The aim of this in vitro study is to investigate the bonding properties of a 3D-printable permanent composite material in comparison to milled composite materials. The tested materials are 3D-printed BEGO VarseoSmile Crown ^plus (VA1_ab, VA1_nt, VA2_ab, VA2_nt), Vita Enamic (EN1, EN2), and 3M Lava Ultimate (UL1, UL2) (N = 64; n = 8). For this purpose, all crowns are luted to polymer tooth stumps #46 (FDI) using dual-curing luting composite, strictly according to the manufacturer’s instructions. VA1_ab and VA2_ab are additionally airborne-particle abraded. 4 groups (VA2_ab, VA2_nt, EN2, UL2) are artificially aged (1,200,000 cycles, 50 N, 10,000 thermocycles), whereby no specimen has failed. All 64 specimens undergo pull-off testing until retention loss. The mean forces of retention-loss is 786.6 ± 137.6 N (VA1_nt, *), 988.6 ± 212.1 N (VA2_nt, *, Ɨ), 1223.8 ± 119.2 N (VA1_ab, Ɨ, ǂ), 1051.9 ± 107.2 N (VA2_ab, *, Ɨ), 1185.9 ± 211.8 N (EN1, Ɨ, ǂ), 1485.0 ± 198.2 N EN2, ǂ), 1533.8 ± 42.4 N (UL1, ǂ), and 1521.8 ± 343.4 N (UL2, ǂ) (one-way ANOVA (Scheffé method); p < 0.05; *, Ɨ, ǂ: group distribution). No characteristic failure modes can be detected. In conclusion, all of the pull-off forces reflect retention values that seem to be sufficiently high for clinical use. Additional airborne-particle abrasion of VA does not result in significantly better retention but can be recommended.

Purpose: Customized healing abutments are utilized to enhance aesthetics and peri-implant soft and hard tissue health, and play a crucial role in the implant-prosthetic workflow. This systematic review was performed to assess and compare the clinical outcomes of customized healing abutments with conventional ones. Methods: The review was registered with PROSPERO (ID: CRD42024532449) and followed the PRISMA-guidelines. The PICO-question addressed was: “In patients with dental implants, do customized healing abutments result in beneficial peri-implant conditions compared with conventional healing abutments?” Clinical trials involving immediate and late implant placement that compared different healing abutments based on quantifiable outcomes were included. The “PubMed”, “PubMed Central”, “Cochrane Library”, and “Web of Science databases” were screened for eligible studies until 4/20/2024. Results: Of 1,396 titles retrieved, 5 studies met the inclusion criteria and were analyzed. The included studies showed a low risk of bias as assessed by the RoB2 tool and Joanna Briggs Institute Critical Assessment questionnaire. Compared to conventional healing abutments, customized abutments were associated with a trend toward better clinical outcomes in peri-implant soft and hard tissue, as well as aesthetics. Several results within the cohorts using customized healing abutments showed significantly improved values in soft and hard tissue results as well as aesthetic parameters. Importantly, none of the included studies reported biological or aesthetic disadvantages associated with the use of customized healing abutments. Conclusions: Customized healing abutments maintain stability of peri-implant hard and soft tissue. However, further studies with larger sample sizes and longer follow-up periods are needed to validate these findings. Graphical

Purpose: This in vitro study aimed to investigate the long-term performance, stability, and fracture mode of monolithic hybrid abutment crowns, and the effect of different materials on the implant-abutment interface (IAI).Methods: Eighty monolithic hybrid abutment crowns luted on titanium bases were manufactured from 3Y-TZP zirconia (ZY3), “Gradient Technology” zirconia (ZY35), 5Y-TZP zirconia (ZY5), lithium disilicate ceramic (LDS), zirconia-reinforced lithium silicate ceramic (ZLS), polymer-infiltrated ceramic network (MHY), polymethylmethacrylate (PMA), and 3D-printed hybrid composite (PHC) (n = 10 for each material). Eighty implants (Camlog Progressive-Line, diameter: 3.8 mm) were embedded in accordance with ISO standard 14801, and crowns were mounted. After artificial aging (1.2 × 106 cycles, 50 N, thermocycling), intact specimens were loaded 30° off-axis in a universal testing machine until failure.Results: Seven specimens in the PHC group failed during artificial aging, and all the others survived. There were two subgroups based on the one-way analysis of variance and Dunnett’s test (p < 0.05) of the mean fracture load values. The first comprised Z3Y, ZY35, Z5Y, and LDS, with mean fracture loads between 499.4 and 529.7 N, while the second included ZLS, MHY, and PMA, with values in the 346.2-416.0 N range. ZY3, ZY35, ZY5, and LDS exhibited visible deformations of the implant shoulders with varying dimensions after load-to-fracture tests.Conclusions: Crowns made of LDS, ZLS, MHY, and PMA may act as potential stress breakers, and prevent possible deformation at IAIs. Further clinical studies need to assess if these materials also withstand relevant loads in-vivo.

Graf T, et al. J Adv Prosthodont. 2021 Dec;13(6):351-360. https://doi.org/10.4047/jap.2021.13.6.351

The thickness of a material has a significant impact on its fracture load. The aim of the study was to find and describe a mathematical relationship between the material thickness and the fracture load for dental all-ceramics. In total, 180 specimens were prepared from a leucite silicate ceramic (ESS), a lithium disilicate ceramic (EMX), and a 3Y-TZP zirconia ceramic (LP) in five thicknesses (0.4, 0.7, 1.0, 1.3, and 1.6 mm; n = 12). The fracture load of all specimens was determined using the biaxial bending test according to the DIN EN ISO 6872. The regression analyses for the linear, quadratic, and cubic curve characteristics of the materials were conducted, and the cubic regression curves showed the best correlation (coefficients of determination (R²): ESS R² = 0.974, EMX R² = 0.947, LP R² = 0.969) for the fracture load values as a function of the material thickness. A cubic relationship could be described for the materials investigated. Applying the cubic function and material-specific fracture-load coefficients, the respective fracture load values can be calculated for the individual material thicknesses. These results help to improve and objectify the estimation of the fracture loads of restorations, to enable a more patient- and indication-centered situation-dependent material choice.

Purpose: Hybrid abutment crowns (HACs) made from monolithic ceramics represent an efficient option for single restorations on implants. However, long‐term data are scarce. The purpose of this clinical trial was to evaluate the survival and complication rates of CAD‐CAM fabricated HACs over a time period of at least 3.5 years.Materials and Methods: Twenty‐five patients with a total of 40 HACs made of monolithic lithium disilicate ceramic bonded to a titanium base CAD‐CAM abutment were retrospectively evaluated. All implants and screw‐retained restorations were placed and manufactured in the same department of a university hospital. Only crowns that had been in service for more than 3.5 years were included in the study. HACs were evaluated regarding technical and biological complications. Functional Implant Prosthodontic Scores (FIPS) were obtained.Results: The mean observation time was 5.9 ± 1.4 years. Implant survival was 100%, and HAC survival was 97.5%. Over the observation period, one crown fracture was observed, necessitating refabricating of the restoration. Three minor biological complications were found. The overall mean FIPS score was 8.69 ± 1.12 points.Conclusions: Within the limitations of this study, monolithic screw‐retained HACs milled from lithium disilicate ceramics and bonded to titanium bases appeared to be a reliable treatment option over more than 3.5 years due to their low biological and technical complication rates.