Comparison of Fracture Toughness of Unreinforced and Glass Fiber Reinforced PMMA Denture Base Resins

Objectives: To compare the maximum fracturing force and fracture toughness of notched unreinforced and glass fiber reinforced specimens
Methods: Preparation and testing of the specimens (n=12), measuring 4×8×40mm, was carried out according to the guidelines of ISO 20795-1 (2013). A “V” shaped mark was placed in the midline of each sample and a pre-crack (notch) having a depth of 3mm was introduced into the specimens along the midline. Notched specimens will be placed in water bath at 37˚C for 7 days. Glass fiber reinforced specimens were prepared by incorporating woven E-glass fibers at a volumetric concentration of 9%.
Prior to testing, each specimen was dried and placed on the supports of the UTM in such a way that the notch faced exactly opposite the load plunger. Force was increased from zero at a displacement rate of 1mm/min until either the maximum load had passed, the crack had almost reached the opposite side of the specimen or when the current load was reduced to 5%. Finally the maximum breaking force was calculated.
Results: Glass fibers reinforced specimens required significantly higher force to fracture (172.25 ± 6.86 MPa), compared with the unreinforced specimens (89.75 ± 2.65 MPa).
Conclusions: Incorporation of glass fibers in PMMA denture base resins can significantly enhance their resistance against fracture as well as crack propagation.