Iranian Endodontic Journal

Discoloration remains an unfavourable complication of otherwise successful regenerative endodontic procedure of immature teeth with necrotic pulp. This review presents a critical view on current knowledge of discoloration sources, its treatment and possible preventive modalities, dealing mainly with the use of antibiotics, ethylendiaminotetraacetic acid, calcium hydroxide, mineral trioxide aggregate, calcium silicate cements, sodium hypochlorite and chlorhexidin during regenerative treatment and their possible interactions. Bleaching as a discoloration treatment modality is discussed as well.

Keywords: Biodentin; Calcium Hydroxide; Calcium Silicate; CEM cement; Mineral Trioxide Aggregate; Regenerative Medicine; Sodium Hypochlorite; Tooth Discoloration

Introduction: The aim of this study was to review the chemical composition of propolis and its application in endodontics. Methods and Materials: For this purpose, keywords were searched on ScienceDirect, PubMed and World of Chemicals databases in order to find published papers from 1988 to February 2018. Results: There are many different compounds in propolis of different geographic regions; flavonoids are one of the most important agents which have anti-inflammatory, anti-viral, anti-allergic, anti-cancer, anti-bacterial and antioxidant effects. According to the mentioned properties, propolis can be used as a canal irrigation solution as well as intracanal medicament in endodontic treatments. Studies have shown that propolis as a storage medium is capable of maintaining the vitality of the periodontal ligaments cells and also has the ability to inhibit osteoclastic activity due to one of the active compounds present in it. In vital pulp therapy, propolis can induce the production of tubular dentin and also decrease the inflammation of the pulp. Conclusion: Considering the propolis components like resin, pollen, vitamins, flavonoids and phenols; it can be used for various purposes in endodontics and would have a promising role in future medicine as well as dentistry.

Keywords: Dentistry; Endodontics; Flavonoids; Honeybee; Phenols; Propolis

Introduction: The aim of this study was to assess the biocompatibility of positively charged imidazolium-based ionic liquid-protected nanosilver solution (AgNPs) root canal irrigant. Methods and Materials: Eighteen male 4- to 5-month old Sprague-Dawley rats, weighing 200-300 gr were selected and randomly divided into 5 groups: Normal saline 0.9% (group 1), 5.25% NaOCl (group 2), 2.5% NaOCl (group 3), 2.0% chlorhexidine solution (group 4) and AgNPs at 5.7×10^-8 M/L (group 5) were randomly injected in 5 sites of dorsal skin of each rat. Tissue inflammatory reaction were evaluated histopathologically after 2 h, 48 h and 14 days. Statistical analysis was done with SPSS version 21 and the Kruskal-Wallis H and Dunn tests were used to find statistically significant differences. The level of significance was set at 0.05. Result: All solutions irritated the highest tissue response after 48 h. Group 1 showed lower inflammatory response compared to groups 2 and 4 (P<0.05). Group 2 displayed higher inflammatory response in comparison with group 5 (P<0.05). Tissue reaction to group 5 was not more severe than the reaction to group 3 or 4. It also would irritate less inflammatory response compared to group 2 (P<0.05). Conclusion: Comparing with NaOCl and CHX, it is possible to label AgNPs as a tissue compatible agent.

Keywords: Biocompatibility; Root Canal Irrigant; Silver Nanoparticle

Introduction: The objective of this study was to evaluate the physical properties, cytotoxicity and sealing ability of HealApex _a new premixed calcium-silicate-phosphate-based biosealer_ in comparison with AH-26. Methods and Materials: Setting time, working time, film thickness, flow and radiopacity evaluation were performed according to ISO 6876 specification. L929 fibroblasts were incubated with the extracts of sealers and cytotoxicity was then evaluated using MTT assay. Thirty intact extracted human premolars were instrumented using step-back technique. The specimens were obturated with gutta-percha and experimental sealers employing lateral condensation technique. Sealing ability of sealers was investigated for up to one month using fluid filtration method. Data were statistically analyzed by t-test and ANOVA. Results: Physical properties of both sealers conformed to ISO specification. AH-26 exhibited significantly higher flow, higher radiopacity and lower film thickness; whereas HealApex showed lower setting time (P<0.05). HealApex represented high cell viability (P<0.05); however, AH-26 demonstrated significantly lower cell viability compared with the negative control group (P<0.05). There was no significant difference in microleakage between the sealers after 1 and 7 days; however, after 30 days, HealApex displayed better sealing ability (P<0.05). Conclusions: In this in vitro study, HealApex revealed acceptable physical properties, biocompatibility and good sealing ability as an endodontic sealer. Obtained results showed the new sealer had acceptable physical properties and good biocompatibility. In short term, the sealing ability of HealApex was comparable with AH-26 whilst in long term, HealApex’s sealing ability was better than the epoxy resin-based sealer.

