Evaluation of proroot MTA and endocem MTA premixed used in regeneration treatment, removal efficiency from the canal under different solvent solutions by micro CT

Aim: The aim of this study is to evaluate the removal efficiency of ProRoot MTA and Endocem MTA Premixed applied to the coronal third according to the regenerative endodontic treatment (RET) procedure by ultrasonic instrumentation and to examine the effect of different acidic solutions on material removal. Materials and Methods In this study, 40 extracted permanent upper central teeth were used. After the access cavity preparation, immature tooth simulation was performed with peeso reamer burs. The samples were irrigated with 1.5% NaOCl for disinfection in accordance with the RET protocol and calcium hydroxide was placed as an intracanal medicament. Samples were incubated in PBS (Phosphate Buffered Saline) at 37˚C for two weeks. Then irrigation was done with 17% EDTA and the samples were randomly divided into 2 groups (n=20) according to the coronal barrier material: Group 1: ProRoot MTA, Group 2: Endocem MTA Premixed. The materials were prepared in according to the manufacturer's instructions, placed in the samples and incubated for two weeks. Then the samples were scanned with micro CT. After scanning, materials were removed by ultrasonic instrumentation using Woodpecker DTE S6 ultrasonic device and Bust 03-05 tips under a dental operating microscope. Removal times were recorded with a digital stopwatch. Micro CT scan of the samples was performed again. After scanning, each material group was divided into 2 subgroups (n=10): Group 1 was BioPure MTAD and group 2 was irrigated with 10% citric acid, and then microCT scanning was performed again. Obtained images were positioned in DataViewer software and analyzed with CTAn software. The residuel material that could not be removed by measuring the remaining material volume (mm³) was expressed as a percentage. The obtained data were statistically analyzed in IBM SPSS 25 program. The percentage differences of the remaining filling material before and after ultrasonic instrumentation within and between groups were statistically compared using the paired sample t test, kruskal wallis test and mann whitney u test, respectively. The significance level was determined as 5%. Results: There was no significant difference between the initial volumes of the materials used (p>0.05). The residuel material that could not be removed after ultrasonic instrumentation was significantly higher in the ProRoot MTA group (0.747%) compared to the Endocem MTA Premixed group (0.009%). There was no significant difference in terms of the amount of substance remaining after irrigation in both acidic solution groups (p>0.05). Conclusion: It was determined that calcium silicate-based materials could be removed to a great extent by ultrasonic instrumentation under the operating microscope. It is predicted that Endocem MTA Premixed can be advantageous in cases requiring retreatment due to its significantly higher removal rate. Key Words: MTA removal, regeneration, micro CT, ultrasonic tips