BackgroundEstablishing the working length at the apical constriction is considered ideal for root canal therapy. Because of the limitations of radiography and complicacy of the apex of the root, electronic measurement of canal length has become valuable for endodontic treatment. This study was designed to evaluation of the accuracy of the Root zx electronic apex locator in the presence of NaOCl 2.5% and chlorhexidine 0.2%.Material and MethodsThirty extracted human premolars with complete root formation were enrolled. The actual length (AL) was assessed visually (under stereo microscope) and teeth mounted in the saline model. The electronic length (EL) measurements were recorded in the presence of NaOCl 2.5% and chlorhexidine 0.2% and the differences between the EL and AL were compared.ResultsBy accepting the error of 0.5 and 1 mm, the accuracy of Root zx was 76.7% and 96.7% in the presence of chlorhexidine 0.2% and 90% and 100% in the presence of NaOCl 2.5%, respectively. No statistical differences was found between the measured groups (P=0.223).ConclusionsOur results confirmed that Root zx can accurately determine the apical constriction in presence of both NaOCl 2.5% and chlorhexidine 0.2%. Key words:Chlorhexidine, Sodium Hypochlorite, Root ZX.

Background and Aim: Evaluation of root and canal morphology and anatomy of the teeth is essential for successful root treatment. This study aimed to evaluate the morphology and anatomy of the root canal of maxillary second premolars using the cone-beam computed tomography (CBCT) technique in a radiology center. Material and Methods: We used CBCT images of a specialized radiology center archived in 2014 in Qazvin and evaluated them by use of Remexis software. Evaluation of the images was carried out by a radiologist and an endodontist. The number of roots and their morphology, number of canals, the direction of root curvature, and canals in buccolingual and mesiodistal directions were assessed using the chi-square test in two genders. The significance level was considered 5%. Results: A total number of 106 CBCT involving 117-second premolar teeth were evaluated. 93.2 % of the teeth had one root and 6.8 % had two roots. There was no significant difference in the number of roots between the two sexes (Pv=0.164). According to Vertucci classification for single-rooted teeth, 59.6 % were of type I, 20.2 % of type II, 9.2 % of type III, 0.9 % of type IV, 6.4 % of type V, 1.8 % of type VI, and 1.8 % of type VII. Among two rooted second premolar teeth, 87.5 % were of type I and 12.5 % of type III. Conclusion:In maxillary second premolars, the majority of teeth had one root with type I and type II canals. During root treatment, these anatomical variations should be considered.

Background and Aim: Common causes of dental discoloration include trauma, drugs, genetic defects, decay, and age. In order to correct discoloration of pulpless teeth, internal bleaching is recommended. The aim of this study was to compare microleakage of resin modified glass ionomer and OrthoMTA used as an intraorifice barrier in non-vital bleaching. Materials and Methods: In this experimental study, 36 extracted mandibular premolars were selected and randomly divided into two experimental (n = 16) and two control groups (n = 2). 2mm of OrthoMTA and RMGI cements were placed as intraorifice barriers in the experimental groups. Subsequently, we placed a mixture of sodium perborate and 30% hydrogen peroxide as internal bleaching material into the canal and replaced it every three days. Leakage was measured using pH diffusion method by a digital PH meter. Data were statistically analyzed by using T-independent test and repeated measures and variance analysis (P<0.05). Results: The pH value of the negative control group was as same as the PH of normal saline while the PH value of positive control group was significantly higher than those of other groups. PH values of Ortho MTA and RMGI at the baseline and on the first, sixth and ninth day did not show significant differences with one another, while microleakage of OrthoMTA group was significantly lower on the third day. Conclusion: In general, OrthoMTA had less leakage than RMGI but both materials can be used as suitable barriers for internal tooth bleaching.

BACKGROUND: Test anxiety is a major educational problem among students all around the world. The purpose of this study was to investigate the relationship between academic procrastination and test anxiety among the dental students of Qazvin University of Medical Sciences. MATERIALS AND METHODS: The present study was a descriptive–analytical study. The study sample consisted of 152 dental students; Solomon and Rothblum's procrastination scale and Friedman's test anxiety questionnaire were used to collect data. To analyze the data, descriptive and analytical statistics (analysis of variance, independent t -test, and Pearson's correlation) were used at a significance level of P < 0.05. RESULTS: The results of the present study showed that there is a significant relationship between procrastination and test anxiety and its components. The relationship between academic procrastination and gender was not significant, but a significant relationship was found between test anxiety and its dimensions with gender in terms of cognitive error and total test anxiety. No significant relationship was found between academic procrastination and test anxiety and their components with marital status, age, and grade point average. CONCLUSION: According to the findings of the present study, people with academic procrastination have more test anxiety and fear of humiliation, irrational and negative thoughts, and more stress.

This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.