Glass fiber reinforcement in PMMA dentures: Industrial vs. commercial fibers for enhanced physico-mechanical properties

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/mm³) and Exp-II (22.71 ± 2.49 μg/mm³) reinforced specimens had significantly lower WS ( p < 0.05) than the control (25.65 ± 2.28 μg/mm³). 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/mm³) and Exp-II (2.38 ± 0.45 μg/mm³) had higher solubility than the control (0.14 ± 0.06 μg/mm³). 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.