FRC Reinforcing Effect on The Flexural Strength of Acrylic Resins

Objective: Fractures of acrylic denture bases are a common problem in dentistry. Various reinforcement methods have been used to prevent recurrent fractures. The purpose of this study was to evaluate the flexural strength of two types of acrylic denture base resins (Meliodent and Acropars) reinforced with glass fibers.

Methods: Twenty-eight rectangular (10×70×3 mm) acrylic specimens were fabricated into 4 groups from 2 types of heat-cured acrylic resins (Meliodent and Acropars). After the fabrication, the specimens were cut from the mid point with a steel disc. Half of the specimens (Meliodent=7, Acropars=7) were reinforced with glass fibers (length 30 mm and depth 3 mm). A groove (36×3×2 mm) was created in center of the acrylic specimens. There were 2 control groups of acrylic specimens repaired without FRC* reinforcement. Specimens were subjected to 5.000 thermocycl. A 3-point flexural test was carried out using a universal testing machine (Zwick) by loading the center of the repaired site. The necessary load to cause a fracture was recorded for each specimen. All data were statistically analyzed using the T square Hotelling test.

Results: The average flexural strength of Meliodent acrylic specimens was 1.136 MPa. The average flexural strength of Acropars acrylic specimens was 1.156MPa (P=0.5). There is no statistically significant difference between them. The average flexural strength for the specimens reinforced with glass fibers was 1.523MPa. The average flexural strength in non-reinforced specimens was 0.769MPa. Flexural strength in the reinforced groups were significantly higher than non reinforced groups (P=0.00).

Conclusions: Fracture load and flexural strength for the two types of acrylic bases (Meliodent and Acropars) were approximately similar and there was no statistically significant difference between them, which indicates that these types of acryl were not efficient in the fracture load and flexural strength. The use of FRC improved the flexural strength in acrylic bases.