Purpose: To assess the influence of the bonding system and restorative material on the marginal integrity and pull-off forces of monolithic all-ceramic crowns bonded to titanium base (ti-base) abutments. Materials and Methods: A total of 108 ti-bases were sandblasted and divided into nine experimental groups (n = 12) according to the combination of crown material (polymer-infiltrated ceramic-network [PI], lithium-disilicate [LD], and zirconia [ZI]) and bonding system (Multilink Hybrid-Abutment [MH], Panavia V5 [PV], RelyX Ul5mate [RU]) with the respective primers. After bonding the crowns to the ti-base abutments, the restorations were screw-retained on implants and thermomechanically aged (1,200,000 cycles, 49 N, 1.67 Hz, 5 to 55°C). Marginal integrity and bonding failures were evaluated under a light microscope, and pull-off forces (N) were calculated. Chi-square tests for marginal integrity as well as one-way and two-way ANOVA statistical tests for pull-off forces were applied (a = .05). Results: PI presented higher marginal integrity than LD (P = .023). Bonding system PV revealed higher marginal integrity than MH (P =.005) and RU (P =.029). Differences in pull-off forces were found between restorative material and resin cements (P < .001), with the highest values for ZI + RU (598 ± 192 N), PI + PV (545 ± 114 N), LD + MH (532 ± 116 N), and PI + RU (528 ± 81 N). Specimens with marginal integrity revealed higher pull-off forces than those with alteration (P = .006). Specimens presenting bonding failures (micromovements) showed lower pull-off forces than those without bonding failures (P < .001). Conclusions: The tested CAD/CAM materials show favorable bonding performances with different bonding systems, nevertheless for each restorative material a specific bonding system has to be recommended. Int J Prosthodont 2023;36:e88–e102

Purpose: Creating wax-ups of missing teeth for backward planning in implant surgery is a complex and time-consuming process. To facilitate implant-planning procedures, the automatic generation of a virtual wax-up would be useful. In the present study, the reconstruction of missing teeth in partially edentulous patients was performed automatically using newly developed software. The accuracy was investigated in order to test its clinical applicability. Materials and methods: This study presents a new method for creating an automatic virtual wax-up, which could serve as a basic tool in modern implant-planning procedures. First, a statistical shape model (SSM) based on 76 maxillary and mandibular arch scans from dentally healthy individuals was generated. Then, artificially generated tooth gaps were reconstructed. The accuracy of the workflow was evaluated on a separate testing sample of 10 individuals with artificially created tooth gaps given as a median deviation, in millimeters. Scans of three clinical cases with partial edentulism were equally reconstructed using the SSM and compared with the final prosthodontic work. Results: The reconstruction of the artificial tooth gaps could be performed with the following median reconstruction accuracy: gap 21 with 0.15 mm; gap 27 with 0.20 mm; gap 34 with 0.22 mm: gap 36 with 0.22 mm; gaps 12 to 22 with 0.22 mm; gaps 34 to 36 with 0.22 mm. A scenario for an almost edentulous mandible with all teeth missing except teeth 33 and 43 could be reconstructed with a median reconstruction accuracy of 0.37 mm. The median tooth gap deviation of the SSM-based reconstruction in clinical cases differed from the final inserted prosthodontic teeth by 0.49 to 0.86 mm in median. Conclusion: A first feasibility of creating virtual wax-ups using an SSM could be shown. Artificially generated tooth gaps could be reconstructed close to the original with the proposed workflow. In the clinical cases, the SSM proposes an anatomical reconstruction, which does not yet consider prosthodontic aspects. To obtain clinical use, contact with antagonist teeth must be considered and more training data must be implemented. However, the presented method offers a fast and viable way for the approximate placement of missing crowns. This could be used in a digital planning workflow when implant position must be determined. (Int J Comput Dent 2022;25(4):349–0; doi: 10.3290/j.ijcd.b2599407) Keywords: statistical shape model, virtual wax-up, partial edentulism, accuracy, implant planning

