effect of combining different bonding agents on the shear bond strength to dentine

ABSTRACT

Dentine bonding adhesives [DBAs] possess different modes of adhesion that may affect their bond strength to dentine. Forty extracted sound premolars were selected and divided into four equal groups of ten teeth each. A circular area of dentine, of 3 mm. in diameter, was denuded on the labial surface using a diamond wheel stone running parallel to the long axis of the teeth. The dentine surface of the samples were treated with EDTA, cleaned, dried and then treated with the DBA. Group I was treated wild Gluma while group II was treated with J and J DBA. Group III received a combinational of both adhesives using a layering technique while group IV was treated by admixed combination of both adhesives. The shear bond strength scores [SBS] of the samples were tested using an Instron machine. The highest mean shear bond strength values were obtained by the combined adhesives applied by the layering technique [12.08 MPa] followed by the samples treated by the Gluma adhesive [9.67 MPa] then those treated by the J and J DBA [6.69 MPa] and finally the samples treated by the admixed combined adhesives. One way analysis of variance and Duncan's Multiple Range test revealed high significant difference between the tested groups and a percentage increase of 140.46 percent of the SBS of the Gluma/J and J DBAs combination if applied by the layering technique denoting its superiority when compared to the admixed technique. These findings were attributed to the reaction of the combined DBAs with more adhesive moities of both organic and inorganic nature. The low SBS of the admixed combined DBA was attributed to the incompatibility of the material in the well mixed technique due to the glutaraldehyde organic solvent action due to the affection of the functional adhesive groups in the J and J DBA