Effect of remaining dentin thickness and the use of conditioner on micro-tensile bond strength of a glass-ionomer adhesive.
OBJECTIVE
The purpose of this study is to investigate the effect of remaining dentin thickness and the use of a 20% polyalkenoic acid conditioner on the micro-tensile bond strength of a glass-ionomer adhesive to dentin.


METHODS
Resin composite was bonded to flat dentin surfaces from 14 extracted human teeth using Fuji BOND LC (GC) with or without a polyalkenoic acid conditioner, then sectioned to thin slabs, trimmed into an hourglass shape with the area of the interface being approximately 1mm(2), and subjected to micro-tensile testing at a cross-head speed of 1mm/min. Micro-tensile bond strengths were determined at three depth levels with a remaining dentin thickness of more than 3mm, between 2 and 3mm, and less than 2mm. Failure modes of the broken interfaces were determined using field-emission scanning electron microscopy.


RESULTS
The micro-tensile bond strength to dentin significantly improved when the remaining dentin thickness increased and the conditioner was used. When the conditioner was used (irrespective of remaining dentin thickness), failures mainly occurred adhesively at the interface between the adhesive and resin composite. When no conditioner was used, no adhesive failures between the adhesive and resin composite occurred, but failures occurred mainly adhesively between dentin and the adhesive, or mixed adhesive-cohesively.


CONCLUSIONS
The bonding effectiveness of the glass-ionomer adhesive tested was affected by the area of intertubular dentin available for micro-mechanical retention through hybrid-layer formation. Removal of the smear layer improved the bond strength of the adhesive to dentin.
Inoue
S
S
Leuven BIOMAT Research Cluster, Department of Conservative Dentistry, School of Dentistry, Catholic University of Leuven, Kapucijnenvoer 7, 3000 Leuven, Belgium.
Van Meerbeek
B
B
Abe
Y
Y
Yoshida
Y
Y
Lambrechts
P
P
Vanherle
G
G
Sano
H
H
D000134:Acid Etching, Dental; D000180:Acrylic Resins / Q000737:chemistry; D000268:Adhesiveness; D000704:Analysis of Variance; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding; D003804:Dentin / Q000648:ultrastructure*; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D005899:Glass Ionomer Cements / Q000737:chemistry*; D006801:Humans; D008855:Microscopy, Electron, Scanning; D012822:Silicon Dioxide; D016369:Smear Layer; D013223:Statistics as Topic; D013314:Stress, Mechanical; D013499:Surface Properties; D013718:Tensile Strength; D015040:Zirconium
D000180:Acrylic Resins; D003188:Composite Resins; D017220:Dentin-Bonding Agents; D005899:Glass Ionomer Cements; C083568:Z100 composite resin; C084541:Fuji glass-ionomer lining cement; C006903:carbopol 940; D012822:Silicon Dioxide; D015040:Zirconium