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One of the main goals of endodontic treatments is to disinfect the root canal and dentin tubules. This study compared the antimicrobial effect of different concentrations of green tea extract with that of two common irrigants on Enterococcus faecalis (E. faecalis) in the root canal system.

In this experimental study on 124 single canal teeth, suspensions derived from the 24-hour culture of E. faecalis were inoculated into the canals, and the samples were incubated for two weeks. Then, the teeth were divided into six experimental groups (n=20) and two control groups (n=2). In the first group, 5% sodium hypochlorite (NaOCl), in the second group, 2% chlorhexidine gluconate (CHX), in the third group, 3.125% green tea extract, in the fourth group, 12.5% green tea extract, in the fifth group, 25% green tea extract, and in the sixth group, normal saline was used for root canal irrigation. The next day, the extracted liquid from vortexed dentin fragments was cultured, and the colony-forming units (CFU) were counted 48 hours later. Data were analyzed using Mann-U-Whitney test.

The CFU count for NaOCl and CHX showed a statistically significant difference compared to different groups of green tea extract (P<0.001). The percentage of microorganism reduction was 100% with NaOCl, 98.9% with CHX, 58.35% with 3.125% green tea, 8.1% with 12.5% green tea, 94.8% with 25% green tea, and 57.5% with normal saline.

The results of this study showed that green tea extract can be used in endodontic treatment as the final root canal irrigant considering its naturalness and its antimicrobial ability.

Lack of proper assessment of students' knowledge regarding theoretical contents leads to disappointment and negligence by weak students. This study assessed multiple-choice questions (MCQs) of oral and maxillofacial medicine courses in the first semester of the academic year 2014-2015. In this cross-sectional study, questions of theoretical oral medicine courses 1, 2, and 3 were assessed according to twelve items in Millman's checklist, including clearness of stem, negative option for stem, specific option, contrastive option, positive words in stem and options, writing structure of stem, duplicated option, the spelling of stem and options, vertically of options, positivity of stem and options, and use of "all of the above" and "none of the above" phrases in options. Difficulty and discrimination coefficients of each question and the rate of compliance with Millman's principles were evaluated using Excel 2007 and SPSS 16. Data were analyzed using descriptive statistics, analysis of variance (ANOVA), and Regression analysis. The responses of 219 students to 113 MCQs were evaluated. In theoretical course 1 with 40 MCQs, discrimination coefficient was 0.36±0.2, difficulty coefficient was 73.2±15.02, and correlation coefficient was 0.58. In theoretical course 2 with 35 MCQs, discrimination coefficient was 0.2±0.04, difficulty coefficient was 70.91±25.13, and correlation coefficient was 0.47. In theoretical course 3 with 38 MCQs, discrimination coefficient was 0.3±0.19, difficulty coefficient was 68.73±26.89, and correlation coefficient was 0.5. The percentage of compliance with Millman's principles was 81.88%, 83.58%, and 84.42% in courses 1, 2, and 3, respectively. The weakest discrimination coefficient was noted in theoretical oral medicine 2. The high percentage of simple difficulty coefficient in the three theoretical courses indicates the necessity of training faculty members in designing questions.

The Gow-Gates (GG) block and the inferior alveolar nerve block (IANB) can be used interchangeably for anesthetizing mandibular molars. The aim of this study was to compare these two injections in root canal therapy of mandibular molars with regard to heart rate (HR) and blood oxygen saturation (BOS) changes. Thirty patients between the ages of 18-70 years having mandibular molars on both sides of their jaw and in need of root canal therapy were recruited after signing a consent form. The patients' HR and BOS were measured 5 minutes before and immediately, 2, 5, 10, 15, and 20 minutes after injection by using a pulse oximeter. Paired t-test and Friedman test were used for statistical analysis of the data. This study was done on 30 patients (60 teeth). The results of HR and BOS showed no significant differences between the two injection techniques (P=0.6 and 0.7, respectively). Also, HR and BOS in each group were not significantly changed during the follow-ups (P=0.7 and 0.6, respectively). According to the results, IANB and GG block by using 2% lidocaine and 1:80000 epinephrine had no significant different effects on HR and BOS.

Debris and the smear layer that remain after root canal preparations may result in failure of root canal therapies. The aim of this study was to compare the smear layer formation and the amount of residual debris following the use of WaveOne and ProTaper rotary files in mesiobuccal root canals of upper first molars by scanning electron microscopy (SEM). In this experimental study, 34 mesiobuccal root canals of human maxillary first molars with 20°-40° curvatures (according to Schneider technique) were randomly distributed in two experimental groups (15 each) and two control groups. The canals in test groups were instrumented according to the manufacturers’ instructions. Five ml of 5.25% sodium hypochlorite (NaOCl) and 5 ml of normal saline were used as irrigants. The roots were split longitudinally, and apical, middle, and coronal radicular sections were randomly scanned by an SEM at ×1000 magnification. Two endodontists scored the data according to Schäfer and Schlingemann scoring system. Data of the amount of debris and smear layer were separately analyzed by Kruskal-Wallis test. Although there was a slight difference in mean scores between the two groups (3.28 for WaveOne and 3.6 for ProTaper), no significant differences in debris amount were noted. The overall mean smear layer formation was not significantly different between the two groups (4.11 for WaveOne and 3.95 for ProTaper). There was no significant difference in remaining debris and smear layer in coronal, middle, and apical parts of root canals. However, ProTaper system appeared to produce less debris during preparation.