Die Diagnostik ist entscheidend für den vorhersagbaren Erfolg einer restaurativen Therapie. Hierbei müssen sich Patient und Zahnarzt vor der Anfertigung der definitiven Restauration auf ein gemeinsames Behandlungsziel einigen, um später Enttäuschungen zu vermeiden. Allerdings kann es schwierig sein, die Patientenwünsche vollständig zu erfassen. Ein nützliches Hilfsmittel zur Lösung dieses Problems sind das diagnostische Wax-up und Mock-up. Mit diesem zeitaufwendigen Verfahren wird jedoch nur eine einzige Variante des möglichen Behandlungsergebnisses visualisiert. Die moderne Digitaltechnik bietet nützliche Funktionen, die bei diesem diagnostischen Schritt zu einer Entscheidungsfindung beitragen können. Im vorliegende Beitrag werden die Möglichkeiten der Digitaltechnik für die prothetische Diagnostik erörtert und die Verfahren anhand von Patientenfällen beschrieben.

Purpose: To evaluate the effect of cementation protocols on the bonding interface stability and pull-out forces of temporary implant-supported crowns bonded on a titanium base abutment (TiB) or on a temporary titanium abutment (TiA). Materials and Methods: A total of 60 implants were restored with PMMA-based CAD/CAM crowns. Five groups (n = 12) were created: Group 1 = TiB/SRc: crown conditioned with MMA-based liquid (SR Connect, Ivoclar Vivadent); Group 2 = TiB/50Al-MB: crown airborne particle–abraded with 50-μm Al2O3 and silanized (Monobond Plus, Ivoclar Vivadent); Group 3 = TiB/30SiOAl-SRc: crown airborne particle–abraded with 30-μm silica-coated Al2O3 (CoJet, 3M ESPE) and conditioned with MMA-based liquid (SR Connect); Group 4 = TiB/30SiOAl-MB: crown airborne particle–abraded with 30- μm silica-coated Al2O3 (CoJet) and silanized (Monobond Plus); and Group 5 = TiA/TA-PMMA: crown manually enlarged, activated, and rebased with PMMA resin (Telio Lab, Ivoclar Vivadent). Specimens in the TiB groups were cemented using a resin cement (Multilink Hybrid Abutment, Ivoclar Vivadent). After aging (120,000 cycles, 49 N, 1.67 Hz, 5°C to 55°C, 120 seconds), bonding interface failure was analyzed (50x). Pull-out forces (N) (0.5 mm/minute) and modes of failure were registered. Chi-square and Kruskal-Wallis tests were used to analyze the data (α = .05). Results: Bonding failure after aging varied from 0% (Group 5) to 100% (Groups 1, 2, and 4) (P .001). Mean pull-out force ranged between 53.1 N (Group 1) and 1,146.5 N (Group 5). The pull-off forces were significantly greater for Group 5 (P .05), followed by Group 3 (P .05), whereas the differences among the remaining groups were not significant (P > .05). Conclusion: The cementation protocol had an effect on the bonding interface stability and pull-out forces of PMMA-based crowns bonded on a titanium base. Airborne particle abrasion of the crown internal surface and conditioning it with an MMA-based liquid may be recommended to improve retention of titanium base temporary restorations. Yet, for optimal outcomes, conventional temporary abutments might be preferred.

