An Assessment of 1067 Light Curing Units Measured Twice Between 2015 and 2021.

Introduction: The physical condition of the tip and the irradiance of LCUs used in dental offices in the United States and Canada was assessed twice.

Methods: The tip irradiance and physical condition of the tip of 1067 LCUs from 544 dental clinics were assessed twice between 2015 and 2021 using the CheckMARC (BlueLight) radiometer. The irradiance values were compared by paired Student's t-test (α = 0.05).

Results: There was a wide range of irradiance values (200 to 3,777 mW/cm²). At the first assessment, only 26% of the LCUs had no visible damage or debris on the LCU tip. When retested up to 36 months later, 70% of the LCUs had their tip damage or debris issues entirely or partially resolved. 2.6% of the LCUs delivered an irradiance below 500 mW/cm² on the first and 1.6% on the second assessments. For the 5 brands that had a sufficient sample size, it was concluded that the irradiance increased when the tip damage or presence of tip debris was resolved.

Conclusions: Initially, most LCUs (74%) had at least one problem related to damage or debris on the LCU tip. The irradiance increased when the tip damage or debris was resolved.