Keywords: Biocompatibility; Calcium Silicate Phosphate; Calcium Enriched Mixture; CEM Cement; Dental Leakage; Endodontic; HealApex; Physical Properties; Sealer

Introduction: The aim of this study was to compare the antibacterial effects of two gels containing zinc oxide and zinc oxide/silver nanoparticles and a mixture of calcium hydroxide and 0.12% chlorhexidine as intracanal medicaments in root canals contaminated with Enterococcus faecalis (E. faecalis) at different time intervals. Methods and Materials: After preparation and culturing of E. faecalis in 132 single root teeth, the initial count of bacteria was performed. Then, different materials as intracanal medicaments were used in periods of 3, 7 and 14 days (group 1: calcium hydroxide with 0.12% CHX paste; group 2 zinc oxide nanoparticles gel; group 3: zinc oxide/silver nanoparticles gel; group 4: normal saline as the control group). After the specified time, intracanal medicament was removed and the final count of bacteria was performed. Antibacterial effect of materials was counted by measuring the percentage reduction in the colony counts (RCC). Data were analyzed using the descriptive statistics (Mean±SD) and multi-factorial analysis of variance (by taking into account the effect of the time factor on the dependent variable). Results: There were no statistically significant differences among mean RCC of different time intervals in each group (P=0.09). However, the differences in mean RCC of different dressing materials were significant (P<0.001). The effect of interaction between time and materials was significant (P=0.015). Comparison of the antibacterial effects of experimental agents at different time intervals showed that the mean RCC in group 1 was higher than other groups (P<0.001). The difference in antibacterial effect between groups 2 and 3 was not significant (P>0.05). The minimum antibacterial effect was observed in group 4 (P<0.0001). Conclusions: The mixture of calcium hydroxide/chlorhexidine as an intracanal medicament was more effective than zinc oxide and zinc oxide/silver nanoparticles gels.

Keywords: Calcium Hydroxide; Chlorhexidine; E. faecalis; Nanoparticles; Zinc Oxide

Introduction: This study compared the cyclic fatigue resistance (CFR) of new instruments manufactured by heat-treated nickel-titanium wire. Methods and Materials: Ninety-six new instruments from HyFlex CM (HF), Edge File (EF), Pro Design S (PDS/L) and Mtwo (MT) (20/0.06 and 25/0.06) (n=12) systems were evaluated. A stainless steel device was used and time and number of cycles to fracture (NCF) were observed. Fragments were measured and fracture surface was evaluated using scanning electron microscope (SEM). ANOVA and Tukey’s tests were applied with the level of significance set at 0.05. Results: PDS 20/0.06 and PDL 25/0.06 instruments presented the highest CFR. MT 20/0.06 and MT 25/0.06 showed the lowest CFR (P<0.05). The length of fragments was similar for 25/0.06 instruments and HF presented the highest one for 20/0.06 instruments. SEM analyses showed morphology suggestive of ductile fracture. Conclusion: Heat treatment increased resistance to cyclic fatigue differently for each type of instrument. PDS 20/0.06 and PDL 25/0.06 present higher cyclic fatigue resistance.

