Laser-induced fluorescence to discriminate between a dental composite resin and tooth

Purpose Investigation of laser-induced fluorescence of an experimental pigment (Flu) to discriminate between a filling and the tooth and its influence on the material properties of experimental dental composites. Materials and methods Three experimental composites (EC) were manufactured. The standard contained no Flu, Flu-0.5 contained 0.5%, Flu-1.0 contained 1%. To judge the extent of fluorescence, specimens and fillings placed in natural teeth were irradiated with an infrared laser (980 nm, 120 mW). Flexural strength, modulus of elasticity, depth of cure, water sorption, solubility, and color (CIE-L*a*b*-values) were measured to investigate the influence of Flu on EC. ANOVA was calculated and the statistical significance was p < 0.05. Results Strong laser-induced green fluorescence was observed so that fillings and tooth structures were clearly discriminated. No influence of Flu on flexural strength and modulus of elasticity occurred. Water sorption and solubility were far below the limits of EN ISO 4049. Increasing Flu concentrations revealed minor but significant reduction of depth of cure, shifts to more white and red and less yellow. Significance Flu provides laser-induced fluorescence allowing an easy discrimination between fillings and teeth. Flu did not severely influence the material properties.