Effect of Light Intensity on the Cure Characteristics of Photo-polymerised Dental Composites.

OBJECTIVE To determine the light intensity emitted by light curing units (LCUs) and its effect on the cure characteristics of composites polymerised with it. DESIGN A laboratory based cross sectional study. SETTING Public and private dental clinics in Nairobi, Kenya. RESULTS Thirty five (42.17%) LCUs produced light of intensity ≤300mWcm⁻² while 43 (51.8%) LCUs had their intensities between 300 and 1200mWcm⁻². Mean DOC and surface hardness for the 0-300mWcm⁻² LCUs was 1.34mm and 46.60VHN respectively. The mean DOC increased steadily from the lowest intensity group (1.34mm) to the 1200-15OOmWcm⁻² group (2.32 mm) and then declined to 1.98mm for the 1500-1800mWcm⁻² group. Statistical analysis showed significant differences in the mean DOC (p=0.000) and surface micro-hardness (p=0.002) for the different intensity groups. CONCLUSION Light intensity output of LCUs has a significant influence on the cure characteristics of dental composites with both DOC and surface micro-hardness increasing with increase in light intensity up to 1500mWcm⁻².