The parameters influencing the increase in pulp chamber temperature when using light-curing devices : cavity preparation, composite filling and power density of curing lights

Abstract

This study examined the effect of both the tooth substance and restorative filling materials on the increase in pulp chamber temperature when using light-curing units with different power densities. The tip of a temperature sensor was positioned on the pulpal dentinal wall of the buccal side of a maxillary premolar. Metal tubes were inserted in the palatal and buccal root of the tooth, one for water inflow and the other for water outflow. Polyethylene tubes were connected from the metal tubes to a pump to control the flow rate. For the unprepared tooth group (group 1), the tooth was light cured from the buccal side using 2 curing lights (3 curing modes): the VIP Junior (QTH, BISCO, Schaumburg, USA) and the Bluephase LED curing lights (2 modes: LEDlow & LEDhigh; Ivoclar Vivadent, Schaan, Liechtenstein). All curing lights were activated for 60 seconds. For the prepared tooth group (group 2), a class V cavity, 4.0 mm (width) X 4.0 mm (height) X 1.8 mm (depth) in size, was excavated on the buccal surface of the same tooth for the temperature measurement of the prepared cavity. The light curing and temperature measurements were performed using the same methods used in group 1.The cavity prepared in group 2 was filled with resin composite with A3 shade (Tetric N Ceram, Ivoclar Vivadent, Schaan, Liechtenstein) (group 3) or flowable composite with A3 shade (Tetric N Flow, Ivoclar Vivadent, Schaan, Liechtenstein) (group 4). The light curing and temperature measurements were performed for these groups using the same methods used in the other groups.The highest intrapulpal temperature (TMAX) was measured, and a comparison was conducted between the groups using a two-way ANOVA with a post-hoc Tukey’s test at a 95% confidence level. The TMAX was 38.35 ℃ (group 1), 38.97 ℃ (group 2), 39.75 ℃ (group 3) and 40.31 ℃ (group 4) for the LEDlow mode. For the QTH mode, the TMAX was 40.06 ℃ (group 1), 40.39 ℃ (group 2), 40.93 ℃ (group 3) and 41.42 ℃ (group 4). For the LEDhigh mode, the TMAX was 43.29 ℃ (group 1), 44.54 ℃ (group 2), 44.67 ℃ (group 3) and 45.33 ℃ (group 4). The statistical analysis revealed the following: the TMAX values were arranged by mode in the following manner: LEDlow < QTH < LEDhigh (p<0.05) and group 1 < group 2 ≤ group 3 ≤ group 4 in (p<0.05).