Temperature Rise within the Pulp Chamber During Curing Resin based Composite By LED and QTH Light Curing Units: An In vitro Study

Abstract

The present study was undertaken to evaluate the change in temperature within the pulp space during curing of composite resins using light emitting diode (LED) and quartz tungsten halogen curing units (QTH) under varying remaining dentin thickness. 60 human mandibular molars were taken and distal root of each sample was resected and the thermocouple probe was placed in the roof of the pulp space. The root was immersed in a water bath with a temperature of 37 ºC. The depth of the cavity was made such that the remaining dentin thickness (RDT) was kept at 0mm, 1mm and 2mm (Group I, II, III respectively). A thermocouple wire was kept in direct contact with the roof of the pulp chamber to record the rise in temperature. A QTH (Hilux Herarus  Kulzer, Germany) and a LED (Optilight LD III Gnatus, Brazil) were used to cure the bonding agent (Adper – single bond 2, 3M/ESPE, St. Paul USA) for 20 seconds followed by 2 mm of posterior composite resin (Filtek P60 3M, ESPE) for 40 seconds. Significantly higher temperature rise was recorded with QTH units than LED units. A one-way analysis of variance ANOVA was conducted to compare the effect of light curing on pulpal temperature rise in 0 mm, 1 mm and 2 mm remaining dentin thickness. Mann Whitney U-test was used for comparisons among groups. The results showed that heat transmitted was inversely proportional to remaining dentin thickness, that is, with decreasing remaining dentin thickness the amount of heat transmitted was more. Our results have shown that both LED and QTH composite curing units can be used safely for composite resin curing at all RDT levels.

Keywords: composite, resin, pulp