Composite Curing Issues during the Use of Transparent Polyvinyl Matrices

Objectives: To study the effects of increasing thicknesses of transparent polyvinylsiloxane matrices on depth of cure in conjunction with the thickness of composite resin utilizing two light sources (halogen and LED). Methods: Three thicknesses (3.0. 3.5, and 4.0 mm) of ring molds 8mm in diameter were filled with Dentstply TPH3 composite resin. Transparent Memosil 2 polyvinylsiloxane (PVS) matrices with thicknesses of 1.0, 2.0, and 3.0 mm, were individually placed over the composite resin samples and the composite was cured using 3M ESPE halogen light source for 20 seconds. Ten samples of each combination were made. Identical combinations were tested using Ultradent Lume 5 LED light source. Hardness of the cured composites was measured at five random locations on both the top and bottom of the samples in alternating sequence with the Barcol Hardness tester immediately after the curing of each specimen. A hardness ratio of 80% between top and bottom of the resin sample was the limit of acceptability. Results: Using 3-way ANOVA model, all three main factors such as light source (P=.003), thickness of polyvinylsiloxane (P<.0001), and resin (P<.0001) showed statistically significant effect. There is statistically significant interaction effect between light source and resin (P<.0001), but not for light source and PVS (P=.896). No statistically significant effect between thickness of resin and PVS (P=.978). A 3-way interaction effect among light source, PVS, and resin (P=.845) showed no statistically significant difference. Conclusion: A halogen light source exhibits better curing capability on the resin thickness of 3mm when compared to LED. Both light sources show similar results on resin thickness of 3.5mm. LED shows better outcome on the resin thickness of 4mm when compared to halogen. If the PVS thickness exceeds 2mm, the Barcol Hardness of resin declines. A resin thickness of 3.5mm or more will negatively affect the curing depth.