Techniques to address fractured instruments in the middle or apical third of the root canal in human permanent teeth: a systematic review of the in vitro studies.

Abstract

The objective of this study is to investigate techniques for approaching fractured instruments in the root canal and to present possible outcomes in relation to dentin thickness, fracture resistance, technique success, and clinical time. The bibliographic research was carried out in PubMed, Cochrane, Lilacs, Web of Science, Scopus, grey literature, and manual search. Following the inclusion and exclusion criteria, the titles and abstracts of 506 articles were read. Of these, 60 articles were selected and read in full. Fourteen articles were included in this systematic review. The most studied technique was the ultrasonic technique and obtained good general results. The more apically the instrument is located, the more difficult it is to remove, the more dentin is removed, and the lower the fracture resistance of the tooth. When removal is not possible, the bypass technique can be performed (bypassing), and on weakened teeth or with little dental remnants, the GentleWave System technique can be used. This systematic review shows the evidence from laboratory studies that the curvature and the root third in which the fracture of instruments occurred is relevant to fracture resistance and success. The ultrasonic technique got the best results. Well-conducted clinical studies should be performed for clinical practice. The approach of fractured instruments in the root canal is efficient with the use of ultrasound, bypass technique, and Gentle Wave System.