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The advent of guided endodontics, combining 3D imaging techniques with digitally designed guides, has led to its utilisation in surgical and nonsurgical root canal treatment. To date, however, guided endodontics has focused mainly on static guidance, with dynamic guidance receiving limited attention. In the present case report, a dynamic navigation implant system was used for guided endodontics. The safe and accurate access cavity preparation, location and negotiation of tahe calcified canals of a maxillary second premolar demonstrate the successful clinical application of dynamic guided endodontics in everyday endodontic practice. Keywords: access cavity, canal location, dynamic navigation, guided endodontics

Objectives: To investigate the novel use of computer-aided dynamic navigation for guided endodontics. Method and materials: Dental casts were fabricated from sets of extracted human teeth. A cone beam computed tomography (CBCT) scan of each cast, with a molded thermoplastic stent and a radiographic marker attached, was obtained and imported into the planning software of a dynamic navigation implant surgery system. Simulating implant surgery but for guided endodontics, the drilling entry point, angle, pathway, and depth of virtual implants were planned for 29 selected teeth. The radiographic marker was replaced with a jaw tag and mounted in a phantom head. A drill tag was attached to the drill handpiece. Following calibration, guided by the stereoscopic motion-tracking camera via the tags and images on a computer monitor providing real-time dynamic plus visual intraoperative feedback, the handpiece was aligned accordingly and endodontic access cavity preparation carried out. Successful root canal location was confirmed using periapical radiographs and CBCT. Results: Conservative access cavities were achieved and all the expected canals were successfully located in 26 teeth (n = 29). Due to tracking difficulties, only one canal was located in two maxillary second molars; in a maxillary first molar, only two canals were located and the access preparation for the third canal was misaligned and off-target. Conclusions: The results of this study demonstrate the potential of using computer-aided dynamic navigation technology in guided endodontics in clinical practice. Keywords: access cavity, cone beam computed tomography, dynamic navigation, endodontics, guided endodontics

Objective: To assess the influence of root-end filling (REF) material on apical surgery outcome. Materials and methods: Cases of apical surgery performed in a private practice limited to endodontics, which had received Intermediate Restorative Material (IRM; Group 1) or mineral trioxide aggregate (MTA; Group 2) as the REF material were collected. Radiographic surgical healing at up to 12 months and 24 months was evaluated using agreed criteria by two trained observers. The results were analysed using the Pearson chi-square and Fisher exact tests, with the level of significance set at P < 0.05. Results: Twenty-two out of the 95 teeth were excluded for various reasons leaving a total of 73 teeth. Group 2 showed a significantly higher healed rate than Group 1 (81% vs 56%; P = 0.0189); however, the difference between 'healed' and 'healing' teeth was not statistically significant for both follow-up periods (≤ 12 months, P = 0.2852; ≤ 24 months, P = 0.1101). As a secondary observation, it was found that 'large' lesions (> 5 mm diameter) required a longer time to heal than 'small' lesions (48% vs 77%; P = 0.0147). Analysis of the REF material in relation to lesion size showed that MTA 'healed' rates were significantly higher for 'small' lesions than 'large' lesions (P = 0.0042), whereas with IRM, the difference was insignificant (P = 0.4217). Conclusions: MTA showed a higher rate of 'complete healing'. 'Large' lesions took a longer time to heal completely. 'Small' lesions had a higher 'healed' rate when MTA was used as the REF material. Keywords: apical surgery, Intermediate Restorative Material, mineral trioxide aggregate, outcome, root-end filling