Purpose: The mechanical and physical properties of implant screw access opening deteriorate if composite resin is not polymerized properly. Therefore, this study aimed to analyze the effect of using composite resin in implant access opening on the degree of conversion (DC).
Materials and methods: Two prosthetic materials (Co-Cr and zirconia), two types of composite resin (low and high viscosity), two light-cured resin depths (2 and 3 mm), and two polymerization methods (max-mode 10 s and mid-mode 20 s: 16 and 22 J/cm2 , respectively) were considered (n = 192). The DC of the polymerized composite resin was measured through Fourier-transform infrared spectroscopy. The top and bottom surfaces of the polymerized composite resin body were observed through scanning electron microscopy. Multiple linear regression analysis and analysis of variance were used to identify significant differences in DC (α = 0.05).
Results: The DC was lower when the low-viscosity composite resin (β = -0.431), light-polymerized resin depth of 2 mm (β = -0.430), zirconia prosthesis (β = -0.191), and mid-mode polymerization method (β = -0.164) were used. The resin type, depth of resin to be light-cured, prosthesis material, and polymerization method had an effect on the DC.
Conclusions: Low-viscosity composite resin should be polymerized at a low irradiance and long polymerization time (such that the light-cured resin depth does not exceed 2 mm) to ensure proper composite resin polymerization in implant screw access opening.
Keywords: composite resin; degree of conversion; photopolymerization; screw access opening.
© 2022 by the American College of Prosthodontists.