Radiant Exitance of Old, New, and Damaged LED Light Curing Units

This study aimed to determine the radiant exitance of new, damaged, and 16-year-old light-curing units (LCUs) with and without infection control barriers, and before and after removal of any debris.

Old LCUs consisted of 62 SmartLite iQ2 lights (Dentsply Sirona, York, PA). New LCUs consisted of 58 SmartLite Focus (Dentsply Sirona) and 58 Valo Grand (Ultradent, South Jordan, UT, USA) LCUs. Each LCU was examined for damage and debris on its tip. A handheld radiometer (CheckUp with BlueLight Analytics app, Halifax, Nova Scotia, Canada ) was used to measure the radiant exitance using a 10-second exposure time. Measurements were made with and without infection control barriers. If debris was present, the radiant exitance was measured before and after removal of debris with and without the barriers. All measurements were repeated three times. The means of the measurements were used for statistical analyses, which consisted of paired t-tests, analysis of variance (ANOVA), and Tukey post-hoc analyses conducted with a 0.05 level of significance.

Infection control barriers significantly reduced the radiant exitance of all LCUs, ranging from 4.35% to 6.91% depending upon the LCU and the presence of debris or damage. Clean undamaged SmartLite Focus (907 mW/cm2) and Valo Grand (Ultradent) LCUs (883 mW/cm2) with barriers had statistically higher radiant exitance than older clean undamaged SmartLite iQ2 (Dentsply Sirona) LCUs (719 mW/cm2) with barriers. All LCUs exceeded the recommended 400 mW/cm2 radiant power to cure 2 mm of Filtek Supreme Ultra shade A2 composite resin (3M ESPE, St Paul MN, USA).

Infection control barriers, debris, damage, and age all significantly reduced radiant exitance of the lights.