Analysis of the effect of poly[bis(HEMA)-phosphazene] and poly[(HEMA-g-PLA)phosphazene] on the photopolymerization contraction of Bis-GMA:TEGDMA

Abstract

One of the most important problems on dental polymeric resins is the polymerization shrinkage effect caused by the in-situ in teeth. Resin shrinkage decreases the performance of the implant because after resin hardening and adhesion to teeth fissures and other defects are formed. These defects lead to microleakage and caries and also affect the mechanical properties. In order to reduce polymerization shrinkage and avoid these problems the chemical structure of the resin and other components are modified. The characteristics of light cured Bis-GMA/TEGDMA resin modified with poly[bis(2-hydroxy ethyl methacrylate)-phosphazene] and poly[(2-hydroxyethylmethacrylate)-graft-poly(lactic acid)]phosphazene at different concentrations are reported here. The contraction range was studied by the bonded-disk method. Total shrinkage-strain of the photo-polimerized resins varied between 5.3 y 3.8% while the contraction rate occurred between 82.7 and 60.1 mm/mín. This analysis showed that polymerization shrinkage decreased in inverse proportion to the double bonds present in the resin.