We use cookies to enable the functions required for this website, such as login or a shopping cart. You can find more information in our privacy policy.
May 1989-Aug. 1994: Study of Dentistry. Oct. 1994-Nov. 2005: Dental Prosthetics at the University of Erlangen. 2005: Habilitation. Dec. 2005-Sep. 2009: Dental Prosthetics at the University of Leipzig. Since Oct. 2009: Dental Prosthetics at the University Clinic Aachen (Director Prof. Dr. S. Wolfart). Since July 2012: W2 Professorship for the Teaching and Research Area of Computer-Aided Dentistry at the Clinic for Dental Prosthetics and Biomaterials.
Aim: To test four different measurement methods to evaluate deviations between planned and actual implant positions within a digital workflow applying 3D-printed surgical guides.
Materials and methods: A fully digital workflow was applied to simulate the single implant insertion to replace a maxillary missing central incisor and first molar in 10 gypsum casts (n = 10). Surgical guides (n = 10 per site) were printed by digital light processing for implant bed preparation and implant insertion. Four methods were used to analyze 3D deviations between the planned (target) and achieved implant positions: Methods 1 and 2 used an automated computer program (ACP) to assess deviations between the initial planning file and a file that represented the actual implant position either by the implant bed [ACP_BED] or by the inserted implant [ACP_IMP]. For Method 3, a standard tessellation language dataset representing the actual implant position was used and equipped with reference planes. This dataset was registered with the target planning, allowing manual measurements [MAN_MEAS]. Method 4 used a reverse engineering approach based on 3D high-resolution scans [REVERSE].
Results: Mean 3D deviations, including for anterior and posterior implant sites, ranged between 0.26 ± 0.11 mm [REVERSE] and 0.40 ± 0.09 mm [ACP_BED] at the implant shoulder, between 0.52 ± 0.24 mm [REVERSE] and 0.91 ± 0.24 mm [ACP_BED] at the implant apex, and between 1.68 and 2.35 degrees in angular deviation. Implant sites did not differ significantly, while some of the evaluation methods differed for shoulder and apex.
Conclusion: [REVERSE] revealed the smallest deviations between planned and actual implant position. 3D implant deviations were comparable with findings in the literature or even lower.
Keywords: digital light processing (DLP), 3D printing, static computer-aided implant surgery (s-CAIS), implant surgical guides, accuracy, trueness, evaluation methods
An increasing number of accuracy studies on 3D digitizing systems, especially intraoral scanning devices, are being published in scientific and educational journals. The methods, measurement values, and statistical parameters of these studies vary. Certain inconsistencies exist, which lead to difficulty in terms of interpretation and sometimes even questionable conclusions being drawn. These issues make it almost impossible to compare the results of such studies. One aspect inherent in this is the mutable use of basic terms describing the quality of measurement outcomes. A clear definition of such terms and clear instructions as to their respective calculation processes is essential for communication among scientists as well as for reporting measurement results to the dental community. Therefore, the aim of the present guideline is to provide a clear definition of the accuracy, trueness, and precision as the basic terms in the context of digital dentistry. The survey for this guideline included the application of ISO Norms and their expansion to special aspects concerning 3D data acquisition and, in particular, surface meshes. Additionally, the literature was screened to collect approaches, which can be seen as useful for dealing with these terms when performing different kinds of studies.
Keywords: intraoral scanning, accuracy, precision, trueness, ISO standard, 3D evaluation
Das Ziel dieser Studie bestand in der Evaluation der klinischen Qualität und Langzeitstabilität von chairside-hergestellten Lithiumdisilikatkeramikkronen nach 10 Jahren.
Keywords: Digitalisierung, Langlebigkeit, Vollkeramik, monolithische Kronen
International Journal of Computerized Dentistry, 4/2019
PubMed ID (PMID): 31840147Pages 381-388, Language: German, EnglishReich, Sven / Hartkamp, Oliver / Düringer, René / Lötzerich, Markus / Brücklmeier, Anna
The present application report describes a cast-free and chairside workflow that enables the manufacturing of monolithic restorations on custom-made abutments without damaging the periimplant soft tissue for impression taking. An easily achievable checklist for the individualization of standard abutments is presented so that the shape of the abutment is compatible with especially developed software after optical impressions. The principle of the method contains an extraoral impression of the finish line of the abutment and an intraoral impression that indicates the abutment position in relation to the adjacent teeth. The software needed for the semi-automated registration of the intra- and extraoral impression operates with .stl data and can be provided by the corresponding author on request.
