Efeito da aplicação de uma camada hidrófoba contendo ou não 10-metacriloiloxidecil di-hidrogênio fosfato na longevidade das propriedades adesivas de sistemas adesivos universais à dentina

Abstract

Objectives: To evaluate the bond strength (μTBS), nanoleakage (NL), and degree of conversion (DC) of an additional hydrophobic coat (HC) containing 10- methacryloyloxydecyl dihydrogen phosphate (MDP) on 2 universal adhesives (UA) on the adhesive properties to dentine at baseline and after thermocycling. Materials and methods: Eighty-four sound third molars were used to evaluate bonding properties to dentin. The teeth were divided into eight experimental groups according to the following variables: 1) Universal adhesive systems: Prime&Bond Universal (PBU) and Allbond Universal (ABU), 2) Adhesive strategies: etch-and-rinse (ER) and self-etch

(SE); 3) HC: Clearfil SE Bond, as an MDP-containing HC and Adper Scotchbond Multi- Purpose as an MDP-free HC, 4) Treatment: Baseline and Termocycling. For the

samples prepare, the enamel was removed, and the adhesive and restorative

procedure was performed with a composite resin. The specimens were cut into resin- dentine bonded sticks. The sticks were tested under tension at 0.5mm/min (μTBS)

and for nanoleakage of the resin-dentine interface, the samples were infiltrated with

silver nitrate and analyzed on a field-emission scanning electron microscope (FE- SEM). For the degree of conversion, the adhesive layer was evaluated by micro- Raman spectroscopy. Data were analyzed with three-way ANOVA and Tukey's test

(α=0.05). Results: Higher and significant μTBS values were observed when an MDP- containing additional coat was applied at baseline and after thermocycling when

compared to the control group for both universal adhesives, however, for Prime&Bond Active no differences were observed between HC. For NL, lower and significant NL values were observed when an HC with or without MDP was used in comparison with the control group. When both control groups are compared, All Bond Universal showed less NL values than Prime&Bond Active. However, all the groups demonstrate worse results after termocycling. Higher and significant DC values were observed

when an MDP-containing additional coat was used in comparison with control or MDP- free additional coat groups. Conclusion: The addition of an HC over UAs improved the

bonding proprieties to dentin at baseline and after thermocycling. The presence of MDP on the HC seems to enhance some immediate proprieties, but after thermocycling aging, non-differences were observed.