Keywords: Cyclic Fatigue; Instrumentation; Nickel-Titanium; Rotary System

Introduction: The aim of the present research was to evaluate the effectiveness of 5% malic acid, 17% EDTA and 10% citric acid solutions used to disinfect gutta-percha cones contaminated by Enterococcus faecalis (ATCC 29212). Methods and Materials: Two hundred and ten previously sterilized gutta-percha cones were contaminated with E. faecalis at concentration of 1.5×10⁸ CFU/mL. The cones were immersed in 5% malic acid, 17% EDTA, 10% citric acid, 1% NaOCl and 2.5% NaOCl for 1, 5 and 10 min. Then each cone was kept in Eppendorf tubes containing BHI sterile solution at 37^°C for 48 h. The presence of turbidity in BHI solution was analyzed. The results were statistically analyzed by Kruskal-Wallis test and 5% Dunn comparisons. P-value was considered statistically significant when P<0.05. Results: Regardless of exposure time, 1% NaOCl and 2.5% NaOCl were the most effective agents for rapid disinfection of gutta-percha cones (P<0.001). All specimens immersed in experimental demineralized solutions presented bacterial growth (P>0.05). Conclusion: Demineralized solutions tested were not effective for elimination of Enterococcus faecalis on the surface of gutta-percha cones.

Introduction: Biodentine has been scarcely studied as a furcation perforation (FP) repair material, mostly by in vitro methodologies. This animal study aimed to compare the histological responses, radiographic, and micro-computed tomographic (micro-CT) outcomes after FP repair with Biodentine or ProRoot MTA (MTA) in dogs’ teeth. Methods and Materials: Fifty teeth from five dogs were divided into 4 groups: MTA (n=20, FP repaired with ProRoot MTA), BDT (n=20, FP repaired with Biodentine), PC (n=5, positive control, FP without repair) and NC (n=5, negative control, without perforation). The animals were euthanized after 4 months. Histological assessment included inflammatory cell infiltration, hard tissue resorption, hard tissue repair, and cement repair in the furcation area. Immediate postoperative and 4months follow-up radiographs were compared for radiolucency in the furcation region. The volume of extruded material was quantified using micro-CT images. Results: The tested materials showed equivalent radiographic response, together with similar hard tissue resorption and repair but, BDT group showed significantly less inflammation, lower volume of extruded material and higher cement repair than MTA group. Conclusion: The outcomes of this study, taken together with other favorable results in literature, are highly suggestive that Biodentine is a promising biomaterial to be used for FP repair.

Keywords: Biodentine; Biomaterial; Endodontics; Furcation Perforation; Imaging; Micro-Computed Tomography

Introduction: This study evaluated the removal of the filling material during endodontic retreatment considering the presence of cracks and the dentin age. Methods and Materials: A total of 20 freshly extracted single-rooted teeth were categorized into the following two groups according to the age of the patients: Group Young (Y; aged 18-30 years) and Group Old (O; aged ≥60 years). Each tooth specimen was scanned by microcomputed tomography (micro-CT) subsequently after endodontic retreatment with the Reciproc instruments (REC). The images were analyzed for differences in the volume of dentin cracks and the presence of the filling material in the middle and apical thirds of the teeth among the groups, according to the dentin age. Results: The micro-CT images showed that after retreatment, there were more cracks in the old root dentin than those in the young root dentin, although the difference was not statistically significant (P>0.05). The greatest reduction in the filling material was achieved when the old root dentin with cracks was retreated when compared with that of the young root dentin with cracks, but the difference was not statistically significant (P>0.05). Conclusion: The dentinal age and the presence of cracks were not found to be relevant factors for the removal of the filling material.

