Modification of silorane based dental resin and its chemical/mechanical characterization

Abstract

It is desirable for a restorative dental material to have bioactive and adequate mechanical properties at the interface between the material and the tissue to prevent micro-leakage and ingress of bacteria. Current dental restorative composites, which consist of mainly polymer matrix, filler particles, and coupling agent, do not exhibit these properties. The presence of discrete zones at the interface between these three components could cause water absorption and the osmotic effect would result in swelling and residual pressure on tooth structure. In this study, a material recently introduced by 3M ESPE with the commercial name of FILTEK Silorane was modified by incorporating nano-hydroxyapatite (HA) and fluoroapatite (FA) crystals and then evaluated for specific properties. Apatite powders have high surface area to volume, tendency to show osteoconductivity, superior chemical homogeneity and micro structural uniformity. Hence, it would be advantageous to combine these two materials to form a new dental material that would possess the above desirable properties. The requirement of a specific material differs according to the nature of the application and there are different techniques in modifying and fabricating different compositions to achieve exact requirements for clinical use HA and FA were prepared in the laboratory by sol gel technique which involved the use of dried oven for ageing and heat treatment in furnace while silorane was dissolved in a Tetrahydrofuran (THF). Once the Silorane got completely dissolved in the solvent, n-HA and n-FA was added in different weight percentages. The mixture was left to mix for 24 hours. After the mixing films were cast from the suspension and dried. The prepared samples were tested for characterization, bioactivity and few mechanical properties. Object of this study was to invent a bioactive restorative material with good mechanical, physical and chemical properties. Result of the study shows that addition of HA and FA by 40 to 60% weight results in the modification of chemical structure because of increase in filler size. In comparison the spectra of 5 and 10% show the presence of fluoroapatite and hydroxyapatite without modifying the chemical structure of the Silorane Moreover fluoride ions are already present in the filler matrix of Silorane and by adding fluoroapatite it may increase the concentration of fluoride in the matrix. Bioactivity and mechanical properties were improved in modified silorane as more the fillers content in any material the more would be the strength and bioactivity of the material. It is also important that a proper balance of the matrix and filler is maintained so that the material does not become too brittle.