FRACTURE STRENGTHS OF PROVISIONAL RESTORATIONS REINFORCED WITH PLASMA-TREATED WOVEN POLYETHYLENE FIBER

Statement of problem. Fracture strength of interim fixed partial prost hesis is of great concern, especially in long-span restorations or are as of heavy occlusal stress. Purpose. Effects of a plasma-treated wove n polyethylene fiber (Ribbond) on the fracture strength of polymethyl methacrylate (Coldpac) and a resin-based two-phase curing provisional restorative material (Provipont DC) were evaluated. Material and metho ds. A polpvinyl siloxane template was used to fabricate three-unit pos terior provisional prostheses on a stainless steel die with two abutme nts 22 mm apart. The reinforced groups were fabricated by affixing 3 m m wide pieces of fiber treated with methyl methacrylate monomer or pol yisocyanate (activator part of Provipont DC) on the occlusal surfaces of abutments. The interim materials were mixed, according to the manuf acturers' specifications, and placed in the template. The template was pressed on the die and held secure until complete setting of the mate rial occurred by light curing (Provipont DC) or autopolymerization (PM MA). The specimens were divided into 4 groups of 10 each (A, reinforce d Provipont DC; B, unreinforced Provipont DC; C, reinforced PMMA; and D, unreinforced PMMA). A central compressive load force was exerted on the specimen to determine the fracture load of the restorations. Resu lts. The data revealed mean fracture loads of A, 65.59 +/- 11.27 kg; B , 46.59 +/- 14.84 kg; C, 53.46 +/- 7.76 kg; and D, 49.86 +/- 14.44 kg. Conclusion. Plasma-treated polyethylene reinforced PMMA restorations showed no significant increase in fracture loads when compared with un reinforced restorations (p > 0.10), whereas reinforced resin-based res torations revealed significantly higher fracture loads (p < 0.01) than the unreinforced resin-based and PMMA provisional restorations.