International Journal of Computerized Dentistry, 03/2019

Objectives: Delamination and chipping are major complications of veneering material on zirconia-based all-ceramic restorations. The digital veneering technique was introduced to overcome these complications as both zirconia frameworks and veneering ceramic are fabricated by computer-aided design/computer-aided manufacturing (CAD/CAM). The aim of this review is to report all articles that evaluate zirconia-based all-ceramic restorations fabricated by the digital veneering technique. Three different digital veneering techniques were detected: the Lava DVS Digital Veneering System (3M ESPE), the Rapid Layer Technology (Vita Zahnfabrik), and the CAD-on technique (Ivoclar Vivadent). There are also some modifications of these techniques in the literature. Materials and methods: For this review, a comprehensive literature search was conducted. Detected studies are reported according to fracture resistance, flexural strength, wear performance, shear bond strength, microtensile bond strength, mechanical performance of restorations on implant abutments, marginal fit, color reproducibility, and clinical success for all types of digital veneering techniques. Results and conclusions: Anatomical framework design and digital veneering using lithium disilicate and fusion porcelain might decrease the risk of chipping and delamination of veneering ceramic on zirconia-supported all-ceramic restorations. However, this result is mainly supported by in vitro studies. More clinical studies with a large sample size, longer follow-up period, and different fixed dental prosthesis designs are needed. Keywords: digital veneering, zirconia, CAD-on, rapid layer, sintering technique

Aim: The purpose of this investigation was to evaluate the impact of print layer thickness and post-curing method on the degree of conversion (DC) of a three-dimensional (3D) print material for temporary restorations. Materials and methods: 120 specimens of the resin material NextDent C&B were additively manufactured in three different print layer thicknesses (25 µm, 50 µm, and 100 µm) using a DLP printer, and post-cured by either Labolight DUO (LL), Otoflash G171 (OF), LC-3DPrint Box (PB) or PCU LED (PCU). Each subgroup contained 10 specimens. Raman spectra were measured for the liquid state of the resin (n = 10), directly after printing (Rprint) and after post-curing (Rcured). DC and ΔDC were calculated. The data were statistically analyzed using the Kolmogorov-Smirnov test, the general linear model analysis together with partial eta-squared (ηP²), Kruskal-Wallis, and Mann-Whitney U tests (P < 0.05). Result: Specimens post-cured by OF showed the highest ΔDC, followed by specimens post-cured by PB, PCU, and LL (P < 0.001). Post-curing by PB, PCU, and LL resulted in the same ΔDC value range (P = 0.076 to 0.209). The print layer thicknesses of 100 µm and 50 µm (P = 0.931) showed higher ΔDC than the print layer thickness of 25 µm (P < 0.001). Conclusion: The choice of the post-curing method has a high impact on the DC of the tested 3D print material followed by the specific print layer thickness. Overall, specimens post-cured by OF showed the highest DC and ΔDC values. Brands Technology Duration Wavelength Manufacturer LC-3DPrint Box (PB) Ultraviolet light (UV) 30 min Range 315 to 550 nm, peaks at approximately 360 and 435 nm NextDent (Soesterberg, Netherlands) Otoflash G171 (OF) Flashlight, nitrogen atmosphere Two processes of 2000 flashes Range 300 to 700 nm, peaks at approximately 480 and 530 nm NK Optik (Baierbrunn, Germany) Labolight DUO (LL) Light-emitting diode (LED) Two processes of 3 min Range 380 to 510 nm, peaks at approximately 395 and 475 nm GC Europe (Leuven, Belgium) PCU LED (PCU) Light-emitting diode (LED), vacuum 5 min Peaks at approximately 410 nm Dreve (Unna, Germany) Keywords: degree of conversion, Raman spectroscopy, post-curing, 3D printing, additive manufacturing, print layer thickness

Aims: The aim of this study was to compare two existing methods and one novel method for measuring the distortion of three-dimensional (3D) models created with complete-arch digital impressions, and to assess the accuracy of different scan patterns using these methods. Materials and methods: Maxillary and mandibular models were imaged with the PlanScan intraoral scanner using four different scan patterns. Accuracy and distortion were assessed by comparing the master scans with the intraoral scans using the following three methods: 1) Mean surface deviation was measured after complete arch superimposition; 2) 28 points were selected identically on the experimental and on the master reference models, and the deviation between identical points was assessed after superimposition over the complete arch; 3) In the case of the novel technique, the superimposition was made only at the scanning origin, and after that the 28 points were compared. Results: Significant differences were found between the three different methods, regardless of the arch and pattern. The overall mean deviation between identical points when the models were aligned at the scanning origin was the highest, and the mean deviation between the non-identical values was the lowest. The novel method revealed local tooth-wise differences between the scan patterns as well as a pattern of amplified model error extending away from the scan origin. Conclusions: The novel method better detects the cumulative deviation of stitching errors in complete arch intraoral scans and is suitable to investigate the effect of scanning pattern in a very sensitive manner. Keywords: digital impression, intraoral scan, accuracy, scan pattern, deviation, stitching, registration, distortion

