Evaluation of the Influence of Three Types of Light Curing Systems On Temperature Rise, Depth of Cure and Degree of Conversion of Three Resin Based Composites (An In vitro study)

Aim of study: The purpose of this study was to evaluate the effect of Quartz tungsten halogen, Light emitted diode & soft start light curing units on temperature rise, depth of cure & degree of conversion of different types of dental composites (Spectrum, Esthet X & Z250). Methodology: Thirty sound, single–rooted human bicuspids extracted for orthodontic purpose were used to measure the temperature rise inside the pulp chamber by using a needle probe, connected to thermocouple thermometer through the apical foramen. Ninety specimens of dental composites (Spectrum, Esthet X & Z250) were prepared by using special mold to determine the depth of cure of different light curing modes (Quartz tungsten halogen, Light emitted diode & soft start) by using the scraping method described by ISO standard for polymer –based filling restorative & luting materials. For the assessment of the degree of conversion, eighteen samples of dental composites were tested by the Fourier – transformed infrared spectrometry according to the standard baseline technique of Rueggeberg et al., 1990. Result and Conclusion: QTH light curing showed the highest temperature rise value, while the soft start gave the lowest values. Soft start light curing revealed the highest depth of cure values, while the QTH showed the lowest values among three curing modes. There were overall statistical significant differences in the depth of cure values among groups of different curing systems & types of dental composites. Soft start light curing system showed the highest degree of conversion and QTH had the lowest values. Esthet X dental composite gave the highest results of the degree of conversion while Z250 showed the lowest values.