Abstract 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-Wallis 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 value for the A/R20 group (1.2E). Regarding ARI, score 2 was the most prevalent in groups A, ATxt, V20 and V3, while score 4 was the most prevalent in the Tse, SBU and R20 groups, with no significant difference between them (p = 1.0). Regarding DC, the factors “polymerization” (R20 = 66.6A; V20 = 58.4B; V3 = 45.1C, p = 0.0001) and “surface treatment” (A = 52B, ATxt = 59.7A, Tse = 51.4B, SBU = 63.8A, p = 0.0001) were statistically significant. Tse was more sensitive to the variations in polymerization protocols than the other surface treatments. Treatment A did not present suitable bond strength or degree of conversion.

OBJETIVO: avaliar o tempo necessário para realização da colagem de braquetes pelas técnicas direta (CDB) e indireta (CIB), mensurando o tempo despendido entre a parte laboratorial (CIB) e a parte clínica (CDB e CIB), e a prevalência de descolamentos durante o período de observação de 24 semanas. MÉTODOS: dezessete pacientes (7 homens e 10 mulheres), com idade média de 21 anos, com necessidade de tratamento ortodôntico, foram selecionados para participar desse estudo. Foram utilizados um total de 304 braquetes, sendo que 151 foram colados pela técnica de CDB e 153 pela CIB, com o mesmo tipo de braquete e material de colagem. Os dados foram submetidos ao teste não paramétrico de Wilcoxon, com significância de 5%. RESULTADOS: o tempo total para realização da CIB foi maior em relação à CDB (p < 0,001). Levando em consideração apenas a fase clínica, foi observado que o tempo para CIB foi menor em relação a CDB (p < 0,001). A comparação entre o tempo despendido para o posicionamento dos braquetes em laboratório mais o tempo em clínica para CIB com o tempo em clínica para a CDB revelou que não houve diferença significativa (p = 0,910), nem tampouco quanto à prevalência de descolamento dos braquetes. CONCLUSÃO: a CIB apresenta-se como uma utilidade clínica singular, pois o tempo em clínica foi menor que o da CDB. O tempo despendido no posicionamento dos braquetes no laboratório e de execução clínica da CIB foi semelhante ao tempo gasto pela CDB, a quantidade de descolamentos foi semelhante entre as técnicas.

OBJECTIVE: The aim of this study was to assess the time spent for direct (DBB - direct bracket bonding) and indirect (IBB - indirect bracket bonding) bracket bonding techniques. The time length of laboratorial (IBB) and clinical steps (DBB and IBB) as well as the prevalence of loose bracket after a 24-week follow-up were evaluated. METHODS: Seventeen patients (7 men and 10 women) with a mean age of 21 years, requiring orthodontic treatment were selected for this study. A total of 304 brackets were used (151 DBB and 153 IBB). The same bracket type and bonding material were used in both groups. Data were submitted to statistical analysis by Wilcoxon non-parametric test at 5% level of significance. RESULTS: Considering the total time length, the IBB technique was more time-consuming than the DBB (p < 0.001). However, considering only the clinical phase, the IBB took less time than the DBB (p < 0.001). There was no significant difference (p = 0.910) for the time spent during laboratorial positioning of the brackets and clinical session for IBB in comparison to the clinical procedure for DBB. Additionally, no difference was found as for the prevalence of loose bracket between both groups. CONCLUSION: the IBB can be suggested as a valid clinical procedure since the clinical session was faster and the total time spent for laboratorial positioning of the brackets and clinical procedure was similar to that of DBB. In addition, both approaches resulted in similar frequency of loose bracket.