Bond strength of a mild self-etch adhesive with and without prior acid-etching.
The self-etch approach provides dentists with a generation of user-friendly and less technique-sensitive adhesives. Nevertheless, some concern has been raised regarding their bonding effectiveness to enamel, in particular when so-called 'mild' self-etch adhesives are employed.


OBJECTIVE
The purpose of this study was to test the hypothesis that the two-step self-etch adhesive Clearfil SE Bond (C-SE; Kuraray, Osaka, Japan) bonds equally effective to enamel/dentin either with or without prior etching with phosphoric acid.


METHODS
Bur-cut enamel/dentin surfaces prepared from human molars were partially split in two halves by cutting a shallow groove. One half was first etched with 40% phosphoric acid (K-etchant), while protecting the other half by holding a razor blade in the groove. Next, C-SE was applied strictly following the manufacturer's instructions, after which the surface was built up using Z100 (3M Espe). After 24-h water storage, micro-specimens were prepared with the interface circularly constricted using a Micro-Specimen Former, prior to micro-tensile bond strength (MPa) measurement. In addition, interfaces of C-SE with enamel/dentin prepared with and without beforehand acid etching were examined by Feg-SEM and TEM.


RESULTS
Beforehand etching significantly increased the bonding effectiveness of C-SE to enamel. A clearly more micro-retentive surface was revealed by TEM and Feg-SEM when enamel was etched. Phosphoric-acid etching prior to C-SE application on dentin significantly decreased the muTBS to dentin. TEM provided indications of a low-quality hybrid layer after beforehand phosphoric-acid etching.


CONCLUSIONS
Using C-SE, additional etching with phosphoric acid to improve bonding effectiveness should be limited to enamel.
Leuven BIOMAT Research Cluster, Department of Conservative Dentistry, School of Dentistry, Oral Pathology and Maxillo-Facial Surgery, Catholic University of Leuven, Kapucijnenvoer 7, B-3000 Leuven, Belgium.
K L
KL
Van Landuyt
P
P
Kanumilli
J
J
De Munck
M
M
Peumans
P
P
Lambrechts
B
B
Van Meerbeek
D000134:Acid Etching, Dental / Q000379:methods*; D000704:Analysis of Variance; D001840:Dental Bonding / Q000379:methods*; D003743:Dental Enamel / Q000648:ultrastructure; D003804:Dentin / Q000648:ultrastructure; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D006801:Humans; D019279:Resin Cements / Q000737:chemistry*; D013718:Tensile Strength
C438313:Clearfil SE Bond; D017220:Dentin-Bonding Agents; D019279:Resin Cements