Microtensile bond strength of different adhesive systems to primary and permanent dentin.
OBJECTIVE
The aims of this in vitro study were to: (1) compare bond strength of different adhesive systems to primary and permanent dentin using microtensile test; and (2) evaluate the interaction of these materials to primary and permanent dentin by means of scanning electron microscopy (SEM).


METHODS
Middle-coronal dentin surfaces of 18 exfoliated primary and 18 extracted permanent molars were exposed and teeth were randomly divided, according to their adhesive system, into 3 groups (N=6 per group): (1) Clearfil SE Bond (SE); (2) One Up Bond F (OU); and (3) Single Bond (SB). Then, 5-mm high composite blocks were constructed. After bonding procedures, the teeth were stored in distilled water at 37 degrees C for 24 hours prior to the specimens' preparation. For the microtensile test, teeth (N=5 per group) were longitudinally sectioned into 2 axes rendering beam-specimens that were glued to special devices, which were mounted in a Universal Testing Machine to be loaded under a crosshead speed of 1 mm/min until fracture. One tooth of each group was prepared for SEM.


RESULTS
Microtensile bond strength mean values (MPa) to primary/permanent dentin were: (1) SE=60.0/61.4; (2) OU=54.5/53.3; and (3) SB=70.1/64.9. Two-way analysis of variance (ANOVA) showed no significant differences (P>.05) for the bond strength values among primary and permanent dentin groups, neither among groups SExSB and SExOU. SEM images of SE and SB showed a well-defined, uniform, and continuous hybrid layer. A continuous hybrid layer, however, was not found for OU.


CONCLUSIONS
Bond strength and micromorphologic characteristics of the adhesive systems evaluated were not influenced by the substrate. OU achieved worse results.
Department of Dental Materials, University of São Paulo, São Paulo, Brazil.
Fabio Zovico Maxnuck
FZ
Soares
Rachel de Oliveira
Rde O
Rocha
Daniela Prócida
DP
Raggio
Fernanda Tranchesi
FT
Sadek
Paulo Eduardo Capel
PE
Cardoso
D000269:Adhesives; D000704:Analysis of Variance; D017438:Bisphenol A-Glycidyl Methacrylate; D016009:Chi-Square Distribution; D001840:Dental Bonding; D003799:Dental Stress Analysis; D003804:Dentin; D003806:Dentin Permeability; D017220:Dentin-Bonding Agents; D006801:Humans; D008422:Materials Testing; D008689:Methacrylates; D008855:Microscopy, Electron, Scanning; D008963:Molar; D019279:Resin Cements; D013718:Tensile Strength; D014094:Tooth, Deciduous
D000269:Adhesives; 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