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 degrees 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.

With the emergence of commercial hyper-branched (HB) and dendritic polymers, having a three-dimensional (3D) morphology with high 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 HB and dendritic polymers into acrylate-based dental composite and adhesive systems. Four commercial HB polymers were evaluated: Polyamidoamine dendrimer, two dendripolyamides and HB polyesteramide. These were added to dental restorative glass filled prepolymers, based on BisGMA, HEMA and TEGDMA. The dendritic and HB polymers blended readily with the prepolymers. A significant effect of HB polyesteramide (HB1), addition (0.1-3.0 wt%) on the mechanical properties was shown. It was found that addition of 0.3 wt% (optimal value) of HB polyesteramide raised the compressive strength from 253 :1: 20 MPa to 386 +/- 20 MPa and lowered the linear shrinkage from 2.4 +/- 0.2% to 1.5 +/- 0.2 % (for a model dental composite formulation). It was shown that the HB polyesteramide added to the dental adhesive compositions increased the shear bond strength and enhanced the bond durability to a variety of dental surfaces.

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.

An advanced dental adhesive system, composed of acrylic monomers and coupling agents, characterized by high tensile bond strength, enhanced durability, and biocompatibility was developed. The adhesive composition is curable chemically (self curing) or by visible light.This adhesive composition can be used for bonding to various substrates such as dentin, enamel, precious and nonprecious alloys, 'fresh' and 'set' amalgam, porcelain, and dental composite. Thus, the developed liquid adhesive composition could be considered as a universal dental adhesive.