Reinforcement of Acrylic Removable Partial Denture Using Different Wire Positions

Purpose: This study investigated effect of wire reinforcement in different positions on the transverse strength of acrylic removable partial denture. Methods: Forty centrally-notched cylindrical heat-cured acrylic rods (90mm length x 8±0.4mm diameter) (Lucitone199 Dentsply International Inc., York, PA.USA) representing lower partial denture were randomly assigned to 4 test groups (n = 10) according to wire position. First group (G1) was without wire reinforcement (control), second group (G2) reinforced with buccally-placed wire, third group (G3) reinforced with lingually-placed wire and fourth group (G4) two- sided reinforcement with both buccally- and lingually-placed wires. All specimens were cured according to the manufacturer recommendations. The wire used was 20mm length and 1.2mm diameter (Remanium, Dentaurum, Pforzheim, Germany). Specimens were stored in distilled water at 37°C for 1 week before testing. Specimens were then subjected to four 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 strength (MPa) were: 16.35(2.41) for G1, 22.02(4.1) for G2, 19.58(6.7) for G3 and 30.61(7.03) for G4. ANOVA revealed high statistical significant difference among the means (P<.0001). Fracture away from the notch was observed in groups G2 &G4 while fracture within the notch was observed in the other two groups (G1,G3). Conclusions: It is concluded that two-sided wire reinforcement (buccally and lingually) for acrylic removable partial dentures resulted in highest fracture resistance followed by buccal reinforcement only. As a result clinically both-sided and buccal wire reinforcement would be expected to perform in a superior manner as compared to lingual reinforcement. Acknowledgements: To support obtained from Faculty of Dentistry, University of Toronto & Egyptian Ministry of Higher Education.