Flexural properties of acrylic resin polymers reinforced with unidirectional and woven glass fibers

Statement of problem. Fiber-reinforced plastics for dental applications hav e been under development for some time. A major difficulty in using reinfor cing fibers with multiphase acrylic resins, such as powder-liquid resins, h as been improper impregnation of fibers with the resin. Purpose. The aim of this study was to describe and test a novel system to u se polymer-preimpregnated reinforcing fibers with commonly used multiphase acrylic resins. Material and methods. Continuous unidirectional and woven preimpregnated gl ass fiber reinforcements (Stick and Stick Net) were used to reinforce heat- curing denture base and autopolymerizing denture base polymers. A temporary fixed partial denture polymer was also reinforced with Stick reinforcement material. Five test specimens were fabricated for unreinforced control gro ups and for Stick- and Stick Net-reinforced groups. A 3-point loading test was used to measure transverse strength and flexural modulus of the materia ls and ultimate strain at fracture was calculated. Cross sections of test s pecimens were examined with a SEM to evaluate degree of impregnation of fib ers with polymer matrix. Quantity of fibers in test specimens was determine d by combustion analysis. Results. Transverse strength of heat-curing denture base polymer was 76 MPa , Stick reinforcement increased it to 341 MPa, and flexural modulus increas ed from 2550 to 19086 MPa. Stick Net reinforcement increased transverse str ength of heat-curing denture base polymer to 99 MPa and flexural modulus to 3530 MPa. Transverse strength of autopolymerizing denture base polymer was 71 MPa; Stick increased it to 466 MPa; and flexural modulus increased from 2418 to 16749 MPa. Stick Net increased the transverse strength of autopoly merizing denture base polymer to 96 MPa and flexural modulus to 3573 MPa. T ransverse strength of temporary tired partial denture polymer increased fro m 58 to 241 MPa and flexural modulus from 1711 to 7227 MPa. ANOVA showed th at reinforcement type and polymer brand affected transverse strength and mo dulus (P<.001). Stick Net reinforcement increased the strain at fracture, w hereas Stick reinforcement decreased the strain values. SEM examination rev ealed well-impregnated glass fibers with polymer matrix. Quantity of glass fibers varied from 6 to 28 vol-%, the lowest being with Stick Net reinforce ment and the highest with Stick reinforcement. Conclusions. Novel glass fiber reinforcements may considerably enhance flex ural properties of multiphase dental polymers, which is due to proper impre gnation of fibers with polymer matrix. By using Stick or Stick Net reinforc ement, the strain at fracture of the material can be modified.