Ulrich Karl Deisenhofer's research while affiliated with evaplan at the University Hospital Heidelberg and other places

Objectives: Guided implant surgery (GIS) requires alignment of virtual models to reconstructions of three-dimensional imaging. Accurate visualization of the tooth surfaces in the imaging datasets is mandatory. In this prospective clinical study, in-vivo tooth surface accuracy was determined for GIS using cone-beam computed tomography (CBCT) and dental magnetic resonance imaging (dMRI). Materials and methods: CBCT and 3-Tesla dMRI were performed in 22 consecutive patients (mean age: 54.4±15.2 years; mean number of restorations per jaw: 6.7±2.7). Altogether 92 teeth were included (31 incisor, 29 canines, 20 premolars and 12 molars). Surfaces were reconstructed semi-automatically and registered to a reference standard (3D-scans of stone models made from full-arch polyether impressions). Reliability of both methods was assessed using intraclass correlation coefficients. Accuracy was evaluated using the two one-sided tests procedure with a predefined equivalence margin of ± 0.2 mm root mean square(RMS). Results: Inter- and intra-rater reliability of tooth surface reconstruction were comparable for CBCT and dMRI. Geometric deviations were 0.102±0.042 mm RMS for CBCT and 0.261±0.08 mm RMS for dMRI. For a predefined equivalence margin, CBCT and dMRI were statistically equivalent. CBCT, however, was significantly more accurate (p ≤ 0.0001). For both imaging techniques, accuracy did not differ substantially between different tooth types. Conclusion: CBCT is an accurate and reliable imaging technique for tooth surfaces in vivo, even in the presence of metal artifacts. In comparison, dMRI in-vivo accuracy is lower. Still, it allows for tooth surface reconstruction in satisfactory detail and within acceptable acquisition times. This article is protected by copyright. All rights reserved.

Objectives To evaluate the diagnostic value of cone‐beam computed tomography (CBCT), intraoral radiography (IR), and dental magnetic resonance imaging (dMRI) for detecting and classifying peri‐implant bone defects at zirconia implants. Materials and Methods Forty‐eight zirconia implants were inserted in bovine ribs, 24 of which had standardized defects (1‐wall, 2‐wall, 3‐wall, 4‐wall) in two sizes (1 and 3 mm). CBCT, IR, and dMRI were performed and analyzed twice by four readers unaware of the nature of the defects. Cohen's and Fleiss' kappa (κ), sensitivity, and specificity were calculated for the presence/absence of bone defects, defect size, and defect type. Cochran's Q‐test with post hoc McNemar was used to test for statistical differences. Results A high intra‐ and inter‐reader reliability (κ range: 0.832–1) and sensitivity/specificity (IR: 0.97/0.96; CBCT: 0.99/1; dMRI: 1/0.99) for bone defect detection were observed for all three imaging methods. For defect type classification, intra‐ (κ range: 0.505–0.778) and inter‐reader (κ: 0.411) reliability of IR were lower compared to CBCT (κ range intrareader: 0.667–0.889; κ inter‐reader: 0.629) and dMRI (κ range intrareader: 0.61–0.832; κ inter‐reader: 0.712). The sensitivity for correct defect type classification was not significantly different for CBCT (0.81) and dMRI (0.83; p = 1), but was significantly lower for IR (0.68; vs. CBCT p = 0.003; vs. dMRI p = 0.004). The sensitivity advantage of CBCT and dMRI for defect classification was smaller for 1‐mm defects (CBCT/dMRI/IR: 0.68/0.72/0.63, no significant difference) than for 3‐mm defects (CBCT/dMRI/IR: 0.95/0.94/0.74; CBCT vs. IR p = 0.0001; dMRI vs. IR p = 0.003). Conclusion Within the limitations of an in vitro study, IR can be recommended as the initial imaging method for evaluating peri‐implant bone defects at zirconia implants. CBCT provides higher diagnostic accuracy of defect classification at the expense of higher cost and radiation dose. Dental MRI may be a promising imaging method for evaluating peri‐implant bone defects at zirconia implants in the future.

Objectives To evaluate the effect of small‐group education including practical training on dental students’ shade determination performance compared with a control group. Methods Sixty‐three non‐colour‐blind preclinical students were asked to participate and belonged to an intervention (n = 31) and a control (n = 32) group, respectively. All students received a lecture on dental shade determination. The members of the intervention group were educated and practically trained in small groups in addition. Ten volunteers, each with unrestored upper right middle and lateral incisors, were recruited. The students of both the intervention and control groups were then asked to determine the colour of the volunteers’ test teeth using the 3D‐Master shade guide (Vita Zahnfabrik, Bad Säckingen, Germany) under artificial daylight illumination. For analytical purposes, the CIE L*a*b* coordinates were obtained using a spectrophotometer. Colour differences, ΔE, between all shade tabs selected by the students and the natural teeth were calculated. ΔE observed in the intervention and control groups were compared using t tests. In addition, a multi‐level regression model was adjusted for age and gender. Results Mean (SD) ΔE between the shade tabs selected by the students and the natural teeth in the intervention and control groups were 3.8 (2.1) and 4.3 (2.3), respectively (P < .001). The effect of group membership was reproduced in multivariate analysis whereas age and gender did not reach statistical significance. Conclusions With more intensive education and practical training the ability to perform clinical shade determinations improved for students without previous clinical experience. The results obtained support the idea of implementing thematic small‐group education in the dental curriculum.

