Thermal variations in the pulp chamber associated with composite insertion techniques and light-curing methods

The aim of this study was to investigate the effect of different incremental insertion techniques, photoactivation, and restorative phases on thermal variations occurring during the polymerization of Filtek Z250 composite resin.

The experiment was conducted using 90 bovine incisor teeth. The teeth were randomly assigned to three groups according to the technique used for photoactivation with a halogen light (continuous, soft-start, or intermittent). The groups were further separated into three subgroups according to method of increment placement (bulk, oblique, or horizontal/vertical) for a total of nine groups (n=10). Restorations were placed in a controlled environment (37 masculineC and 50+/-10% RU) and the temperature recorded using a digital thermometer coupled to a Type-K thermocouple inserted in the pulp chamber through the root canal in contact with the dentin. Data were analyzed using an analysis of variance (ANOVA) and the Tukey's test.

Higher temperature values were found for continuous light photoactivation in combination with the placement of horizontal/vertical composite increments and photoactivation of the adhesive using a continuous light exposure.

The light source is the most important factor producing temperature changes during photoactivation of resin composite.

Temperature increases in the pulp chamber due to light curing should be considered to avoid harming the delicate pulp tissue when large restorations or inlays/onlays require several consecutive light curing exposures for a complete cure.