Iranian Endodontic Journal
Volume:16 Issue: 1, Winter 2021

 Our study aimed to compare the incidence and intensity of postoperative pain after endodontic instrumentation with reciprocating and rotary systems.

An electronic literature search was performed with MEDLINE via PubMed, Scopus, and Web of Science databases from January 2008 to June 2020. Two high-impact endodontic journals were also hand searched. The selection criteria were: Population; patients requiring endodontic treatment, Intervention and Comparison; endodontic instrumentation with reciprocating versus rotary systems, and Outcome; postoperative pain. We extrapolated all included research data and reported them as dichotomized ordinal variables to evaluate the incidence of pain and continuous variables to assess pain intensity. Standardized mean difference (SMD) was calculated with Inverse Variance method for pain intensity; the incidence of postoperative pain was calculated using relative risk (RR) with the Mantel-Haenszel method. Random-effects model and 95% confidence interval (CI) were used for all meta-analyses. The I2 statistic was used to evaluate the statistical heterogeneity among studies (P<0.05). 

 Twenty-one articles were selected and 17 of them were included in the meta-analysis for the evaluation of postoperative pain in the first 24h. The meta-analysis was performed in two steps: a) all studies were included; b) subsequently studies with preoperative pain were excluded. A significant difference was observed in the intensity of postoperative pain; with rotary system having more favorable in both steps [a) SMD: 0.27; 95% CI: 0.13 to 0.41; P=0.0002; b) SMD: 0.37; 95% CI: 0.15 to 0.58; P=0.0010]. There was no significant difference in the incidence of pain, and the incidence of mild, moderate and severe pain . 

 The meta-analysis results revealed that rotary system were the instrument of choice as they had lower intensity of postoperative pain. Further controlled studies are advocated to provide clarification for intensity/incidence of postoperative pain in endodontic treatment with mechanized instruments.

The aim of our systematic review was to assess the impact of gutta-percha solvents on the bond strength of endodontic sealers to intraradicular dentin using the push-out bond test.

The literature was searched in databases (PubMed, Web of Science and Scopus) up to September 2020, using the following search terms: (bond strength AND solvent* AND sealer* AND (tooth root OR dentin OR retreatment OR root canal). No date limits were implemented, and English languages were included. The question research was constructed based on the PICO (Population, Intervention, Comparison, and Outcome) strategy: “Does gutta-percha solvents effect the bond strength of sealers to intraradicular dentin?”. The studies were analyzed by two reviewers and were included if they utilized extracted permanent human teeth with completely formed apices, as well as assessed the influence of gutta-percha solvents on the bond strength of sealers to intraradicular dentin using push-out bond test. Review articles, case reports and studies that included immature, bovine or artificial teeth were excluded. The risk of bias was evaluated based on the Cochrane criteria adopted to in vitro studies.

Thirty-two papers were analyzed, seven accomplished the eligibility criteria and were selected for our systematic review. The global risk of bias was high. Due to variations in the methodological variables, a meta-analysis could not be performed.

Our systematic review highlighted the adverse effect of chloroform, which decreased the bond strength of different sealers, and the generally higher bond strength of epoxy resin-based sealers, detected with the push-out bond test. We recommend the standardization of methods in future studies to obtain a more definitive conclusion about the influence of solvents on the bond strength of sealers to intraradicular dentin.

 The aim of this study was to compare the efficacy of passive ultrasonic irrigation (PUI) versus mechanical agitation of the irrigant promoted by the EasyClean (EC) and XP-Endo Finisher (XP-F) systems in removing debris from root canal walls, using environmental scanning electron microscopy (ESEM). 

Twelve curved mesiobuccal canals of mandibular molars were prepared with the ProTaper Next system up to file X2 (25/0.06). The specimens were embedded in flasks containing silicone putty, sectioned lengthwise, and a 4-mm long groove was made on the canal wall of the buccal half of the specimen, extending from 2 mm up to 6 mm short of the apex. Five cross-sectional markings were made along this groove to establish standardized locations for imaging. The same specimens were used to prepare a negative control group (without debris), a positive control group (completely covered by debris), and 3 experimental groups according to the final irrigation protocol employed: PUI, EC or XP-F. ESEM images were obtained and evaluated by 3 examiners. The amount of debris observed on the images was classified according to a 4-category scoring system. The kappa test was used to assess inter-examiner agreement, and the Kruskal-Wallis and Dunn tests were used to compare the scores (P<0.05). 

