Sealant and composite bond strength to enamel with antibacterial/self‐etching adhesives

Abstract

The enamel in pits and fissures undergoing preventive or ultraconservative resin restorations may be affected by secondary caries. An antibacterial adhesive bond may be a useful choice to prevent and reduce demineralization. The purpose of this study was to determine the shear bond strength of an experimental antibacterial bond, a self-etch bond, and an ormocer-based adhesive bond using an ormocer-based fissure sealant and a composite resin on intact enamel. Twenty-four extracted human molars were sectioned bucco-lingually to obtain two flat and sound enamel surfaces. Forty-eight specimens were randomly assigned into four groups. The groups were prepared to receive the following treatments: (1) Admira Bond + Admira Seal (n = 10); (2) ABF Bond + Admira Seal (n = 11); (3) Clearfil SE Bond + Clearfil AP-X (n = 12); and (4) ABF Bond + Clearfil AP-X (n = 11). A cylindrical mould was placed over the bonded surface, and both materials were applied according to the instructions. The teeth were thermocycled 500 cycles between 5 and 55 degrees with a dwell time of 30 s. For shear bond strength testing, the load was applied vertically to the base of the mould. The cross-head speed was 5 mm min(-1). The maximum load that a specimen can withstand until failure was determined and shear bond strength was calculated by dividing the load at failure by the surface area of the mould. The results (median, minimum and maximum, respectively) for the four groups were: (1) 7.9, 4.2 and 13.6 MPa; (2) 8.6, 2.6 and 15.9 MPa; (3) 5.9, 5.3 and 8.2 MPa; and (4) 8.8, 3.0 and 19.2 MPa. Kruskal-Wallis and Mann-Whitney U-tests were performed for the statistical analysis. Groups 3 and 4 were statistically significantly different (P = 0.005; P < 0.05). There was no statistically significant difference between the sealant and composite groups for ABF (P = 0.375). Fracture sites were viewed by microscope under x 16 magnification to determine if the mode of failure was adhesive or cohesive. The results (number of adhesive failed specimens and number of cohesive failed specimens, respectively) for the four groups were: (1) 7 and 3; (2) 3 and 8; (3) 2 and 9; and (4) 8 and 3. The ABF bond has sufficiently physical qualities to be used under fissure sealant and composite resin on uncut enamel, its antibacterial efficiency notwithstanding.