The inadequacy of in-vitro orthodontic bond strength testing in clinical application

Enamel etching was first proposed by Buonocore in 1955, which became the basis for bonding of orthodontic brackets to the enamel surface. In orthodontic practice, it is essential to obtain a reliable adhesive bond between an orthodontic attachment and the tooth surface since replacing loose brackets is inefficient and time-consuming. Bond failure usually occurs as a result of stress caused by the orthodontic procedure, normal oral functions such as mastication or due to inconsistencies in the bonding technique. Sufficient bond strength is a factor that contributes to the clinical success of orthodontic treatment. Thus, a continuous search is on for higher bond strengths adhesives. Largely the assessment of bonding agents has been done in-vitro using shear bond strength measurement. Extrapolation of results from such studies to clinical studies becomes difficult due to a large variability in the study designs. This article intends to address the variability in evaluation of the in-vitro bond strength and its inadequacies.