The application of robots in oral treatment can not only reduce the work intensity of clinicians but also improve the accuracy of treatment. In this article, the application and research status of robots in stomatology are reviewed. Keywords: robotics, stomatology, digital medicine

Objectives: The use of computer-aided design/computer-aided manufacturing (CAD/CAM) technology in restorative dentistry has increased significantly and should consequently be taught more intensively at university dental schools. This study describes the evaluation of a new CAD/CAM teaching concept. Methods: CAD/CAM technology was implemented into a 4th-year clinical student course according to Miller's pyramid principle. Fifty-eight students with no clinical experience participated in a 2-day theoretical and practical introductory course and rated its didactic outcome (Questionnaire 1). Students selected the fabrication method for indirect single tooth restorations during a 5-month patient treatment course. 54 conventional (e.max Press) and 68 CAD/CAM (Lava Ultimate) indirect Cerec-method restorations were fabricated and seated adhesively (Syntac, Variolink II). The success of the CAD/CAM integration was analyzed by the students, who were grouped according to their selected fabrication method (Questionnaire 2), as follows: Group A (CAD/CAM, n = 18); Group B (conventional and CAD/CAM, n = 17); Group C (conventional, n = 23). Results: The questionnaire ratings were expressed as a percentage of the number of students' answers and are presented as diagrams. 95% of all the students in all the groups wanted CAD/CAM technology to be integrated into the subsequent (5th-year) clinical course. The rating for the CAD/CAM introductory course on a scale of 1 (very good) to 6 (poor) was 1.86 on average for the theoretical part, and 2.20 for the practical part. Statistically significant differences were found among the technology groupings (Pearson's chi-squared test, P < 0.05). Conclusions: CAD/CAM technology was highly welcomed by the 4th-year students and was introduced successfully into the clinical student course. Students tended to favor technology in accordance with the extent of its clinical application. Keywords: curriculum innovation, curriculum development/evaluation, evaluation of clinical performance, self-assessment, teaching assessment, teaching methods, advanced dental education, undergraduate teaching, CAD/CAM, Cerec, clinical implementation

This case report describes the digital and clinical workflow of a guided endodontic access approach in a mandibular central incisor with pulp canal calcification (PCC). The access to the remaining pulp space was planned virtually using cone beam computed tomography (CBCT) and the Sicat Endo software (Sicat, Bonn, Germany). Sicat produced the corresponding Accessguide after matching a digitized cast model and the virtual treatment plan. The clinical access was prepared using a carbide bur with a diameter of 1.2 mm. After the root canal was localized successfully, it was disinfected chemomechanically, dried, and obturated using a warm vertical compaction technique. Keywords: calcification, CBCT, guided endodontics, root canal treatment, Sicat Endo

A patient with arthrogenic temporomandibular dysfunction (TMD) complaints presented. In addition to a clinical diagnosis, an instrumental one with Sicat Function (Sicat) was performed. For this purpose, movements of the mandibular function were recorded with an ultrasonic-based measuring system (JMT+) and correlated with cone beam computed tomography (CBCT) image data. A reference tray (FusionBite) ensured spatial agreement. In addition, full-arch scans taken with the Cerec Omnicam intraoral scanner (Dentsply Sirona) were matched to the CBCT data. From the movement data, a biomechanically optimized joint position was determined, for which an occlusal splint was milled. Subsequently, the functional result achieved was retained with computer-aided design/computer-aided manufacturing (CAD/CAM) temporary restorations and tabletops and was monitored with Sicat Function until delivery of the final rehabilitation. To this end, the movements were tracked with the JMT+ after each treatment step. The reference tray was successively adapted and augmented so that the original jaw relation in the FusionBite could be maintained, which guaranteed comparability with the initial situation without the need for an additional CBCT image. Sicat Function has proven to be an excellent system supporting a digital workflow in situations where controlled bite-position changes are indicated in patients with arthrogenic TMD complaints. Keywords: instrumental digital functional diagnostics, Sicat Function, CAD/CAM, Cerec, digital workflow, TMD diagnostics, digitally guided bite-position change