Effects of Reinforcement Materials and Mechanical Retention on the Flexural Strength and Deflection of Repaired Denture Base Resin

The increasing prevalence of denture base fractures among older patients underscores the clinical importance of effective repair strategies. The present study aimed to evaluate the effects of mechanical retention forms and reinforcement materials on the flexural strength and deflection of repaired denture base resin. Rectangular specimens (65 × 10 × 2.5 mm) were prepared from autopolymerizing resin and divided into seven groups: control (C), resin-only (R), primer-treated (RP), two interlocks (IL2), four interlocks (IL4), two parallel wires (W2), S-shaped wire (WS), and metal mesh (MM). Repairs were performed using autopolymerizing resin and tested under three-point bending (span: 50 mm; crosshead speed: 5 mm/min). The C group exhibited a flexural strength of 157.1 ± 14.3 MPa, while the R group showed the lowest (54.4 ± 10.2 MPa). Primer application improved strength to 92.2 ± 19.0 MPa, and wire reinforcement, particularly the W2 configuration, restored flexural strength comparable to the C group (163.5 ± 18.7 MPa). All repair groups showed reduced deflection relative to the C group, with the W2 group demonstrating the greatest preservation of flexibility (4.9 ± 1.0 mm vs. 7.7 ± 1.4 mm). These findings indicate that primer treatment combined with suitable reinforcement effectively enhances the mechanical properties of repaired denture base resin. Although full recovery of original strength and flexibility was not achieved, wire reinforcement provided superior load resistance, while metal mesh offered practical advantages for chairside or domiciliary repairs. Further studies on primer formulations and long-term durability are recommended to refine clinical repair protocols.