Silane increases the repair strength of resin composite restorations

The aim of this in vitro study was to evaluate the effect of using 2-part silane coupling agent (SA) before applying 2-step self-etch (SE) bonding when repairing both old and new composite restorations.

Method:

Sixty approximately 7 yrs. old resin composite (RC) test substrates, made of 6 different composites (Z250, Silorane, Charisma, CeramX, Tetric Evo Ceram and Supreme XTE) were treated with 2-part  silane (Bisco, Bis-Silan, SA) before applying bonding agent (Kuraray Clearfil Bond SE, CB) following the manufactorers specifications for repairing composite restorations. The repair material was Supreme XTE. Shear Bond Strength (SBS) was tested according to ISO/TS 11045 after thermo cycling (5000/5-55°C). As control the same 60 substrates were prepared with the same bonding agent without SA and tested. New RC substrates (N=44) were made from Supreme XTE and divided into two groups of 22 specimens each. Composite, Supreme XTE, was fixed to these according to the same protocol as described for the old RC. One group was tested with SA, the other group, without SA, served as control.

Result:

Test of old RC repair with silane: Mean SBS: 14,80 MPa ± 7,83 MPa. Without silane: Mean SBS: 6,21 MPa ± 4,01 MPa. Test of new RC repair with silane: Mean SBS: 23,38 MPa ± 8,33. Without silane: Mean SBS: 15,41 ± 8,63. The differences between repair with and without use of silane agents are statistically significant (p<0,01).

Conclusion:

Repair with silane performed significantly better than repair without SA. Use of SA on old RC repair gave similar results as repair of new RC without silane.