Group 2 ITI Consensus Report: Technological developments in implant prosthetics.

OBJECTIVES: Group-2 reviewed the scientific evidence in the field of «Technology¼. Focused research questions were: (1) additive versus subtractive manufacturing of implant restorations; (2) survival, complications, and esthetics comparing prefabricated versus customized abutments; and (3) survival of posterior implant-supported multi-unit fixed dental prostheses. MATERIALS AND METHODS: Literature was systematically screened, and 67 publications could be critically reviewed following PRISMA guidelines, resulting in three systematic reviews. Consensus statements were presented to the plenary where after modification, those were accepted. RESULTS: Additively fabricated implant restorations of zirconia and polymers were investigated for marginal/internal adaptation and mechanical properties without clear results in favor of one technology or material. Titanium base abutments for screw-retained implant single crowns compared to customized abutments did not show significant differences concerning 1-year survival. PFM, veneered and monolithic zirconia implant-supported multi-unit posterior fixed dental prostheses demonstrated similar high 3-year survival rates, whereas veneered restorations exhibited the highest annual ceramic fracture and chipping rates. CONCLUSIONS: For interim tooth-colored implant single crowns both additive and subtractive manufacturing are viable techniques. The clinical performance of additively produced restorations remains to be investigated. Implant single crowns on titanium base abutments show similar clinical performance compared to other type of abutments; however, long-term clinical data from RCTs are needed. The abutment selection should be considered already during the planning phase. Digital planning facilitates 3D visualization of the prosthetic design including abutment selection. In the posterior area, monolithic zirconia is recommended as the material of choice for multi-unit implant restorations to reduce technical complications.

Trueness and Precision Achieved With Conventional and Digital Implant Impressions: A Comparative Investigation of Stone Versus 3-D Printed Master Casts.

OBJECTIVE: To analyze implant casts obtained from intraoral optical scanning and conventional impressions. MATERIALS AND METHODS: Ten optical scans (test) and ten conventional polyether impressions (control) were obtained from a two-implant reference model. Ten casts each were manufactured additively or from stone. All casts were digitized and virtually superimposed to the digital reference (trueness) applying a best-fit algorithm, and secondary analysis for intra-group comparisons (precision). The signed nearest neighbor distance of each surface point (FDI:24/26) was computed and deviations of the three-dimensional vectors (X,Y,Z) analyzed. The groups were compared with the Wilcoxon's rank sum test. RESULTS: The printed casts had mean deviations of 106.0µm and the stone casts 187.9µm compared to the reference. Controls had significantly higher deviations and dispersion (p⟨0.001). The printed casts showed mean intra-group deviations of 149.8µm and the stone casts 181.2µm without significant differences (p=0.162). There was no statistically significant difference in any of the vector analyses (X:p=0.105, Y:p=0.089, Z:p=0.123). CONCLUSION: Optical scanning seems to be an alternative to conventional impressions in terms of trueness and precision of implant master casts, simulating the scenario of a three-unit implant-supported fixed dental prosthesis. Digitally manufactured master casts might serve as reliable reference for the final restorations.

Disruptive Innovation in Dentistry: What It Is and What Could Be Next.

Dentistry is a technically oriented profession, and the health care sector is significantly influenced by the ubiquitous trend of digitalization. Some of these digital developments have the potential to result in disruptive changes for dental practice, while others may turn out to be just a pipedream. This Discovery! essay focuses on innovations built on artificial intelligence (AI) as the center-technology influencing 1) dental eHealth data management, 2) clinical and technical health care applications, and 3) services and operations. AI systems enable personalized dental medicine workflows by analyzing all eHealth data gathered from an individual patient. Besides dental-specific data, this also includes genomic, proteomic, and metabolomic information and therefore facilitates optimized and personalized treatment strategies and risk management. Based on the power of AI, the triangular frame of "data"/"health care"/"service" is supplemented by technological advancements in the field of social media, Internet of things, augmented and virtual reality, rapid prototyping, and intraoral optical scanning as well as teledentistry. Innovation continues to be critical to tackle dental problems until its routine implementation based on sound scientific evidence. Novel technologies must be viewed critically in relation to the cost-benefit ratio and the ethical implications of a misleading diagnosis or treatment produced by AI algorithms. Highly sensitive eHealth data must be handled responsibly to enable the immense benefits of these technologies to be realized for society. The focus on patient-centered research and the development of personalized dental medicine have the potential to improve individual and public health, as well as clarify the interconnectivity of disease in a more cost-effective way.

