Factors Affecting the Energy Delivered to Simulated Class I and Class V Preparations(5)

e, the Bluephase G2 unit (Ivoclar Vivadent, Amherst, NY) used at high power and the Demi unit (Kerr Corp., Orange, CA). Participants also used the VALO unit in the plasma mode for two 3-second curing cycles.

For each simulated curing exposure, custom software (24/7, Halifax, NS) recorded the irradiance delivered to the preparation site in real time. The software calculated the resulting real-time energy density delivered to the 3.9-mm diameter detector as the product of irradiance and time. Three-way analysis of variance (ANOVA) was used to evaluate the effect of operator, choice of curing light and location of the preparation on the amount of energy received at each preparation site. The Fisher protected least significant difference (PLSD) test for post hoc comparisons was used to examine pairwise differences in the energy density delivered by the curing units. All statistical testing was performed at a preset alpha of 0.05.

Results

The maximum possible irradiance delivered by the curing lights over 4 curing cycles under ideal laboratory conditions, with the light guide fixed directly above and at an angle of 90° with respect to the light detector, at distances of 4 mm (representing a Class I restoration) and 2 mm (representing a Class V restoration), varied by a factor of more than 2 (Table 1). In the clinical situation, the distance and angle are less easily controlled, and they change with any movements of the operator and the patient. Figs. 2 and 3 illustrate real-time delivery of irradiance to the simulated Class I and Class V preparations by 2 operators using the same curing lights: one operator delivering consistent, high levels of energy (part a in each figure) and the other delivering consistently less energy (part b in each figure). Because of differences in the operators' clinical technique, there were clear differences in the irradiance delivered during the exposures. A comparison of Table 1 with Figs. 2 and 3 indicates that the operators did n