Tissue Necrosis due to Chloroform: A Case Report

For many years, gutta-percha has been the root canal filling material of choice. Chloroform is one of the most efficient solvents widely used for gutta-percha removal in retreatment cases, despite being toxic and carcinogenic. The present case report discusses a chloroform extrusion through an existing perforation to the surrounding periodontal ligament space and subsequent necrosis in supporting bone and tissues, during an endodontic retreatment visit for an addicted patient. Subsequently, the management and preventive options are reviewed

The Effect of Size and Taper of Apical Preparation in Reducing Intra-Canal Bacteria: A Quantitative SEM Study

Introduction: Bacteria and their byproducts are major etiologic factors in endodontic diseases. Prevention or reduction of root canal bacterial contamination is the main aim of endodontic treatment. The purpose of this in vitro study was to evaluate the effect of size and taper of master apical file (MAF) in reducing bacteria from the apical third of the curved canals using a quantitative scanning electron microscope (SEM) study. Methods and Materials: Eighty-nine human mandibular first molars with curved MB canals (20º-35º) were divided into one control group (n=5) (without rotary instrumentation) and 6 experimental groups (n=14). The canals were prepared using RaCe rotary files to the MAF sizes 25/0.04, 25/0.06, 30/0.04, 30/0.06, 35/0.04 and 35/0.06, in groups 1 to 6, respectively. All the experimental groups were finally rinsed with 2 mL of 17% EDTA followed by 3 mL of 5.25% NaOCl. The mesial roots were split longitudinally. Remaining bacteria in the apical third of MB canals were evaluated using SEM (2000×). Data analysis was performed using one way ANOVA with Tukey’s post hoc test. The level of significance was set at 0.05. Results: All the experimental groups showed significant bacterial reduction (P<0.001). Although the greater size and/or taper resulted in decrease in bacteria, differences between the groups were not significant. Conclusion: Based on this in vitro study the MAF #25/0.04 had no significant difference compared to other groups with greater apical size/taper; all groups could effectively reduce intra-canal bacteria

Technical Quality of Root Canal Treatment Performed By Undergraduate Dental Students

INTRODUCTION: This study was carried out to evaluate the technical quality of root canal treatment (RCT) performed by undergraduate dental students at the Islamic Azad University in Tehran, Iran. MATERIALS AND METHODS: Four-hundred records of patients who had received RCT at faculty of dentistry, between the years 2004-2006 were evaluated. For each treated tooth at least three periapical x-rays were assessed: preoperative, working length measurement, and postoperative. Evaluation of root canal filling was based on two variables: length and density. The filling length was recorded as adequate, under- or overfilled. Density of filling was recorded as poor or adequate. Fillings with adequate length and density were recorded as acceptable. Detected iatrogenic errors were: ledge formations, root perforations, furcation perforations, strip perforations and presence of fractured instruments. Results were evaluated statistically using one-way ANOVA and Chi-square analysis. RESULTS: Out of the 400 teeth, 50.5% had at least one of the mentioned errors. Acceptable filling was observed in 32.5% of all studied teeth. Ledge was found in 17.5% of the teeth. Canal curvature was the most important factor associated with ledge formation (P<0.05). CONCLUSION: The technical quality of RCT performed by undergraduate dental students using step-back preparation and cold lateral condensation was classified as acceptable in 32.5% of the cases

In vitro Comparison of Apical Debris Extrusion Using Rotary and Reciprocating Systems in Severely Curved Root Canals

Introduction: The aim of this in vitro study was to compare the amount of apically extruded debris after root canal preparation using rotary and reciprocating systems in severely curved root canals. Methods and Materials: Thirty six extracted human mandibular first molars with 25-35° curvature in their mesiobuccal (MB) canal (according to Schneider’s method) were cleaned and shaped with ProTaper and WaveOne systems. The extruded debris was collected and their net weight was calculated. To compare the efficiency of the two systems, the operation time was also measured. The data were analyzed with t-test. Results: The amount of extruded debris in WaveOne group was significantly greater in comparison with ProTaper group (26%). The operating time for ProTaper was however, significantly longer than WaveOne. Conclusion: Both root preparation systems caused some degree of debris extrusion through the apical foramen. However, this amount was greater in WaveOne instruments.Keywords: Apical Extrusion; Curved Canals; Reciprocating File; Root Canal Preparation; Rotary Instrumentatio