Effect of Thickness and Shade of Resin and Ceramic- Based Hybrid Materials on Color Masking Abilities and Optical Performance of CAD/CAM Materials.

Scientific data analysing color masking abilities of chairside CAD/CAM materials is lacking. The purpose of this in-vitro study was to evaluate the thickness and shade influence of three materials on their optical behaviour. Three materials: a) LD: Lithium disilicate glass ceramic (Emax, Ivoclar Vivadent), b) LDS: Lithium-disilicate-strengthened aluminosilicate glass ceramic (N!ce, Straumann) and c) RNC: Resin Nanoceramic (Lava Ultimate, 3M ESPE) were polished in different shades (A1,A2,A3) and thicknesses (0.1- 1.2mm). Specimens (N=108; n=36 per group) (12x12x1mm3) were positioned on resin composite base (Clearfil AP-X, Kuraray) in shade A3. Spectrophotometric measurements were performed and the parameters thickness, shade and material were analysed using three-way ANOVA, and pairwise T-tests (P-values ⟨ 0.05). Both the shade (p⟨0.001) and the interaction of material in correlation to thickness (p⟨0.001) were significant. Shade value A1-A3 comparisons were significant A1 vs. A2 (p=0.045); A2 vs. A3 (p=0.002); A1 vs. A3 (p⟨0.001)). A significant correlation of the material and thickness was observed when comparing LD and LDS (p=0.007) at the thickness of 0.1-0.4 mm. Masking abilities were influenced by material and thickness choice. Reinforced glass ceramics showed the best results in the smallest thickness tested (0.1-0.4 mm). LDS could be considered as an advantageous alternative in minimal-invasive cases.

In Vitro Static and Fatigue Behavior of Ceramic Occlusal Veneers Using CAD/CAM.

To evaluate fracture resistance of occlusal veneers made of glass-ceramic and zirconia with and without fatigue. Occlusal overlays (N=80; n=10 per group) were milled out of CAD/CAM materials, namely: a)LD:Lithium disilicate glass ceramic, b)LDS:Lithium-disilicate- strengthened aluminosilicate glass ceramic, c)ZLT:Zirconium dioxide ceramic and d)ZMT:Zirconium dioxide ceramic. The overlays were cemented on polymeric duplicates, randomly distributed to aging or non-aging conditions and loaded until fracture. Ultimate catastrophic failure strength(Fmax) and Initial crack formation load(Finitial) values were analysed using two-way ANOVA. For Finitial, material type and aging and their interaction resulted in significant values (p =⟨0.001). Finitial mean±SD values ranged from ZMTa (593 N ±205 N) to LDSb (118 N ±42 N). As for Fmax, the material type significantly affected the outcome (p⟨0.001), while aging type did not show an influence (p=0.795). The non-aged Fmax specimens values presented were: LDSa (877 N ±253 N)⟨LDa (2029 N ±412 N)⟨ZLTa (2049 N ±379 N)⟨ZMTa (2144 N ±333 N), LDSa being significantly lower (p⟨0.001). The aged Fmax values were: LDSb (1313 N ±599 N)⟨ ZLTb (1715 N ±453 N)⟨ZMTb (2018 N ±300 N)⟨LDb (2134 N ±289 N). LDS yielded significantly lower Fmax values without and non-significant less favourable results with aging. The mechanical properties following aging and lack of additional firing makes LDS an interesting restorative material for clinical application.

Precision of maxillo-mandibular registration with intraoral scanners in vitro.

