Comparison of Methods for the Characterization of Light Curing Units

Objectives: To characterize four light curing units (LCUs) and compare two different methods to examine the light beam profile.
Methods: BS- Bluephase Style (Ivoclar Vivadent), S10- Elipar S10 (3M Oral Care), OP- Optilight Prime (Gnatus) and VL- Valo (Ultradent) were characterized regarding tip diameter, radiant power, radiant emittance, emission spectrum and light beam profile. Tip diameter was measured with a digital caliper. Radiant power, radiant emittance and emission spectrum were evaluated using an integrating sphere coupled to a spectrometer. The light beam profile was evaluated with two methods: using a beam profiler camera and using the fiber-end from an optical spectrum analyzer. The Flatness Top-Hat factor (THF) of the light emitted by the LCUs was calculated for the beam profiles generated: Fn_(Z)=E_n/E_max, where E_nis the effective average power of the light beam and E_maxis the peak power in the light beam. The beam profile images produced with the OriginPro software were visually compared and Pearson correlation test was applied to the THF data, to verify if there was a correlation between results obtained by the two methods.
Results: The LCUs were different in all characteristics. THF results obtained by the beam profile camera were: BS– 0.423; S10– 0.635; OP– 0.343; VL– 0.637. THF results obtained by the optical spectrum analyzer were: BS– 0.493; S10– 0.516; OP– 0.367; BL– 0.698. Pearson correlation test showed no correlation between THF data obtained by the two methods (p≥0.05). However, visually there was a high correlation and also a high Pearson’s r value (r: 0.82) between the images.
Conclusions: The LCUs examined displayed different characteristics. Images of the entire beam taken with a beam profiler camera at a single timepoint is preferred.