Microleakage - The Main Culprit in Bracket Bond Failure?

Microleakage is the most common cause of bracket debonding. Moreover, different thermal expansion coefficients between the enamel, the adhesive, and the bracket bases will cause repeated expansion and contraction, adding more stress to the bonding strength. Debonding represents the failure of the adhesion between the brackets and the tooth enamel. The debonding of brackets from the enamel surface is the result of several factors, such as acid-etching and drying, adhesive application, and the time and type of photo activation. The under polymerization process of composite photo activation may lead to early bracket debonding. Objective. The aim of this research is to review the available studies assessing bracket debonding due to microleakage. Material and Methods. An electronic search in Pub Med database and Web of Science was conducted between September-October 2018. The inclusion criteria were articles written in English, full-text articles, studies published in the last 5 years, studies in vivo, ex vivo, and in vitro. The outcome measures in this research were the conditions that determine orthodontic bracket debonding due to microleakage. Results. The MEDLINE search resulted in 510 titles and abstracts that were relevant to the present topic; after selecting the articles published in the last five years, 74 were available for further selection. After the exclusion of all the studies irrelevant for the aim of the paper, 13 articles were finally included in this research. In vitro studies showed that microleakage score was higher in the gingival margin at the enamel-adhesive interfaces and in the occlusal margin at the adhesive-metal bracket interfaces. Conclusion. Bracket debonding remains the main concern during the orthodontic treatment, despite the new techniques.