Original Article

Canal Transportation and Centering Ability of Twisted File and Reciproc: A Cone-Beam Computed Tomography Assessment

Kiumars Nazari Moghaddam, Shahriar Shahab, Golriz Rostami

Iranian Endodontic Journal, Vol. 9 No. 3 (2014), 6 Tir 2014, Page 174-179

Introduction: The purpose of this in vitro study was to compare the canal transportation and centering ability of Twisted File (TF) to that of Reciproc system. Methods and Materials: Forty noncalcified roots with mature apices, minimum length of 19 mm and an apical curvature of 15-30 degrees (according to Schneider’s method), from freshly extracted mandibular and maxillary teeth, were selected for this study. Samples were randomly divided into two groups (n=20) and canal preparation with either TF or Reciproc was performed according to manufacturers' instruction. Pre- and post-instrumentation cone-beam computed tomography (CBCT) images were captured and the extent of canal transportation and centering ability of the files were calculated, using the NNT Viewer software and Photoshop CS5, at levels of 3, 4, and 5 mm from the apex. The Mann-Whitney U test was used to analyze the statistical significance between the two groups. Results: One fracture occurred in the TF group. TF produced more transportation than Reciproc in both mesiodistal and buccolingual directions; however, the difference between the two systems were not statistically significant except for the TF group at 5-mm distance from the working length, where the difference was significant(P>0.05). Conclusion: Both file systems were able keep the original curvature of the canal and thus can be considered safe for clinical application.

Cone-Beam Computed Tomography Comparison of Canal Transportation after Preparation with BioRaCe and Mtwo Rotary Instruments and Hand K-Flexofiles

Hadi Mokhtari, Mahdi Niknami, Aydin Sohrabi, Ehsan Habibivand, Hamid Reza Mokhtari Zonouzi, Saeed Rahimi, Vahid Zand

Iranian Endodontic Journal, Vol. 9 No. 3 (2014), 6 Tir 2014, Page 180-184

Introduction: The aim of this in vitro study was to evaluate the transportation of mesiobuccal canals of mandibular first molars prepared with either BioRaCe or Mtwo rotary instruments or hand K-Flexofile, by means of cone-beam computed tomography (CBCT). Methods and Materials: Forty-five mandibular molars were selected and randomly divided into three groups (n=15). Mesiobuccal roots of these teeth were prepared by BioRaCe, Mtwo, or hand K-Flexofile. Transportation was measured by pre- and post-operative CBCT images. Two-way ANOVA analysis was applied to detect any differences between the groups followed by the post hoc Tukey’s tests. The level of significance was set at 0.05. Results: The non-parametric Friedman test was used to compare the behavior of each file at 3-, 6- and 9-mm levels. There were no significant differences between different levels in Mtwo group (P=0.15); however, the differences in K-Flexofile and BioRaCe groups were significant (P>0.05). Post hoc Tukey’s test revealed significant differences between BioRaCe and K-Flexofile and also between Mtwo and K-Flexofile, both in the 3-mm depths (P<0.05). Conclusion: Under the limitations of the present study, BioRaCe and Mtwo rotary instruments are considered suitable for canal preparation to greater apical sizes provided that the recommended sequences are observed.

The Long-Term Effect of Calcium Hydroxide, Calcium-Enriched Mixture Cement and Mineral Trioxide Aggregate on Dentin Strength

Fariborz Moazami, Safoora Sahebi, Davoud Jamshidi, Aliasghar Alavi

Iranian Endodontic Journal, Vol. 9 No. 3 (2014), 6 Tir 2014, Page 185-189

Introduction: Many of highly-alkaline dental materials have some adverse effects on physical properties of dentin. As basic substances, mineral trioxide aggregate (MTA), calcium hydroxide (CH) and the new endodontic material, calcium-enriched mixture (CEM) cement, may adversely affect dentin. The purpose of this in vitro study was to evaluate the effect of long-term application of CEM cement, MTA and CH on flexural strength of bovine dentin. Materials and Methods: Three hundred and twenty bovine dentin samples were divided into 4 groups, which were either exposed to CEM cement, CH, MTA or normal saline (control group). Samples of each group were divided into 4 subgroups which were tested by means of Instron Universal Testing Machine for periods of 7, 30, 180 and 365 days after exposure to the test materials. The required force for sample breakage was recorded. The data were analyzed by the two-way ANOVA and Tukey tests. Results: The mean value of forces to break the samples in CEM cement and CH groups was significantly lower than the control group after 1 month (P<0.05). After 180 days, the samples of CEM cement group retrieved their strength but in MTA and CH groups the time interval weakened the samples. After one year of exposure to CH and MTA, flexural strength of the dentin reduced to 72% and 38.7%, respectively (P<0.05). Yet the flexural strength of samples in CEM cement group did not change significantly compared to control group. Conclusion: Following 365 days of application of experimental materials to bovine dentin, the CEM cement showed an interesting result and the samples in this group reached their initial strength during the first week of the study but the other materials caused a reduction in dentin strength at the end of the study.

