The aim of this study was to observe the root canal flora and possible penetration of microorganisms into dentinal tubules in teeth with necrotic pulps. Ten infected maxillary and mandibular molars with periapical lesions were extracted and fixed in 2.5% phosphate-buffered glutaraldehyde solution for nine days. After separation from the crowns, longitudinal grooves were cut in the roots, and they were split into two halves. The specimens were prepared for SEM. The root canals and the dentinal tubules of the fractured dentin were scanned systematically from the cervical to the apical area of the root. Cocci and rods were seen in 6 specimens. Penetration of bacteria into the dentinal tubules ranged from 10 to 150 microns. In 4 specimens, the root canals were heavily invaded by yeasts. The antimicrobial effect of routinely used endodontic disinfectants also on yeasts may be considered in persistent root canal infections.

Summary. Fifteen anterior teeth and 15 artificial canals obtained from five molar teeth were used in this study. The artificial and natural canals were instrumented with K‐files and then divided into three groups. The first group was irrigated with 20 ml saline, the second with 20 ml EDTA, and the third with 10ml EDTA followed by 10ml NaOCl solution. Following this experimental procedure, all canals were split and examined in a scanning electron microscope. The results showed that the smear layers in both artificial and natural canals were similar in appearance and responded similarly to all irrigation solutions. In addition, in the artificial canals, it was observed that the dentinal tubule orientation had no detectabie effect on formation and removal of smear layers.

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Introduction The aim of this study was to evaluate usage habits, attitudes and perceptions towards mobile learning (m-learning), as well as to identify variables related to those attitudes amongst undergraduate dental students. Materials and Methods The study consists of 81 dental undergraduate students who who volunteered to participate. The data collection tool consists of an m-learning attitude scale, a questionnaire, and open-ended questions. To compare the total scores and factors of m-learning attitude scale for demographic information and mobile technology usage habits of the students; the Mann–Whitney U test was used for two independent groups such as gender, presence of electronic devices, and places of Internet usage. The Kruskal–Wallis test was also used to compare the total scores and factors of m-learning attitude scale for more than two independent groups including internet usage purposes and opinions. Spearman’s correlation coefficient was performed, and linear regression analysis was used to predict the change in total score according to the purposes of Internet usage. Results The majority of students thought that the use of mobile devices in dentistry courses was useful and their attitudes towards m-learning were high. The students generally use the Internet for online shopping, connecting to social networks, and communication. They tend to use mobile technologies for personal use, followed by educational purposes. There were significant differences found in the m-learning attitudes for gender, having a portable power supply and use of mobile devices in dentistry courses. Communication was found significant in predicting the change in total score for the m-learning attitude scale according to the purpose of Internet usage. Conclusion Dental students have generally positive attitudes towards m-learning. Students raise awareness towards the promise of m-learning in order to apply their individual technology use and learning behaviours. Designing learning materials and applications for mobile devices may increase students’ performances.

An in vitro study of a possible correlation between penetration of dentinal tubules by four root canal sealers and microleakage of external fluids into the canal was done using a dye leakage method and scanning electron microscopy. The root canals of 45 teeth were instrumented and the smear layer removed prior to obturation of root canals with gutta-percha and one of four sealers: Diaket, Endomethasone, CRCS or Ketac-Endo. The extent of leakage was scored after immersion in India ink for 72 h. The same specimens were also used for scanning electron microscopic evaluation. There was a statistical difference in leakage patterns between the groups (P < 0.05). Diaket had lower microleakage scores than the other sealers (P < 0.05). When the scores for penetration of sealers into the tubules were analysed, Ketac-Endo demonstrated the least penetration (P < 0.01). There appeared to be a converse relation between tubular penetration and dye leakage, but the correlation was not statistically significant (P > 0.05).