A critical analysis of research methods and experimental models to study apical extrusion of debris and irrigants

Abstract

During root canal treatment, intra-canal content as well as irrigants and root filling materials may be extruded into the periapical tissues, leading to undesirable consequences such as delay of healing and flare-ups. Although apical extrusion of debris is an inherent occurrence of root canal treatment and no instrument or technique has totally solved this problem, attempts are underway to minimize the harm exerted to periapical tissues with the development of new techniques. This has led researchers to continuously evaluate new instruments and methodologies in terms of apical extrusion. New research on extrusion is frequently published some of which utilize traditional experimental designs and others assessing extrusion using modified or innovative methodologies. This review focuses on the research methods and experimental models to study apical extrusion of debris and irrigants by making a critical analysis of each technique. A PubMed and Scopus search was conducted and 144 articles relevant to apical extrusion were retrieved from 1968 until 2021. The methodologies used in every research article were evaluated and a classification was created. Each methodology is described with the general outlines and advantages and drawbacks of each technique summarized with a critical approach. It appears that the collection of debris in a vial still serves as a method chosen by authors even in most recent studies. On the other hand, development of experimental models that include multiple factors considering the drawbacks of the existing study designs is essential to draw more reliable conclusions on the apical extrusion phenomenon.

A Comparative Evaluation of the Apically Extruded Debris from Root Canals Prepared by R-Motion NiTi File System

“…Choosing a root canal shaping system that extrudes the least amount of apical debris improves the endodontic treatment success rate [ 22 ]. Thus, many studies have emphasized investigating this parameter when evaluating the clinical performance of newly developed endodontic instrumentation systems [ 13 ].…”

“…The adoption of the Myers and Montgomery Methodology in the present study was for its main advantage of assessing the exact quantity of extruded debris with feasibility using a high-precision electronic balance and the possibility of incorporating other modifications to simulate clinical circumstances [ 13 ].…”

“…Mimicking the periapical tissue resistance could have been done using floral foam. However, it would affect the accuracy of the results by absorbing irrigation solution and debris [ 13 , 17 ]. Therefore, the periapical tissue was not simulated in the present study.…”

“…Careful handling of the sensitive electronic balance was considered in the current study to eliminate the influence of external factors that might compromise the weight conduction procedure [ 13 ].…”

“…New advances in endodontic instrumentation attempted to improve instrument properties [ 7 ]. AED has been identified as a critical clinical parameter for assessing the efficacy of instrumentation techniques and currently launched instruments [ 13 ]. Consequently, many researchers are constantly investigating novel characteristics to provide evidence of their effectiveness [ 5 ].…”