Does the acidity of self-etching primers affect bond strength and surface morphology of enamel?
OBJECTIVE
This study examined the ultrastructure and microtensile bond strengths (TBS) of self-etching (with different acidity) and conventional adhesive systems bonded to unground enamel.


METHODS
Resin composite (Filtek Z250) buildups were bonded to unground enamel surfaces of third molars after adhesive application with the following materials: Clearfil SE Bond (CSE); Optibond Solo Plus Self-Etch (OP); Tyrian Self Priming Etching (TY), and the controls Scotchbond Multi-Purpose Plus (SBMP) and Single Bond (SB). Six teeth were assigned to each material. After storage in waterfor 24 h at 37 degrees C, the bonded specimens were sectioned into beams of approximately 0.8 mm2 and subsequently subjected to microTBS testing at a crosshead speed of 0.5 mm/min. The average values were subjected to one-way ANOVA (alpha = 0.05). The effect of surface conditioning of each material was observed under scanning electron microscopy (SEM).


RESULTS
The highest resin-enamel bond strength was observed for SBMP (22.7 +/- 5.2) and SB (26.7 +/- 5.2 MPa). The lowest mean bond strengths were 10.9 +/- 3.2 and 7.8 +/- 1.5 MPa for TY and OP, respectively. CSE showed an intermediate performance (18.7 +/- 4.6 MPa). An overall increase in porosity was evident along the entire enamel surface treated with the self-etching primers; however, no selective demineralization similar to that with 35% phosphoric acid was observed.


CONCLUSIONS
The highest bond strength means and the more retentive etching pattern were observed for the two-step etch-and-rinse adhesives. Among the self-etching systems studied, Clearfil SE Bond should be preferred.
Moura
Sandra Kiss
SK
Department of Dental Materials, University of São Paulo, FOUSP, Brazil.
Pelizzaro
Arlete
A
Dal Bianco
Karen
K
de Goes
Mario Fernando
MF
Loguercio
Alessandro Dourado
AD
Reis
Alessandra
A
Grande
Rosa Helena Miranda
RH
D000134:Acid Etching, Dental / Q000379:methods; D000143:Acids; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding; D003743:Dental Enamel / Q000648:ultrastructure*; D017220:Dentin-Bonding Agents / Q000737:chemistry; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D010756:Phosphoric Acids / Q000737:chemistry; D016062:Porosity; D019279:Resin Cements / Q000737:chemistry*; D013314:Stress, Mechanical; D013499:Surface Properties
D000143:Acids; C438313:Clearfil SE Bond; D003188:Composite Resins; D017220:Dentin-Bonding Agents; C444701:Filtek Z250; D008689:Methacrylates; C500960:OptiBond Solo Plus Self-Etch; D010756:Phosphoric Acids; D019279:Resin Cements; C425844:Scotchbond Multi-Purpose Plus; C481138:Tyrian SPE; C115612:single bond; D017438:Bisphenol A-Glycidyl Methacrylate; C030242:phosphoric acid