Microtensile bond strength to root canal vs pulp chamber dentin: effect of bonding strategies.
OBJECTIVE
The aim of this in vitro study was to compare the microtensile bond strength (MTBS) between root canal and pulp chamber dentin with two bonding strategies (self-etching primer and total-etch technique).


METHODS
The pulp chamber of four human canines was accessed and the pulp chamber and root canal prepared with spiral drills. The teeth were cut into halves parallel to the long axis of the tooth and randomly assigned to two groups: Clearfil SE Bond + AP-X(SE) (Kuraray) and SingleBond + Filtek Z250(SB) (3M ESPE). After 24 h in water storage, the specimens were cut perpendicular to the root into 1.0-mm slices with a low-speed diamond saw. Specimens were trimmed to obtain hourglass shapes with a bond area of 1.0 mm2 (n = 12). Three specimens were obtained from the cervical root canal dentin (R) and from the coronal pulp chamber dentin (C). The MTBS was measured in a Bencor device with an Instron machine at a crosshead speed of 0.5 mm/min. The data was analyzed with two-way ANOVA and Tukey LSD post hoc (p < 0.05).


RESULTS
MTBS in MPa (mean +/- SD) were: SB.C = 25.3 (+/-6.5)a; SB.R = 16.9 (+/-6.0)b; SE.C = 16.9 (+/-3.4)b; SE.R = 16.8 (+/-5.3)b. Means with the same letter are not statistically different at p < 0.05. When data were pooled for "dentin region", coronal pulp chamber dentin resulted in statistically higher bond strengths than root canal dentin (p < 0.013).


CONCLUSIONS
Bonding to pulp chamber dentin seems to be more predictable than to root canal dentin. In the former region, the total-etch technique may result in a higher bond strength.
Professor, Department of Operative Dentistry, Universidade Federal de Santa Catarina, Florianpólis, Brazil. guilherme_lopes@ig.com.br
Guilherme Carpena
GC
Lopes
Paula de Carvalho
Pde C
Cardoso
Luiz Clovis Cardoso
LC
Vieira
Luiz Narciso
LN
Baratieri
D000134:Acid Etching, Dental / Q000379:methods*; D000704:Analysis of Variance; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding / Q000379:methods*; D003786:Dental Pulp Cavity / Q000648:ultrastructure*; D003804:Dentin / Q000648:ultrastructure*; D006801:Humans; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D010756:Phosphoric Acids / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry; D013696:Temperature; D013718:Tensile Strength; D019237:Tooth Cervix / Q000648:ultrastructure; D014867:Water / Q000737:chemistry
C112828:Clearfil AP-X; C438313:Clearfil SE Bond; D003188:Composite Resins; C444701:Filtek Z250; D008689:Methacrylates; D010756:Phosphoric Acids; D019279:Resin Cements; C115612:single bond; D014867:Water; D017438:Bisphenol A-Glycidyl Methacrylate