Keywords: Dentin; Microcomputed Tomography; Retreatment

Introduction: The use of bioactive glasses to re-establish or increase mechanical properties of the root dentin may be an interesting alternative. The aim of this study was to evaluate the effect of root repair materials and bioactive glasses on the microhardness of human root dentin. Methods and Materials: Sixty-four sectioned palatal roots of human molars were prepared and two slices were obtained of the middle third of each root (one corresponding to the control group, without treatment, and the other to the experimental group). The pairs of slices were randomly divided into four groups (n=16). The root canal of experimental slices were filled with one of the following materials: mineral trioxide aggregate (Angelus MTA, Angelus, Londrina, Paraná, Brazil), EndoSequence Root Repair Material (ERRM, Brassler, Savannah, GA, USA), Bioglass (45S5) and an experimental niobophosphate glass (NbG). The specimens were stored in an oven at 37^ºC, in an environment with 100% humidity for 60 days. The specimens were subjected to a microhardness test. Four indentations were made at a distance of 20 µm from the root canal lumen. For microhardness analysis, comparing the experimental groups and their respective controls, the Student’s-t test was applied. For comparison of the percentage increase in microhardness between the groups, the data were statistically analyzed by using One-way ANOVA and Tukey’s test. The level of significance was set at 0.05. Results: All the materials significantly increased the dentin microhardness values (P<0.05). MTA showed a higher increase in microhardness (94.8±42.7%), similar to that of EndoSequence (62.3±39.9%). The 45S5 (46.5±30.0%) and NbG (53.8±31.3%) showed the lowest percentages of increase in microhardness, but were statistically similar to those of EndoSequence. Conclusion: All the materials tested were capable of increasing root dentin microhardness.

Introduction: During pulpectomy of primary teeth, cytotoxic medicaments such as formocresol or camphor mono-chlorophenol (CMCP) are used as medicaments. For the first time it is theorized that chitosan can substitute these traditional materials used in pulpectomy of infectious primary teeth. Methods and Materials: This preliminary in vitro study consisted of two separate phases (n=75), each of which assessed the antibacterial effects of chitosan versus formocresol and CMCP and positive/negative controls (n=15) on three bacteria types [Enterococcus ‎faecalis, Staphylococcus aureus, Streptococcus ‎mutans, (n=5 per subgroup)]. Phases 1 and 2 concerned respectively with 1- and 7-day effects of these materials. Bacteria were cultured and injected into sterilized canals and colonies were counted. Medicaments were applied and colonies were re-counted after 1 day of treatment (phase 1). Specimens were re-sterilized and re-randomized, and used for phase 2, in which the same procedures were performed for a 7-day period. Effects of agents on bacteria were analyzed statistically (Kruskal-Wallis α=0.05 and Mann-Whitney α=0.017). Results: Treatments reduced bacterial count either after 1 or 7 days (P=0.000). Their effects on different bacteria types were not significant either after 1 or 7 days (P>0.48). Antibacterial efficacies of treatments (indicated by colony reduction) were significantly different, after 7 days (P=0.045). Antibacterial efficacy of chitosan was similar to that of formocresol or CMCP, in both phases [either after 1 or 7 days of treatment (P>0.017). Formocresol and CMCP had similar efficacies in either phase (P>0.017). Conclusions: This preliminary study confirmed the appropriate antibacterial efficacy of chitosan as a medicament in pulpectomy of infectious primary teeth.

Keywords: Antibacterial Agents; Camphor Mono-Chlorophenol; Chitosan; CMCP; Enterococcus ‎faecalis; Formocresol; Medicament; Pulpectomy; Staphylococcus aureus; Streptococcus ‎mutans

Introduction: Different techniques have been proposed to help achieving apical patency during endodontic treatment and retreatment. The objective of this in vitro study was to compare reestablishment of apical patency in teeth previously subjected to root canal treatment using manual and reciprocating instruments. Methods and Materials: A total of 40 single-rooted extracted human mandibular incisors were selected and prepared using the Hero 642 sequence to 45/0.02 and obturated using Tagger’s hybrid technique to 1 mm short of the apex. Teeth were divided into two groups according to the type of instrument used to regain patency: group 1, hand K-files and group 2, reciprocating WaveOne Primary files (25/0.08). Fisher’s exact test was used in the statistical analysis. Result: In group1, apical patency was regained in 9 of the 20 teeth tested (46%), compared to 20 teeth (100%) in group 2. The difference between the groups was significant (P<0.0001). Conclusion: Our study shows that reciprocating instrumentation is more successful in regaining apical patency in single-rooted, previously treated teeth.

