The effect of grafted caged silica (polyhedral oligomeric silesquioxanes) on the properties of dental composites and adhesives

Abstract

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.

The influence of POSS substituent on synthesis and properties of hybrid materials based on urethane dimethacrylate (UDMA) and various polyhedral oligomeric silsesquioxane (POSS)

“…An increased roughness leads simultaneously to a reducing of the thermal properties, especially the value of T g , according with the results obtained by Dodiuk et al23, 24 This statement confirms the T g results recently reported by our team 16…”

A Nanoimprint Lithography Hybrid Photoresist Based on the Thiol–Ene System

“…Compared with the typical methacrylate‐based resist, the bulk volume shrinkage (∼5.3%) of the typical hybrid resist (JTHC‐a) was lower than that of the methacrylate system (10.6%). The lower shrinkage of our hybrid resist may be due to the thiol–ene photopolymerization18–20 and/or the incorporation of POSS‐SH 33, 47…”

A Nanocage for Nanomedicine: Polyhedral Oligomeric Silsesquioxane (POSS)

“…It was concluded that the mechanical properties of the dental composites were significantly improved by acrylated POSS, but diminished with octaphenyl-grafted POSS, indicating that the chemical functionality of the side-chain groups had a strong influence on the dental materials and their adhesive behaviour. [98] The main obscurity in developing dental materials with low polymer shrinkage rates is the shortfall in mechanical properties to achieve the requirements that are necessary for clinical use. It has been frequently mentioned that POSSmodified polymers can be achieved at relatively low cost and have good processability, toughness, and thermodynamic and anti-oxidative surface properties.…”