Objectives: This study determined the effects of contamination by ferric sulfate (Viscostat, VS) and aluminum chloride (Hemodent, HD) astringents on the bond strength of composite bonded to superficial dentin using two self-etching adhesives (Clearfil SE Bond, SEB; and Clearfil SE Bond Plus,SEP). Methods: Freshly extracted human teeth were ground to expose superficial dentin and polished to 600 grit. Each adhesive system was bonded to the specimens, using one of 2 astringents and 3 surface conditions [Control (moist dentin); contaminant, air, adhesive; or contaminant, water rinse, gentle air, adhesive]. Composite (Clearfil APX) was bonded to the surfaces in the shape of an inverted, truncated cone (n=5, 60 specimens total). Specimens were stored in water at 37° C for 24 hours, then debonded in tension with a testing machine at a cross-head speed of 0.5 mm/min. Tensile bond strengths (MPa) were calculated. Results: Means (SD) were compared using ANOVA (see table). Fisher’s PLSD (0.05 significance level) for adhesive, astringent, and surface condition were 2.8, 2.8 and 3.5 MPa, respectively.
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| SEB | SEP | ||
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| VS | HD | VS | HD |
| Control | 21.4 (2.6) | 18.8 (7.5) | 20.2 (4.2) | 25.9 (5.2) |
| Astr., Air, Adh | 1.0 (0.2) | 6.7 (4.9) | 3.8 (3.4) | 11.4 (3.3) |
| Astr., Rinse, Adh | 10.0 (4.4) | 20.5 (11.0) | 14.0 (3.2) | 12.5 (7.6) |
Conclusions: Adhesives were the same in most cases for the control groups, and SEP had higher bond strengths than SEB for HD and VS contamination, except for one group (HD, rinse). In all cases, astringent contamination decreased the bond significantly, and VS caused lower bond strengths than HD. Rinsing after contamination restored the bond to 50% of original bond strength or better. (Supported in part by Kuraray America.)