One-step self-etch adhesives bond less effectively to enamel/dentin than two- and three-step self-etch and etch&rinse adhesives. Objectives: In search for improved bonding effectiveness, the micro-tensile bond strength (μTBS) of experimental one-step self-etch adhesives to diamond-cut enamel (E) and dentin (D) was determined. Methods: The experimental adhesives contain either a phosphate-based (P-MA) or carboxylate-based (C-MA), or a combined phosphate- and carboxylate-based (P/C-MA) functional monomer, all three dissolved in ethanol/water (pH≈2). In addition, P/C-MA was also applied to 600-grit SiC-sanded enamel/dentin (P/C-MAs), following a rubbing application technique (P/C-MAr), or followed by the additional application/curing of a non-solvent containing adhesive resin (Unifil Bond Bonding Agent, GC; P/C-MAa). Control was the two-step self-etch adhesive Unifil Bond (UF-B, GC). Results:
μTBS in MPa ([SD]; n³ 10; statistics by Kruskal Wallis: p<0.05)
|
|
P-MA |
C-MA |
P/C-MA |
P/C-MAs |
P/C-MAr |
P/C-MAa |
UF-B |
|
E |
22.0 [4.6]a |
18.6 [11.7]a,b |
14.8 [6.9]*a,b |
14.3 [3.9]b |
22.2 [6.7]a,b |
22.3 [5.7]a |
14.5 [6.0]*b |
|
D |
2.1 [3.8]†z |
17.5 [14.5]#x,y,z |
19.1 [5.0]y |
29.5 [12.3]*x |
28.7 [6.3]x |
27.6 [11.5]x,y |
30.4 [12.9]x,y |
*1 pre-testing failure (ptf); #4 ptf; †8 ptf; different superscript letters indicate significant difference.
Considering the bonding potential to enamel and dentin together, among the three experimental one-step self-etch adhesives the combined phosphate- and carboxylate-based (P/C-MA) adhesive bonded most effectively. Application of this adhesive following a rubbing application technique or a two-step self-etch approach improved the bonding effectiveness. Conclusion: Both chemical composition and application procedure improve the bonding performance of the one-step self-etch adhesive.
This study was supported in part by the Toshio Nakao Chair funded by GC.