Light-Curing Distance and Resin Thickness Effects on the Shortfiber–reinforced Resin Composites’ Depth of Cure

Abstract

Objective: This study evaluated the light-curing distance and resin thickness effects on the depth of cure of short fiber-reinforced resin composites (SFRCs). Methods:Fifteen SFRC specimens with a diameter of 6 mm and thickness of 4 mm were divided into groups (n=5) with light-curing distances of 0, 2, and 4 mm. Another 15 specimens with a diameter of 6 mm and thicknesses of 3, 4, and 5 mm (n=5) were subjected to a 0-mm light-curing distance. Microhardness tests were conducted using a Vickers hardness tester (load: 200 g; dwell time: 15 s), and the depth of cure was assessed by calculating the hardness ratio of the bottom to the top surface (%). Statistical tests included one-way analysis of variance (ANOVA) followed by post hoc Fisher's LSD tests. Results:The depths of cure with 0-, 2-, and 4-mm light-curing distances were 79.0±0.7%, 77.0±0.6%, and 75.0±0.8%, while those with thicknesses of 3, 4, and 5 mm were 81.0±1.0%, 78.2±1.0%, and 34.4±2.0%, respectively. Significant differences (p<0.05) in the depth of cure were found in all groups. Conclusion:A depth of cure >80% was only attained with a 3-mm resin thickness and 0-mm light-curing distance.

Influence of Polymerization Factors and Varying Shade Compositions of Bulk Fill Resin-Based Nanohybrid Composites on Under-Surface Temperature

“…Bulk fill resin-based nanohybrid dental composites are composed of a complex mixture of matrices, nanohybrid fillers, coupling agents, photoinitiators, and optical modifiers that may be polymerized in bulk to a depth of cure of up to 4-5 mm without needing the use of incremental techniques, thus have excellent mechanical properties [1][2][3][4]. In order to improve mechanical properties, more nanohybrid reinforcement fillers are added to the resin-based dental composites than the matrices, which are consisted of a group of crosslinked dimethacrylate monomers, including BisGMA (bisphenol A-diglycidylether dimethacrylate), UDMA (urethane dimethacrylate), TEGDMA (triethylene glycol dimethacrylate), and BisEMA (ethoxylated bisphenol A glycol dimethacrylate) [5][6][7][8][9]. The optical properties of resin-based composites can be improved by adding optical modifiers of metal oxide pigment to adjust the visual shade so that it more closely resembles dentin and dental enamel [9].…”