Accuracy of Hand-Held Curing Radiometers

Objectives: To determine the accuracy of contemporary hand-held dental curing radiometers to a laboratory standard. Methods: Light curing units in the clinical settings of the College of Dentistry at Georgia Health Sciences University were tested for total emitted irradiance. The control method consisted of power emission measurement using a thermopile calibrated to NIST standards (Detector PM10-19C, Meter: Fieldmate, Coherent, Santa Clara, CA).  Emitting optical tip diameter was measured and area calculated. Irradiance determined by dividing measured power by tip area. Output was also measured using three different commercial dental hand-held meters: Cure Rite (Caulk/Dentsply), Model 100 and,  MODEL L.E.D. Radiometer (Demetron/Kerr). Three measurements were made for each light tested, and averaged to represent the reading from that light. Light curing units (LCU's) measured consisted of blue LED (LEDemetron (Kerr) and Demetron A.2 (Kerr)) and a quartz-tungsten-halogen unit (Optilux 401, Demetron). Forced-origin, linear was performed to determine the correlation between irradiance values obtained using the laboratory grade instrument (independent variable), and the other measurement methods as dependent variables. The correlation coefficient (slope) and its 95% confidence interval were determined and compared.   Results: Table presents coefficients and 95% confidence intervals. P-values for all slopes were < 0.0001.

Compared to the laboratory irradiance method, the Cure Rite meter provided higher irradiance than the control method (slope greater than 1.000). Both the Model 100 and L.E.D. Radiometer generated irradiance values lower than that of the control laboratory standard (slopes less than 1.000).  The bluephase meter always included a slope of value 1.000 within its confidence interval, indicating no significant difference between its irradiance values and those of the laboratory standard. Conclusions: The bluephase meter provided irradiance values not significantly different from those of a laboratory thermopile, while other hand-held radiometers over- or under-estimated the laboratory control method.