Cone-Beam Computed Tomography Evaluation of Maxillary First and Second Molars in Iranian Population: A Morphological Study

Armita Rouhani, Ali Bagherpoor, Majid Akbari, Majid Azizi, Amirhosein Nejat, Neda Naghavi

Iranian Endodontic Journal, Vol. 9 No. 3 (2014), 6 Tir 2014, Page 190-194

Introduction: The aim of this study was to identify the root and canal morphology of maxillary first and second molars in Iranian population by taking and analyzing cone-beam computed tomography (CBCT) scans. Methods and Materials: Extracted maxillary first (n=125) and second (n=125) molars were collected from native Iranians and scanned by using a CBCT scanner. The number of roots and configuration of root canal system were classified according to Vertucci’s classification. Results: Two (1.6%) maxillary first and two (1.6%) maxillary second molars had four roots. Prevalence of root fusion was 2.4% and 8.8% in maxillary first and second molars, respectively. The most common canal morphology in the mesiobuccal roots of three-rooted first and second molars was Type I (46.4% and 80.8%, respectively), followed by Type VI (17.6%) in first molars. The predominant morphology of distobuccal and palatal roots in first and second molars was Type I. Additional canal types were also identified. Conclusion: Profound knowledge of anatomic variations is necessary prior to cleaning and obturation of the root canal system. The most common discovered root morphology was three separate roots in both tooth types. The greatest variation in canal anatomy was discovered in the MB canals of both the first and second molars.

Antimicrobial Effects of Four Intracanal Medicaments on Enterococcus Faecalis: An in Vitro Study

Mohammad Ali Mozayeni, Ali Haeri, Omid Dianat, Ali Reza Jafari

Iranian Endodontic Journal, Vol. 9 No. 3 (2014), 6 Tir 2014, Page 195-198

Introduction: The aim of this in vitro study was to evaluate the antimicrobial activity of four intracanal medicaments on Enterococcus Faecalis (E. Faecalis). Methods and Materials: Fifty extracted single-rooted human teeth were prepared with standard method. After contaminating the canals with E. Faecalis, the samples were divided into one control and four experimental groups (n=10). The teeth in each group were treated with one of the experimental medicaments, including calcium hydroxide (CH), 2% chlorhexidine (CHX), triple antibiotic paste (TAP) and nanosilver (NS). In control group, canals were filled with neutral gel. Microbial samples were obtained from the roots after 7 days and optical density of the cultures was determined after 24h incubation. Optical density values were analyzed with one-way analysis of variance and Tukey’s post hoc tests. Results: CHX gel and TAP were significantly more effective against E. Faecalis than CH, which was also significantly more efficient than NS and normal saline. In the paper cone samples, CHX gel was more effective than TAP; however, samples obtained with #2 and 4 Gate Glidden drills, indicated that TAP was much more efficient than CHX gel. Normal saline and NS had similar effects on E. Faecalis. Conclusion: Nanosilver gel was not efficient enough against E. Faecalis; however, TAP and CHX gel showed better antibacterial efficacy than CH and can be used as an alternative intracanal medicament in root canal therapies.

The Efficacy of FlexMaster’s IntroFile, PreRaCe and Gates Glidden Drills in Straight-Line Access: A CBCT Assessment

Narges Farhad Molashahi, Mahdi Sohrabi, Leila Farhad Molashahi, Mojdeh Mehdizadeh