Students’ Knowledge Comprehension after Implementation of Live Conventional Demonstration, Video Teaching and Video-Assisted Instruction Methods in Endodontic Practice

Introduction: Video-assisted clinical instruction (VACID) has been found to be a beneficial teaching tool for various fields in dentistry. The aim of this interventional study was to compare the efficacy of live conventional demonstration (CD), video teaching, and VACID (video with explanation) methods in teaching of root canal treatment to undergraduate dental students. Methods and Materials: Forty-two undergraduate senior dental students participated in this study. The students experienced this course for the first time and were randomly divided into three groups (n=14). Group A attended live CD on a patient; group B watched a professionally produced demonstration video without any verbal explanation during 1 h; and finally group C watched the same video alongside live explanation by a mentor during the 1.5 h (VACID). The whole process was performed by an experienced endodontist on maxillary central incisors. All of The students carried out a multiple choice question exam to evaluate their comprehension. The mean score of the experimental groups were compared using ANOVA test and multiple comparisons were carried out with Tamhane test. The level of significance was set at 0.05. Results: There was significant difference among three groups according to the ANOVA test (P<0.05). Group VACID had the highest mean scores. There was significant difference between the groups VACID and VT (P=0.011); no significant differences were found in other inter-group comparisons. Conclusion: According to the results, VACID may improve the quality of endodontic training in undergraduate dental students.Keywords: Conventional Education; Endodontic Treatment; Knowledge; Performance; Video-Assisted Clinical Instructio

Root Canal Anatomy and Morphology of Mandibular First Molars in a Selected Iranian Population: An In Vitro Study

Introduction: The aim of this study was to evaluate root canal anatomy of mandibular first molars (MFM) in a selected Iranian Population using clearing technique. Methods and Materials: A total of 150 extracted MFMs were cleared. The root canal morphology (including the root numbers and root length) and the anatomy of the root canal system (including is the number and type of canals based on Vertucci’s classification, canal curvature according to Schneider's method and the presence of isthmus) was evaluated using the buccolingual and mesiodistal parallel x-rays and stereomicroscope. The data were analyzed using the chi-square test. Results: Two and three roots were present in 96.7% and 33% of the teeth, respectively (P=0.0001). All the teeth (100%) had two canals in the mesial root, while 61.3% of the samples had one distal root canal (P=0.006). The root canal configuration in the mesial canal included type IV (55.3%) and type II (41.3%) (P=0.0001). In doubled-canalled distal roots, 68.8% and 24.3% were type II and type IV, respectively (P=0.0001). Isthmii were observed in 44.6% of mesial and 27.3% of distal roots (P=0.0001). Conclusion: The notable prevalence of type IV configuration in both roots of mandibular first molars, presence of isthmus and root curvature, necessitates the careful negotiation and cleaning of all accessible canal spaces.Keywords: Iranian Population; Mandibular First Molar; Root Canal Anatomy; Root Canal Morphology; Tooth Clearin

Comparison of transportation and centering ability using RECIPROC and iRace: A cone-beam computed tomography study

BACKGROUND AND AIM: Root canal treatment, especially in curved and constricted root canals, can be very difficult and time consuming. Several investigations have compared the reciprocating and full sequence motions in terms of shaping ability. The purpose of the present study was to compare the root canal transportation and centering ability of RECIPROC and iRace using cone-beam computed tomography (CBCT). METHODS: Thirty-two mesiobuccal (MB) root canals of maxillary first molars with curvature ranged 25-40 degrees were selected. Pre-instrumentation CBCT images were captured at 2, 4 and 6 mm distances from the root apex. Thirty samples were randomly divided into two groups (n = 15). After root canal preparation using either iRace or RECIPROC #25, post-instrumentation CBCT images were obtained at the same levels. Two specimens served as control group. Pre- and post-CBCT images were evaluated to measure root canal transportation and centering ability. Mann-Whitney and Friedman tests were used for statistical analysis. RESULTS: There was no significant difference between the groups (P > 0.05). CONCLUSION: iRace and RECIPROC maintained original root canal geometry and may be safe to be used in curved root canals. KEYWORDS: Cone-Beam Computed Tomography; Root Canal Preparation; Transportatio

