Efecto de la intensidad de las unidades de fotopolimerización sobre la biocompatibilidad y resistencia a la flexión de una resina compuesta

Objective: To determine the effect of the in - tensity of two light curing units on the bio - compatibility, flexural strength and elastic modulus of a composite resin. Methodology: Two groups of Filtek Z250XT (3M ESPE) composite resin were created, each one photopolymerized using different intensities (<400 mW/cm 2 for 40s and> 800 mW/cm 2 for 20s). Cell viability was analyzed by MTT assay at 24 and 48 hours following the ISO 10993-5 standard. The flexural strength and elastic modulus were analyzed following the ISO 4049 standard. Results: In the group photopolymerized with an intensity <400 mW/cm 2 , cytotoxicity was statistically higher both at 24 and 48 hours and flexural strength and elastic modulus were statistically lower. Conclusion: A polymerization intensity <400 mW/cm 2 increases the levels of cytotoxicity and decreases the mechanical properties of composite resins. The importance of the pe - riodic control of the light curing units is em - phasized.