-on technique from Ivoclar is the latest procedure in which a zirconium oxide framework and a veneer structure of e.max-CAD are bonded together by ceramic. Intraoral data acquisition with Cerec-Connect, design with Cerec-inLab and fabrication of the three-unit FDP are described and illustrated with a clinical case, and further developments are suggested.
Keywords: Cerec FDP, multilayer FDP, CAD-on technique, lithium disilicate FDP, impression-free dentistry
PubMed ID (PMID): 21657125Pages 47-53, Language: English, GermanMadan, Nishtha / Pannu, Karneev
The success of all-ceramic crowns and increased patient demand for metal-free, tooth-colored restorations has led to the development of many different restorative systems for all-ceramic fixed dental prostheses (FDPs). The most recent core materials for all-ceramic FDPs are the yttrium-tetragonal zirconia polycrystal (Y-TZP)-based materials. Yttrium oxide is a stabilizing oxide added to pure zirconia to stabilize it at room temperature and to generate a multiphase material known as partially stabilized zirconia. This exhibits very high flexural strength and fracture toughness along with good biocompatibility and excellent esthetics. This clinical report describes the use of the Lava All-ceramic system, based on Y-TZP, for the fabrication of two fixed dental prostheses (FDPs) in the maxillary anterior region of the patient, restoring both esthetics and function.
Keywords: all-ceramics, esthetics, crowns, fixed dental prostheses, CAD/CAM technology, zirconia
PubMed ID (PMID): 21657126Pages 59-66, Language: English, GermanKurbad, Andreas
Digital acquisition of the clinical situation in the mouth seems much more logical than digitizing the impressions. Intraoral scanning systems are laser supported or video based. The retraction of the gingiva plays a special part in the accurate display of the preparation border. The working procedures in the dental practice and in the dental laboratory have been changed fundamentally by this new technology. Workable solutions are already available and rapid further developments can be expected in the near future.
Keywords: CAD/CAM, digitization, impression, intraoral scanner, model production