Micro-CT evaluation of voids using two root filling techniques in the placement of MTA in mesial root canals of Vertucci type II configuration.

OBJECTIVE: The present study aims to compare two mineral trioxide aggregate (MTA) placement techniques, manual compaction and ultrasonic activation of manually compacted MTA, with warm vertical compaction (WVC) for orthograde obturation of mesial root canals of mandibular first molars showing Vertucci type II root canal configuration. MATERIALS AND METHODS: Thirty roots were selected according to their micro-CT scanned images. Root canals were chemomechanically prepared using Reciproc R25 and NaOCl using EndoVac. The specimens were divided into three groups according to the root canal filling technique, as manual compaction of MTA, ultrasonic activation of manually compacted MTA and WVC using gutta-percha and AH Plus (Denstply Sirona, Ballaigues, Switzerland). Percentages of voids located in apical 3 mm and remaining coronal half until the level where separate root canals re-join within filling were calculated. Data were analyzed using the Kruskal-Wallis and Dunn's tests, and significance was set at 5%. RESULTS: No significant difference was found among the filling techniques regarding the percentage volume of voids at apical 3 mm (P > 0.05). At the coronal half of the isthmus, WVC produced significantly less percentage volume of voids than manual compaction of MTA (P < 0.05) and similar to ultrasonic activation group did (P > 0.05). There was no significant difference between two MTA placement techniques at the coronal half of the isthmus (P > 0.05). CONCLUSIONS: No filling technique produced void-free fillings. The percentage of void volume was similar among groups at apical 3 mm but was different at the coronal half of the isthmus. CLINICAL RELEVANCE: Warm vertical compaction and ultrasonically activated MTA fillings revealed similar quality at the isthmus area, which was superior to manually compacted MTA.

Supplementary Steps for Removing Hard Tissue Debris from Isthmus-containing Canal Systems.

INTRODUCTION: The purpose of this ex vivo study was to evaluate the percentage reduction of accumulated hard tissue debris (AHTD) in the mesial root canal system of mandibular molars under different final irrigation regimens by means of micro-computed tomographic imaging. METHODS: Sixty curved mesial roots of mandibular molars with 2 independent canals joint apically by an isthmus (Vertucci type II) were selected. Specimens were scanned at a resolution of 12.5 µm, anatomically matched, and distributed into 3 groups (n = 20) according to the preparation protocol: Self-Adjusting File (SAF; ReDent Nova, Ra'anana, Israel), Reciproc (VDW GmbH, Munich, Germany), and Revo-S (Micro-Mega, Besançon, France) systems. Then, each group was subdivided into 2 subgroups (n = 10) according to the final irrigation protocol with the SAF or EndoVac system (Discus Dental, Culver City, CA). The percentage volume and percentage reduction of AHTD after root canal preparation and final irrigation protocols were statistically compared using 1-way analysis of variance, the paired sample and the independent Student's t tests. The level of significance was set at 5%. RESULTS: Within groups, the mean percentage volume was significantly reduced after the final irrigation procedures in either the SAF (from 1.52%-1.78% to 1.01%-1.20%) or EndoVac (from 2.11%-2.23% to 1.31%-1.52%) subgroups (P < .05). In the experimental groups, the mean percentage reduction of AHTD ranged from 29.15%-39.90% after the irrigation protocols, with no statistical difference between groups (P > .05). CONCLUSIONS: None of the irrigation approaches succeeded in rendering the mesial root canal system free of AHTD. A similar percentage reduction of AHTD was achieved after final irrigation protocols using either the SAF or EndoVac system.

Middle mesial canals in mandibular first molars: A micro-CT study in different populations.

OBJECTIVE: To describe the morphological aspects of middle mesial canals (MMC) in mandibular first molars using micro-CT. DESIGN: Mandibular first molars collected from the Brazilian (n=136) and Turkish (n=122) populations were scanned (voxel size: 9.9µm) and mesial roots with MMC (n=48) evaluated regarding several morphological aspects. The incidence of MMC in each population was statistically compared using Chi-square test (α=0.05). RESULTS: Overall, the incidence of MMC was 18.6% (48 out of 258 molars) and was significantly higher in the Brazilian (n=30; 22.1%) than in the Turkish (n=18; 14.8%) population (p<0.05). In both populations, confluent configuration of the MMC was the most frequent anatomy. Most of the specimens with MMC had 3 independent orifices (n=26; 54.2%) and 3 apical foramina (n=21; 43.8%). The mean minor diameter of the MMC orifice (0.16mm) was 3 times less than the other orifices (∼0.50mm). In mesial roots with independent configuration (n=3; 6.3%), the mean volumes (mm(3)) of the MMC, mesiobuccal (MBC) and mesiolingual (MLC) canals were 0.20±0.10, 0.75±0.28, and 0.88±0.19, respectively. In the specimens with canal confluence (n=26; 54.2%), MMC merged to the MBC (n=8; 16.7%), MLC (n=4; 8.3%), or to both MBC and MLC (n=14; 29.2%). Double mesial canal was observed in only 1 specimen. MMC with an independent foramen was observed mostly in Brazilian specimens. CONCLUSIONS: Incidence of MMC was higher in the Brazilian molars. Confluent configuration was the most prevalent anatomic variation, while independent and fin configurations, as well as, double MMC, were found only in a few specimens.

