Evaluation of the apical infiltration after root canal disruption and obturation

Abstract

The aim of this study was to evaluate two root canal filling techniques used in teeth that had their apical foramen disrupted and compare the apical infiltration with an ideal clinical situation. Twenty-seven freshly extracted single-rooted teeth were selected and radiographed to confirm the existence of a single and straight root canal. The crowns were removed at a mean distance of 11 mm from the apex. The teeth had the root canals instrumented and were randomly assigned to 3 groups (n=9): ND group - root canals were filled using the lateral compaction technique and no disruption was performed; DRF group - the apical constriction was disrupted by advancing a #40 K-file 1 mm beyond the original working length, the canals were reinstrumented to create an apical ledge at 1 mm from the apical foramen and were obturated with a master gutta-percha cone with same size as the last file used for reinstrumentation; DF group - the teeth had the apical constriction disrupted and the canals were obturated with a master gutta-percha cone that fit at 1 mm from the apex. The teeth were submitted to dye leakage test with Rhodamine B for 7 days, using vaccum on the initial 5 min. The teeth were sectioned longitudinally and the leakage was measured in a linear fashion from apex to crown. There was no statistically significant difference (p>0.05) between the groups that had the apical foramen disrupted (DF, DRF), but significant difference was found between the disrupted groups and the non-disrupted one (p<0.01). In conclusion, none of the evaluated techniques was able to prevent apical infiltration, so working length so the working length determination has to be established and maintained carefully.

Relationship between the Apical Preparation Diameter and the Apical Seal: An In Vitro Study

“…Both of these two positions provide no evidence-based data to support them as the ideal working-length technique for instrumentation and obturation [ 18 ]. A meta-analysis evaluation of success/failure showed a better success rate when the obturation was confined to the canal space [ 8 ].…”

“…Similarly, another study of Yared and Dagher showed that the canals instrumented to a size 40 file had significantly more overextensions than those instrumented to a size 25 file [ 31 ]. The study of Gomes-Filho et al showed that greater dye leakage occurred after disruption and enlargement of the apical foramen [ 8 ]. Mente et al evaluated the influence of the apical enlargement on sealing ability and observed a positive correlation between large apex diameter and greater leakage [ 32 ].…”

“…The advantage of the crown-down technique is to allow the cleaning of the canal as the instruments progress in the apical direction, which limits the extrusion in the periapex; a continuously tapering preparation from the access cavity to apical foramen facilitates efficient delivery of irrigant and creates apical resistance, which maintains the gutta-percha in the canal space and reduces the possibility of overfilling [ 34 ]; in order to preserve apical foramen and to avoid the creation of apical zips or transport, it is important that instrumentation is performed according to all the principles of root canal therapy. Apical disruption violates one of these principles, which is to maintain the apical foramen in its original position [ 8 ]. …”

“…On the other hand, if the main objective of endodontic therapy is to create a favorable environment in the apical healing process, all instrumentation beyond the foramen causes damages to the periapical tissues due to extrusion of the debris and the irrigation solutions and impairs the adequate seal of the apical foramen [ 7 , 8 ].…”

Factors affecting the periapical healing process of endodontically treated teeth

“…According to some authors, the compaction of debris into the apical third of the root canal should be removed mechanically 106 , while others believe that it can be removed with the use of abundant irrigation 52 , and that the infection could be additionally eliminated with the use of an intracanal dressing 54 . Moreover, the enlargement of the foramen appeared to hinder the apical seal 39 .…”