n roghanizad

Maintaining the original shape and path of the canal is among the most important criteria for optimal root canal preparation. The aim of this study was to compare the centering ability of F6 SkyTaper and RaCe rotary files in mesiobuccal canals of mandibular molars.  

In this experimental study, 30 mesiobuccal canals of extracted human mandibular molars with 25-30-degree curvature were randomly divided into two experimental groups (n=15) of RaCe and F6 SkyTaper. After mounting of the teeth in a putty mold, the distance between the canal walls and the outer surface of the roots in mesial and distal aspects was measured. The measurements were made at 1, 3 and 7 mm from the apex. Initial glide path in the canals was achieved using a # 15 K-file. Then, the canals in group A were prepared by RaCe rotary file #25/6% while the canals in group B were prepared by F6 Sky Taper rotary file #25/6%. Measurements were repeated and the difference between the two measurements was calculated and compared with the Mann-Whitney U test.

The mean centering ability was 0.72 ± 0.62 in the RaCe group and 0.95 ± 1.39 in F6 SkyTaper group. the centrality was better in F6 SkyTaper group (it was closer to 1) but the difference was not statistically significant (P=0.4).

Both RaCe and F6 SkyTaper rotary systems partially offset the centrality of the root canal system.

The main goal of root canal treatment is to prevent or treat apical periodontitis. The aim of the present study was to assess the coronal restoration status, root canal filling quality, periapical health condition, and related factors in endodontically treated teeth at the Dental Faculty of Islamic Azad University of Medical Sciences, Tehran, Iran, in 2011-12.
In this descriptive, historical cohort study, a total of 160 teeth submitted to endodontic treatment were clinically and radiographically reexamined one year (minimum) postoperatively. Each volunteer answered a questionnaire on demographic and socioeconomic factors. They were also questioned about the factors related to endodontic and restorative treatments. The restoration and root canal filling quality was classified according to the modified criteria introduced by Tronstad et al. The periapical status was evaluated according to the periapical index (PAI) scores.
Periapical lesions (diseased/failure) were most prevalent in Inadequate Restoration/Inadequate Root Canal Filling group (70%) followed respectively by Inadequate Restoration/Adequate Root Canal Filling group (52.2%), Adequate Restoration/Inadequate Root Canal Filling group (30%), and Adequate Root Canal Filling/Adequate Restoration group (15.5%).
According to the results, an efficient appointment scheduling system has the greatest impact on the completion of coronal restoration after endodontic treatments. Provision of adequate root canal filling and perfect coronal restoration can reduce the prevalence of postoperative periapical lesions and increase the success rate of endodontic treatments.

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.

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.