Two treatment plans were presented to the patient, non-surgical root canal retreatment and surgical root canal retreatment. After intra-oral examination, the quality of the prosthodontic treatment was found to doubtful (Fig. 24). The decision was made to remove the crown and perform non-surgical retreatment.
After local anaesthesia, the crown was cut with a high-speed handpiece (Fig. 25). The post was exposed and removed (Fig. 26 & 27). The pulp chamber and root canal orifices were examined for cracks. After inspection, a gingivectomy was performed (Fig. 28) and a dental dam (Kerr Dental) was placed (Fig. 29). The dental dam was sealed with a temporary flowable material (Fig. 30). After sealing the dental dam, the full adhesion protocol with a sixth-generation self-adhesive primer and bonding agent was performed, and the pre-endodontic build-up was created (Fig. 31). Residues of the cement and root canal filling materials were removed with a diamond-coated ultrasonic tip (Woodpecker; Fig. 32). Patency was easily established with hand files (VDW), and the canals were shaped with rotary martensitic files (Poldent) up to 40/0.04. Each step of instrumentation was performed with lubricating cream containing EDTA (VDW; Fig. 33). After each instrument, the canals were flushed with 5.25% sodium hypochlorite (Cerkamed). After reaching the final sizes of the root canals, the irrigation protocol was performed: three sequences of 5.25% sodium hypochlorite and 40.00% citric acid (Cerkamed) activated with an ultrasonic file (MANI), followed by 5.25% sodium hypochlorite activated with the ultrasonic file for approximately 10 minutes (Figs. 34 & 35). The flow of the liquid between both mesial canals was visible.
At this stage, one of the most important decisions had to be made regarding the resorption and isthmus present in the mesial root. On the one hand, in the case of non-penetrating internal resorption, the material of choice is gutta-percha with a sealer. On the other hand, in the case of apical inflammatory root resorption, it is recommended to use mineral trioxide aggregate (MTA) or putty materials. There is no problem with using these two materials in the same root in most cases, but in this case, the canals were too narrow to use the MTA comfortably and the quality of filling of the isthmus that could be achieved was questionable.
From this point of view, a novel approach of placing a tricalcium silicate-based sealer was a promising idea. The sealer was placed in the previously described manner. The premixed sealer in the plastic syringe (Meta Biomed) was placed in the mesiobuccal canal and the syringe depressed until it filled the mesiolingual canal. The distal canal was filled separately. In each canal, pistons from the previously heated gutta-percha extruder were placed and the warm gutta-percha was slightly compacted with stainless-steel hand condensers. A periapical radiograph was taken to evaluate the quality of the obturation. The bioceramic sealer was slightly extruded through the resorbed apex into the periapical area (Fig. 36). After the obturation, the chamber and orifices were cleaned (Fig. 37). A resin core with fibre posts was placed, and the temporary pink material was removed. The patient was referred to the prosthodontist for final restoration.
The recall appointment was performed after three years. The periapical radiograph and CBCT scan revealed healing of the periapical tissue and no resorption of the bioceramic sealer (Fig. 38). The tooth remained asymptomatic.
Conclusion
The piston technique suggested in this article is a predictable and efficient method of obturation of the canal space. It requires further research and discussion; however, it appears to be especially promising in compromised cases with difficulties such as complex anatomy, foreign objects or procedural errors during initial treatment.
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