86 - Effect of varying functional monomers on marginal microleakage in self-adhesive composites.

To evaluate the marginal microleakage of novel self-adhesive composites bonded to enamel and dentin surfaces, without the use of an adhesive, in comparison to experimental conventional composite and a commercial control group featuring an adhesive. Sixty extracted sound human third molars were assigned to 6 experimental groups, according to the composite used. Five experimental self-adhesive composites were formulated, with urethane dimethacrylate (UDMA) as a base monomer, and triethylene glycol dimethacrylate (TEGDMA) as a diluent. To this mixture, 1 wt.% camphorquinone alone was added to all and 10 wt. % of distinct functional monomers, to four experimental groups - 10-MDP, HEAA, HEMA or GPDM (UT_10MDP, UT_HEAA and UT_HEMA and UT_GPDM respectively), leaving UT_CTRL with UDMA/TEGDMA only, as a negative control group. The powder phase comprised a hybrid barium glass/silica filler phase. Composites were mixed at a powder-liquid-ratio of 1.2/1 (centrifugal speed mixer 45 s, 1500 rpm). A positive commercial control group (OBFL) was also tested, where Optibond FL® and Filtek™ Z250 were used. Class V standardized cavities were prepared in each sample using a rotatory instrument calibrating platform. The composites were applied directly in thin layers without the use of any conditioning method/adhesive. Each increment was cured for 20 s with a LED blue light curing unit (LCU DB686; COXO Medical Instrument Co., Guangzhou, China), with a measured peak irradiance of 950 mW/cm2, at zero distance. All samples were stored in an incubator (37ºC, 24 h). Samples were further divided into two additional groups, based on artificial aging simulation (10 000 cycles at 5º/55º) or no aging (TC or 24 h, respectively). All samples were sealed and immersed in 0.5% basic fuchsin for 24 h. Each sample was sectioned in the occlusal-cervical direction and classified using a semi-quantitative scale. Statistical tests included Kruskal-Wallis and binomial analyses (α=0.05). There were no differences in microleakage score distribution among the formulated self-adhesive composites with functional monomers or the negative control group (for the occlusal and cervical margin at both aging conditions). All experimentals had > 40% chance of microleakage in both margins and aging conditions. UT_HEMA registered microleakage scores in all sample margins for both aging conditions. However, the OBFL group performed significantly better than all experimentals (p<0.05), with no microleakage score in all tested groups. Adding a functional monomer to a flowable composite does not seem to be enough to improve its sealing ability. Self-adhesive composites are still unmatched to classical dental adhesives. [ABSTRACT FROM AUTHOR]