 The scores attributed to the PUI, EC, and XP-F groups were statistically similar to those attributed to the negative control group (P>0.05). 

 Based on this in-vitro study, the mechanical agitation of the irrigant promoted by EC and XP-F was as effective as using PUI to remove debris from the root canal walls.

 Our study evaluated the impact of sodium thiosulfate (ST) irrigation, subsequent to sodium hypochlorite (NaOCl) and just before root canal filling, on the filling quality (interfacial adaptation and penetration segment) of an epoxy resin-based root canal sealer. 

Twenty single-rooted human teeth were prepared with the ProTaper system. The specimens were then divided into the following groups: 5.25% NaOCl irrigation (NaOCl group) and 5.25% NaOCl irrigation+0.5% sodium thiosulfate (NaOCl+ST group). The root canals were filled using single-cone technique with ProTaper F3 cones and AH-Plus sealer, labeled with rhodamine B dye to allow analysis under a confocal laser scanning microscopy (CLSM). All samples were sectioned at 2, 4, and 6 mm from the apex and prepared for CLSM analysis. The percentage of voids, gaps and dentinal sealer penetration segment of the canal were calculated at the apical, middle and coronal thirds. The non-parametric Mann-Whitney statistical test was used at 5% significance level. 

 Higher percentage of gaps and voids were observed at all root thirds of the NaOCl group when compared to the NaOCl+ST group (P<0.05). There was a significant increase in the penetration segment of NaOCl+ST group at the coronal and middle root third when compared to the NaOCl group (P<0.05). 

 Our in vitro results showed that the use of ST as an antioxidant agent after NaOCl irrigation promoted a better interfacial adaptation and penetration of epoxy resin-based root canal fillings.

 The aim of this study was to analyze the effect of rotation speed on the instrumentation time of root canals with different curvatures using Mtwo NiTi rotary instruments. 

Forty root canals were selected and divided into 2 groups, according to the angle of curvature (group A>30°, group B<30°). Both groups were divided into 2 subgroups (n=10), according to the rotational speed used for root canal instrumentation (150 rpm: group A1 and B1; 250 rpm: group A2 and B2). The total instrumentation time and the total number of instrumentation cycles (NCI) required to complete root canal preparation were registered for each canal. The mean and standard deviation were then calculated. Data were then statistically analyzed using two-way ANOVA and interaction effect P-values (P<0.05). 

 During root canal instrumentation, there were no file fractures. Total instrumentation time of the low speed groups A1 (150 rpm) and B1 (150 rpm) were significantly higher (P<0.05) than that of the high speed groups, A2 (250 rpm) and B2 (250 rpm); however, there was no statistically significant difference in terms of NCI between the different groups (P>0.05). Statistical difference was not found between the different angles of curvature, group A1 vs B1 and A2 vs B2 in terms of total instrumentation time (P>0.05) and NCI (P>0.05). 

 This ex-vivo study showed that canal preparation with Mtwo rotary files could be completed safely with an increase of the instrumentation time at low rotational speed independently of the root canal curvature.

 Our study aimed to assess the diagnostic accuracy of different voxel sizes for cone-beam computed tomography (CBCT) when detecting strip perforations of variable sizes. We used 0.2 and 0.3 mm3 voxel for detecting root strip perforations. 

This was an in vitro study conducted on 155 extracted humans' mandibular first molars. The teeth were randomly divided into five groups (n=31). Perforation were not induced in the control group. In the remaining four groups, strip perforations of 0.5, 1, 1.5, and 2 mm diameters were created in the mesiolingual canal using #3 Gates Glidden drills. The CBCT scans were taken first with a 12×9 cm field of view (FOV), 90 kVp, 4 mA, and 0.2 mm3 voxel size for 24 sec and then with a 12×9 cm FOV, 90 kVp, 2 mA, and 0.3 mm3 voxel size for another 24 sec. Two observers evaluated the images and reported the largest diameter of perforations. The results were compared with the gold standard values (determined by an electronic digital caliper) using statistical methods, including the kappa coefficient and generalized estimating equation (P<0.05). 

