Effect of Retainer Design and Materials on the Fracture Resistance of Anterior Cantilever Resin Bonded Fixed Dental Prosthesis

Document Type : Original Article

Authors

1 Postgraduate Student, Department of Fixed Prosthodontics, Mansoura University, Mansoura, Egypt

2 Associate Professor, Department of Fixed Prosthodontics, Mansoura University, Mansoura, Egypt

3 Professor, Department of Fixed Prosthodontics, Mansoura University, Mansoura, Egypt

Abstract

Aims & Background: Resin-bonded fixed dental prostheses (RBFDPs) are a conservative and minimally invasive treatment option for replacing missing tooth, particularly in the anterior region. This study aimed to evaluate the effect of retainer design and material type on the fracture resistance of anterior cantilever RBFDPs.
Materials and methods: Forty-eight sound human maxillary canines were collected, divided into two main groups based on retainer design (conventional palatal wing, groove modification palatal wing, and box modification palatal wing) and material type (zirconia and lithium disilicate). The RBFDPs were fabricated using CAD/CAM technology, cemented with resin cement, and subjected to 10 000 thermal cycles. Each specimen was subjected to axial loading until fracture using a universal testing machine. For each specimen, the failure load was recorded and failure mode was studied. Representative specimens were studied using scanning electron microscope. Data was analyzed using two-way ANOVA was used to analyzed the combined effect of study variables followed by the post hoc Tukey test (α=.05).
Results: The results showed that zirconia RBFDPs with groove modification exhibited the highest fracture resistance (265.57 ±27.42 N), while lithium disilicate RBFDPs with box modification showed the lowest fracture value (164.28 ±27.32 N). Two-way ANOVA test revealed a significant combined effect (P=.001) of design and material type. Adhesive failure was more common with zirconia compared to lithium disilicate exhibited more fracture failures.
Conclusion: Both material and design significantly affect the fracture resistance of RBFDPs, with groove-modified zirconia RBFDPs being the most resistant to fracture.

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Egyptian Dental Journal
Volume 71, Issue 3 - Serial Number 4
Fixed Prosthodontics, Removable Prosthodontics and Dental Materials
July 2025
Pages 2223-2235

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