Iranian Endodontic Journal, Vol. 9 No. 3 (2014), 6 Tir 2014, Page 199-203

Introduction: An overlooked but important part of successful root canal treatment is a straight-line access (SLA). The purpose of this in vitro study was to compare the efficacy of IntroFile and PreRaCe rotary instruments with Gates Glidden (GG) drills in gaining SLA by cone-beam computed tomography (CBCT). Methods and Materials: A total of forty five extracted mandibular first molars were selected and mounted in dental like arches. Subsequently, they were randomly classified into three groups (n=15). After preparation of a standard access cavity, orifices of the mesiobuccal canal was reached and a #10 file was inserted to explore the canals until the file tip was visible at the apex. Then, preoperative CBCT images were taken. SLA was gained in three groups; group 1, FlexMaster’s IntroFile (FM); group 2, PreRaCe (RC) and group 3, GG. Again, the first binding file at the working length (WL) was placed in the canal and postoperative CBCT images in similar positions were taken. The pre/post operative morphology of the canal was evaluated for changes. Data was analyzed using the one-way ANOVA and post-hoc Bonferroni analysis. Results: The average amount of reduction in coronal canal curvature in FM, RC and GG groups was 2.43±1.79, 3.17±2.05 and 8.7±3.45, respectively. This descending trend was statistically significant. The difference between pre/post SLA changes in FM and RC groups was significant compared to GG group, while there were no significant differences between RC and FM. Conclusion: GG drills produced extraordinary results in reducing coronal curvature of the canal and achieving SLA. They are also more effective than nickel-titanium (NiTi) rotary instruments in canals with coronal curvature.

Comparative Evaluation of Physical Surface Changes and Incidence of Separation in Rotary Nickel-Titanium Instruments: An in Vitro SEM Study

Rudra Kaul, Riyaz Farooq, Vibhuti Kaul, Shafayat Ullah Khateeb, Aamir Rashid Purra, Roopali Mahajan

Iranian Endodontic Journal, Vol. 9 No. 3 (2014), 6 Tir 2014, Page 204-209

Introduction: The aim of the present study was to comparatively evaluate the physical surface changes and incidence of separation in rotary nickel-titanium (NiTi) instruments using scanning electron microscope (SEM). Methods and Materials: A total number of 210 freshly extracted human maxillary and mandibular first molars were selected and distributed between three groups. Three different systems of rotary NiTi instruments, namely ProFile (PF), RaCe (RC) and Twisted File (TF), were used to prepare the canals using crown-down technique. All instruments were evaluated by means of SEM with 500× and 1500× magnifications, at four different stages; before use, after preparation of 7 and 14 canals and after instrument separation. Photomicrographs were also taken. The data was analyzed using the Kruskal-Wallis test and the level of significance was set at 0.001. It was found that H (HAT matrix) was 15.316 with 2 degrees of freedom. Moreover the various groups were compared using the Student-Newman-Keuls test with P<0.05 and it was found that all groups were significantly different. Results: RC showed the maximum wear of the surface followed by TF (P<0.05). PF showed the minimum wear except for its tip. There was no correlation between electropolishing and file fracture. Insignificant difference was observed in the mean number of canals shaped by PF and TF before their separation. Conclusion: Clinically, TF performance was superior, followed by PF then RC. RC fracture rate was the greatest after preparing the least number of canals.

Smear Layer Removal in the Apical Third of Root Canals by Two Chelating Agents and Laser: A Comparative in vitro Study

Hengameh Ashraf, Mohammad Asnaashari, Soheila Darmiani, Reza Birang

Iranian Endodontic Journal, Vol. 9 No. 3 (2014), 6 Tir 2014, Page 210-214

Introduction: Smear layer (SL) is produced as a result of mechanical instrumentation of the canal(s). Despite the controversies regarding its removal, the evidence-based trend has shifted towards removing and eliminating the SL. Different methods have been used to remove the SL and the aim of this in vitro study was to evaluate the ability of 17% ethylenediaminetetraacetic acid (EDTA), 18% etidronate and Er: YAG on effective removal of the SL. Methods and Materials: Fifty straight single-rooted teeth were divided into three experimental groups (n=15) and one control group of five. The canals were instrumented with HERO 642 rotary files up to 30/0.06. In group 1, canals were irradiated with Er: YAG laser; in groups 2 and 3, canals were irrigated with 17% EDTA and 18% etidronate, respectively. In group 4 (control) distilled water was used for canal irrigation. The amount of remaining SL was quantified according to Hulsmann’s method with scanning electron microscopy (SEM). Data was analyzed by the Kruskal-Wallis and Mann-Whitney U tests (P<0.05). Results: The results showed statistically significant differences in terms of SL removal among the groups (P<0.05). The amount of removed SL by EDTA was significantly greater followed by Er: YAG laser and 18% etidronate. Conclusion: Within the limitations of this study, EDTA was more effective in removing SL compared to Er: YAG and etidronate.

