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

Objective: 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.

Materials And Methods: 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%.

Results: 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/cm for Emitter A (256 mW/cm), CuringPen (573 mW/cm), and Valo X (955 mW/cm), but not for the Pinkwave (1157 mW/cm). 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/cm and 1089 mW/cm; 4 mm: 979 mW/cm and 945 mW/cm, p > 0.05). The Valo X emitted the most homogeneous beam profile, irrespective of the distance.

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

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