Study guide is a tool for establishing the student-centered learning process. It is an assortment for directing the student in the management of his learning by foreseeing educational obligations, aims and contents. Considering the important role of study guides in students' learning process, the aim of the present study was to explain the point of view of dental students towards the study guide of the oral medicine course. This study was performed in two phases: 1-compilation of a study guide for the practical oral medicine course, and 2- implementation of the study guide by 73 dental students, evaluation of their point of view towards its items, and also estimation of their level of satisfaction. 48.6% of the participants were completely satisfied, 18.1% were moderately satisfied; whereas, 6.9% were unsatisfied with the study guide. 26.4% of the students had left the open questions unanswered. 71.2% of the students needed some examples for implementing theoretical lessons in the clinical setting. Few students felt the need to know about the role of the department's personnel. A high percentage of the students were moderately or completely satisfied with the study guide. They believed that the study guide has improved their learning process, and has even resulted in higher final scores. Knowing the opinion of students is useful for revision and improvement of the study guide.

Dental injuries are one of the common problems in children. Considering that nowadays, more attention is being paid to dental health and that school health teachers play a key role in the management of dental injuries, this research was designed with the aim of determining the extent of the knowledge of elementary school health teachers of Tehran city on how to control students’ teeth injuries at school. This research is a cross-sectional study. The questionnaires were given to 280 elementary school health teachers in Tehran city. Of the 280 questionnaires, 216 were answered (77.14%). Data were collected and statistical analysis was performed using descriptive statistics methods and inferential statistics test in two study populations, chi-square independence and Spearman correlation coefficient with 95% confidence interval (CI). Receiving medical emergency training courses affected the responses to the questions regarding the maximum time to restore the teeth to their location (p = 0.001), and the most appropriate action in case of altered consciousness (p = 0.05). Receiving dental emergency training courses had no impact on the responses to any of the other questions (p = 0.231). According to Spearman correlation test results, there was a weak reverse significant correlation between age and the question regarding the most appropriate way to reposition the teeth in this case (p = 0.031 and correlation coefficient = - 0.157), and between work experience and the question regarding distinguishing the tooth type (p = 0.042 and correlation coefficient = - 0. 153). the results indicated that the knowledge of these teachers is not adequate, and that there is a need for education regarding the management of dental injuries. Furthermore, there is no significant correlation between the responses to the questionnaire and receiving dental emergency training courses.

Gathering information about the patient's present illness by allocating adequate time to detect the main reason of referral is of utmost importance. This is mostly related to the manner of communication and interaction with the patient and active listening to his/her statements. Registering the information related to the illness and its history has an effective role in patient satisfaction, treatment outcomes, and dental expenses and even in lawsuits against practitioners. Therefore, the present study aimed to compare the average time allocated by general dentists and senior dental students of the dental school of Tehran University of Medical Sciences to obtain the history of the patient's present illness during 2012-2013. In this cross-sectional study, 60 senior dental students of the dental school of Tehran University of Medical Sciences and 60 general dentists that had been graduated at least five years ago were selected. Each of them randomly selected three patients and recorded the patients' demographics such as age, gender, education level, and the chief complaint or the main reason of the patient's visit. The duration of the patient's statements regarding the present illness and its history was recorded in seconds in the designed questionnaire. Afterwards, the data were analyzed using T-test and Mann-U-Whitney, Kendall-tau and Chi-square tests. The average interview time in the students and dentists groups was 24.41±9.17 seconds and 27.9±7.82 seconds, respectively, which were significantly different according to T-test (p=0.003). Generally, the longest allocated time equaled 49 seconds, while the shortest interview duration was 6 seconds. According to the results of the present study, it seems that dentists do not allocate the necessary and adequate time to gather information about the chief complaint and the history of the patient's reason of referral to guide them towards the correct diagnosis and suitable treatment method, and even the passage of time and the level of experience have no effect on this issue.

The purpose of this study was to evaluate the effect of autoclave sterilization on the fracture rate of ProTaper instruments (ex vivo). One hundred shaping and finishing ProTaper instruments were used in a crown – down technique for cleaning and shaping the mesial canals of extracted mandibular molars using 5.25% NaOCl for irrigation. In the experimental group, 50 files were steam autoclaved before each use. In the control group, the files were not exposed to the sterilization process. The working time was reported for each file. Independent t- test was employed to evaluate the statistical significance of the measured values. The instruments that underwent the sterilization processes did not show any statistically significant differences in comparison with those of the control group. The results of this study showed that sterilization in autoclave in the presence of NaOCl did not lead to a decrease in survival time of the files.

The purpose of this study is to compare the effect of Ledermix® paste and green tea extract on the concentration of inflammatory mediators. In this in-vitro experimental study, first, the noncytotoxic concentrations of Ledermix® medicament and green tea extract were determined by MTT assay. Afterwards, the concentrations of IL-1β, IL-6, and TNF-α inflammatory mediators were assessed by ELISA test in the four experimental groups and also in the control group at different time intervals of 2, 24, and 48 hours and after 7 days. One-way analysis of variance (ANOVA) was used for statistical analysis of the obtained raw data followed by Tukey's post-hoc test for pair comparisons. the noncytotoxic concentration of green tea extract and Ledermix® paste equaled 12 µg/ml and 0.25 µg/ml, respectively. Time interval had no significant effect on the concentration of the mediators. Generally, both substances significantly decreased the concentration of IL-1β and IL-6 inflammatory mediators in comparison with the control group. Green tea extract is less cytotoxic and more biocompatible than Ledermix® paste. Both Ledermix® paste and green tea extract expressed anti-inflammatory effects.