The Influence of Composite Thickness with or without Fibers on Fracture Resistance of Direct Restorations in Endodontically Treated Teeth

Hassan Torabzadeh, Amir Ghassemi, Masoud Sanei, Sara Razmavar, Seyedeh Mahsa Sheikh-Al-Eslamian

Iranian Endodontic Journal, Vol. 9 No. 3 (2014), 6 Tir 2014, Page 215-219

Introduction: This in vitro study evaluated the influence of composite thickness (with or without fiber reinforcement) on fracture resistance of direct restorations in endodontically treated teeth. Methods and Materials: Fifty-six intact human premolars were chosen and randomly divided into four groups (n=14). After preparation of a mesio-occluso-distal (MOD) cavities and cusp reduction, the teeth were endodontically treated. Subsequently, the samples were restored with composite resin using the following protocols: group 1; composite onlay with cusp coverage of 1.5 mm, group 2; composite onlay with cusp coverage of 2.5 mm, group 3; composite onlay (including resin-impregnated fiber) with cusp coverage of 1.5 mm and group 4; composite onlay (including resin-impregnated fiber) with cusp coverage of 2.5 mm. The fracture resistance of teeth in all test groups was calculated by subjecting them to a progressively increasing compressive axial force in the universal testing machine with the cross-head speed of 1 mm/min to the point of fracture. The data were analyzed using the Kruskal-Wallis test. Results: The mean fracture strengths and obtained standard error were 1263.85±74.03 N, 1330.26±128.01 N, 1344.92±64.40 N and 1312.54±75.63 N for groups 1 to 4, respectively. Statistical analysis revealed no significant difference between groups. Conclusion: Cusp coverage of 1.5 and 2.5 mm in MOD access cavities with or without insertion of resin impregnated fiber had similar fracture rates in the endodontically treated teeth.

Effect of Mineral Trioxide Aggregate, Calcium Enriched Mixture and Mineral Trioxide Aggregate with Disodium Hydrogen Phosphate on BMP-2 Production

Negin Ghasemi, Saeed Rahimi, Mehrdad Lotfi, Jafar Solaimanirad, Shahriar Shahi, Hajar Shafaie, Amin Salem Milani, Sahar Shakuie, Vahid Zand, Majid Abdolrahimi

Iranian Endodontic Journal, Vol. 9 No. 3 (2014), 6 Tir 2014, Page 220-224

Introduction: One of the hypotheses regarding the calcification induction by mineral trioxide aggregate (MTA) is the involvement of transforming growth factor-Beta (TGF-β) super family. Calcium-enriched mixture (CEM) cement is one of the endodontic biomaterials with clinical applications similar to MTA. The aim of the present in vitro study was to compare the induction of bone morphogenic protein-2 (BMP-2) by a combination of disodium hydrogen phosphate (DSHP) and tooth colored ProRoot MTA (WMTA), to that of CEM cement and WMTA. Methods and Materials: Human gingival fibroblasts (HGFs) were obtained from the attached gingiva of human premolars. HGFs were cultured in Dulbecco’s Modified Eagle’s medium, supplemented with 10% fetal calf serum, penicillin, and streptomycin. Cells in groups 1, 2 and 3 were exposed to WMTA, CEM and WMTA+DSHP discs, respectively. The fourth group served as the control. After 72 h of exposure, HGF viability was determined by Mosmann’s tetrazolium toxicity (MTT) assay. BMP-2 levels in cell-free culture media were determined by enzyme-linked immunosorbent assay (ELISA). Statistical analysis was performed using the one-way ANOVA, followed by the post hoc Games-Howell test for BMP-2 and post hoc Tukey’s test for the results of MTT assay. Results: Cellular viability was significantly higher in group 3 compared to the other groups (P<0.05); however, CEM and WMTA did not exhibit significant differences (P=0.08). The control group exhibited significantly higher cellular viability in comparison to the other groups of the study (P<0.05). The highest and lowest protein production rates were observed in the WMTA (3167±274.46 pg/mL) and WMTA+DSHP (1796±839.49 pg/mL) groups, respectively. There were no significant differences between the control, WMTA and CEM groups (P>0.05). Conclusion: WMTA and CEM did not exhibit any significant differences in inducing BMP-2 production compared to control; however, incorporation of DSHP into WMTA resulted in a decrease in the induction of this protein.

