Influence of phosphoric acid pretreatment on self-etching bond strengths.
OBJECTIVE
The purpose of this investigation was to evaluate the influence of phosphoric acid pretreatment on shear bond strength of two self-etching bonding systems to enamel and dentin.


METHODS
Forty-eight extracted third human molar teeth were mounted, embedded into polystyrene resin, polished with 600-grit aluminum oxide papers, and randomly divided into four groups (n = 12): group 1-Clearfil Liner Bond 2V (Kuraray Co. Ltd., Osaka, Japan); group 2-One Up Bond F (Tokuyama Corp., Tokyo, Japan); group 3-phosphoric acid (Condicionador Dental Gel, Dentsply Ind. Com. LTDA, Rio de Janeiro, Brazil) and Clearfil Liner Bond 2V; group 4-phosphoric acid and One Up Bond F. In groups 3 and 4 the substrate was pre-etched for 15 seconds with 37% phosphoric acid, rinsed, and dried with an air stream. In all groups adhesive systems were applied according to manufacturers' instructions and light cured; then a restorative composite resin (TPH Spectrum, Dentsply Ind. Com. LTDA) was placed in a polytef matrix and cured. The specimens were stored in humidity for 7 days at 37 degrees C. The shear bond strength test was performed in a universal test machine with a crosshead speed of 0.5 mm/min. All procedures were repeated for the dentin evaluation. Mean values were analyzed with two-way analysis of variance and Duncan tests (p < .05).


RESULTS
The values obtained are listed in decreasing order: enamel-group 3 = 24.6 MPa, group 4 = 23.6 MPa, group 1 = 19.2 MPa, group 2 = 8.5 MPa; dentin-group 1 = 17.2 MPa, group 2 = 16.1 MPa, group 4 = 13.1 MPa, group 3 = 11.3 MPa.


CONCLUSIONS
Under the conditions of this study, enamel etching with 37% phosphoric acid provided statistically significant higher shear bond strength values, regardless of the adhesive system. However, in dentin, for Clearfil Liner Bond 2V, phosphoric acid pretreatment negatively affected bond strength values.


CONCLUSIONS
The use of self-etching systems in composite-to-enamel bonding restorative techniques still needs improvement when compared with the high bond strengths obtained with phosphoric acid treatment. However, lower shear bond strengths were observed in dentin when phosphoric acid was used in association with either adhesive system.
Erhardt
Maria Carolina Guilherme
MC
Fundação de Amparo à Pesquisa do Estado de São Paulo, São Paulo, Brazil.
Cavalcante
Larissa Maria Assad
LM
Pimenta
Luiz André Freire
LA
D000134:Acid Etching, Dental / Q000379:methods*; D001840:Dental Bonding / Q000379:methods*; D003743:Dental Enamel / Q000187:drug effects*; D003793:Dental Restoration, Permanent / Q000379:methods; D003799:Dental Stress Analysis; D003804:Dentin / Q000187:drug effects*; D006801:Humans; D066298:In Vitro Techniques; D008689:Methacrylates / Q000494:pharmacology; D008964:Molar, Third; D010756:Phosphoric Acids / Q000494:pharmacology*; D011292:Premedication; D019279:Resin Cements / Q000494:pharmacology; D033081:Shear Strength
C084544:Clearfil Linerbond System; D008689:Methacrylates; C446260:One-Up-Bond F; D010756:Phosphoric Acids; D019279:Resin Cements; C030242:phosphoric acid