Evaluation of ex vivo removal effectiveness of tricalcium silicate-based hydraulic cements used in ‘regenerative endodontic procedures’ as capping material: a Micro-computed tomography analysis.
Introduction: To evaluate ex vivo the efficiency of specific ultrasonics for the removal of different tricalcium silicate-based hydraulic cements (TCS) as capping material for regenerative endodontic procedures. Methods: To prepare the immature teeth simulations, the apices freshly extracted 30 maxillary incisors were cut, then root canals were shaped up to #6 Peeso reamers. The current regeneration steps of the American Association of Endodontists(AAE) were followed for the ex vivo specimen preparations. The mixture of Ciprofloxacin and Metronidazole with glycerine was placed in each canal for 2 weeks. Then capping material groups were created: BioDentine, ProRootMTA, and RetroMTA(n=10). The sealed specimens were stored for 2 weeks at 37ºC at 100% humidity then were scanned using X-ray µ-computed tomography(µ-CT). The set TCSs were retrieved using a specific removal kit by a single operator as blind. The post-treated specimens were scanned again. The total and residual volumes and the durations were evaluated. One-way ANOVA followed by Post-hoc or Kruskal-Wallis followed by Mann-Whitney U tests were performed(p=0.05). Results: The capping materials were mostly removed from the root canals(>99%), whereas, significant differences were revealed among the residual volume of BioDentine, ProRootMTA, and RetroMTA as 0.31±0.0026%, 0.05±0.0009%, and 0.12±0.0009%, respectively(p<0.05). There was no significant difference among the mean durations. Conclusion: Within the limitations, it can be concluded that when the capping material is essential to remove, the specific ultrasonic kit seems to be an efficient tool for the slow-setting or fast-setting TCSs. Relatively high residual volume of BioDentine might be ascribed to its high adhesive property.
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Each specimen was scanned two times (preoperative and postoperative scans) using a µ-CT instrument (Skyscan 1272; Bruker Corp., Billerica, MA) at 90 kV and 100 μA. Regarding the scan parameters, the pixel size was 33 μm, beam hardening correction was 69%, smoothing was 2, and ring artifact correction was 4. The set capping materials were retrieved using an ultrasonic TCS removal kit (BioMTA, Yuseong-gu, Daejon, Korea) by a single operator as blind. The manufacturer's instructions were followed for each tip of the kit. Accordingly, the surface of each capping material was softened with a single drop of 10% glycolic acid (Bio Retrievability I; BioMTA, Yuseong-gu, Daejon, Korea) application. Then, 'Bust-05' and 'Bust-03' ultrasonic tips were gently used, respectively at the lowest output (E.M.S. Electro Medical Systems S.A., Nyon, Switzerland) until the visible material mass was eliminated under 2.5X magnification. The cavity was copiously irrigated with saline during the ultrasonic tip applications. The removing durations were recorded using the chronometer application of an IOS smartphone. The specimens were scanned again using µ-CT at the same parameters. Three-dimensional models were visualized using with CTVox software (v2.2.3; Bruker Corp., Billerica, MA). The total and residual volumes of material in each specimen were analyzed using the CTAn software (v188.8.131.52; Bruker Corp., Billerica, MA).