Keywords: Apical Patency; Reciprocating; Retreatment; Root Canal Treatment

Introduction: The type of materials and application time of veneering restorations on calcium silicate cements are important factors which influence the interfacial properties. The aim of this study was to measure the micro-shear bond strength of a resin composite (RC) using several adhesive systems and a resin-modified glass ionomer cement (RM-GIC) to different aged Biodentine specimens. Methods and Materials: A total of 15 Biodentine blocks were prepared and assigned to three aging periods: 12 min, one week and one month. Then they were subdivided into five sub-groups to receive cylinders of resinous materials. RC was applied using different adhesive systems: A) no adhesive B) etch and rinse C) two-step self-etch and D) universal adhesive in self-etch mode and E) RM-GIC applied directly over Biodentine. Micro-shear bond strength was measured and the data were analyzed using one-way and two-way ANOVA. The level of significance was set at 0.05. Result: There was significant interaction between Biodentine aging periods and resinous materials (P<0.05). The highest value was obtained in group D bonded to the recently set Biodentine. Increasing the aging period to one week resulted in increased micro-shear bond strength in all groups expect for group D. One-month incubation time led to reduced shear bond strength in group A, C and D. Micro-shear bond strength values of group E increased to the longer aged Biodentine. Conclusion: Group D showed the highest bond strength to freshly mixed Biodentine.

Keywords: Bond Strength; Composite Resin; Dental Adhesive; Glass Ionomer Cement; Tricalcium Silicate

Introduction: The aim of this study was to compare root preparation of deciduous teeth with WaveOne Large (WO) and ProTaper F4 (PT) instruments with or without passive ultrasonic irrigation (PUI). Methods and Materials: Forty-eight deciduous teeth were scanned before and after root preparation and divided in four groups (n=12): WO+EDTA (WO); WO+EDTA with PUI (WOPUI); PTF+EDTA (PT); and PT+EDTA with PUI (PTPUI). Root canal enlargement by micro-computed tomography and root canal cleaning by scanning electron microscopy (SEM) were analyzed. Data were submitted to two-way ANOVA and Tukey’s tests to analyze the root canal volume variation, and Kruskal-Wallis followed by Friedman and Wilcoxon tests were used to evaluate the cleaning efficacy. The level of significance was set at 0.05. Results: No significant difference occurred in total volume between groups (P>0.05). On analysis by thirds of the root canal, there was a difference in volume between WO (cervical) compared to WO and PT (apical), and PTPUI (middle and apical) (P<0.05). When cleaning of the thirds within the same group was compared, there was a significant difference in all groups (P<0.05). Among the groups, in the thirds, in the cervical a difference occurred (P=0.028), and the pairwise comparisons indicated statistically difference between WO and PT, and WO and PTPUI (P<0.05). In the pairwise comparisons among thirds, in the groups, difrences occured in all of them when compared the cervical and apical thirds (P<0.05). Conclusion: Passive ultrasonic irrigation has not improved the smear layer removal in deciduous teeth. Despite the differences in performance between WO and PT instruments, both were suitable for preparation of deciduous teeth.

Keywords: Deciduous Teeth; Endodontic; Passive Ultrasonic Irrigation; Root Canal Preparation; Ultrasonic

Introduction: The aim of this in vitro study was to evaluate the effects of sodium hypochlorite (NaOCl), ethylenediaminetetraacetic acid (EDTA), chlorhexidine (CHX) and hydroxyethylidene bisphosphonate (HEBP), also known as etidronate, on susceptibility to root fracture resistance (RFR) in human teeth subjected to endodontic preparation. Methods and Materials: Seventy extracted single-rooted human teeth were selected, endodontically prepared using the ProTaper Next rotary system (PTN, Dentsply, Maillefer, Ballaigues, Switzerland) and then randomly divided according to the following irrigation regimes (n=10): G1, saline solution (0.9% NaCl); G2, 2.5% NaOCl + 17% EDTA; G3, 2% CHX gel + 17% EDTA; and G4, a mixture of 5% NaOCl + 18% HEBP. After this step, all samples received a final irrigation with distilled water. The samples were subjected to axial forces by mechanical compression testing in a universal testing machine (Dynamometers KRATOS, LTDA, SP, Brazil). Data analyses included the Shapiro-Wilk normality test, analysis of variance (one-way ANOVA) and a subsequent multiple comparison test (Tukey’s test). Results: The results indicated that G1 (0.9% NaCl) presented greater resistance to root fracture. No significant differences were observed in G2 (2.5% NaOCl + 17% EDTA) and G3 (2% CHX gel + 17% EDTA). A significant difference was identified in G4 (mixture of 5% NaOCl + 18% HEBP) (P<0.05). Conclusion: A mixture of 5% NaOCl + 18% HEBP resulted in a lower fracture resistance when used to irrigate canals during endodontic instrumentation.

