Purpose: This study aimed to investigate if the hardness ratio of the bulk-fill-type resin composite is higher than that of the hybrid-type resin composite, to determine when the radiant exposure was the same, and to investigate if the polymerization of resin composites at the top and bottom surfaces and the hardness ratio is affected by differences in irradiance light sources. Methods: The light-curing unit used was the LED G-Light Prima-II Plus (blue + violet LED) light-curing unit. The light-cured resin composites were hybrid-type Clearfil AP-X and bulk-fill flowable-type Gracefil BulkFlo. Composite specimens with 2-mm-thick were polymerized in Teflon molds using radiant exposure of 24 J/cm2. The light-curing methods were 1,100 mW/cm2 for 22 s and 600 mW/cm2 for 40 s. Just after light-curing, the Knoop hardness was measured at the top and bottom surfaces of each specimen using a hardness tester, and the hardness ratio was calculated. Results: The bulk-fill flowable type resin composite, Gracefil BulkFlo, showed a lower hardness ratio than the hybrid-type resin composite, Clearfil AP-X. When radiant exposure was the same, 600 mW/cm2 irradiance light created more uniform polymerization of the resin composite than 1,100 mW/cm2 irradiance light for both bulk-fill and hybrid-type resin composites.Conclusion: It was suggested that curing with an irradiance of 600 mW/cm2 for 40 s created more uniform polymerization for both materials.

Purpose: The aim of this study was to determine fluoride deposition by a fluoride-calcium-phosphate (FCP) of varying F:Ca:P ratios with the goal of maximizing the fluoride deposition at a fixed fluoride concentration of 12 mmol/L.Methods: The FCP solutions, prepared using NaF, CaCl2, H3PO4 and de-ionized water, had a calcium concentration of (7, 20, or 50) mmol/L, a phosphate concentration of (0.5, 2, or 10) mmol/L, and pH in the range of 2.73 to 3.43. A 12 mmol NaF solution was used as a control. A previously reported in vitro model was used for accessing fluoride deposition. The results were analyzed using multiple comparison with calcium and phosphate concentrations as the independent variables.Results: All FCP solutions were stable as expected. Both the calcium and phosphate concentrations effects and their interactions were significant (P < 0.01). Fluoride deposition, ranging from (3.08 to 4.57) µg/cm2, were at least 3.5 times greater than that produced by the NaF control. Higher calcium and phosphate concentrations did not necessarily increase fluoride deposition.Conclusion: FCP has the potential for use in fluoride rinses and dentifrices that will produce greater fluoride deposition without increasing the F dose.

Indirect composite restorations made of highly loaded light and heat polymerized material were applied to the mandibular premolars of a 23-year-old female patient. Enamel cavity margins were etched with phosphoric acid. Dentin surfaces to be bonded were treated with ferric chloride-citric acid solution, and coated with tri-n-butylborane (TBB)-initiated 4-META resin. Inner surfaces of the inlays were treated with phosphoric acid. The restorations were then seated with dual-polymerized composite luting agents. Although cavosurface discoloration, wear, loss of marginal integrity, and change in surface texture were detected, both restorations are still functioning after 33 years. Restorations made with such system is applicable for premolar class II cavities and have a favorable prognosis.