Effect of different bonding protocols on degree of monomer conversion and bond strength between orthodontic brackets and enamel

The objective of the present study was to evaluate the effect of different surface treatments and polymerization protocols on the bond strength of brackets to enamel, and the degree of conversion of the bonding agents. 120 bovine crowns were embedded in acrylic resin blocks and sanded. Next, the blocks were randomly assigned into 12 groups. Metal brackets were bonded to enamel according to the “ surface treatment ” factor (A: Phosphoric Acid; ATxt: Phosphoric Acid + Transbond XT Primer ®; Tse: Transbond Plus Self Etching Primer®; and SBU: Scotchbond Universal®) and “ polymerization ” factor (R20: Radii-Cal ®/20 seconds; V20: Valo Cordless®/20 seconds; and V3: Valo Cordless®/3 seconds). All samples were stored for 6 months (water, 37ºC) and then subjected to a shear bond strength test (SBS). Bond failures were classified according to the Adhesive Remnant Index (ARI) and analyzed with the Kruskal-Wa llis and Mann-Whitney tests (5%). Using the same factors, 120 resin discs were made to assess the degree of conversion (DC) of the monomer. Data from the SBS (MPa) and DC (%) were analyzed by analysis of variance (2 factors) and Tukey ’ s test (5%). For the SBS, the factors “ polymerization ” (R20 = 8.1B; V20 = 13.2A; V3 = 5.2C, p = 0.0001) and “ surface treatment ” (A = 3.1C; ATxt = 13.6A; Tse = 12.3A; SBU = 6.3B, p = 0.0001) were statistically significant among groups. The highest adhesion value were found for the ATxt/V20 group (22.2A) and the lowest ...
Source: Brazilian Oral Research - Category: Dentistry Source Type: research