Bond Strength after Er:YAG Laser Preparation in Primary Teeth

Objectives: the purpose of this “in vitro” study was to evaluate the shear bond strength of two different adhesives to dentin of primary teeth.Methods: Forty primary canines were embedded in self-curing acrylic resin with the facial surfaces exposed. The specimens were grounded with water sandpapers n. 240, 320 e 600 to expose a flat dentin surface. The materials used were: Single Bond (3M) e Adper Prompt (3M/Espe), according to the manufactures' instructions. The surfaces were divided in 4 Groups G1 37% phosphoric acid gel and Single Bond; G2 Adper Prompt (control group); G3 laser Er: Yag (300mJ, 2 Hz), 37% phosphoric acid gel and Single Bond; G4 laser Er: Yag (300mJ, 2 Hz) Adper Prompt. The specimens were stored in distilled water at 37ºC for 24 hours and they were debonded using a Universal Testing Machine at a crosshead speed of 0.5 mm/min. Failure mode was assessed using a X40 magnification stereomicroscope. Data were submitted to statistical analysis (ANOVA) and Scheffé's test. Results: The means (MPa) were: I-A 14,14 (±5,40); II-A 6,88 (±3,29); I-B 8,41 (±3,57) e II-B 4,19 (±2,24). It was observed statistically significant difference (p<0.05) between the tested adhesive systems, as well as for the laser use. The highest values were presented by Single Bond and phosphoric acid application. There were no differences in the Adper Prompt groups. Conclusion: It may be concluded that Er:YAG laser preparation negatively influenced the adhesive resistance of the employed systems, being more evident for Single Bond.