The effect of length parameter on the repair strength of acrylic resin using fibers or metal wires.

Fractures of acrylic resin dentures occur quite often in prosthodontic practice. Autopolymerized acrylic resin is the most popular material for denture repair; however, it is significantly weaker than the intact heat-polymerized resin. Metal strengtheners or fibers have been used to reinforce the resin. This study investigated the fracture force, deflection, and toughness of a heat-polymerized denture resin that had been repaired either with autopolymerized resin alone or with autopolymerized resin that had been reinforced with metal wire or woven glass fibers. This study also investigated how these qualities were affected when the length of the strengthener was reduced. Sixty specimens were divided into six groups of ten (depending on the repair method), together with a control group of intact heat-polymerized resin specimens. The group repaired with autopolymerized resin alone reported significantly lower (p < 0.05) fracture force, deflection at fracture, and toughness when compared to the control. When metal wire or glass fiber at full or half-length was used for reinforcement, only the original fracture force was restored; deflection and toughness remained significantly lower (p < 0.05). Based on this study, it appears that the group reinforced with full lengths of metal wire offered the best potential for reinforcement.