Evaluation of etching time on dentin bond strength using single bottle bonding systems.
OBJECTIVE
Incomplete infiltration of the demineralized collagen network may result in a weak zone within the hybrid layer and between the hybrid layer and dentin. The current study evaluates whether reducing the etching time to 5 s from the recommended 15 s or increasing it to 30 s has an effect on dentin bonding.


METHODS
108 extracted molars were assigned to 3 bonding agent groups (n = 36): (a) Single Bond (SB), (b) One-Step (OS), and (c) Syntac Single Component (SSC). Each group was further divided into three subgroups (n = 12) of different etching times: 5, 15, and 30 s. All groups were bonded with Z100 composite resin according to the manufacturer's instructions. All specimens were thermocycled 300 times between +/-5 degrees C and +/-55 degrees C, and shear bond strength testing and mode of failure analysis were performed.


RESULTS
The bond strength of SB (5 s: 15.5 MPa +/- 4.4; 15 s: 16.5 MPa +/- 3.1; 30 s: 16.8 MPa +/- 3.2) and OS (5 s: 13.7 MPa +/- 1.8; 15 s: 12.4 MPa +/- 3.8; 30 s: 10.6 MPa +/- 3.8) showed no significant differences (p < 0.05) for the different etching times. For SSC, different etching times showed significant differences (5 s: 10.9 MPa +/- 1.8; 15 s: 7.5 MPa +/- 2.5; 30 s: 6.4 MPa +/- 2.1). The mode of failure for SB and OS was adhesive or mixed adhesive/cohesive. For SSC, all failures were adhesive.


CONCLUSIONS
Etching times of less than 15 s do not seem to adversely affect bonding to dentin.
Abu-Hanna
Amer
A
Department of Operative Dentistry, College of Dentistry, University of Florida, Health Science Center, Gainsville, Florida, 32610-0415, USA. aabuhanna@dental.ufl.edu
Gordan
Valeria V
VV
D000134:Acid Etching, Dental / Q000379:methods*; D000268:Adhesiveness; D000704:Analysis of Variance; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D016009:Chi-Square Distribution; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding; D003804:Dentin / Q000648:ultrastructure; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D006801:Humans; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry; D033081:Shear Strength; D012822:Silicon Dioxide / Q000737:chemistry; D013696:Temperature; D013997:Time Factors; D015040:Zirconium / Q000737:chemistry
C103506:Bis-GMA, BPDM, HEMA dental-bonding resin; D003188:Composite Resins; D017220:Dentin-Bonding Agents; D008689:Methacrylates; D019279:Resin Cements; C078484:Syntac dentine adhesive; C083568:Z100 composite resin; C115612:single bond; D017438:Bisphenol A-Glycidyl Methacrylate; D012822:Silicon Dioxide; D015040:Zirconium