Evaluation of the Effect of Different Curing Units and Exposure Times on Pulp Chamber Temperature Using Simulated Pulpal Microcirculation

Abstract

Objective: To compare the elevations in physiological pulp chamber temperature and blood microcirculation during light curing using four different light sources at two different exposure times.

Materials and Methods: The study was performed on eighty Class-V cavities divided into eight groups of ten experiments each, according to the curing unit and exposure time. Short-term curing was performed in four groups: quartz-tungsten-halogen (QTH)-20 seconds (s) (XL3000, 3M ESPE, St. Paul, MN, USA); Woodpecker (WP)-15s (Lux V Light Cure Unit, WP, Apexion Dental Products); KR-10s (Demi Plus Dental Curing Light, Kerr Dental) and VL-3s (VALO light-emitting diode Curing Light Xtra Power mode, Ultradent Products, South Jordan, UT, USA). The same units were used for long-term curing at double the exposure time (i.e., CHI-40s, WP-30s, KR-20s, VL-3+3s). Composite material (Filtek Ultimate, 3M/ESPE) was placed into the cavities, followed by light curing performed at a distance of 1 mm. Temperature changes in the pulp chamber were recorded. The Kruskal-Wallis test, followed by Mann-Whitney U multiple comparisons test, were used for statistical analyses, with p<0.001 considered to be statistically significant.

Results: There were no significant differences among the curing units at the same exposure times. However, increases in pulp chamber temperatures varied significantly depending on the curing time (p<0.001). All the curing units induced significantly higher intrapulpal temperature changes at long-term curing times, except the WP groups (p<0.001). WP-30s, KR-20s and VL-3+3s exhibited critical temperature increases >5.5 C.

Conclusion: Longer curing times led to critical temperature increases in the pulp chamber. Shorter curing times can protect the pulp tissue against damage caused by temperature elevations above a certain threshold.