Keywords: Chlorhexidine; EDTA; Etidronic Acid; Root Canal Irrigant; Sodium Hypochlorite

Introduction: This study sought to assess root canal morphology of maxillary second molars regarding age and gender in an Iranian population using cone-beam computed tomography (CBCT). Methods and Materials: Totally, 157 maxillary second molars of patients presenting to a radiology clinic were evaluated on CBCT scans. Tooth length, number of roots, root fusion, coronal and sagittal root deviation, number of canals per root, prevalence of second mesiobuccal canal, root canal morphology according to the Vertucci’s classification and the correlation of these variables with age and gender were evaluated. Data were analyzed using the Mann Whitney U, Kruskal Wallis and Fisher’s exact tests. Results: Of 157 teeth, 98 belonged to females and 59 to males. The mean tooth length was significantly greater in males than in females (P=0.002) and it was shorter in 50-60 years old group. The rate of root fusion was 18.6%. Distobuccal and palatal roots were mainly straight in both sagittal and coronal planes while mesiobuccal roots mostly had a distal-buccal deviation; 67.5% of the teeth had four canals. Number of canals was significantly correlated with gender and was higher in males (P<0.05). The most prevalent canal type was type VI in second mesiobuccal, and type V in palatal and distobuccal canals. The most common types in mesiobuccal canal were types I, VI and II, respectively. In the remaining two roots, type I was the most common. Conclusion: Root and canal morphology of the maxillary second molars in Iranian population showed features different from those in other populations.

Keywords: Age; Cone-Beam Computed Tomography; Gender; Maxillary Second Molar; Root Canal Anatomy; Root Canal Morphology

Introduction: Accurate measurement of working length of the root canal is an important factor in endodontic treatment, because it determines the level of cleaning and shaping of the canal. This can be performed using numerous methods including conventional, digital and self-developing methods, which are studied in this work. Methods and Materials: In this study, 50 maxillary molars with appropriate conditions for the analysis were collected and their mesiobuccal canal lengths were estimated by three different types of radiographs with and without file. Next, two endodontists and a radiologist reviewed all the images under the same conditions. The precise lengths of the canals were measured by removing teeth from their casts and direct observation. Finally, data regarding differences in radiographic length and actual length were examined by SPSS 16.0 software and Repeated Measures ANOVA test. Results: There was no significant difference in any of the radiographic states. The differences of root canal lengths were not significant for the first (endodontist) and third (endodontist) observers; whereas, there were significant differences for the second observer (radiologist). The differences were not significant for samples without files (P=0.89). However, the differences were significant for samples with files (P=0.03). Conclusion: Since analysis showed that there were no significant differences between the results of digital radiography, conventional film and self-developing film methods in working length determination, the clinician can choose any of these methods according to the working conditions without being concerned about losing the accuracy.

Keywords: Conventional Radiography; Digital Radiography; Self-developing Film; Working Length

