The inappropriateness of conventional orthodontic bond strength assessmentprotocols

The purpose of this article is to examine the soundness of conventional ort hodontic bonding assessment methods. A classification of bond strength stud ies is proposed with the testing environment (in vivo, in vitro, and ex viv o), loading mode (shear, tensile, and torsion), and bonding substrate (enam el, restorative, and prosthetic materials) serving as discriminating variab les. Inconsistencies throughout the various stages of research protocols ar e analysed. These include the following: tooth selection, storage, and prep aration; bonding; testing; and data analysis with regard to the clinical ap plicability of the reported information, as well as the scientific integrit y of the testing procedure. Contradictory models may partially account for the considerable variability noted for reported bond strength values of different orthodontic bonding s ystems. Such discrepancies may also explain the conflicting evidence report ed on the failure characteristics of the components of the bonding system i n different trials examining the efficacy of nominally identical materials. A novel approach to study the fatigue life of materials is proposed to unde rstand the processes occurring prior to bond failure. Mock research data ma nipulation is also utilized to illustrate the correct statistical treatment of findings, and recommendations for future research are made to ensure sc ientific soundness and clinical applicability of data.