An in-vitro evaluation of the flexural strength of heat-polymerized poly (methyl methacrylate) denture resin reinforced with fibers.

Fracture strength of denture base resins is of great concern and many approaches have been made to improve the fracture resistance of acrylic resin dentures by strengthening them. Purpose of the study was to assess the effect of a Novel pre-impregnated glass fiber reinforcement system and nylon fiber reinforcement on the flexural strength of conventional heat-polymerized poly(methylmethacrylate) [PMMA] denture resin under dry and wet storage conditions. Forty specimens of standard dimensions were prepared for each of the four experimental groups; unreinforced conventional acrylic resin and the same reinforced with unidirectional Stick (S) glass fibers, woven Stick Net (SN) glass fibers and nylon fibers. Each group was further subdivided into two groups of 20 specimens each on the basis of storage conditions (dry and wet). All 160 specimens were then subjected to a 3-point bending test and flexural strength was calculated. Statistical analysis was carried out using student t test and 1-way analysis of variance (ANOVA). Stick and Stick Net glass fiber reinforcements enhanced the flexural strength of conventional heat-cured PMMA denture resin. Specimens reinforced with Stick glass fibers exhibited highest flexural strength followed by those reinforced with Stick Net glass fibers. Nylon fiber reinforcement decreased the flexural strength of acrylic resin. All the specimens in the four groups stored under wet conditions showed decrease in flexural strength in comparison to those stored in dry conditions. The reinforcement of denture base resin with pre-impregnated glass fibers may be a useful means of strengthening denture bases. Use of nylon as a reinforcement fiber is not desirable as it decreased the flexural strength of acrylic resin.