An In Vitro Comparison of Epoxy Resin Sealer Removal During Endodontic Retreatment

Background Endodontic retreatment involves the removal of root canal filling materials to address treatment failure or persistent infections. The success of retreatment depends on effective clearing of sealers and gutta-percha, which varies based on sealer properties and canal anatomy, especially in the apical region. This in vitro study evaluated the retreatment efficacy of three epoxy resin-based sealers in single-canal premolars, focusing on the residual sealer on dentinal walls and the time required for retreatment. Methodology A total of 33 extracted single-canal premolars were collected, decoronated to a standardized 17 mm length using a diamond disc, and prepared using a high-speed airotor with an endodontic access bur. Canal patency was established with a size 10 K-file, and cleaning and shaping were performed with the rotary file system up to #25/04, with irrigation using 5.25% sodium hypochlorite and 17% ethylenediamine tetraacetate gel. The teeth were divided into three groups, each having 11 teeth and obturated with gutta-percha (NeoEndo, Haryana, India), AH Plus (Dentsply, Konstanz, Germany), Sealmax-R (MAARC, India), or Epoxidin (TehnoDent, Belgrade, Serbia) using a thermoplasticizing technique. Retreatment was performed using a single retreatment file, and the times were recorded using a digital chronometer. Cone-beam computed tomography was used to assess the sealer remnants. Results All sealers showed comparable remnant scores in the coronal (p = 0.553) and middle (p = 0.093) thirds, but AH Plus exhibited greater apical retention (p = 0.153), leading to a higher overall score (1.48 ± 0.38) compared to Sealmax-R (1.27 ± 0.25) and Epoxidin (1.12 ± 0.17; p = 0.038). Post-hoc analysis confirmed significant differences between AH Plus and Epoxidin (mean difference = 0.36, p = 0.031). Retreatment times were the longest for AH Plus (mean = 5.97 ± 1.06 minutes), followed by Sealmax-R (mean = 5.30 ± 0.66 minutes), with Epoxidin requiring the least time (mean = 4.34 ± 0.61 minutes; p = 0.001). Apical retention was consistent across groups, suggesting anatomical challenges. Conclusions Epoxidin offered superior retreatability compared to AH Plus and Sealmax-R, likely due to reduced adhesive tenacity, making it preferable for anticipation of retreatment. The strong adhesion of AH Plus complicated its removal, while Sealmax-R balanced sealing and retreatability. Apical anatomy universally affected debridement, emphasizing the need for advanced retreatment techniques.