Wire Position Effect on Repaired Acrylic Removable Partial Denture Strength

Purpose: This study investigated effect of wire position on repaired acrylic removable partial denture strength. Methods: 40 fractured centrally-notched heat-cured acrylic rods (90mm length x 8±0.4 mm diameter) (Lucitone199, Dentsply) representing lower partial denture were randomly assigned to 4 test groups (n=10) according to wire position. Fractures were repaired with cold-cured acrylic resin (Hygienic, Coltene/Whaledent). In first group (G1) specimens were repaired without wire reinforcement (control), in second group (G2) specimens received wire-reinforcement on buccal side, in third group (G3) specimens received wire-reinforcement on lingual side and in fourth group (G4) specimens received wire-reinforcement on both buccal and lingual sides. Fractured segments were reassembled using stone mold and repaired according to manufacturer's instructions. Wire used was 20mm length and 1.2mm diameter (Remanium, Dentaurum). Specimens were stored in distilled water at 37°C for 1 week. Specimens were then subjected to 4 point bending test using Instron universal testing machine (model 8503) at crosshead speed of 5mm/minute .Load at fracture was recorded for each specimen. Data were statistically-analyzed using ANOVA at (p<.05). Results: Means and SDs of transverse strengths (MPa) for repaired acrylic specimens were: 10.9(4.5) for G1, 20(3) for G2, 11.2(2.6) for G3 and 25.7(3) for G4. ANOVA revealed statistically-significant difference among means (P<.0001). Fracture away from the notch was observed in specimens of two groups (G2, G4) while recurrent fracture within the notch was observed in other two groups (G1,G3). Conclusions: It is concluded that strength of repaired acrylic removable partial dentures could be enhanced using two-sided wire reinforcement positioned on buccal and lingual sides or alternatively wire reinforcement positioned buccally. This would decrease the incidence of fracture recurrence as compared to no reinforcement or wire placement on lingual side. Acknowledgements: To support obtained from Faculty of Dentistry, University of Toronto & Egyptian Ministry of Higher Education.