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Purpose To evaluate the failure load of 3D-printed denture resin material and teeth before and after dynamic loading. Materials and methods A total of 40 specimens were fabricated following ISO/TS 19736 and were divided into two equal groups. In the test group, the cylindrical base and denture teeth were 3D printed separately and then luted together. In the control group, the specimens were fabricated from conventional heat-cured polymethyl methacrylate (PMMA) and commercially available denture teeth using the compression-molding technique. Ten specimens from each group were subjected to dynamic load of 50 N for 250,000 cycles in a chewing simulator. All specimens were subjected to static load of 50 N using Instron machine with a crosshead speed of 1 mm/minute until fracture. The fractured surfaces were analyzed using field emission scanning electron microscopy. The failure loads were calculated and compared using analysis of variance (P Results All specimens survived the loading, undergoing 250,000 cycles without fracture. The mean failure load was influenced by fabrication technique and was significantly higher for the 3D-printed test group (P = .028). 3D-printed teeth showed a mixed mode of fracture, whereas in the control group, the specimens showed cohesive fracture within the teeth. Conclusion The fabrication technique has an influence on the mode of failure between acrylic teeth and resin base material. Cohesive failure in teeth was predominant in the conventional group, suggesting possibly higher bond strength between the teeth and resin base in this group. The observed failure modes reveal that both fabrication techniques exhibited satisfactory bond strength. Chewing simulation did not significantly influence the bond strength of any of the tested groups.

Purpose To evaluate the effect of build direction on the surface roughness (Ra) of stereolithography (SLA) printed full-coverage anterior dental restorations before and after surface polishing. Materials and methods A total of 45 full-coverage dental restorations were 3D printed using the SLA additive manufacturing technique. Five groups were defined based on the build angles: 90, 120, 135, 150, and 180 degrees. The Ra was measured with the contact profilometer to evaluate the arithmetic average of the absolute Ra value on the labial surface before and after polishing procedures. Data were analyzed using two-way ANOVA, and statistical significance was set at α = .05. Results The highest Ra was recorded in specimens printed with the 90-degree build angle, whereas the lowest values were recorded in specimens printed with the 180-degree build angle (P = .000). In all groups, the Ra values measured after polishing were significantly lower than prepolished values (P = .000), with no difference among the different build angles. Conclusion Build angle significantly influenced the Ra of the SLA-printed full-coverage restorations. Polishing minimized the effect of build angle on the Ra. The 180-degree build angle is recommended when SLA printing an anterior restoration, as it provides the lowest Ra values and also requires a minimal support area and minimal number of support structures.

Purpose: The aim of the present study was to evaluate the effect of the build angle and the support configuration (thick versus thin support) on the dimensional accuracy of 3D-printed full-coverage dental restorations. Materials and Methods: A full-coverage dental crown was digitally designed and 3D-printed using stereolithography-additive manufacturing (SLA-AM) technology. Nine different angles were used during the build process: 90, 120, 135, 150, 180, 210, 225, 240, and 270 degrees. In each angle, the crown was printed using a thin and a thick support type, resulting in 18 specimens. The specimens were digitally scanned using a highresolution optical surface scanner (IScan D104i; Imetric 3D). The dimensional accuracy was evaluated by digital subtraction technique. The 3D digital files of the scanned printed crowns (test model), exported in standard tessellation language (STL) format, were superimposed with the STL file of the designed crown (reference model) using Geomagic Studio 2014 (3D Systems). Results: The root mean square estimate value and color map results suggest that the build angle and support structure configuration have an influence on the dimensional accuracy of 3D-printed crown restorations. Among the tested angles, the 120-degree build angle showed a minimal deviation of 0.029 mm for thin support and 0.031 mm for thick support, indicating an accurate fit between the test and reference models. Furthermore, the deviation pattern observed in the color map was homogenously distributed and located further away from the critical marginal area. Conclusions: Within the limitations of this study, the selection of build angle should offer the crown the highest dimensional accuracy and self-supported geometry. This allows for the smallest necessary support surface area and decreases the time needed for finishing and polishing. These properties were mostly observed with a build angle of 120 degrees combined with a thin support type.

