Computed tomography assessment of three techniques for removal of filling material.

Department of Nursing and Dentistry, Universidade de Santa Cruz do Sul, Santa Cruz do Sul, RS, Brazil.
Australian Endodontic Journal (Impact Factor: 0.74). 01/2009; 34(3):101-5. DOI: 10.1111/j.1747-4477.2007.00088.x
Source: PubMed

ABSTRACT In this study, computed tomography (CT) was used to assess three techniques for root canal filling removal. Seventy-five roots of extracted human lower incisors were filled with zinc oxide-eugenol sealer and gutta-percha and separated into three groups before gutta-percha removal (group 1, Gates Glidden burs + K-type hand instrumentation; group 2, K-type reciprocating instrumentation + NSK TEP E16R; group 3, ProTaper rotary instrumentation + NSK NAC E16R). Specimens were CT-scanned before and after filling removal. The mean rate of filling removal was 94.88%. Reciprocating instrumentation was the most effective and manual instrumentation associated with Gates Glidden burs was the least effective technique. Removal rate was significantly different for the three groups according to one-way anova (P = 0.049). The Tukey test showed a significant difference between groups 1 and 2 (P = 0.039) only. CT proved to be a reliable method for assessing root filling removal techniques.

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    ABSTRACT: AIM: To investigate nondestructively the percentage of 3D voids and marginal gaps in a pre-defined interface volume of interest (VOI) within root fillings produced by Thermafil Obturators with either a hydrophobic epoxy-resin-based sealer (AH Plus) or a hydrophilic flowable calcium-silicate sealer [mineral trioxide aggregate (MTA) Flow]. METHODOLOGY: Sixteen single root canals from extracted premolar teeth were prepared with ProTaper rotary instruments, randomly allocated into two groups (n = 8) and filled with size 30 Thermafil Obturators in association with AH Plus or MTA Flow sealers. The filled roots were stored at 37 °C in 5 mL of Hank's balanced salt solution (HBSS) used to represent body fluids and scanned after 7 days and 6 months using a high-resolution micro-CT. From each root, images of 3000 sections were analysed in 3D and binarized using a high-resolution micro-CT (4-μ resolution). The 3D distribution of voids (porosity and marginal gaps) at the gutta-percha-sealer-dentine interface was detected through a threshold grey level and expressed as percentage of the 40-μ-thick pre-defined interface VOI (20 μ of interface dentine and 20 μ of gutta-percha/sealer). A method of analysis based on the root canal segmentation was used, and coronal, middle and apical thirds considered separately. The percentage of 3D void volume was compared statistically using one-way anova (significance for P < 0.05). Environmental Scanning Electron Microscope with Energy Dispersive X-ray (ESEM-EDX) analysis was performed on the surface of both sealers after soaking in HBSS. RESULTS: Micro-CT detected gaps at the dentine-sealer interface in both groups. Void volumes wider than 10.21 μm(3) with 1.35 μm diameter were detected. Cul-de-sac-type voids (blind pores) and through-and-through voids (continuous pores) were discriminated. The apical thirds had a significantly lower 3D void volume (P < 0.05) than the middle and coronal thirds. The 3D void volume reduced significantly (P < 0.05) over time. ESEM-EDX analysis revealed that MTA Flow sealer created a dense apatite layer after 7 days of immersion in HBSS, whilst only sparse calcium phosphate deposits were detected on AH Plus even after 28 days. CONCLUSIONS: Micro-CT proved to be a powerful nondestructive 3D analysis tool for visualizing the porous internal microstructure of dental/endodontic materials at the interface with dentine. The proportion of voids was least in the apical third of root canals. Voids reduced over time in the presence of simulated body fluid.
    International Endodontic Journal 10/2012; 46(3). DOI:10.1111/j.1365-2591.2012.02124.x · 2.27 Impact Factor
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    ABSTRACT: The retreatability of recent calcium silicate or mineral trioxide aggregate (MTA) sealers has not yet been assessed. The aim of this study was to evaluate the removal of 2 MTA-based sealers (MTA Fillapex [Angelus Soluções Odontológicas, Londrina, PR, Brazil] and MTA Plus [Prevest-Denpro, Jammu City, India]) using a rotary retreatment system, considering an epoxy resin sealer (AH Plus [Dentsply Maillefer, Ballaigues, Switzerland]) as the standard for comparison. Root canals in 45 single-rooted teeth were instrumented using a rotary nickel-titanium system (MTwo; VDW GmbH, Munich, Germany) and obturated with gutta-percha using one of the following sealers (n = 15): group 1, MTA Fillapex; group 2, MTA Plus; and group 3, AH Plus. The teeth were scanned using a cone-beam computed tomography scanner. After 2 months, the root canals were retreated with a rotary retreatment system (ProTaper Universal Retreatment; Dentsply Maillefer, Ballaigues, Switzerland) and a second cone-beam computed tomography scan was performed to assess the amount of remaining root filling material (in percentage) and dentin removal (in cubic millimeters). The time taken to reach the working length was calculated in minutes. Group comparisons were performed using 1-way analysis of variance and the Student-Newman-Keuls post hoc test (P = .05). There was a significant difference in the amount of remaining root filling material between the 3 groups (P < .05), with group 1 showing the least amount of root filling material (1.8% ± 0.22%) and group 3 showing the highest (10.4% ± 0.71%). The amount of dentin removal and the time taken to reach the working length was significantly higher in group 3 than in groups 1 and 2 (P < .05). There was no significant difference between groups 1 and 2 in these outcome variables (P > .05). The rotary retreatment system evaluated was not able to completely remove any of the sealers. MTA Fillapex showed less remaining root filling material than MTA Plus.
    Journal of endodontics 07/2013; 39(7):893-6. DOI:10.1016/j.joen.2013.04.022 · 2.95 Impact Factor
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    ABSTRACT: Aim To compare the effectiveness of ProTaper Universal retreatment instruments with continuous rotation and adaptive motion (a modified reciprocating motion that combines rotational and reciprocating motion) in the removal of filling material. Methodology Mesiobuccal root canals in 36 mandibular first molars were instrumented up to size F2 with the ProTaper Universal instrument (Dentsply Maillefer, Ballaigues, Switzerland) and filled using sealer and ProTaper Universal F2 gutta-percha cones. Gutta-percha was then down-packed and the root canal backfilled using the extruder hand-piece of the Elements Obturation System (Sybron Endo, Orange, CA, USA).. The teeth were assigned to two groups (n = 18), and retreatment was performed using one of the following techniques: group 1) ProTaper Universal retreatment files used with rotational motion (RM) and group 2) ProTaper Universal retreatment files used with adaptive motion (AM) (600° clockwise/0° counter-clockwise to 370° clockwise/50° counter-clockwise). The teeth were sectioned, and both halves were analysed at 8× magnification. The percentage of remaining filling material was recorded. The data were analysed statistically using the Student's T-test at a 95% confidence level (P < 0.05). Results There was no significant difference between the groups with respect to the total time required for retreatment (P = 0.481). The AM technique left significantly less filling material than the RM method (P = 0.013). Conclusion The use of ProTaper Universal retreatment files with adaptive motion removed more filling materials from root canals.
    International Endodontic Journal 01/2015; 48(1):79-83. DOI:10.1111/iej.12279 · 2.27 Impact Factor