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With the emergence of commercial grafted caged silica (Polyhedral Oligomeric Silesquioxanes, POSS) having a three-dimensional (3D) morphology with peripheral functionality, new opportunities have been created for formulating dental adhesives and composites with enhanced mechanical and physical properties. The objective of the present study was to investigate the properties obtained by incorporating grafted caged silica into acrylate based dental composite and adhesive systems. Two commercial POSS materials (methacrylated and octaphenyl grafted) were added to dental restorative-glass-filled pre-polymers, based on BisGMA (bis-phenol A-glycidyldimethacrylate), HEMA (2-hydroxyethylmethacrylate) and TEGDMA (tetraethylglycidylmethacrylate). The nanostructured organic/inorganic hybrid compounds exhibited enhanced mechanical and thermal properties in cases where the POSS added was in concentrations up to 2 wt%. Beyond this threshold concentration, properties decreased due to agglomeration. In the case of the acrylated POSS, the T g increased by 5 • C, the composite compressive strength by 7%, and the bond shear strength by 36% and the shrinkage was reduced by 28% compared with neat dental composites and adhesives. Furthermore, in the case of octaphenyl grafted POSS, the compressive strength was reduced by 20%, the adhesive shear bond strength decreased by 49% and the shrinkage was reduced by 67%. It was concluded that the type of the grafted functional group of the caged silica was the dominant factor in nano-tailoring of improved dental composites and adhesives.

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A dental adhesive system was developed to yield a high bond strength to different substrates, enhanced durability, biocompatibility, and absence of interfacial microleakage. Such a system can be cured chemically (self-curing) or by visible light. Based on the assumption of an anaerobic character of the system's polymerization, the effect of the addition of an anaerobic accelerator (saccharin) on the curing mechanism was studied. Subsequently, the composition of the developed adhesive system and its curing conditions were evaluated and optimized. The developed adhesive compositions demonstrate high and durable bonding to dentin, enamel, porcelain, base and precious alloys, and amalgam, and can be used in different adhesive systems.