Die Diagnostik ist entscheidend für den vorhersagbaren Erfolg einer restaurativen Therapie. Hierbei müssen sich Patient und Zahnarzt vor der Anfertigung der definitiven Restauration auf ein gemeinsames Behandlungsziel einigen, um später Enttäuschungen zu vermeiden. Allerdings kann es schwierig sein, die Patientenwünsche vollständig zu erfassen. Ein nützliches Hilfsmittel zur Lösung dieses Problems sind das diagnostische Wax-up und Mock-up. Mit diesem zeitaufwendigen Verfahren wird jedoch nur eine einzige Variante des möglichen Behandlungsergebnisses visualisiert. Die moderne Digitaltechnik bietet nützliche Funktionen, die bei diesem diagnostischen Schritt zu einer Entscheidungsfindung beitragen können. Im vorliegende Beitrag werden die Möglichkeiten der Digitaltechnik für die prothetische Diagnostik erörtert und die Verfahren anhand von Patientenfällen beschrieben. Keywords: CAD/CAM, Mock-up, Visualisierung, additive Fertigung, 3-D-Druck

Purpose: To test the accuracies of different methods of digital vertical dimension augmentation (VDA) by comparison with a clinical situation. Materials and Methods: Bite registrations with approximately 5 mm of VDA were made in the incisor regions of 10 subjects (mean VDA 4.5 mm). The conventional maxillary and mandibular stone casts in maximum intercuspation (MICP) and VDA bite registrations were digitized for all subjects using a laboratory scanner (control group). Lateral portraits were taken of all subjects to locate the position of the condylar axis. Four different digital VDA methods were compared to the control group: 100% rotation of the mandible referring to the lateral picture (100RL); 85% rotation and 15% translation referring to the lateral picture (85R15TL); 100% rotation in normal mounting mode of the Trios virtual articulator (100R); and jaw-motion analysis (JMA) equipment. The amount of VDA for each experimental group was compared to the control group. The augmented distances between the central incisors and the second molars were measured using 3D analyzing software. The ratio of the augmented distances between the posterior and anterior regions (P/A ratio) was calculated. One-way analysis of variance and multiple comparisons via least significant difference test were carried out to determine statistical significance. Results: The P/A ratio of each group was as follows: Control = 0.61; 100RL = 0.55; 85R15TL = 0.61; 100R = 0.53; JMA = 0.52. Significant differences were observed for control vs JMA and for 85R15TL vs JMA (P .05). The addition of translational movement was the primary factor for increasing the accuracy of digital VDA, with the lateral picture being a secondary factor. Conclusion: VDA using a virtual articulator with 100% rotation induces an error when compared to the clinical situation. When a clinician performs digital VDA, the setting of 85% rotation and 15% translation produces results closer to the real clinical condition.

Background: Accurate implant placement in the bone is key to successful implant treatment. Once inserted, it can be difficult to correct the orientation of the implant axis, especially of a one-piece implant. Prosthetic-driven digital implant planning in combination with fully guided implant surgery can offer additional safety in such cases. Case presentation: The patient presented with a wide, edentulous interdental space extending from sites 13 to 16, which was to be restored with three one-piece zirconia implants supporting a zirconia fixed partial denture comprizing a cantilever to the mesial aspect. Digital planning based on DICOM (Digital Imaging and Communications in Medicine) and intraoral surface data was performed to ensure optimal positioning. Guided implant placement was executed using a contra-angle handpiece with special attachments and a compatible, sleeveless drill guide. Impressions of the implants for the final restoration were acquired using an intraoral scanner. Reflection-related errors were compensated for by using the given digital abutment geometry. The DICOM and STL datasets were superimposed and used as the basis for fabricating a monolithic zirconia restoration through a subtractive milling process. The final restoration was adhesively cemented. Conclusions: By using a prosthetic-driven implant planning strategy, it was possible to place the one-piece ceramic implants without an available implant manufacturer's guide-based solution. This was accomplished using a contra-angle surgical handpiece with special attachments and a compatible drill guide. This approach is particularly recommended for the placement of one-piece implants, which otherwise require irreversible abutment grinding for the adjustment of the implant axis orientation after placement. To increase the precision of the digital impressions of the implants, the ideal abutment geometry was imported and superimposed onto the scan data. The results demonstrate that the proposed method can dispense with the need for gingival retraction when acquiring impressions for implants of this type in the future. Keywords: ceramic implants, guided implant surgery, backward planning, intraoral scan, CAD/CAM, digital workflow,