Case Report

Repair of a Strip Perforation with Calcium-Enriched Mixture Cement: A Case Report

Mohammad Jafar Eghbal, Mahta Fazlyab, Saeed Asgary

Iranian Endodontic Journal, Vol. 9 No. 3 (2014), 6 Tir 2014, Page 225-228

The present report reviews the diagnostic and treatment challenges of a mandibular molar with previous root canal treatment and signs of a procedural mishap, i.e. furcal radiolucency and localized swelling of the gingival margin in which a sinus tract was present. By tracing the sinus tract, it became evident that the lesion originated from the furcation area, not the root apices. This case was treated by cleaning/filling the coronal half of the canals and leaving the rest of obturating material in situ. The strip perforation zone in the mesial root was sealed off with calcium-enriched mixture cement. One-week post-operative, patient’s symptoms faded away and after one year, the lesion completely healed with bone replacement.

Presence of Two Distal and One Mesial Root Canals in Mandibular Second Molars: Report of Four Cases

Masoud Parirokh, Paul V Abbott, Mohammad Hosein Yosefi, Hamid Reza Hosseini

Iranian Endodontic Journal, Vol. 9 No. 3 (2014), 6 Tir 2014, Page 229-232

Most mandibular second molars have one and two canals in distal and mesial roots, respectively. This report represents four cases of mandibular second molars with a single mesial and two distal root canals with two different canal configurations. After access cavity preparation, two teeth had one distal and two mesial orifices, whereas in the two other teeth one mesial and two distal orifices were found. In the teeth with two mesial canal orifices, the distal root canal and one of root canals with a mesial orifice joined together in the apical part of the root, whereas in the two other teeth with one mesial and two distal canal orifices, three separate canals each with a different apical foramen were detected. Dental practitioners should be aware that despite higher prevalence of one distal and two mesial root canals, the mandibular second molar teeth may also have one mesial and two distal root canals.

Management of Complicated Crown Fracture with Miniature Pulpotomy: A case report

Saeed Asgary, Mahta Fazlyab

Iranian Endodontic Journal, Vol. 9 No. 3 (2014), 6 Tir 2014, Page 233-234

Crown fractures account for the majority of dental traumas If handled properly, prognosis of the pulp following a traumatic crown fracture can be favorable. The present case report focuses on the treatment of a traumatized mature permanent incisor with exposed pulp that was treated with the novel technique of miniature pulpotomy using calcium-enriched mixture (CEM) cement. One-year follow-up revealed that the tooth was responsive to vitality tests and radiographic assessment showed the presence of a thick dentinal bridge beneath the CEM layer.

Review Article

A Review of Antibacterial Agents in Endodontic Treatment

Saeed Rahimi, Maryam Janani, Mehrdad Lotfi, Shahriar Shahi, Amirala Aghbali, Mahdi Vahid Pakdel, Amin Salem Milani, Negin Ghasemi

Iranian Endodontic Journal, Vol. 9 No. 3 (2014), 6 Tir 2014, Page 161-168

Microorganisms play a major role in initiation and perpetuation of pulpal and periapical diseases. Therefore, elimination of the microorganisms present in the root canal system is the fundamental objective of endodontic treatment. The use of mechanical debridement, chemical irrigation or other antimicrobial protocols and intra-canal medicaments are critical to attain this goal. The aim of this article was to review the antimicrobial agents and their properties in endodontics.

Hepatitis C Virus; Its Implication for Endodontists

Nima Mahboobi, Nastaran Mahboobi, Parvin Oliaei, Seyed Moayyed Alavian

Iranian Endodontic Journal, Vol. 9 No. 3 (2014), 6 Tir 2014, Page 169-173

Over 170 million patients worldwide are chronically infected with Hepatitis C virus (HCV); making it a globally important infection. Dentists constantly handle sharp instruments infected with biological fluids and are therefore considered at high-risk of contracting HCV infection. Needle-stick injuries seem to be the most common route of exposure to blood-borne pathogens in dental practice. Moreover, endodontist’s constant use of sharp instruments such as endodontic files with limited operative vision in a small working field (i.e. root canal system) increases their risk of exposure to infection. The aim of this study was to review the epidemiology of HCV infection in dental healthcare staff and the tests required for its diagnosis. We also look at the protocols for dental treatment in infected individuals and screening and dental examination tailored for HCV patients.