The effect of glass fiber reinforcement on the fracture resistance of a provisional fixed partial denture

Purpose. This study determined the load required to fracture a three-unit provisional fixed partial denture restoration, which had been reinforced with an experimental glass fiber reinforcement. Material and methods. Provisional fixed partial dentures (n = 5) were fabricated from a resin of polyethyl methacrylate powder and n-butylmethacrylate liquid. The fixed partial dentures in the control group were unreinforced. In the other groups, the fixed partial dentures mere reinforced either with one, two, or three unidirectional glass fiber reinforcements and one glass fiber weave reinforcement. The load was applied to the fixed partial dentures by a steel ball placed in the cavity in the middle fossa of the pontic tooth. A longitudinal section of the fixed partial denture was made to determine the position of the reinforcements. Means were compared by analysis of variance. Results. The load required to fracture the unreinforced fixed partial denture was 614 N, while incorporation of one unidirectional reinforcement increased the load to 660 N, two reinforcements to 818 N, three reinforcements to 827 N, and three reinforcements with one weave reinforcement to 973 N. It was found that the unidirectional reinforcements were positioned on the side of the occlusal surface of the fixed partial denture, namely, the side of compression during loading. Conclusion. The results suggest that, even though the glass fiber reinforcements were positioned on the least favorable side of the fixed partial denture in terms of the physical properties of the materials, these reinforcements considerably increased the fracture resistance of the provisional fixed partial denture.