Analysis of photocuring resins shrinkage by optical techniques

GUSTAVO ARENAS; MARCELO GUZMAN; CLAUDIA VALLO; RICARDO DUCHOWICZ

Conferencia; 23rd ICO conference, Santiago de Compostela; 2014

Determination of volumetric shrinkage in curing resin is a topic of great importance in developing and designing of new and better dental resins formulations. Polymerization reaction itself has an inherent impact on this, which could lead to the formation of further caries in the teeth. In addition, the stress resulting from the polymerization reaction may generate fractures and detachments while the exothermic nature of the reaction is a parameter that should be considered to prevent damage to the dentin. More biocompatible formulations are made by loading with glass material (nano-particles) in order to reduceboth thermal effects and polymerization shrinkage [1-3]. Consequently, modern  formulations have minimized these issues and therefore conventional methods used some decades ago have been out of range. However, from all the set of techniques employed before, those optical ones remain as the most efficient and suggested to deal with such characterization of materials, mainly due to its high resolution and its non-invasive nature.In this work a characterization method based on two specific and complementary techniques is presented: a) dynamic speckle analysis that allows qualitative descriptions on the behavior of samples during the reaction from it upper surface. b) a distance meter based on Fiber Optic Fizeau Interferometer, to quantitatively assess shrinkage value on local points as required. In order to introduce this technique, a very known and widespread commercial resin is used (3M Filtek P60 ®), with continuous light irradiation and analyzed under equivalent conditions.