Profilometeric and SEM evaluation of effect of polishing on surface roughness of two composites [silorane-based and methylmethacrylate-based] and a Glass ionomer

To evaluate the effect of polishing on surface roughness of silorane-based composite using profilometery and Scanning Election Microscopy [SEM] and compare it with that of a methylmethacrylate- based composite and a glass ionomer. In this study, 3 groups [n=28] were tested: specimens of two composites [Filtek P90 and Filtek P60] and a glass ionomer [Fuji IX] which were prepared in polyethylene molds [4 mm diameter x10 mm Height]. Half of the specimens in each group were finished with 180-grit silicon carbide paper and the remaining were finished with 180-grit, and subsequently polished with 250, 400, 800, 1000, 2000, and 2500-grit silicon carbide papers. The surface roughness was evaluated using a contact profilometer and then mean [R[a]] and maximum [R[max]] of surface roughness were recorded. Then, the surface of 4 specimens of each subgroup was observed under SEM. Statistical analysis was performed with T-test, ANOVA and Dunnett T3 tests. In all materials, Ra was different between polishing with 180 and 2500-grit silicon carbide papers. In 180-grit group, only Ra of Filtek P60 and Fuji IX showed significant difference [P=0.01]. In 2500-grit group, there was no significant difference between the Ra of Filtek P60 and Filtek P90 [P=0.56]. Polishing is recommended for the glass ionomer and posterior composite restorations

effect of load cycling on microleakage of low shrinkage methacrylate base composite compared with silorane base composite and SEM evaluation of marginal integrity

Marginal seal in class V cavity and determination of the best restorative material in reducing microleakage is of great concern in operative dentistry. The aim of this study was to evaluate the effect of load cycling on the microleakage of low shrinkage composites compared with methacrylate-based composites with low shirinkage rate in class V cavity preparation. Marginal integrity of these materials was assessed using scanning electron microscope [SEM]. In this in vitro study, class V cavity preparations were made on the buccal and lingual surfaces of 48 human premolars and molars [96 cavities]. The specimens were divided into four groups each containing 12 teeth [24 cavities]: group 1 [Kalore-GC+ G-Bond], group 2 [Futurabond NR+Grandio[, group 3 [All Bond SE+ Aelite LS Posterior], group 4 [LS System Adhesive Primer and Bond+Filtek P90]. All the specimens were thermocycled for 2000 cycles [5-50°C]. In each group, half of the specimens [n=12] were subjected to 200,000 cycles of loading at 80 N. Epoxy resin replicas of 32 specimens [4 restorations in each subgroup] were evaluated using SEM and the interfacial gaps were measured. Finally, the teeth were immersed in 0.5% basic fuchsin dye for 24 hours at 37°C, then sectioned and observed under stereomicroscope. The data were analyzed using Kruskal-Wallis and Mann-Whitney U tests and the comparison between occlusal and gingival microleakage was made with Wilcoxon test. Within unloaded or loaded specimens, there were no significant differences in microleakage among four groups on the occlusal margins [P>0.05]. But there were statistically significant differences in microleakage between silorane and Aelite on the gingival margins [P<0.05]. No statistically significant differences were found between the microleakage of the loaded and unloaded groups on both occlusal and gingival margins for all materials [P>0.05]. Silorane did not perform better than the conventional low shrinkage methacrylate-based composite in terms of sealing ability [except Aelite]. Cyclic loading did not increase the extent of leakage in any groups

[Effects of leached components from a hybrid resin composite on the reproductive system of male mice]

In the present animal study, twenty adult Syrian male mice were divided into two groups of 10 mice each. In the test group, components which leached from samples made from Filtek Z250 resin composite into 75% ethanol were daily administered to the mice for 28 days. In the control group, the procedure was repeated in the same way as the test group but without placing composite samples in the solution. Then, the body weight, weights of paired testes, Gonado Somatic Index, sperm viability, sperm motility, epididymal sperm reserve and daily sperm production were recorded. Four male mice in each group were mated with untreated female mice for 10 days. After that, the number of pregnant females and number of infants were recorded. The data were analyzed using repeated measures ANOVA, Chi-square test and t-test. There was a significant reduction in the sperm viability and sperm motility of male mice in the test group compared to the control group [P=0.001]. There was no any significant differences in other parameters between two groups [P>0.05]. This study showed that the leached components from resin composites cannot cause infertility but they could potentially cause some adverse effects on the reproductive system of male mice.

effects of cured dentin bonding agents on secretion of pro-inflammatory cytokines, IL-1beta and TNF-alpha, by human monocytes

Dentin Bonding Agents [DBA] have been used as root-end filling materials. Present study evaluated the effects of polymerized DBA on secretion of pro-inflammatory cytokines by normal human monocytes. In this study, monocytes were directly isolated from human peripheral blood, and exposed to cured Scotch Bond 1 [single bond] and Prime and Bond for 36 and 72 hours. Secretion of IL-1beta and TNF-alpha in the presence of lipopolysaccaharide was evaluated in supernatants of monocyte culture. DBAs significantly caused reduction of cytokine production by human monocytes after 36 and 72 hours. Prime and bond exposure caused more prominent decrease in TNF-alpha production after 72 hours. We conclude that DBA in polymerized form can alter normal function of human monocytes