engleski

Real-time Light Transmittance and Temperature Monitoring of Experimental Remineralizing Composites

Objectives To investigate the changes in light transmittance and temperature during light- curing of experimental remineralizing composites. Additionally, simultaneous real-time transmittance and temperature measurements were used to gain information on polymerization kinetics. Methods Five light-curable experimental composites were prepared in a centrifugal mixer by blending a BisGMA/TEGDMA resin mixture with 45S5 bioactive glass (BG), barium glass and silica in variable ratios. Total filler load was 70 wt% and the ratio of BG was varied from 0-40 wt%. Three commercial composites were used as references. Uncured composite was applied in a black Teflon ring (diameter=6 mm, height=2 mm) and sandwiched between two glass plates. During the curing (LED, 30 s, 1200 mW/cm2 ), light transmittance and temperature were measured with a charge- coupled device array fiber spectrometer and a T- type thermocouple, respectively. Light transmittance and temperature data (n=6 per group) were collected by a custom-made computer program at 20 s-1 . Results Initial light transmittance values for BG-composites and commercial reference composites amounted to 5.0- 8.4% and 1.7-3.4%, respectively. During light- curing, the transmittance values increased to 8.6-15.3% for BGcomposites and 2.3-5.1% for the commercial references. Temperature rise during light-curing was higher for BGcomposites (12.2- 14.1 °C) than for the commercial references (9.7-12.6 °C). The share of the temperature rise attributable to the polymerization reaction exotherm showed an inverse relationship with the BG-filler loading and ranged between 3.1 and 5.6 °C. The exothermic peaks in temperature curves were shifted towards later times with the increasing load of BG. These findings, together with the shape of transmittance and temperature curves, suggest that higher ratios of BG may act to decrease the polymerization rate. Conclusions Experimental composites showed higher light transmittance and higher temperature rise than the commercial references. The possible effect of BG on polymerization kinetics should be confirmed by real-time measurements of monomer conversion.

Light Transmittance, Temperature Monitoring, Experimental Remineralizing Composites

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