Influência da condição das ponteiras de fotopolimerização na irradiância de aparelhos led utilizados em odontologia

Introduction: Direct composite resin restorations are widely used in dentistry as an aesthetic and functional treatment option. Their clinical performance depends not only on the properties of the restorative material and the operative technique, but also on the efficiency of light curing. Adequate light activation promotes the conversion of monomers, contributing to the microhardness, mechanical strength, dimensional stability, and marginal integrity of the restoration. In this context, the condition of the light-curing tips may interfere with light transmission and with the amount of energy effectively delivered to the restorative material. Objective: To analyze the influence of the condition of light-curing tips on the irradiance emitted by LED curing units and discuss its possible implications for the quality of composite resin restorations. Methodology: A quantitative and descriptive field study was conducted in association with a literature review. Two LED light-curing units and six light-curing tips used under dental conditions were evaluated. Irradiance was measured using an RD-7 digital radiometer in continuous and turbo modes, before and after cleaning the tips with 70% alcohol. For each condition, measurements were performed while maintaining the same positioning over the sensor. The data were organized in tables and analyzed descriptively and comparatively. The literature review addressed light curing, irradiance, tip integrity, degree of conversion, microhardness, curing depth, polymerization shrinkage, microleakage, and restorative performance. Results: Before cleaning, irradiance ranged from 438 to 910 mW/cm² in continuous mode and from 248 to 1368 mW/cm² in turbo mode. After cleaning, the values ranged from 475 to 1411 mW/cm² and from 475 to 1430 mW/cm², respectively. An increase in mean irradiance was observed after cleaning, particularly in turbo mode, although the response was not uniform among all tips. Turbo mode generally presented higher values than continuous mode. Conclusion: Cleaning the light-curing tips may improve light transmission; however, it does not replace visual inspection, radiometric monitoring, or the replacement of damaged components. The observed variability reinforces that light-curing efficiency depends on the interaction among the equipment, the tip, the restorative material, and the clinical technique. Although this study did not directly evaluate mechanical properties or clinical performance, its findings highlight the importance of periodic maintenance of light-curing units to support the quality of composite resin restorations.