PURPOSE: To compare the precision of maxillo-mandibular registration and resulting full arch occlusion produced by three intraoral scanners in vitro. METHODS: Six dental models (groups A-F) were scanned five times with intraoral scanners (CEREC, TRIOS, PLANMECA), producing both full arch and two buccal maxillo-mandibular scans. Total surface area of contact points (defined as regions within 0.1mm and all mesh penetrations) was measured, and the distances between four pairs of key points were compared, each two in the posterior and anterior. RESULTS: Total surface area of contact points varied significantly among scanners across all groups. CEREC produced the smallest contact surface areas (5.7-25.3mm2), while PLANMECA tended to produce the largest areas in each group (22.2-60.2mm2). Precision of scanners, as measured by the 95% CI range, varied from 0.1-0.9mm for posterior key points. For anterior key points the 95% CI range was smaller, particularly when multiple posterior teeth were still present (0.04-0.42mm). With progressive loss of posterior units (groups D-F), differences in the anterior occlusion among scanners became significant in five out of six groups (D-F left canines and D, F right canines, p<0.05). CONCLUSIONS: Maxillo-mandibular registrations from three intraoral scanners created significantly different surface areas of occlusal contact. Posterior occlusions revealed lower precision for all scanners than anterior. CEREC tended towards incorrect posterior open bites, whilst TRIOS was most consistent in reproducing occluding units.

Augmented and virtual reality in dental medicine: A systematic review.

BACKGROUND: The aim of this systematic review was to provide an update on the contemporary knowledge and scientific development of augmented reality (AR) and virtual reality (VR) in dental medicine, and to identify future research needs to accomplish its clinical translation. METHOD: A modified PICO-strategy was performed using an electronic (MEDLINE, EMBASE, CENTRAL) plus manual search up to 12/2018 exploring AR/VR in dentistry in the last 5 years. Inclusion criteria were limited to human studies focusing on the clinical application of AR/VR and associated field of interest in dental medicine. RESULTS: The systematic search identified 315 titles, whereas 87 abstracts and successively 32 full-texts were selected for review, resulting in 16 studies for final inclusion. AR/VR-technologies were predominantly used for educational motor skill training (n = 9 studies), clinical testing of maxillofacial surgical protocols (n = 5), investigation of human anatomy (n = 1), and the treatment of patients with dental phobia (n = 1). Due to the heterogeneity of the included studies, meta-analyses could not be performed. CONCLUSIONS: The overall number of includable studies was low; and scientifically proven recommendations for clinical protocols could not be given at this time. However, AR/VR-applications are of increasing interest and importance in dental under- and postgraduate education offering interactive learning concepts with 24/7-access and objective evaluation. In maxillofacial surgery, AR/VR-technology is a promising tool for complex procedures and can help to deliver predictable and safe therapy outcomes. Future research should focus on establishing technological standards with high data quality and developing approved applications for dental AR/VR-devices for clinical routine.

Esthetic and Clinical Performance of Implant-Supported All-Ceramic Crowns Made with Prefabricated or CAD/CAM Zirconia Abutments: A Randomized, Multicenter Clinical Trial.

Patients' esthetic expectations are increasing, and the options of the prosthetic pathways are currently evolving. The objective of this randomized multicenter clinical trial was to assess and compare the esthetic outcome and clinical performance of anterior maxillary all-ceramic implant crowns (ICs) based either on prefabricated zirconia abutments veneered with pressed ceramics or on CAD/CAM zirconia abutments veneered with hand buildup technique. The null hypothesis was that there is no statistically significant difference between the 2 groups. Forty implants were inserted in sites 14 to 24 (FDI) in 40 patients in 2 centers, the Universities of Bern and Geneva, Switzerland. After final impression, 20 patients were randomized into group A, restored with a 1-piece screw-retained single crown made of a prefabricated zirconia abutment with pressed ceramic as the veneering material using the cut-back technique, or group B using an individualized CAD/CAM zirconia abutment (CARES abutment; Institut Straumann AG) with a hand buildup technique. At baseline, 6 mo, and 1 y clinical, esthetic and radiographic parameters were assessed. Group A exhibited 1 dropout patient and 1 failure, resulting in a survival rate of 94.7% after 1 y, in comparison to 100% for group B. No other complications occurred. Clinical parameters presented stable and healthy peri-implant soft tissues. Overall, no or only minimal crestal bone changes were observed with a mean DIB (distance from the implant shoulder to the first bone-to-implant contact) of -0.15 mm (group A) and 0.12 mm (group B) at 1 y. There were no significant differences at baseline, 6 mo, and 1 y for DIB values between the 2 groups. Pink esthetic score (PES) and white esthetic score (WES) values at all 3 examinations indicated stability over time for both groups and pleasing esthetic outcomes. Both implant-supported prosthetic pathways represent a valuable treatment option for the restoration of single ICs in the anterior maxilla ( ClinicalTrials.gov NCT02905838).