Objectives The study aims to evaluate the effect of electroplated telescopic removable dental prostheses (E-RDPs) with zirconia primary crowns on oral-health-related quality of life (OHRQoL). Materials and methods For E-RDPs, electroplating is used to produce precisely fitting gold copings on telescopic primary crowns. These copings are bonded intra-orally to the denture framework. Fifty-six participants in need of 60 removable restorations were randomly allocated one of two materials for the primary crowns: cobalt–chromium alloy or zirconia. OHRQoL was assessed by use of the 49-item Oral Health Impact Profile (OHIP-49) and by additional patient self-rating at baseline before treatment, and after 6 and 12 months. Statistical analysis was performed by use of one- and two-sample t-tests and analysis of covariance. Results Mean OHIP sum score at baseline was 53.4 (SD 37.4, 95 % CI 41.3–62). At follow-ups, it decreased significantly (after 6 months: mean 20, SD 26, 95 % CI 13–27.1; after 12 months: mean 16.4, SD 17.9, 95 % CI 11.6–21.2). The mean reduction in OHIP sum score after 12 months was 25 (SD 31.2, 95 % CI 13.1–36.9) for cobalt–chromium alloy and 44.4 (SD 32.3, 95 % CI 31.1–57.8) for zirconia. However, no statistically significant difference of the two materials on OHIP change or patient self-rating was detected. Conclusions Although OHRQoL was improved by using both cobalt–chromium alloy and zirconia primary crowns for E-RDPs, post-treatment differences between the groups were not statistically significant. Clinical relevance Zirconia E-RDPs enhance OHRQoL. However, zirconia primary crowns do not outperform cobalt–chromium alloy crowns regarding patient satisfaction—despite their tooth-like color.

Der Einsatz von Doppelkronen erlaubt neben der Anfertigung konventionellen Zahnersatzes auch die Herstellung implantatgetragener Restaurationen sowie die Kombination von Restzähnen und Implantaten. Es lassen sich starr abgestützte und resilient gelagerte Doppelkronenarten unterscheiden. Studien zu implantatgetragenen Doppelkronenprothesen zeigen homogene Überlebensraten auf einem sehr guten Niveau. Die vorliegende Evidenz zu zahnimplantatgetragenen Doppelkronenprothesen ist zwar geringer, es deutet sich jedoch an, dass diese ebenfalls hohe Überlebensraten aufweisen. Allerdings stellen die Kunststoffanteile von Doppelkronenprothesen eine Schwachstelle (Verblendungsabplatzungen, Kunststofffrakturen, Verschleiß von Prothesenzähnen) dar. Verglichen mit festsitzenden Versorgungen ist der Nachsorgebedarf als höher, verglichen mit tegumental getragenem Zahnersatz als geringer einzuschätzen.

The aim of this study was to evaluate a hands-on computer-assisted design/computer-assisted manufacture (CAD/CAM) module in a preclinical dental course in restorative dentistry. A controlled trial was conducted by dividing a class of 56 third-year dental students in Germany into study and control groups; allocation to the two groups depended on student schedules. Prior information about CAD/CAM-based restorations was provided for all students by means of lectures, preparation exercises, and production of gypsum casts of prepared resin teeth. The study group (32 students) then participated in a hands-on CAD/CAM module in small groups, digitizing their casts and designing zirconia frameworks for single crowns. The digitization process was introduced to the control group (24 students) solely by means of a video-supported lecture. To assess the knowledge gained, a 20-question written examination was administered; 48 students took the exam. The results were analyzed with Student's t-tests at a significance level of 0.05. The results on the examination showed a significant difference between the two groups: the mean scores were 16.8 (SD 1.7, range 13-19) for the study group and 12.5 (SD 3, range 4-18) for the control group. After the control group had also experienced the hands-on module, a total of 48 students from both groups completed a questionnaire with 13 rating-scale and three open-ended questions evaluating the module. Those results showed that the module was highly regarded by the students. This study supports the idea that small-group hands-on courses are helpful for instruction in digital restoration design. These students' knowledge gained and satisfaction seemed to justify the time, effort, and equipment needed.