Flexural strength of a polymethylmethacrylate resin produced by computer-aided design and computer-aided manufacturing system after repeated usage of tungsten carbide burs and thermocycling

The purpose of this study was to examine how new and used burs affected the flexural strength of a polymethylmethacrylate resin produced by computer-aided design and computer-aided manufacturing system following thermocycling. A total of 40 rectangular-shaped specimens (14 mm×4 mm×1.2 mm) for flexural strength test were fabricated from one brand of a polymethylmethacrylate resin produced by computer-aided design and computer-aided manufacturing system. Half of the specimens (Group N) were milled using the new tungsten carbide bur set, while the other half (Group U) was milled using the used (250 machining time) tungsten carbide bur set. The specimens were subjected to flexural strength test before and after thermocycling. The One way Analysis of Variance and Duncan tests were used for statistical analysis. Group N had the highest mean flexural strength values, while Group NT (specimens milled with the new bur/before thermal cycling) had the lowest mean flexural strength values. New and used burs have an effect on the flexural strength of a polymethylmethacrylate resin specimens produced by computer-aided design and computer-aided manufacturing system. Thermocycling process have an effect on the flexural strength values of specimens milled with the new tungsten carbide bur.