Abstract
OBJECTIVES: This study was aimed at comparing the effects of incorporating pre-silane-treated commercial (StickNET) (Exp-I) and industrial-grade (Exp-II) glass fibers (GFs) into polymethyl methacrylate (PMMA) (control) on fracture toughness (FT), hydrolytic degradation, and micromorphology. MATERIALS AND METHODS: Specimens were prepared and tested according to the ISO 201795-1 (2013) guidelines for denture base materials. The FT of notched specimens (40 mm × 8 mm × 4 mm) was evaluated with a universal testing machine. Water sorption (WS), mass uptake, desorption, and solubility of the specimens (40 mm × 8 mm × 4 mm) were measured through drying, immersion in deionized water, and drying in a dry-heat oven at 38 °C. Micromorphological/chemical assessment of prepared and fractured specimens was performed with scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). RESULTS: Significant improvements in FT were observed after GF incorporation into PMMA. Exp-I showed the highest FT (3.96 ± 0.05 MPa m(1/2)) and was followed by Exp-II (3.94 ± 0.16 MPa m(1/2)) and the control (3.32 ± 0.18 MPa m(1/2)). Exp-I (22.09 ± 0.86 μg/mm(3)) and Exp-II (22.71 ± 2.49 μg/mm(3)) reinforced specimens had significantly lower WS (p < 0.05) than the control (25.65 ± 2.28 μg/mm(3)). The control exhibited the highest mean mass uptake (p < 0.05), whereas the desorption (p < 0.01) was highest for Exp-I at equilibrium. By contrast, Exp-I (1.22 ± 0.71 μg/mm(3)) and Exp-II (2.38 ± 0.45 μg/mm(3)) had higher solubility than the control (0.14 ± 0.06 μg/mm(3)). SEM surface imaging confirmed that both GFs had a woven design, and the fractured specimens in both groups revealed a brittle fracture type with void-free bonding between PMMA and GFs due to sufficient silane treatment. CONCLUSION: GF incorporation significantly increased the FT of PMMA, thus decreasing WS and increasing solubility. Morphologically, both unreinforced and GF-reinforced PMMA specimens exhibited a brittle fracture type, and GF incorporation resulted in void-free impregnation of the matrix. GF incorporation is recommended as a viable option for enhancing the FT of PMMA denture base resins.