Clinically, PMMA resin is extensively used for fabricating provisional FPDs. However, fracture often occurs due to the unsatisfactory mechanical strength, especially within connectors of long-span provisional FPDs. The purpose of this study is to evaluate the fracture load of fiber-reinforced provisional FPDs with various pontic span lengths, and to identify the most suitable span length for fiber-reinforced long-span provisional FPDs. Fifty-six provisional FPDs with various pontic span lengths were fabricated. Seven samples from each group were reinforced with glass fibers. Unreinforced counterparts served as control. The samples were fixed on the abutments after thermocycling and then received a fatigue test. Subsequently, they were mechanically loaded until fracture, and the initial fracture load and fracture patterns were recorded. Statistical analysis, including two-sample t-test, one-way, two-way ANOVA, Tukey-Kramer HSD post hoc analysis and χ2 test were used to evaluate mechanical performance. The mean fracture load of FPDs with 14 mm pontic span length is significantly higher than the other lengths. The fracture load of each reinforced group is significantly higher than each counterpart control. There is no interaction between two variables, pontic span and fiber reinforcement. With fiber reinforcement, the fracture patterns were altered from catastrophic fracture to bent or partial fracture. But, the fracture patterns were not affected by pontic span. The fracture load of acrylic FPDs decreases significantly when pontic span length is greater than 17 mm. Adding glass fibers into long-span provisional FPDs can significantly improve the fracture resistance and fracture patterns.

CAD/CAM technologies have been embedded into the fabrication of removable partial denture (RPD). Various materials such as zirconia and polyetheretherketone (PEEK) are developed for subtractive manufacturing. As for additive manufacturing, dental professionals have begun to use selective laser melting (SLM) techniques for fabricating metallic RPD frameworks. This report demonstrates a case rehabilitated with a maxillary telescopic crown-retained combining PEEK and zirconia material denture and a mandibular Kennedy Class I RPD fabricated with SLM techniques. First, a conventional impression was performed and the master cast was mounted with a centric relation record. Digital models were obtained using tabletop scanners and then the telescopic primary zirconia crowns were designed and milled. After transferring the intraoral distribution of primary crowns using pick-up impression, secondary PEEK crowns and framework were designed, milled, and veneered with composite resin. Mandibular framework was designed and constructed using SLM technique with Ti-6Al-4V. Definitive prostheses for both jaws were finished and delivered. Delivered prostheses functioned well for a one-year period. The was patient satisfied with the improvements in chewing function and esthetics. Both substrative and additive manufacturing techniques are suitable for framework fabrication. Further investigation is needed for improving the mechanical performance and long-term prognosis of digitally made prostheses.

This in vitro study investigated the accuracy and wear conditions of three drill sleeve distances (0.01, 0.02, and 0.03 mm) for 3D-guided stents in simulated clinical dental implant surgery. Fifteen sets of upper and lower partially edentulous epoxy tooling board models with four edentulous first molar sites were prepared in a Nissin Simple Manikin II and set on a dental chair. Sixty computer-aided design and computer-aided manufacturing (CAD/CAM) designed and guided stents with three drill sleeve distances were prepared in this study. The maximum height (Sz) of the wear roughness of drills, maximum deviation, and drilling time were observed. The highest maximum horizontal deviations were observed at the upper first molar (0.48 ± 0.12 mm, p < 0.001). The highest maximum vertical and angular deviations were observed at the lower left first molar (1.08 ± 0.35 mm and 5.61° ± 1.21°, respectively, p < 0.001). Only angular deviation significantly differed among the three drill sleeve distances (p = 0.046); the 0.03 mm distance exhibited the maximum angular deviation (3.92° ± 1.87°). The bigger drill sleeve distance (0.03 mm) was associated with more wear roughness (8.70 ± 2.29 µm) of the drills. Guided stents with varying drill-sleeve distances (0.01, 0.02, and 0.03 mm) exhibited no significant difference in preparation drilling time and abrasive wear. In practice, the optimal drill sleeve distance for single-type CAD/CAM-guided stents of dental implantation was 0.01 mm.