Use of EndoVac System for Aspiration of Exudates from a Large Periapical Lesion: A Case Report.

Large cyst-like periapical lesions can heal after nonsurgical root canal treatment. Decreasing the hydrostatic pressure within a periapical lesion can be achieved with the aspiration technique by using EndoVac when there is drainage of cystic fluid through the canals. Clinical examination of a 21-year-old male patient revealed a large periapical lesion extending from the distal aspect of tooth #26 and reaching the mesial surface of tooth #22. During root canal treatment of teeth #23, #24, and #26, serous exudate drained from the root canal of tooth #24. The MacroCannula component of EndoVac apical negative pressure irrigation system was used to aspirate the inflammatory fluid. The technique produces a vacuum effect in the periapical region through the root canal, which facilitates evacuation of large amounts of exudate. Two-year clinical and radiographic examinations revealed resolution of the mandibular radiolucency, and the adjacent tooth #25 retained its vitality. The healing of a large periapical lesion can be achieved by the correct diagnosis and the proper treatment approach, without the need for surgery. EndoVac negative irrigation system might be useful for intracanal aspiration of exudates.

Retreatment of flat-oval root canals with a self-adjusting file: an SEM study.

This study evaluated the efficacy of the Self-Adjusting File (SAF) in removing the root filling remnants and smear layer left in oval shaped root canals after using R-Endo retreatment files, by using scanning electron microscopy (SEM). Forty eight maxillary premolars were prepared and the SAF was used in all of the teeth to remove debris and smear layer. Sixteen teeth were used as control and the other 32 teeth were obturated and randomly assigned to two groups according to the retreatment procedures: R-Endo retreatment files and R-Endo retreatment files+SAF. Then, all roots were split longitudinally for SEM evaluation. Using SEM pictures, the number of dentinal tubules and the surface area covered by filling remnants were evaluated. None of the techniques removed root filling remnants and smear layer completely. Additional use of SAF after the retreatment procedures may improve root canal cleanliness in the coronal and middle thirds of oval root canals.

Oval-shaped canal retreatment with self-adjusting file: a micro-computed tomography study.

OBJECTIVES: The aim of this study was to assess the efficacy of removing the filling material from oval-shaped canals with rotary retreatment files, with or without the additional use of self-adjusting file (SAF), using micro-computed tomography. MATERIALS AND METHODS: Oval-shaped canals from 20 maxillary premolars were prepared and assigned to two groups (n = 10), according to the obturation technique: cold lateral condensation (CLC) or vertical condensation (VC). Then, retreatment procedure was performed with retreatment rotary instruments followed by SAF. The specimens were scanned after each procedure and the volume of the filling material calculated. Median and interquartile range (IQR) percentages of the remaining filling material after each retreatment technique were statistically compared by Wilcoxon and Mann­Whitney U tests with a significance level of 5 %. RESULTS: The median percentage volume of the filling residue after rotary retreatment procedure was 1.59 (IQR = 1.26) and 0.42 (IQR = 0.86) in the CLC and VC groups, respectively (p < 0.05). After the use of SAF, the median percentage was 1.26 (IQR = 0.75) and 0.12 (IQR = 0.53) in the CLC and VC groups, respectively (p < 0.05). Statistically significant difference was also observed within the group after the additional use of SAF (p < 0.05). CONCLUSIONS: None of the retreatment procedures completely removed the filling material. The additional use of the SAF improved the removal of filling material after the retreatment procedure with rotary instruments. CLINICAL RELEVANCE: Filling material left after retreatment procedure may harbour necrotic tissue and bacteria, which could lead to a persistent disease and reinfection of the root canal system. The additional use of self-adjusting file after the conventional retreatment procedures may improve root canal cleanliness, allowing a better action of the irrigating solution.