Many studies on in-vitro orthodontic bond strength fail to report test conditions that could significantly affect their outcomes
INTRODUCTION The aims of this study were to systematic ally review the available literature regarding in-vitro orthodontic shear bond strength testing and to analyze the influence of test conditions on bond strength .
Effect of changing a test parameter on the shear bond strength of orthodontic brackets.
The purpose of this study was to determine the effect of changing the crosshead speed of the testing machine on the shear bond strength of orthodontic brackets to enamel while st and ardizing all the other variables . Forty freshly extracted human molars were bonded using the Transbond XT adhesive system ( 3 M Unitek , Monrovia , Calif ) . The teeth were r and omly divided into two groups . In group I , the shear bond strength was measured at a crosshead speed of 5.0 mm/min , and in group II the shear bond strength was measured at a crosshead speed of 0.5 mm/ min . Within half an hour from the initial bonding of each tooth , an occlusogingival load was applied to the bracket , producing a shear force at the bracket-tooth interface . This was accomplished by using the flattened end of a steel rod attached to the crosshead of a Universal Test Machine ( Zwick GmbH & Co , Ulm , Germany ) . The t-test results ( t = 2.71 ) indicated that there was a significant difference ( P = .014 ) in the shear bond strengths between the group tested at a crosshead speed of 5.0 mm/min and the group tested at a crosshead speed of 0.5 mm/min . The mean shear bond strengths for the two groups were 7.0 + /- 4.6 MPa and 12.2 + /- 4.0 MPa , respectively . These findings indicated that it is important to identify the parameters included in shear bond testing in order to enable meaningful comparisons of the performance of different material
Many studies on in-vitro orthodontic bond strength fail to report test conditions that could significantly affect their outcomes
INTRODUCTION The aims of this study were to systematic ally review the available literature regarding in-vitro orthodontic shear bond strength testing and to analyze the influence of test conditions on bond strength .