Evaluating the efficacy of curing lights

The use of light curing units has increased tremendously over the past few years with the introduction of photoactivated composite restorative resins. The advantages of light-cured composites are well documented especially the ease of placement of restorations as a result of extended working time and control of setting. Many of the advantages of these composites are dependent on the adequate polymerisation and therefore the source of the visible light, especially the wavelength and the intensity of the light source. The aims of this study were (i) to determine the intensity output of curing lights in state clinics, private dental practices and dental clinics run by trade unions using a radiometer and (ii) to relate their output to various factors that may affect the intensity of the light produced by each unit. The light intensity of each light curing unit was measured using the Efos Cure Rite radiometer (Cure Rite, Efos model #8000; Efos Inc, Mississauga, Canada). Mean readings ranged from a high of 448 to a low of 22 mW/cm2 for curing lights at the time of evaluation. Nineteen (54.3%) of the light curing units were functioning at optimal intensities, followed by 10 (28.6%) functioning at levels between 150 and 300 mW/cm2 and 6 (17.1%) functioning at levels far below that required to achieve adequate photocuring. No statistically significant differences were found when comparing intensity readings with age, last maintenance service and bulb replacement (P > 0.05). All of the clinicians interviewed (100%) expressed subjective satisfaction with the performance of the light curing units, even though 45.7% functioned below optimal intensities (P > 0.05). Not one of the clinicians expressed dissatisfaction with the performance of any of the light curing units. The results of this study showed that the light intensities f light curing units used within private dental practices, state and trade union dental clinics were inadequate for optimum curing.