The composite resins used in this study were cytotoxic after 48 h pre-incubation, but this toxicity disappeared after pre-incubation in a biological medium for 7 days. Curing did not have a significant effect on the cytotoxicity of the composite materials tested.

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A Nalçaci • N Ulusoy • O Atakol Clinical RelevanceUnder the conditions of this study, when compared to standard QTH, both standard LED and high-intensity QTH light curing resulted in lower levels of the elution of TEGDMA, which is suspected to be the prime cause of cytotoxic reactions in resin composite restorations. SUMMARYThis study measured the elution of TEGDMA and BisGMA monomers from hybrid, micro-filled resin composites over 72 hours at different time intervals after polymerization with standard quartz-tungsten-halogen (QTH), high-intensity fast-curing QTH and standard blue light emitting diode (LED) light units. Samples were polymerized from the top and bottom surfaces, then immersed in methanol. High performance liquid chromatography (HPLC) was used to measure the amount of monomers released from the samples at various time intervals, ranging from 0 to 72 hours (0, 3, 6, 9, 12, 24, 48 and 72 hours). Data was analyzed using two-way ANOVA and Duncan tests with a significance level of 0.05. No significant differences were observed among curing groups in the elution of TEGDMA monomers at 0, 9, 12, 24, 48 and 72 hours; whereas, significant differences were observed among curing groups at 3 and 6 hours. BisGMA elution in samples immersed for longer periods (9-72 hours) were significantly higher than samples immersed for shorter time periods (0-6 hours); however, 72 hours appeared to be too short a period for the total elution of BisGMA into methanol.

Objective: The aim of this study was to examine the effect of temperature on fluoride uptake by enamel specimens from a 0.05% NaF-fluoridated mouthrinse (Oral-B Advantage; Oral-B Laboratories, Newbridge, UK).Methods: Enamel specimens were prepared from extracted human maxillary central incisors. A fluoride-specific ion electrode was used to measure the uptake from a 2 ppm fluoride solution containing 50.0 mL of distilled water, total ion strength adjustment buffer, and fluoridated rinse at 3 different temperatures (room temperature, 25°C; human body temperature, 37°C; hyper-fever temperature, 43°C). One-way analysis of variance and least significant difference were used to assess intragroup and intergroup differences (P<.05).Results: The study found that both the amount and the rate of fluoride uptake increased significantly with increase in temperature. This effect was particularly noticeable at 43°C.Conclusions: The temperature of the NaF mouthrinse may easily and safely be increased beyond room temperature by placing a container of the NaF mouthrinse in a bowl of hot water, allowing greater fluoride penetration into the enamel from the mouthrinse when used at home as a routine prophylactic agent. (Eur J Dent 2012;6:361-369)

The aim of this in vitro study was to compare the surfaces hardness of a nano-hybrid composite resin material by using different light curing units. Disc-shaped composite specimens (10 x 2 mm) were made using stainless steel mold. The resin materials were placed into the holes and covered by transparent mylar strips at the top and bottom. The material was compressed at both ends by glass slides 1mm thick. The light source tips of the curing units were positioned directly over the mylar strip. The specimens were polymerized for Group 1: halogen light curing unit (LCU) (600 mW/cm 2 ) with 40 seconds, for Group 2: light-emitting-diode (LED) LCU (400 mW/cm 2 ) with 40 seconds, for Group 3: LED LCU (1000 mW/cm 2 ) with 10 seconds and for Group 4: LED LCU (1000 mW/cm 2 ) with 20 seconds. After light curing the specimens were kept in 37°C distilled water for 24 hours. Three hardness readings on the top and bottom of each specimen were taken with Knoop Hardness Measurements. Statistical measurements were made by using one-way analysis of variance (ANOVA) and Tukey test. LED (1000 mW/cm 2 ) with 10 seconds LCU in group 3 showed lower top and bottom surfaces.