Tensile bond strength of different adhesive systems between bone and composite compared: an in vitro study

The aim was to compare tensile bond strength of three dentine adhesive systems (Excite, Clearfil New Bond, Etch & Prime 3.0) and two cyanoacrylate adhesives (Cyano Veneer, Histoacryl) to animal bone in vitro.

Specimens from five porcine mandibles (diameter 9 mm) with a total thickness of 4mm (+/-0.5mm) and a cortical layer of 1.5mm (+/-0.2mm) were prepared using trephine burs under constant water cooling and under standardized conditions. They were assigned to five experimental groups. Tensile bond strength of five different adhesive agents (Clearfil New Bond, Etch & Prime 3.0, Excite, Histoacryl and Cyano Veneer was measured 15 min after application and after light curing of a composite material (Tetric Ceram, colour A2) added thereupon using a universal testing machine. Qualitative control was performed by scanning electron microscopy, while examining loaded and unloaded specimens.

The measured tensile bond strength was as follows: Clearfil New Bond 8.00 MPa (+/-1.36 MPa), Etch & Prime 3.0 4.05 MPa (+/-1.52 MPa), Excite 2.96 MPa (+/-1.34 MPa), Histoacryl 5.22 MPa (+/-2.00 MPa), Cyano Veneer 4.56 MPa (+/-0.76 MPa). Clearfil New Bond showed significantly higher bond strength than the other four adhesives. Scanning electron microscopy analysis of unloaded specimens showed mixed modes of fracture. As regards the loaded specimens, no tag formation as known for dentine was found.

Within the limitations of an in vitro investigation it can be concluded that dentine adhesive systems might be useful for bone bonding. Tensile bond strength of the dentine adhesive systems tested on bone is comparable to that evaluated for dentine in earlier investigations.