Effect of surface conditioning on the retentive bond strengths of fiberreinforced composite posts.
BACKGROUND
Debonding is a common cause of failure encountered with fiber-reinforced composite (FRC) posts, and usually occurs along the post space-dentin adhesive interface. Surface conditioning of posts is expected to increase the chemical and mechanical bond between the luting composite resin and the post, but the best method has not been definitively determined.


OBJECTIVE
The purpose of this in vitro study was to compare the effects of 3 surface-conditioning methods on the retentive bond strengths of FRC posts using 5 composite resin materials, and compare results to those of unconditioned FRC posts as well.


METHODS
Post space preparations (DentinPost ER root post system, length of 12 mm) were performed on 200 human anterior teeth. Groups of 50 FRC posts (ISO size 90) each were treated using 1 of the following conditioning methods: silanization, etching with 5% hydrofluoric acid, tribochemical coating (CoJet system), or were left untreated (control group). FRC posts (n=10) in each group were placed using 1 of 5 composite resin materials (Calibra or RelyX Unicem resin cements or Build-It, MultiCore Flow, or Rebilda DC foundation composite resins). Following water storage (37 degrees C, 24 hours) and thermal cycling (5000 cycles, 5 degrees -55 degrees C, 30-second dwell time), tensile strength testing was performed. Fracture modes were assessed using a light microscope. Data were analyzed statistically (1-way and 2-way ANOVA, Bonferroni-Dunn correction, alpha=.05).


RESULTS
Retentive bond strengths of FRC posts luted with MultiCore Flow in combination with the CoJet system, and of posts inserted with Rebilda DC in combination with hydrofluoric acid (HF) etching as well as with the CoJet system, were significantly higher than those of the corresponding unconditioned FRC posts (P<.001). No significant differences were noted between the bond strength values of RelyX Unicem with CoJet, MultiCore Flow with CoJet, and Rebilda DC with either CoJet or HF etching (P>.05). Retentive bond strengths were significantly lower for HF etching (Calibra, RelyX Unicem, Build-It), and for the treatment with the CoJet system in combination with Build-It compared to the corresponding control groups (P<.001). Fracture modes were primarily adhesive at the post surface or cohesive within the composite resin layer or within the FRC post.


CONCLUSIONS
The retentive bond strengths differed significantly with respect to the tested combinations of conditioning method and luting composite resin.
Schmage
Petra
P
Department of Restorative and Preventive Dentistry, School of Dental and Oral Medicine, University of Hamburg, Hamburg, Germany.
Cakir
Filiz Yalcin
FY
Nergiz
Ibrahim
I
Pfeiffer
Peter
P
D000134:Acid Etching, Dental; D000537:Aluminum Oxide; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding; D017268:Dental Prosthesis Retention; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D017276:Friction; D006801:Humans; D007180:Incisor; D008422:Materials Testing; D011176:Post and Core Technique; D019279:Resin Cements; D012821:Silanes; D012822:Silicon Dioxide; D013499:Surface Properties; D013718:Tensile Strength
D003188:Composite Resins; D019279:Resin Cements; D012821:Silanes; D012822:Silicon Dioxide; D000537:Aluminum Oxide