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Background/purpose: Retainer debonding of resin-bonded fixed dental prostheses (RBFDPs) is one of the major reasons for their lower survival rates than fixed dental prostheses (FDPs) with full-coverage crowns. Recent advances in milling technology have enabled the fabrication of RBFDPs with complex retainers (D-shaped designs). This study aimed to assess the marginal fit and retention force of zirconia RBFDPs with inlay-, L-, and D-shaped designs to clarify their clinical applications. Materials and methods: Three abutment teeth models without maxillary second premolars were created using inlay-, L-, and D-shaped retainer designs. The zirconia RBFDPs were designed and fabricated according to the manufacturer’s instructions (n = 10). The marginal gap was measured using the silicone replica technique. Zirconia frameworks were bonded to the abutment teeth using resin cement. Tensile test was conducted after thermal cycling and dynamic loading tests. The loads during debonding or fracture were recorded. The failure pattern was analyzed by observing the fracture surface using a scanning electron microscope. Results: D-shaped RBFDPs showed a significantly larger marginal gap than inlay- and L-shaped RBFDPs (P

Background/purpose: High translucent zirconia has been used as a new monolithic zirconia prosthesis, which has the potential to make anterior resin-bonded fixed dental prostheses (RBFDPs) without veneering porcelain. However, it is unclear whether the RBFDPs retainer can be thinned as much as conventional zirconia RBFDPs. The aim of this study was to assess the usability of high translucent zirconia RBFDPs with a thin retainer thickness by evaluating differences in retainer thickness on the surface strain. Materials and methods: A model with a missing upper lateral incisor was used. The abutment teeth were upper central incisor and canine. Three types of RBFDPs were fabricated as follows: metal RBFDPs with a retainer thickness of 0.8 mm (0.8M), and high translucent zirconia RBFDPs with a retainer thicknesses of 0.8 and 0.5 mm (0.8Z, 0.5Z) (n = 10). The fitness of the margins was evaluated by the silicone replica technique. The surface strain of each retainer under static loading was measured and statistically analyzed using a t-test with Bonferroni correction. Results: The marginal fitness of all RBFDPs was under 76.1 μm, which was clinically acceptable. Each strain of the 0.8Z and 0.5Z groups was significantly lower than that of the 0.8M (p

Purpose: This study introduces a newly developed zirconia complete denture (ZrD) that incorporates a ceria-stabilized zirconia/alumina nano-composite framework fabricated with computer-aided design/computer-aided manufacture (CAD/CAM).Materials and Methods: Twenty-nine edentulous patients received either a maxillary ZrD (n = 10) or a maxillary conventional complete denture (CD) (n = 19). Patient satisfaction was evaluated before and 12 months after prosthesis placement using the McGill Denture Satisfaction Instrument.Results: During follow-up periods of up to 2 years, no denture fractures were found in the ZrD or CD group. All aspects of patient satisfaction improved, and no significant group differences were found.Conclusion: Within the limitations of this study, it can be concluded that maxillary complete dentures with nano-zirconia frameworks might be an alternative prosthetic treatment option. [ABSTRACT FROM AUTHOR]

This study aims to elucidate the relationships between the flexural strength and surface topography of composite resin blocks, utilized for the CAD/CAM system, after milling in various step-over amounts. The rectangular specimens were milled from CAD/CAM blocks with step-over amount 0.01, 0.02, 0.05, 0.1, and 0.2 mm; further, a three-point bending test was conducted to reveal the flexural strength. The surface morphology after milling was assessed by a 3D laser microscope. The surface roughness significantly decreased by reducing the step-over amount. Although there was significant association between the surface roughness and flexural strength by the Pearson correlation, the 95% confidence intervals of the flexural strength were between the mirror-polished and sand-blasted groups. These results suggest that a precise step-over amount enables us to obtain a smooth surface. Furthermore, the flexural strength of the rough surface milled by a large step-over amount caused no damage to the composite resin for CAD/CAM crown. [ABSTRACT FROM AUTHOR]

The purpose of this study was to evaluate the surface strain of zirconia fixed partial denture frameworks and their abutment rootswhen restored with two types of post and core materials. Artificial mandibular first premolars and second molars were used as theabutment teeth. Posts and cores were of two types: resin composite with glass fiber posts (RC) and cast platinum gold alloy (MC).The cores and 4-unit zirconia frameworks were bonded to the specimens. Static loading was applied to the occlusal surfaces, and thesurface strain of the frameworks and roots (distal premolar and mesial molar) was measured by strain gauge method. Premolar rootshowed a significantly higher magnitude of principal strain than molar root. RC showed a significantly higher magnitude of principalstrain than MC. The results suggest that MC restrain the surface strain compared to RC when the missing teeth are replaced by a4-unit zirconia framework. [ABSTRACT FROM AUTHOR]