[EO-16] Evaluation of Connection between Co-Cr Retainer Alloy and Denture Base Resin Fabricated with CAD/CAM Technology
[Abstract]
[Objective]
The fabrication of removable partial dentures (RPD) using CAD/CAM technology has been under development. We have proposed a method for fabricating resin-based RPD using CAD/CAM1). However, one of the problems to be clarified is the connection between components. This study focuses on the connection between resin-based RPD's retainer and denture base. The purpose of the study was to evaluate the connection between Co-Cr retainer alloy and denture base resin fabricated with CAD/CAM technology.
[Method]
Bar specimens that mimicked the clasp tang were cast from the Co-Cr ingot using milled wax patterns. Test blocks for denture base resin were fabricated under three conditions: compression molding (CM) as a conventional technique, milling (ML), and additive manufacturing (AM). CM blocks were fabricated using heat-curing acrylic resin. ML blocks were milled from resin discs. AM blocks were fabricated via vat photopolymerization from resin ink. Co-Cr alloy burs and blocks were fixed using heat-curing resin for CM, autopolymerized resin for ML, and filled and cured to resin ink for AM. Eleven samples were made under each condition. One was cut using a cutting machine (Figure) and observed under a scanning electron microscope (SEM; SU6600, Hitachi High-Tech). The other ten samples were used to pull-out bars using the universal testing machine (AG-I 20kN, Shimadzu) at 1.5mm/min. Pull-out strengths were analyzed using Kruskal-Wallis and Steel-Dwass test (α=0.05).
[Results and Discussion]
The cross-sectional SEM images observed mechanical interlocking between bur and filled resin materials under all conditions. However, some bubbles were partially observed at the interface between bur and resin in AM. The median pull-out strength of CM, ML, and AM were 702N, 775N, and 667N, respectively; there was no statistically significant difference among the three conditions (p= 0.14). In conclusion, the strength of the connection in this study between Co-Cr retainer alloy and denture base fabricated by milling and additive manufacturing could be sufficient, suggesting that it could be clinically applicable.
[References]
1) Tasaka A, Mori R, Hirabayashi T et al. A new proposal for the workflow using CAD/CAM technology for fabrication of resin-based removable partial dentures. J Prosthodont Res 2023.
[Objective]
The fabrication of removable partial dentures (RPD) using CAD/CAM technology has been under development. We have proposed a method for fabricating resin-based RPD using CAD/CAM1). However, one of the problems to be clarified is the connection between components. This study focuses on the connection between resin-based RPD's retainer and denture base. The purpose of the study was to evaluate the connection between Co-Cr retainer alloy and denture base resin fabricated with CAD/CAM technology.
[Method]
Bar specimens that mimicked the clasp tang were cast from the Co-Cr ingot using milled wax patterns. Test blocks for denture base resin were fabricated under three conditions: compression molding (CM) as a conventional technique, milling (ML), and additive manufacturing (AM). CM blocks were fabricated using heat-curing acrylic resin. ML blocks were milled from resin discs. AM blocks were fabricated via vat photopolymerization from resin ink. Co-Cr alloy burs and blocks were fixed using heat-curing resin for CM, autopolymerized resin for ML, and filled and cured to resin ink for AM. Eleven samples were made under each condition. One was cut using a cutting machine (Figure) and observed under a scanning electron microscope (SEM; SU6600, Hitachi High-Tech). The other ten samples were used to pull-out bars using the universal testing machine (AG-I 20kN, Shimadzu) at 1.5mm/min. Pull-out strengths were analyzed using Kruskal-Wallis and Steel-Dwass test (α=0.05).
[Results and Discussion]
The cross-sectional SEM images observed mechanical interlocking between bur and filled resin materials under all conditions. However, some bubbles were partially observed at the interface between bur and resin in AM. The median pull-out strength of CM, ML, and AM were 702N, 775N, and 667N, respectively; there was no statistically significant difference among the three conditions (p= 0.14). In conclusion, the strength of the connection in this study between Co-Cr retainer alloy and denture base fabricated by milling and additive manufacturing could be sufficient, suggesting that it could be clinically applicable.
[References]
1) Tasaka A, Mori R, Hirabayashi T et al. A new proposal for the workflow using CAD/CAM technology for fabrication of resin-based removable partial dentures. J Prosthodont Res 2023.