Fracture resistance of fiber-reinforced PMMA interim fixed partial dentures.

PURPOSE To compare different fiber reinforcements on fracture toughness of interim polymethyl methacrylate materials and then use the best combination to determine the optimal position for fiber placement in an interim 3-unit fixed partial denture (FPD). MATERIALS AND METHODS In the first stage of the study, five groups of notched fracture toughness specimens were fabricated and loaded to failure (Instron): (1) unreinforced (control); (2) reinforced with pre-impregnated silanized E-glass fibers (Fibrestick); (3) cold plasma-treated woven polyethylene fibers (Ribbond triaxial); (4) pre-impregnated silanized plasma-treated woven polyethylene fibers (Construct); and (5) 1.0-mm-diameter stainless steel wire. In the second stage, the optimal position (occlusal, middle, or cervical third of pontic) for reinforcement with glass fibers (regimen 2) was tested by loading a 3-unit FPD to failure. All groups were compared with analysis of variance (alpha < 0.05). RESULTS The fracture toughness (in MPam(1/2)) for each reinforced group (Fibrestick 2.74 +/- 0.12, Construct fibers 2.59 +/- 0.28, Ribbond triaxial 2.13 +/- 0.20, and orthodontic wire 1.66 +/- 0.09) was statistically greater (p< 0.05) than for the unreinforced group (control = 1.25 +/- 0.006). Fracture loads for FPDs were greatest when the fiber reinforcements were placed in the cervical third (cervical = 1165 N). CONCLUSIONS The use of fiber and, to a lesser extent, orthodontic wire is an effective method to reinforce interim restoration resins.