title: Curing efficiency of three different curing modes at different distances for four composites.
abstract: This study investigated the influence of the different curing distances with three polymerization modes in terms of the surface microhardness of four resin composites as a function of energy density. A hybrid resin composite and flowable composite from each of two manufacturers were evaluated. The specimens were polymerized with one of two light-curing units: 1) Mini LED AutoFocus (1500 mW/cm2) with a fast curing mode, for which two polymerization regimens were used: a) one AutoFocus function cycle and b) two AutoFocus function cycles, and 2) LEDemetron I (950 mW/cm2) with a 20-second curing time. Polymerization was performed with the curing tip at a distance of 0 mm, 3.0 mm, 6.0 mm, and 9.0 mm from the top surface of the specimen, and the power density of each light source was measured with a spectrophotometer. All specimens were stored in distilled water in a light-proof container at 37°C for 24 hours, and their top and bottom surface Knoop hardness numbers were determined. Microhardness data were submitted to two-way analysis of variance and multiple comparisons with a Tukey test. All statistical analyses were performed at a significance level of 0.05. Though the curing lights tested exhibited a decrease in power density with distance, the rate and extent of power density loss were not the same. The polymerization mode and curing tip distance had a significant effect on the composite microhardness. There was also a significant interaction among polymerization mode, curing tip distance, and microhardness. The curing ability of the three polymerization modes was ranked in terms of the hardness percent values: the LEDemetron I > two cycles of the Mini LED AutoFocus > one cycle of the Mini LED AutoFocus.
authors.affiliation: Department of Prosthetic Dentistry, JiLin University, JiLin, China.
authors.forename: S
authors.initials: S
authors.lastname: Zhu
authors.forename: J
authors.initials: J
authors.lastname: Platt
mesh_terms: D000704:Analysis of Variance; D003188:Composite Resins / Q000528:radiation effects*; D006244:Hardness; D006801:Humans; D055115:Light-Curing of Dental Adhesives / Q000295:instrumentation / Q000379:methods*; D012666:Semiconductors; D018709:Statistics, Nonparametric; D013997:Time Factors
chemical_list: D003188:Composite Resins