Flexural strength and hardness of acrylic resin reinforced with fibers

Objectives: The objective of this study was to analyse the incorporation of glass fibers, not commercialized for odonthology purposes, in the flexural strength (FS) and hardness (Vickers) of the acrylic resin. Methods: Sixty four proof bodys (PB) were made from Dencor acrylic resin, devided into four groups: G1: mediate without fibers; G2 mediate with fibers; G3: immediate without fibers and G4: immediate with fibers. In groups 2 and 4, 0,250g of glass fibers was chopped and added to the resin mass. The FS test, using the test machine MTS- 810 with a load of 1 KN at 5mm/min., was done after 30 minutes the PB was made in groups 1 and 2 and after 48 hours in groups 2 and 4, during this period, the PB were stored in distillate water at 37ºC. The hardness was read at microhardness Micromet 2100 after the FS test, selecting the biggest fragment of each PB in a period up to 12 hours after the FS trial. It was made six lectures for each fragment with a load of 25 Kgf. The data were filled in Excel 2000 and submmited to a variance analisys. Results: The FS values in MPa were: G1 = 67.75; G2 = 82.43; G3 = 52.29; G4: 63.85; for the hardness (VHN) the values were: G1 = 12.47; G2: 12.00; G3 = 9.88; G4 = 8.51. Statistic differences between the groups were obtained; and the p values found for RF and hardness were respectively p=7.35E- 12 e p=1.08E-08 comparing the groups with and without fibers and p=4.96 E-16 e p=.043 refering to groups mediate and immediate. Conclusions: It was concluded that the incorporation of glass fibres in the acrylic resine increased the flexural strength and lowered the Vickers hardness with increase of these values as some destiled water was added.