Fast curing of restorative materials through the soft light energy release.

ABSTRACT

OBJECTIVE: The effect of a novel light curing process, namely soft light energy release (SLER), on shrinkage, mechanical strength and residual stress of four dental restorative materials (DEI experience, Gradia Direct, Enamel Plus HFO and Venus) was investigated. METHODS: Composite specimens were fast cured through high level of power density and soft light energy release. Temperature, linear shrinkage and light power measurements were acquired in parallel in order to assess the effect of light modulation on temperature and shrinkage profiles during the light curing process and the following dark reaction phase. The small punch test and Raman spectroscopy were adopted to investigate the effect of SLER on mechanical strength and on internal stress, respectively. RESULTS: The soft light energy release photo-polymerization allows to reduce of about 20% the shrinkage rate and to increase the strength of fast light cured specimens. In addition, a more relaxed and homogeneous internal stress distribution was observed. SIGNIFICANCE: Properties of fast cured restorative materials can be improved by adopting the soft light energy release process.