Microtensile testing of dentin adhesives.
OBJECTIVE
This study was conducted in order to compare the microtensile and shear bond strengths of five commercial dentin adhesive systems. Scotchbond Multipurpose with maleic acid (SM), Scotchbond Multipurpose with phosphoric acid (SP), Scotchbond Multipurpose Plus (SBP), Clearfil Liner Bond System (CL), and Prime and Bond (PB) were tested.


METHODS
Thirty extracted unerupted third molars, in groups of six teeth per adhesive system, were prepared for microtensile testing. The specimens were tested following a 24 h incubation at 37 degrees C in normal saline. Shear bond testing was performed on 35 additional teeth, using seven teeth per adhesive system. After testing, the fracture sites were observed using light microscopy and a scanning electron microscope to determine the type of failure involved.


RESULTS
The microtensile test results (mean +/- SD) were SM, 24.6 +/- 7.2 MPa; SP, 28.8 +/- 11.8 MPa; SBP, 22.7 +/- 6.5 MPa; PB, 25.5 +/- 9.4 MPa; and CL, 36.8 +/- 10.0 MPa. A Bonferroni post-hoc test showed significantly (p < 0.05) greater strength for CL compared to SM, SP, SBP, and PB. The shear bond strength test results were SM, 19.4 +/- 4.4 MPa; SP, 24.5 +/- 8.4 MPa; SBP, 15.3 +/- 4.9 MPa; PB, 23.2 +/- 7.1 MPa; and CL, 24.8 +/- 3.5 MPa. No statistically significant differences were found among the shear bond strength test results. The shear bond test produced significantly more failures within dentin and composite than the microtensile method.


CONCLUSIONS
It is concluded that the microtensile test produced a more definitive assessment of adhesive bond strength than the shear bond test. Microtensile testing showed CL to be significantly stronger than SM, SP, SBP, and PB (p < 0.05).
Schreiner
R F
RF
University of Missouri-Kansas City School of Dentistry, USA.
Chappell
R P
RP
Glaros
A G
AG
Eick
J D
JD
D000704:Analysis of Variance; D017438:Bisphenol A-Glycidyl Methacrylate; D001840:Dental Bonding; D017220:Dentin-Bonding Agents; D006801:Humans; D008422:Materials Testing / Q000379:methods*; D008689:Methacrylates; D008855:Microscopy, Electron, Scanning; D011109:Polymethacrylic Acids; D019279:Resin Cements; D013718:Tensile Strength
C084544:Clearfil Linerbond System; D017220:Dentin-Bonding Agents; D008689:Methacrylates; D011109:Polymethacrylic Acids; C103500:Prime & Bond; D019279:Resin Cements; C084018:Scotchbond Multi-Purpose; D017438:Bisphenol A-Glycidyl Methacrylate