Primary dentin etching time, bond strength and ultra-structure characterization of dentin surfaces.
OBJECTIVE
To evaluate the effect of shortening the etching time on roughness, microhardness and bond strength of three adhesive systems to primary tooth dentin.


METHODS
Flat dentin surfaces from primary molars were randomly assigned to six experimental groups. Three different adhesive systems were used: an etch-and-rinse adhesive (Single Bond), a two-step self-etching (Clearfil SE Bond), and a one-step self-etching (One-Up Bond F) adhesive. In half of the specimens, the recommended etching time was used, in the other half the etching time was 50% reduced. After applying the adhesive, resin composite build-ups were constructed and stored in a humid environment for 24h at 37 degrees C. Specimens were sectioned into 1mm(2) beams and tested for microtensile bond strength (MTBS). Debonded surfaces were analyzed by scanning electron microscopy (SEM). Additional surfaces were conditioned for microhardness measurements (KHN) and for atomic force microscopy (AFM) analysis. Intertubular and total surface roughness (Ra) were recorded. Results were analyzed with ANOVA and Student-Newman-Keuls tests (P<0.05).


RESULTS
Single Bond and Clearfil SE Bond showed higher MTBS than One-Up Bond F. Bond strength and intertubular roughness increased when Single Bond and One-Up Bond F were used with a reduced etching time. For Clearfil SE Bond no differences in MTBS were detected when reducing the etching time. The application of phosphoric acid, Clearfil SE Bond primer and One-Up Bond F decreases dentin microhardness.


CONCLUSIONS
Shortening One-Up Bond F application time and reducing the etching time of phosphoric acid to one-half of the manufacturer's recommended etching time when using Single Bond are recommended when bonding to primary dentin.
Osorio
Raquel
R
Department of Dental Materials, School of Dentistry, University of Granada, 18071 Granada, Spain.
Aguilera
Fátima S
FS
Otero
Pilar R
PR
Romero
Martín
M
Osorio
Estrella
E
García-Godoy
Franklin
F
Toledano
Manuel
M
D000134:Acid Etching, Dental; D017438:Bisphenol A-Glycidyl Methacrylate; D001840:Dental Bonding; D003799:Dental Stress Analysis; D003804:Dentin / Q000648:ultrastructure; D017220:Dentin-Bonding Agents; D006244:Hardness; D006801:Humans; D008422:Materials Testing; D008689:Methacrylates; D018625:Microscopy, Atomic Force; D019279:Resin Cements; D013499:Surface Properties; D013718:Tensile Strength; D013997:Time Factors; D014094:Tooth, Deciduous
C438313:Clearfil SE Bond; D017220:Dentin-Bonding Agents; D008689:Methacrylates; C446260:One-Up-Bond F; D019279:Resin Cements; C115612:single bond; D017438:Bisphenol A-Glycidyl Methacrylate