The effects of surface treatments and bonding agents on the bonding of metal-indirect laboratory composite materials

Background: The aim of this in-vitro experimental study was to evaluate the shear bond strength between the base metal Co-Cr alloy and laboratory-cured composite with mechanic retention, chemical treatment and the combination of both treatments on a metal framework. Materials and Methods: 200 alloy discs (Co-Cr) were prepared, half of the specimens were prepared with retention beads and the other half was grind. All test specimens were divided into 5 groups; control, sandblasted, sandblasted and Metal primer II (GC Co., Tokyo, Japan), sandblasted and Metal photo primer (Shofu, Kyoto, Japan), Rocatectribochemical silica coating system (3M ESPE, Seefeld, Germany) are used for each group. Then; Gradia opaque and Gradia indirect laboratory composites (GC Co., Tokyo, Japan) were applied to all groups. Half of the specimens are subjected to thermal cycling (TC) after the application of Gradia. Shear bond strength of each specimen was tested in an universal testing machine and fractured specimens were examined with SEM. Results: While the lowest bond strength was obtained in with both control groups of retention beads with TC or without TC (1.37 MPa, 1.19 MPa), the highest bond strength was obtained in group that used Metal primer II with TC (21,45 MPa). Conclusion: Indirect laboratory composites shows higher shear bond strengths when first sandblasted and then used metal primer for bonding.