Introduction: The purpose of this study was to evaluate the changes of canal configuration in simulated type II root canals that were instrumented by two different techniques using ProTaper Universal rotary files. Methods and Materials: Sixty simulated type II root canal in resin blocks were made and randomly divided into two groups. Pre and post-instrumentation images of resin blocks were prepared using stereomicroscope from three surfaces of blocks included two longitudinal section (mesiodistally and buccolingually), and one cross sectional surface. In the first group (G1) the straight canal was instrumented to the working length and the other canal was instrumented up to the area of canals junction. In second group (G2) both canals were instrumented to working length. The superimposed pre and post instrumentation images were assessed by the Adobe Photoshop software. The degree of transportation, centering ability, perimeter, surface and aspetic ratio (AR) in cross section and longitudinal section at apex, 3 mm and 5 mm above the apex, were measured. SPSS software, t-test and Mann-Whitney test were used for statistics analysis. Result: In mesiodistal direction, canal transportation was more (P=0.024) only in junction point in G2 which both canals were instrumented to working length. Also, surface changes were more significant (P=0.02) in G2 in cross sectional direction. The other parameter and also apical transportation had not significant difference in two groups. Conclusion: According to the results of this study, it can be concluded that both two preparation methods of type II canals can be used by rotary instruments.

Keywords: Apical Transportation; Canal Transportation; Nickel Titanium; Root Canal Preparation; Root Canal Shape

Introduction: Root canal irrigation has an extremely important role in the success of endodontic treatment. During endodontic treatment, the irrigants will be in contact with pulpal and periapical tissues. The purpose of this study was to clarify the potential toxicological implications of NaOCl, EDTA, MTAD, CHX and QMix on periapical and periodontal tissues. Methods and Materials: Cytotoxicity of solutions was evaluated on cultured human periodontal ligament (hPDL) that were carefully removed from the middle third of premolar roots. Cytotoxicity of the materials was assessed after 1, 5 and 15 min of exposure using the Mosmann’s Tetrazolium Toxicity (MTT) assay. Optical density of the solution was read at 540-690 nm wavelength. The intensity of color generated correlated with the percentage of viable cells. Data were statistically analyzed using repeated measures ANOVA followed by Bonferroni test. Results: The mean percentage of viable cells in all experimental groups was significantly different from sterile saline groups at all time points (P<0.0001). The mean percentage of viable cells significantly decreased over time in MTAD and NaOCl groups. The lowest and highest cytotoxicity belonged to MTAD and EDTA groups, respectively at all the time points (P<0.05). Conclusion: MTAD had the lowest cytotoxicity compared to NaOCl, CHX, QMix and EDTA. These impacts have been time dependent. These irrigation fluids may cause unfavorable effects on vital tissues.

Keywords: Cytotoxicity Test; MTT Tetrazolium; Periodontal Ligament; Root Canal Irrigants

Introduction: Calcium-enriched Mixture (CEM) cement is an endodontic reparative material available in the form of powder and liquid. The purpose of this in vitro study was to determine the effect of different water-to-powder (WP) proportions on the compressive strength (CS) of the cement. Method Materials and: One gram of CEM cement powder was mixed with either 0.33 g, 0.4 g or 0.5 g CEM liquid. The mixture was transferred to metallic cylindrical molds (n=10) with internal dimensions of 6±0.1 mm height and 4 ±0.1 mm diameter. After 4 days, the specimens were subjected to compressive strength tests using a universal testing machine. The data were analyzed by One-way ANOVA and Tukey’s tests at a significance level of 0.05. Results: Statically significant difference was found among experimental groups (P<0.05). The 0.33 WP ratio showed significantly greater CS value compared to 0.4 and 0.5 proportions (P=0.012 and P=0.000, respectively). The CS of 0.4 WP ratio was also significantly higher than that of 0.5 WP ratio (P=0.014). Conclusion: According to the results, higher WP ratios results in lower CS of the cement.

Keywords: Calcium-enriched Mixture; CEM cement; Compressive Strength; Water-to-Powder Ratio

Introduction: The purpose of this study was to analyze the differences between irrigant replacement in the positive and negative pressure irrigation systems regarding root canal cleaning efficacy. Methods and Materials: A total of 27 extracted single-root mandibular premolars with 18-20 mm root canal length were decoronated and equally divided into three groups (n=9) based on the irrigation system used: positive irrigation with side-vented needle as the control group (C), positive irrigation with an open-ended needle as the first group (T1) and negative irrigation as the second group (T2). The root canals were irrigated with 2.5% NaOCl between each instrumentation, followed by a final irrigation with 5 mL of sterile distilled water. The irrigation replacements were monitored by means of computational fluid dynamic (CFD), while a scanning electrone microscope (SEM) was used to observe the smear layers and plug evaluations after the teeth had been sectioned longitudinally and buccolingually halves subsequently cut in apical third area. The result was analyzed using the Kruskal Wallis, Mann Whitney and Spearman correlation tests. The level of significance was set at 0.05. Result: Irrigant replacement in the negative pressure irrigation system tends to produce a greater effect in reaching the apical end compared to in the positive pressure irrigation system. This resulted in significantly superior smear layer removal in the apical third area (P<0.05). Conclusion: The irrigation solution exchange of the negative pressure irrigation system is more capable of reaching the apical end compared to the positive pressure irrigation system, resulting in a higher sanitation level in the apical third of the root canal.