Keywords: customized abutments, chairside, cast-free, registration, intraoral, scanner, software, finish line
An entirely digital concept has previously been proposed for the reconstruction of the occlusal plane in the case of wear-induced loss of the vertical dimension of occlusion (VDO). The concept, however, calls for a face scan. Since this technology is less frequently available than a facebow, the concept discussed in this article proposes a combination of analog and digital techniques. It takes into account the problem of redefining the occlusal plane in the case of occlusal alteration, and tries to avoid a situation where the chairside digital design of the occlusal surfaces is performed without any anatomical references. Such a situation poses a significant risk if the treatment indication for bite elevation exists in both the maxilla and the mandible.
Keywords: vertical relation, bite raising, chairside, CAD/CAM, planes, facebow, alternating, ceramic, composite
A 24 months pilot study using the intraoral digital impression technique
Aim: The aim of this in vivo study was to measure antagonist wear caused by polished monolithic posterior zirconia crowns over a 24-month period using the intraoral digital impression (IDI) technique.
Materials and methods: Thirteen zirconia crowns were placed in nine patients. The crowns and adjacent teeth were captured using an intraoral scanner (Lava C.O.S.). The corresponding antagonist teeth and the respective neighboring teeth were also scanned. Scanning was performed immediately after the restoration (baseline) as well as 12 and 24 months after crown placement. Geomagic Qualify software was used to superimpose the follow-up data sets onto the corresponding baseline data set, identify wear sites, and measure maximum vertical height loss in each individual wear site. Overall antagonist wear was then determined as the mean of wear rates measured in all of the individual antagonist units. In addition, wear rates in enamel and ceramic antagonists were analyzed as part of the scope of this study.
Results: The maximum mean wear with standard deviation (SD) in the overall sample with a total of nine patients, 13 antagonist units, and 98 evaluable wear sites was 86 ± 23 µm at 12 months, and 103 ± 39 µm at 24 months. The maximum mean wear in the enamel antagonist subgroup was 87 ± 41 µm at 12 months, and 115 ± 71 µm at 24 months; and in the ceramic antagonist subgroup 107 ± 22 µm at 12 months, and 120 ± 27 µm at 24 months.
Conclusions: The wear rates determined in this study are comparable to those of existing studies. The IDI technique of wear analysis can be carried out in a practical manner and produces useful results.
Keywords: wear, zirconia, monolithic, antagonist, clinical, digital, intraoral scan
In vitro feasibility study of vertical wear measurement
Aim: The aim of this study was to evaluate the difference in maximum height loss values obtained from datasets based on optical profilometry and intraoral scanning. Additionally, two analysis applications were tested with respect to their correspondence.
Materials and methods: To obtain baseline data, the occlusal surface of a metal phantom tooth was scanned by optical profilometry [WLP] and an intraoral scanner [IOS]. Then, wear was simulated at two locations of the tooth, three times each ([wear1], [wear2], and [wear3]), and the surface was captured after each status of wear, applying [WLP] and [IOS]. The maximum vertical height loss was evaluated by comparing the 3D datasets of [WLP] and [IOS] at [wear1], [wear2], and [wear3] with the baseline data of [WLP] and [IOS], respectively. For this purpose, two commercially available applications, Geomagic Qualify and Oracheck, were used.
Results: Apart from one outlier of 16% difference between the data obtained from [WLP] and [IOS], the maximum difference was 12.6%, which was equal to a metrical value of 15 µm. For the corresponding values, which were calculated with Geomagic Qualify and Oracheck at identical wear facets, maximum differences between +7% and -6.7% were obtained.
Conclusions: According to this in vitro study, the wear measurement on the basis of [IOS] seems to be a cost-effective, quick, and easily applicable tool for clinical screening purposes, with an acceptable reliability. With respect to the minor variations between each other, the Geomagic Qualify and Oracheck measurement applications are equivalent.
Keywords: profilometry, wear, digital, intraoral, impression, in vitro, analysis
The face scan can serve as a means for the visualization of planes relevant for extensive prosthetic reconstructions. The key prerequisite is the availability of data in stl format for further processing in different software programs. The method is described in this article by a patient case.
Keywords: face scan, reconstruction, prosthetic planes, digital impression, registration