Effect of Moving the Tip of the Light Curing Unit on the Irradiance Value Delivered

To determine the effect of differences in the distances and radial positions of the tips of Light-Curing Units (LCU) on the irradiance values delivered.

Four LCUs-Valo X, Emitter A, CuringPen, and Pinkwave were tested at different distances from the tip (0, 2, 4, 6, 8 mm) and radial displacements (2 and 4 mm East, West, North, South). The radiant power (mW) and emission spectrum (mW/nm) were measured using an integrating sphere with a 4 mm aperture. Calibrated irradiance beam profiles were recorded across the tip using a laser beam analyzer. Data were analyzed with a two-way ANOVA at a significance level of 5%.

Radial displacement significantly reduced the irradiance values delivered from all four LCUs (p < 0.05). At 4 mm, the mean irradiance value was below 1000 mW/cm² for Emitter A (256 mW/cm²), CuringPen (573 mW/cm²), and Valo X (955 mW/cm²), but not for the Pinkwave (1157 mW/cm²). At the 2 and 4 mm distance from the tip, the Valo X delivered consistent mean irradiance values at both the center and radial positions (2 mm: 1120 mW/cm² and 1089 mW/cm²; 4 mm: 979 mW/cm² and 945 mW/cm², p > 0.05). The Valo X emitted the most homogeneous beam profile, irrespective of the distance.

Variations of 2 or 4 mm in the radial tip position negatively affected irradiance values from the LCUs tested.

The radial position and LCU choice can significantly affect the irradiance delivered.