احسان اثنی عشری

The present paper aimed to assess a comprehensive risk analysis in public-private partnership (PPP) infrastructure projects using library studies and surveys in transportation infrastructure projects. By separating risks through Delphi technique based on expert opinions, 42 structural risks and 41 operational risks in 12 main areas including political, economic, laws(regulations), cultural(social), environmental(natural), preparation(development), investment, Design, construction (completion), operation, revenue (market), management(organizational) were identified. Then, using a questionnaire survey and data analysis in SPSS, screening and determining the preferred risks based on statistical tests including Kolmogorov-Smirnov(K-S) tests, Kendall ranking and factor analysis were performed. Based on the results, 36 risks with lower Kendall mean were eliminated and the remaining 47 risks were analyzed. Also, by factor analysis, the main components affecting the incidence of risk in these projects were identified according to the factor load of the main variables (12 areas of risk). The results of KMO and Bartlett sphericity test showed that there is a significant relationship between the variables. The five latent factors, including government, financing, operational, social and organizational risks with specific values greater than 1.0, were able to explain 69.817% of the variances. Critical risks were identified by developing an integrated assessment approach based on the Relative Significance Index (RII) and the occurrence-effect intensity (PI) matrix. Based on the results, the risks of "termination of the contract by the government and cancellation of the contract", "termination of payments by the government" and "corruption of the government system in the contracting process" were identified as critical risks.

One of the important measure of proper root canal preparation is Maintaining the original position of the root canal.so ;instrument that result in Minimal change of canal position ,result in better cleaning and shaping . the aim of This study was to comparison of effect of Joy Taper and Bio Race on maintaining of Canal centering ability and transportation by CBCT in mesio buccal canals of human Extracted mandibular first molars in dental branch of Islamic Azad University of Tehran in2017-2018

In this experimental study a total of 30 of mesiobuccal Root canals of human mandibular first molars with curvature ranging between 20-40 were randomly divided by Schneider and in two groups of 15 canals each , and Two In control Group and were imbedded in a puty imperession material and Submitted To CBCT. Group A was prepared with Joy Taper and group B was Prepared with Bio Race .According to manufactures protocol .pre and post Instrument image was Recorded .Image Were reconstruction and cross sections Corresponding to distance 1,3,7 mm from The anatomic apex were selected for Analysis by Gambill. Statistical analysis was performed With T-test and Repeated Measure ANOVA .

There was no significant different between the two groups of Joy Taper And Bio Race systems in maintaining the canal centralization P=0.930 and canal Transportation P=0.190, but significantly only in the 7mm control of the Bio Race system,it Was better in centering ability P=0.048  , also in each group at different sections of coronal , Mid and apical there was no significant difference .

Our findings showed that Joy Taper and Bio Race having the same Result in transportation and centring ability.

In recent years, advances in various technologies have come with the help of the building industry and have not only mitigated some of the dilemmas but also introduced new solutions to the factors of construction . In this study, we evaluate the use of smartphones in manufacturing control and monitoring and develop a model of stakeholders and factors for this purpose. The data collection and analysis method included evaluation of research background, use of statistical questionnaire and hierarchical process analysis. Statistical analysis was performed using SPSS software and AHP was done by "Expert choice" software. The statistical population of the study consisted of 60 experts. At the end of the statistical section, 21 general criteria are identified. These criteria, along with seven different stakeholder groups that can be used in the use of smartphones to monitor manufacturing, have been analyzed through hierarchical process analysis. The results showed that three groups of stakeholders are more important. Among the identified criteria, three main criteria are structural resistance, compliance with national building regulations, and technical requirements. In the use of documentation such as photos and videos in the software, prioritizing the respondents in the software by the examiner based on the importance of each stakeholder, the user-friendliness of the software, and its ease of use are some of the solutions provided.

Root perforation is an endodontic procedural error. Treatmentof perforation depends on the location and size of perforation،duration of exposure to the oral cavity، patient''s cooperation and degree oftissue inflammation. Several materials have been introduced to seal off the perforation. MTA is one of the best materials for this purpose. Case Report: We report the repair of distal root perforation in a primary mandibular second molar of a 9 year-old boy who had congenital absence of the second premolar tooth at the same quadrant. The perforation site was sealed with MTA and the three root canals were filled with gutta percha. Follow up visits at 1، 3، 6، 12، 21 and 24 months showed clinical and radiographic success of treatment.