ABSTRACT
Success rate in composite restorations is associated with the degree of polymerization and light intensity. The aim of this study was to evaluate the light intensity of curing units in private offices in Qazvin 2003. In this analytical study the light intensity of 62 light curing units were investigated before and after cleaning their light emitting tips using a radiometer. The results were classified in 3 groups as follows: A: sufficient intensity > 300 mw/cm2, B: borderline intensity [200-299 mw/cm2], and C: insufficient intensity < 200 mw/cm2. Data were analyzed using chi-square and Pearson correlation tests. Mean intensity of curing units was 350.96mw/cm2 which increased significantly to 371.6mw/cm2 [p=0.01]. Before cleaning, 67.8% of curing tips were in group A, 14.5% in B and 17.7% in C. After cleaning, 72.6% were in sufficient intensity group, 11.3% in borderline intensity, and 14.1% in insufficient intensity. Removing curing tips' contamination caused a significant increase in light intensity [p=0.01]. Periodic assessment of light intensity and quality control of light curing units are mandatory