Purpose: The purpose of this study was to determine the prosthodontic outcomes of one-piece zirconia implants and their attachment systems in edentulous participants with maxillary and mandibular overdentures after 1 year of a randomized controlled trial. Materials and Methods: Random allocation of 24 edentulous participants (age range: 45 to 86 years) into titanium (control) or zirconia (test) groups using onepiece implants and a planned unsplinted prosthodontic design was performed. Four maxillary implants (one midpalatal; three anterior crestal) and three mandibular implants (one midsymphyseal; two bilateral distal) were conventionally loaded with the overdentures. Similar attachment systems were used throughout: ball abutment–type patrices (diameter: 2.25 to 3.1 mm as part of the one-piece implants) and custommade plastic matrices (with or without metal housings depending on the patrix size). Prosthodontic outcomes were documented during the first year of the clinical trial. Results: Following three deaths and two dropouts, there were 19 participants who were available at the 1-year recall. Of these participants, 3 had early maxillary implant failure and had to be converted to conventional maxillary complete dentures opposing mandibular implant overdentures. There were 79 maintenance events, 34 in the titanium (control) group and 45 in the zirconia (test) group. Patrix loss occurred as a result of three zirconia implant fractures (one mandibular and two crestal maxillary implants). Maintenance events were principally the replacement of matrices and overdenture fracture. Although relines and replacement overdentures also occurred, overall there were no significant differences in prosthodontic maintenance between the control and test groups. A six-field prosthodontic-success analysis table showed no statistically significant difference between the two groups; however, 50% of participants in each group were allocated to the retreatment (repair) field, which produced a low prosthodontic success rate. Conclusions: Removable overdentures can be used on both one-piece titanium and zirconia implants with these attachment systems, due to no difference in prosthodontic maintenance and success. Before recommending routine use of a “metal-free” overdenture treatment option in clinical practice, consideration must be given to the success of the implants themselves

Limited clinical research identifies prosthodontic perspectives of novel designs for zirconia implants supporting overdentures. Four pilot study participants were selected before a planned randomized clinical trial on zirconia implants supporting overdentures. Novel designs for maxillary four-implant overdentures (quadrilateral design) and mandibular three-implant overdentures (tripodal design) were used with 28 implants (maxilla, n = 16; mandible, n = 12). Four implants failed to achieve osseointegration prior to loading. At the 1-year follow-up appointment, all implants were surviving, the overdentures were in function, and there were no clinical signs of wear of the attachment system. A proof-of-principle for prosthodontic perspectives of a novel design using one-piece zirconia implants supporting maxillary and mandibular implant overdentures was achieved.

The aim of this article is to systematically review the literature on prosthodontic maintenance requirements of maxillary implant overdentures with different prosthodontic designs.A standard approach of searching MEDLINE, PubMed, and Google Scholar databases as well as early online journal articles was followed. Hand-searching identified other relevant articles from the reference lists of the articles found. Selection criteria were details of prosthodontic maintenance related to different prosthodontic designs of maxillary implant overdentures, regardless of the dentition of the opposing arch or prosthesis.From a total of 58 relevant studies identified, only 18 met the criteria. Several categories were used to document the prosthodontic maintenance of maxillary implant overdentures, usually with four or more splinted or unsplinted implants using different attachment systems. Aspects of patrix and matrix maintenance were primarily reported, although soft tissue complications were described frequently. Subjective information on relines and the rationale for minimizing overdenture fractures was found.Prosthodontic maintenance requirements of maxillary overdentures are a direct consequence of the attachment system, together with differing numbers and distributions of implants. The reviewed literature does not provide a clear controlled indication of prosthodontic maintenance requirements of maxillary overdentures for different prosthodontic designs and attachment systems. Future standardization of maxillary implant overdenture design is recommended, and universally accepted criteria for reporting maxillary implant overdenture maintenance should be implemented to establish accurate comparative data analysis.