Background and Aim: Determining the best restorative material to decrease micro leakage in class V restorations is of great importance in operative dentistry. The aim of this in-vitro study was to evaluate the micro leakage of silorane-based COMPOSITES compared to low shrinkage methacrylate-based COMPOSITES in class V restorations.Materials and Methods: In this in vitro study, class V cavities were prepared on the buccal and lingual surfaces of 24 human premolars and molars (48 cavities). The specimens were divided into four groups of 6 (12 cavities) as follows: group 1 (LS System Adhesive, Primer & Bond + Filtek P90), group 2 (Kalore-GC+ Clearfil SE bond), group 3 (Clearfil SE bond + Grandio) and group4 (Clearfil SE bond + Aelite LS Posterior). All the specimens were thermo cycled for 2000 cycles (5-50oC).The teeth were then immersed in 0.5% basic fuchsin dye for 24 hours at 37oC, sectioned and observed under stereomicroscope. Data were analyzed using Kruskal-Wallis and Wilcoxon tests at a P<0.05 level of significance.Results: There were no significant differences in micro leakage among the four groups at the occlusal margin (P>0.05). But, there were statistically significant differences in micro leakage between Silorane and Aelite at the gingival margin (P<0.05).Statistically significant differences were also found in micro leakage between occlusal and gingival margins (except for Kalore and Silorane) (P>0.05)Conclusion: Silorane was not superior to the conventional low shrinkage methacrylate-based COMPOSITES except for A elite in terms of micro leakage.

Hybrid MMCs are a new class of materials that exhibit superior characteristics and functional response when compared to monolithic alloys and mono-reinforced MMCs, and thus have tremendous potential for widespread application in modern industrial and engineering applications. Since the manufacturing fraternity is proliferating, a cyclic evaluation of understanding the behavior of hybrid MMCs and their evolution is needed. Therefore, to address this necessity, this paper presents a detailed review of hybrid MMC manufacturing methods, materials (matrix and reinforcement) used, physicomechanical, tribological, and corrosion properties, and challenges associated with hybrid MMCs. This retrospective investigation presents the state of the art of hybrid MMC materials in the categories involving matrix materials and their alloys, ceramics reinforcements and secondary reinforcements, and the applications and formation of microstructures. This paper also discussed the overview and the status of various matrix and reinforcement materials in manufacturing hybrid MMCs using different fabrication methods. Further, the significant challenges associated with the fabrication of hybrid MMCs using different manufacturing methods, such as distribution of reinforcement, wettability, and other common limitations identified in the literature, are presented. This paper provides a broad-spectrum attitude on hybrid MMCs techniques, challenges, and future research directions.

Objectives: Repairing composite restorations is a challenging procedure especially when two different types of COMPOSITES are used. This study aimed to compare the repair strength of silorane-based composite (SC) (Filtek P90) with that of preheated SC, methacrylate composite (MC) (Z250), flowable MC (Filtek Supreme Plus) and different adhesive/composite combinations.Materials and Methods: Eighty-four SC specimens were fabricated and randomly divided into seven groups (G). In the control group (G7), SC was bonded immediately to SC. The other specimens were water-aged for two months and were then roughened, etched and repaired with the following materials: G1) Silorane Adhesive Bond (SAB) /SC, G2) Preheated SC, G3) SAB/MC, G4) Adper Single Bond (SB) /MC, G5) Flowable MC/MC, G6) Preheated MC. After water storage and thermocycling, the repaired specimens were subjected to shear bond strength testing. The data were analyzed using ANOVA and Tukey’s test.Results: Preheated SC and MC, flowable MC and SAB/SC resulted in bond strength comparable to that of the control group. Preheated SC showed significantly higher bond strength when compared to SAB/MC (P=0.04) and SB/MC (P<0.001). Bond strength of SB/MC was significantly lower than that of the other groups (P<0.05), except for SAB/SC and SAB/MC.Conclusion: All repairing materials except for SB/MC resulted in bond strength values comparable to that of the control group. Repair with preheated SC yielded the highest bond strength.

With the idea of exploring the biological activity of some newly synthetized chemical compounds and their combinations for development of novel antimicrobial collagen biomaterials, a serial investigation was initiated, starting with the preparation and biological activity study of Collagen/ ZnTiO3 nano- COMPOSITES. This serial investigation continued with the preparation and biological activity study of new collagen-based COMPOSITES in which self- prepared reduced graphene oxide (RGO) sheets were included as an antimicrobial agent. The new porous collagen/RGO COMPOSITES demonstrated specific antimicrobial activity to different types microbial species; well pronounced activity against Gram- positive microorganisms (Listeria innocua and Bacillus cereus, both bacteria with typical chains forming, large size cells, and Candida lusitaniae, fungus with specific micelle organization) and lack of activity against Gram- negative bacteria (Pseudomonas putida, Salmonella enterica, Pseudomonas aeruginosa, and Escherichia coli; all bacteria with small size cells) combined with lack of cytotoxicity to eukaryotic cells. For the first time, well-pronounced antifungal activity of collagen/ RGO COMPOSITES, depending on the RGO concentration was observed. Sterile zone of 17mmwas measured forC. lusitaniae on collagen/RGO composite, 2: 1 wt/wt. The possible mechanism of the biological activity of the new collagen/ RGO COMPOSITES was correlated with their characteristics and the specific cell morphology and size of the test microorganisms. The results of this investigation demonstrated that with their specific and adjustable bioactivity, the new collagen/RGO COMPOSITES are promising antimicrobial biomaterial for variety of biomedical applications, including tissue engineering.