Incidence, location, and type of isthmus in mandibular second molars among individuals of an Iranian population

BACKGROUND AND AIM: Isthmuses are narrow and strip shaped connections between two canals containing pulpal tissue that may encompass bacteria as well. They are hardly accessible for cleaning; therefore, success and failure of root canal treatments could be affected by their presence. The present study was carried out aiming to evaluate the incidence, location, and type of isthmus in mandibular second molars (MSMs) among individuals of an Iranian population. METHODS: 80 MSMs with inclusion criteria, belonging to individuals of an Iranian population were collected and disinfected. After embedding the samples’ roots in the acrylic resin, teeth were sectioned horizontally at 2, 4, and 6 mm distances from the apices. Then they were viewed and recorded by a stereomicroscope under × 30 magnification. According to Kim classification, two endodontists recorded the number of canals, incidence, and type of the isthmuses. In cases of disagreement, a third endodontist was involved to judge on the right opinion between the two. The acquired data were analysed using chi-square test. RESULTS: The results showed that 96.3% and 3.75% of MSMs had two and three roots, respectively. Type V (described in the following) was the most frequent type of isthmus at mesial and distal roots. C-shaped canals composed 3.7% of the samples and showed isthmus at all the three sections. There was a significant difference in the distribution of isthmuses (P < 0.001). CONCLUSION: According to this study, different types of isthmuses prevail in high rate of mesial and about half of the distal roots of MSMs, which are important for root canal cleaning and shaping. KEYWORDS: Anatomy; Molar; Tooth; Root Cana

Efficacy of MTAD, Glyde and EDTA in debridement of curved root canals

INTRODUCTION: This study aimed to compare the efficacy of MTAD, Glyde and EDTA in removing the post-preparation smear layer and debris produced in apical third of curved molar root canals. MATERIALS AND METHODS: Forty extracted human maxillary first molars with curved mesiobuccal canals (30˚-35˚), similar root lengths and morphologies were divided into 3 experimental groups (n=12) and one control group (n=4). Canals were prepared by RaCe rotary files and were treated with the following materials between each two files: Group A (control group); 5 mL of distilled water, Group B; 1 mL of 17% ethylenediamine tetra-acetic acid (EDTA) for 1 min, Group C; BioPureä MTAD (according to the manufacturer’s instruction; 5mL for 5 min), and Group D; Glyde File Prep alternated with sodium hypochlorite (NaOCl) between each two files. Debridement of the apical third was evaluated using scanning electron microscope (SEM) (×5000). The data were statistically analyzed using the Kruskal-Wallis and Mann-Whitney U tests (P&lt;0.05). RESULTS: Statistical analysis of the data showed that MTAD and 17% EDTA were effective in removing smear layer and debris from the apical thirds. MTAD was more effective than EDTA in smear layer removal. Glyde did not adequately debride curved root canals of molar teeth. CONCLUSION: MTAD and 17% EDTA were effective in debriding the apical third of curved molar root canals during endodontic treatment, whereas Glyde File Prep does not provide adequate debridement

Effect of master apical file size and taper on irrigation and cleaning of the apical third of curved canals.

Canal preparation generates a substantial amount of debris and smear layer (SL). The size and taper of the Master Apical File (MAF) affects on penetration of irrigants and subsequently canal cleaning efficacy. The aim of this study was to evaluate the effect of MAF size and taper on penetration of irrigants to the apical third of curved mesiobuccal (MB) canals of mandibular first molars.Eighty-nine human mandibular first molars were divided into one control group (n=5) without rotary instrumentation and 6 experimental groups (n=14 each) that were prepared with the following RaCe rotary files as MAF: 25.04 (group1), 25.06 (group 2), 30.04 (group 3), 30.06 (group 4), 35.04 (group 5) and 35.06 (group 6). All the experimental groups were rinsed with 2 ml of 17 % EDTA followed by 2 ml of 5.25% NaOCl. Debridement of the MB canals was evaluated using scanning electron microscope (SEM). The data were statistically analyzed using Kruskal-Wallis and Mann-Whitney U tests (