Márcia Helena Wagner

Computed tomography assessment of three techniques for removal of filling material

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.

The effect of final irrigation on the penetrability of an epoxy resin-based sealer into dentinal tubules: a confocal microscopy study

IntroductionThe aim of this study was to compare the effect of QMix, BioPure MTAD, 17xa0% EDTA, and saline on the penetrability of a resin-based sealer into dentinal tubules using a confocal laser scanning microscope (CLSM) and to describe the cleaning of root canal walls by SEM.MethodsEighty distobuccal roots from upper molars were selected and randomly divided into four groups (nu2009=u200920) before root canal preparation according to the solution used in the final rinse protocol (FRP): QG (QMix), MG (BioPure MTAD), EG (17xa0% EDTA), and CG (control group: saline). Ten roots of each group were prepared for SEM, and images (×2000) from the canal walls were acquired. The remaining canals were filled with a single gutta-percha cone and AH Plus with 0.1xa0% Rhodamine B. The specimens were horizontally sectioned at 4xa0mm from the apex, and the slices were analyzed in CLSM (×10). Sealer penetration was analyzed with Adobe Photoshop software.ResultsQG and EG presented similar amounts of sealer penetration (Pu2009>u2009.05). MG and CG presented the lowest penetrability values (Pu2009<u2009.05). The best results for smear layer removal of the apical third of the root canal were achieved by the QG and EG groups when compared with MG and CG (Pu2009<u2009.05).ConclusionsSeventeen percent EDTA and QMix promoted sealer penetration superior to that achieved by BioPure MTAD and saline.Clinical relevanceDespite studies have not confirmed the relationship between sealing ability of endodontic sealers and their penetration in dentinal tubules, sealer penetration assumes importance, since endodontic sealers, unlike gutta-percha, are able to penetrate in dentinal tubules, isthmus, and accessory canals, filling the root canal system.

NSK reciprocating handpiece: in vitro comparative analysis of dentinal removal during root canal preparation by different operators

The purpose of this study was to assess dentin removal during root canal preparation by different operators using a NSK reciprocating handpiece. Eighty-four human single-rooted mandibular premolars were hand instrumented using Triple-Flex stainless-steel files (Kerr) up to #30, weighed in analytical balance and randomly assigned to 4 groups (n=21). All specimens were mechanically prepared at the working length with #35 to #45 Triple-Flex files (Kerr) coupled to a NSK (TEP-E10R, Nakanishi Inc.) reciprocating handpiece powered by an electric motor (Endo Plus; VK Driller). Groups 1 to 4 were prepared by a professor of Endodontics, an endodontist, a third-year dental student and a general dentist, respectively. Teeth were reweighed after root canal preparation. The difference between weights was calculated and the means of dentin removal in each group were analyzed statistically by ANOVA and Tukeys test at 5 % significance level. The greatest amount of dentin removal was found in group 4, followed by groups 2, 3 and 1. Group 4 differed statistically from the other groups regarding dentin removal means [p<0.001 (group 1); p=0.005 (group 2); and p=0.001 (group 3)]. No statistically significant difference was found between groups 1 and 2 (p=0.608), 1 and 3 (p=0.914) and 2 and 3 (p=0.938). In conclusion, although the group prepared by a general dentist differed statistically from the other groups in terms of amount of dentin removal, this difference was clinically irrelevant. The NSK reciprocating handpiece powered by an electric engine was proved an effective auxiliary tool in root canal preparation, regardless of the operators skills.

Evaluation of Epoxy Resin Sealer After Three Root Canal Filling Techniques by Confocal Laser Scanning Microscopy

The aim of this study was to evaluate the penetration of endodontic sealer into the dentin tubules, the integrity of the sealer layer perimeter, and the sealer area at the apical third after different filling techniques by confocal laser scanning microscopy (CLSM). Forty‐five mandibular premolars were mechanically prepared with ProTaper files, until F5 file. Thereafter, they were filled with an epoxy‐resin sealer (AH Plus) mixed with Rhodamine B dye (0.1% proportion) and allocated in three groups: Group 1, single master cone; Group 2, cold lateral compaction; and Group 3, Thermafil. For confocal laser scanning microscopy analysis, the specimens were transversely sectioned at 4 mm from the apex. The images at ×10 and ×40 were analyzed by Imagetool 3.0 software. Significant differences were not found among the three experimental groups according the dentin‐impregnate area by the sealer (P = 0.68) and between the sealer and root canal perimeter (P = 0.18). However, root canal filling techniques were significantly different when apical sealer areas were compared (P = 0.001). Thermafil group showed smaller sealer areas (8.09%) while cold lateral compaction and gutta‐percha master cone showed similar areas (17.37 and 21.18%, respectively). The dentin‐impregnated area was not dependent on the root canal filling technique. Single master cone, cold lateral condensation and Thermafil techniques presented integrity of the sealer perimeter close to 100% and Thermafil resulted in a significantly thinner sealer layer. Microsc. Res. Tech. 75:1277–1280, 2012.

