Blue Laser for Polymerization of Bulk Fill Composites: Influence on dentin bond strength and temperature rise during curing and co-curing method.

Abstract

Blue diode lasers are alternative curing devices for dental composites. The aim of this study was to investigate the influence of blue diode laser polymerization on shear bond strength of bulk fill composites to human dentin and temperature rise during two types of polymerization. Composite cylinders of SDR Plus(SDR) and Ever X Flow(EX) were bonded to dentin slabs using Adhese Universal and curing devices blue diode laser (449nm, 1.6 W) and Power Cure LED. For each material and curing device there were two polymerization approaches: 1)conventional: separate curing of adhesive; 2)co-curing: simultaneous adhesive and composite curing. Polymerization modes for each material in conventional and co-curing(c) approach were: blue laser 2000 mW/cm2 for 5s (L5 and L5c); blue laser 1000 mW/cm2 for 10s (L10 and L10c); Power Cure 2000 mW/cm2 for 5s (LED5 and LED5c); Power Cure 1000 mW/cm2 for 10s (LED10 and LED10c). Temeperature was measured using thermal vision camera. For SDR, the highest bond strength was 24.3MPa in L10c, and the lowest 9.2MPa in LED5c. EX exhibited the highest bond strength(21.3MPa) in LED5, and the lowest in L5(7.7MPa). The highest temperature rise for SDR was in L10 and L5 (7.3 and 7.2°C), and the lowest in LED5(0.8°C). For EX, the highest temperature rise was in L5 (13.0°C), and the lowest in LED5 (0.7°C). Temperature rise was higher during blue laser polymerization, especially at high intensity and with conventional curing. Preferable blue laser curing mode is co-curing at 1000mW/cm2 for 10s.