Contemporary curing profiles: Study of effectiveness of cure and polymerization shrinkage of composite resins: An in vitro study

Abstract

Aims:This study was undertaken to determine the effect of step-curing, ramp curing, single intensity on the effectiveness of cure and polymerization shrinkage of composite resin. The influence of filler loading on the effectiveness of cure and polymerization shrinkage of composite resin was investigated.Materials and Methods:In this study, a total of 80 specimens divided into four groups were used. Group I – specimens cured with the step-cure mode. Group II – specimens cured with single high intensity. Group III – specimens cured with the ramp-cure mode. Group IV – specimens cured with single low intensity. Each group had two subgroups based on the composite resins used for making the specimen. The effectiveness of cure was determined from surface hardness values obtained from Rockwell hardness testing. A mathematical volumetric method was used to assess the volumetric shrinkage.Results:Group III showed the best effectiveness of cure followed by group I and II. Group IV showed the least. Polymerization shrinkage was highest with group III and group II, were as was lowest for group I and IV. Charisma showed better effectiveness of cure and low polymerization shrinkage compared to Durafill VS.Conclusion:This study emphasizes on the fact that, the soft–start polymerization modes (step curing and ramp curing) should be preferentially used over the conventional single (high or low light) intensities to cure composite resins, as its use results in optimal properties.