Improvements in self-curing composites.

PURPOSE: The purpose of this study was to test the influence of a barbituric acid derivative acting as a catalyst and small amounts of pyrolytic silica in acrylic resins on color stability, solubility and sorption of a composite.

MATERIALS AND METHODS: A series of two-component powder/liquid resin systems were prepared. Monomer-like mixtures (bis-GMA, TEGDMA, tertiary amine 60/40) and a quartz powder with additions of various silica and barbituric acid derivatives were used. Temperature of the material during polymerization was measured with the use of a thermometer. In addition, the material's flexural and compressive strength, sorption and solubility were tested pursuant to ISO4049:2009.

RESULTS: The powder-based acrylic composition in a liquid mixed immediately before use, after an addition of a 0.5% barbituric acid derivative, has a lower temperature during the polymerization process (a reduction from 43°C to 37°C), whereas color stability over time is improved, with ΔE=1.81 for samples of powder mixtures containing between 0.45% of BPO and 0.15% of barbituric acid derivatives. For silanized quartz powder with 0.55% BPO and 0.1% BA+0.5% Aerosil R711, the obtained sorption value was 4.57±0.22μg/mm3 , whereas solubility was 1.60±0.32μg/mm3 .

CONCLUSIONS: New catalytic system with barbituric acid derivative, improves color stability for samples stored at room condition and under light of high intensity. A two-phase composite (bis GMA TEGDMA/Quartz), with a new catalytic system with barbituric acid derivatives, has a lower self-cured temperature. Adding a small quantity of hydrophobic silica (0.5%) has a significant influence, with reduced sorption and solubility of the material.