Keywords: Computational Fluid Dynamics; Negative Pressure Irrigation; Positive Pressure Irrigation; Root Canal Irrigants; Smear Layer

The principle of ferrule effect is of prime importance when restoring an endodontically treated tooth. A severely broken down tooth due to subgingival caries almost always end up with extraction as inadequate ferrule effect would compromise the predictability of restorative treatment. This clinical case report describes a treatment approach that combines non-surgical endodontic treatment, orthodontic extrusion and prosthetic rehabilitation to restore the function and aesthetic aspect of an extensively carious premolar with compromised prognosis. One year follow-up indicated stable periodontal health with evidence of periapical healing radiographically.

Keywords: Interdisciplinary Treatment; Orthodontic Extrusion; Root Canal Treatment

Variations in the number of roots and canals have been extensively reported in endodontic literature. One rare variation is presence of two separate root canals in maxillary lateral incisors. This study reports a maxillary lateral incisor with two canals. Although rare, knowledge about this anatomical variation can help in successful endodontic treatment of such teeth.

Keywords: Anatomic Variation; Root Canal; Tooth Abnormalities

This case report documents the clinical approach adopted for two maxillary incisors with intrusion and horizontal root fracture in the middle third after trauma. The proposed procedures involved maintaining pulp vitality and periodontal stability of the fractured teeth with 8 years of follow-up.

Keywords: Intrusion; Multiple Trauma; Tooth Fractures

A case of unusual anatomy in a maxillary lateral incisor is presented. A 20-year old female presented with failing endodontics. Clinical examination and radiographs revealed poorly obturated maxillary left lateral incisor with an untreated patent second root and a palatogingival groove. A decision was made to treat the tooth non-surgically. After removing gutta-percha from main canal, the orifice of second root could not be located from inside the chamber. After determining the position of this root to be mesial and palatal to main canal, gingival tissue was removed from mesio-palatal side and access was extended to include the cingulum and orifice was located mesio-palatally. This canal was mechanically prepared and both canals were filled with calcium hydroxide. Three weeks later when symptoms subsided, the canals were obturated using the warm vertical technique. However, patient returned after a month complaining of pain and pus discharge. The tooth was surgically retreated; the enucleation was performed without root end resection. Patient returned after two years and reported complete healing but with mild discoloration of crown which was treated with walking bleach technique.

As the dental pulp could not be directly inspected before endodontic treatment, indirect evaluation of the pulp status via clinical tests should be performed which need careful inspection. This report presents a root-treated right maxillary first molar with recurrent abscess formation and a radiolucent periradicular lesion surrounding the distobuccal root of the right maxillary second molar. The patient underwent surgical retreatment, employing CEM root-end filling, which resulted in no relief from sign/symptoms. In the cone-beam computed tomography (CBCT), the relationship of the lesion with the mesio-buccal root of the adjacent tooth maxillary first molar was detected. Despite the latest tooth showed positive responses to pulp sensibility tests, endodontic therapy was planned for it. During treatment, it became clear that the mesiobuccal canal pulp was necrotic, although vital pulp tissues were present in two other root canals. Following treatment, full recovery from all discomforts was obtained and the lesion healed after 18 months. This case showed that a more complicated evaluation such as CBCT should be used for diagnosis of perpetuated lesions. Furthermore, it might be probable that root canals of vital teeth become necrotic due to involvement in the adjacent apical lesion, a phenomenon known as anachoresis.