Back-scattered electron imaging for leakage analysis of four retrofilling materials

This study aimed to evaluate, ex vivo, the nanoleakage in dentinal tubules, the linear infiltration of silver nitrate in the dentin wall/root‐end filling material interface, and the presence of gaps in this interface in root‐end cavities filled with 4 filling materials. Forty‐eight disto‐buccal root canals of maxillary molars were instrumented and filled. Retrograde cavities were prepared with ultrasonic points (apical 2 mm). The samples were divided into 2 control groups (n = 4) and 4 experimental groups (n = 10): Group I – white mineral trioxide aggregate (MTA); Group II – Super EBA; Group III – Portland cement; and Group IV – Sealer 26. After 1 week, the specimens were subjected to silver nitrate and prepared for SEM (backscattered electrons). In the apical‐apical segment, an area with significantly higher leakage was observed for Super EBA, followed by Portland cement, MTA, and Sealer 26 (P = 0.0054). In the medium and cervical segments, all materials showed the same leakage behavior (P = 0.1815 and P = 0.1723, respectively). The linear infiltration at the dentin wall/root‐end filling material interface was higher with Super EBA than the other groups. No differences in the percentage of gaps along the 3 mm of dentin wall/root‐end filling material interface between the 4 materials were evident (P > 0.05). Nanoleakage occurred mainly in the apical segment of the samples, and Super EBA showed the highest values. The area and linear leakage were lower in the middle and coronal segments, regardless of the root‐end filling material. No material perfectly sealed the root‐end cavities, which allowed for the leakage occurrence. Microsc. Res. Tech. 75:796–800, 2012.

Endodontic treatment of a 36-mm long upper cuspid: clinical case report

Purpose: To report a clinical case of a 36 mm long upper cuspid submitted to root canal treatment, with emphasis on the alternative technique employed. nCase description: A 32 years old, male patient had suffered subluxation of teeth 12 and 13 and coronal fracture involving enamel and dentin, as well as pulp exposition, of tooth 14 because of a motorcycle accident. The man was given dental assistance and a semi-rigid splinting of teeth numbers 12 and 13 was carried out followed by the root canal treatment in a single visit on tooth no. 14. At 30-day follow-up pulp necrosis was detected in teeth 12 and 13 and the root canal treatment was implemented. The tooth 13 was 36 mm long and since the longest possible file (31 mm) was already in use, the cervical limit of the access cavity was considered as the reference point. nConclusion: This technique not only provided adequate disinfection, preparation and filling of the root canal, but it also allowed preservation of the remaining tooth structure.

Accuracy of an electronic foramen locator in determining working length during retreatment: an in vitro study

Objective: To assess, in vitro, the accuracy of MiniApex® for electronic working length (EWL)xa0determination during three stages of root canal treatment/retreatment: EWL-1 (during treatment),xa0EWL-2 (after filling removal), and EWL-3 (after reinstrumentation). Methods: EWL was determined when the MiniApex® display showed the green light at the ‘0.5’ markxa0and compared with radiographic findings. Results were classified as accurate when the file tip wasxa0located in a range of (1) 0.5 to 1.0 mm and (2) 0.5 to 2.0 mm from the radiographic apex, and asxa0inaccurate when the file tip was outside that range of values. Means were compared between groupsxa0considering all values and only accurate measurements, for both tolerance limits. Results: MiniApex® was highly accurate at the larger tolerance range (0.5 2.0mm): 82.3% (EWL-1),xa088.2% (EWL-2), and 91.1% (EWL-3). During root canal retreatment, EWL-3 provided more accuratexa0measurements than EWL-2, but without statistical difference (p>0.05). There was no statisticalxa0difference (p>0.05) when only accurate measurements were evaluated. Conclusion: MiniApex® was highly accurate to determine the location of the instrument tip at 0.5 toxa02.0mm from the radiographic apex during treatment and retreatment (EWL-2 and EWL-3).