 Based on the findings of our study, the inter-observer agreement ranged from 58-100%, while the intra-observer agreement was reported to be around 100%. The difference in accuracy between 0.2 and 0.3 mm3 voxel sizes was not statistically significant (P>0.05). In addition, the accuracy of detecting different perforation sizes in the CBCT did not follow a specific pattern. 

 This in vitro study showed that CBCT is a reliable diagnostic tool, and even in lower dosages of 0.3 mm3 voxel size, image resolution and diagnostic accuracy was not affected. Moreover, smaller root perforations could be detected as accurately as larger ones with CBCT.

 The objective of this study was to compare the mechanical and structural properties of the nickel-titanium (Ni-Ti) alloy already used in endodontics with titanium-molybdenum (Ti-Mo) and titanium-niobium (Ti-Nb) alloys to determine if these can be suggested in the manufacture of endodontic files. Methods and Materials: Orthodontic wires made of the different alloys were used. The previously mentioned alloys were characterized by energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and torsion tests. Cyclic fatigue tests were performed on a simulated canal with a curvature of 86° to 375 rpm. The fractured surfaces of the wires were observed by means of scanning electron microscopy (SEM). A Kruskal-Wallis test and U Mann Whitney test were used to determine significant differences in cyclic fatigue between groups. 

 In the mechanical tests, similar values of torsion were found for the three alloys. In XRD, the Ti-Nb showed less structural changes. In the cyclic fatigue test, Ti-Nb was found to be significantly more resistant with respect to Ni-Ti and Ti-Mo. 

 Based on our in vitro study, Ti-Nb is suggested as a possible alloy for the manufacture of rotary files due to its impressive properties.

Guided endodontic access is a promising method to treat teeth with pulp calcification. This report aimed to describe a case of root canal treatment performed through guided endodontic access in a calcified anterior tooth with apical periodontitis. A 23-year-old female with a history of trauma 10 years ago in the anterior maxilla was referred to the dental office.  Her chief complaint was discolouration of the left central incisor crown. The tooth was sensitive to percussion and responded negatively to pulp sensitivity tests. The periapical radiography showed pulp calcification and periapical radiolucency. Cone-beam computed tomography (CBCT) was obtained to allow a more detailed view of the pulp canal and the periapical area. An intraoral scan was performed and the standard tessellation language (STL) archive was combined with digital imaging and communications on medicine (DICOM) images from CBCT in the Implant Viewer software. Subsequently, a 3D model was designed and printed to guide the endodontic access in position and appropriate angulation for dental instrumentation. The mold was positioned on the patient's tooth and the root canal treatment was performed. After two years, complete healing of periapical tissues was observed. This method facilitates the drill targeting during access, reducing the risk of deviations and perforations.

Dens invaginatus (DI) is a dental anomaly associated with complex internal anatomy. Our article discusses an unusual maxillary lateral incisor with two DI. The treatment was planned and performed using cone-beam computed tomographic (CBCT) imaging. During clinical and radiographic evaluations, tooth #7 was diagnosed with DI and pulp necrosis with asymptomatic apical abscess. Periapical radiographs of the tooth showed 2 roots and complex internal anatomy. CBCT evaluation revealed tooth #7 had 2 separate cul-de-sacs (that separate the main canal into four portions). Root canal treatment was completed in 2 visits. The tooth was obturated with EndoSeal MTA. At the 6-month re-evaluation, the patient remained asymptomatic and his tooth had remained functional. Clinical and radiographic examination showed tooth #7 had no sensitivity to percussion or palpation, probe depths within normal limits (#3 mm), no mobility and continued improvement of periapical lesion, despite the commencement of orthodontic Rx 3months previous. Radiographic assessment at the one-year follow up showed significant osseous healing of the preoperative lesion even after the orthodontic forces.

The purpose of this article is to report a successful endodontic treatment of a mandibular first molar with six canals; three root canals in the mesial root, two root canals in the distal root, and one radix entomolaris. The incidence of two anatomical variations presented in this report, middle mesial canal and radix entomolaris, is generally low. Knowledge of the internal anatomy of the root canals and their possible variations, and use of magnification, such as the operating microscope or loupes, can increase the chances of finding additional canals, contributing to the success of endodontic treatment.