Phosphoric Acids Before Application of Universal Adhesive on Dental Enamel

Objectives: To evaluate the resistance to microshear bond strength and morphological characteristics of tooth enamel by evaluating different phosphoric acids combined with an universal adhesive system.
Methods: 84 enamel samples were used, which were divided according to the acid conditioning: G1: Scotchbond^TM etchant (3M ESPE), G2: Ultra-Etch (Ultradent), G3: Eco-Etch (IvoclarVivadent), G4: ETCH-37 with BAC (Bisco), G5: Etching gel (Densell), G6: Condac 37 (FGM) y G7 Scotchbond^TM Universal Adhesive (3M ESPE) in self-etch mode. For the adhesive procedure, Scotchbond^TM Universal Adhesive was the one used as indicated the manufacturer's instructions, 0.9 mm-diameter resin cylinders were placed. The microshear bond strength test was performed after being stored for 24 hours in water, using the OM100 semi-universal test machine. The morphological characteristics of tooth enamel were analyzed using the Raman confocal microscope alpha300RA. For the statistical test the SPSS 20.0 program was used. The ANOVA test and Tukey's post test were used to analyze the differences between the groups (a=0.5).
Results: The microshear bond strength values obtained for groups 1,4,5 were significantly greater than groups 2,3,6 and 7. Groups 1,2,3,4 and 5 presented type II etching pattern, while group 6 presented an irregular type III pattern. Few signs of demineralization were evident in group 7.
Conclusions: Acid etching with ETCH-37 with BAC, Etching gel and Scotchbond^TM etchant improved the adhesive strength in the enamel by using Scotchbond^TM Universal Adhesive and acid etching with Condac 37, Ultra-etch, Eco-etch provides similar adhesive strength values to self-etch mode of Scotchbond^TM Universal Adhesive.