فهرست مطالب kiumars nazari moghaddam

Pulpectomy of primary teeth is commonly performed with hand files and instruments. However, it is a time consuming procedure. Compared to hand files, rotary instrumentation has more advantages. The purpose of this in vitro study was to compare the cleaning efficacy and time taken for instrumentation of deciduous mo-lars using Reciproc and Mtwo rotary systems.
In this experimental study, 96 canals of 28 extracted primary molars with at least two-thirds of intact roots, with no previous treatment and 7-12 mm length were selected. After access cavity preparation, size #15 K-file was introduced into the root canal and India ink was injected with an insulin syringe. Then, 96 samples were randomly divided into two experimental groups and one control group. In group I (n=44), root canals were prepared with Reciproc; in group II (n=44), Mtwo files were used for instrumentation, and in group III, eight samples were considered as negative controls. After clearing and root sectioning, the removal of India ink in the cervical, middle, and apical thirds was scored. Data were analyzed using Student's t-test and Mann-Whitney U test.
There was no significant difference between the experimental groups regarding cleaning efficacy at the apical third of root canals (P>0.05). The coronal and middle thirds scored higher in the Reciproc group (P Using new systems such as Reciproc file for pulpectomy of primary teeth is beneficial.

As a consequence of root canal preparation, dentinal chips, irrigants and pulp remnants are extruded into preradicular space. This phenomenon may lead to post endodontic flare-ups. The purpose of this study was to compare the amount of extruded debris with four endodontic NiTi engine-driven systems.
Methods and Materials: Sixty mesiobuccal roots of maxillary molars with 15-30˚ curvature were divided randomly into four groups (n=15). Each group was instrumented up to apical size of 25 using Reciproc, ProTaper Universal, Neolix and Hyflex. Bidistilled water was used as irrigant and extruded debris was collected in pre-weighted Eppendorf tubes. Tubes were stored in incubator for drying the debris. Extruded debris were weighted in electronic microbalance with accuracy of 0.0001 g. The raw data was analyzed with one way analysis of variance (ANOVA) and Tukey’s HSD post hoc test. Level of significance was set at 0.05.
The debris extrusion with Reciproc files was significantly higher than the other groups (P All systems extruded debris during the instrumentation. Reciproc system significantly extruded more debris. Caution should be taken when interpreting the results of this study and applying it to the real clinical situation.

Instrumentation with rotary instruments could potentially cause dentinal cracks possibly leading to tooth fracture. Reciproc files require a single file to finalize the root canal preparation and the effect of this procedure has not been compared with other systems.

The aim of this study was to compare the incidence of dentinal micro-cracks following root canal preparations with ProTaper, Mtwo and Reciproc files.

In an experimental in vitro trial, 80 maxillary and mandibular first molars were selected and their crowns and distal roots were cut. The roots were then examined to remove any previous cracks and defects. An impression polyether material was used to simulate teeth periodontal ligament (PDL). The teeth were divided to four experimental groups (n = 20) and prepared using Reciproc, Mtwo and ProTaper or remained unprepared as a control group. The specimens were then sectioned horizontally on 3, 5 and 9 mm from the apex and number of micro-cracks was determined by stereomicroscope. The incidence of dentinal cracks on different systems or sections were statistically analyzed by means of the chi-square test.

Dentinal defects on 3-mm, 5-mm and 9-mm sections from the apex were noted in 10 (5.6%); 7 (3.9%) and 9 (5.0%) samples of all, respectively. Following canal preparation using Reciproc, ProTaper and Mtwo systems, the defects were observed in 7 (3.9%), 12 (6.7%) and 7 (3.9%) the sections, respectively. No significant differences were observed regarding the defect incidence on the studied instrumentation files or sections.

Regarding the study limitations, dentinal cracks were observed in all files and distances from the apex. Although there was more crack incidence in ProTaper files, no significant differences were noted regarding the studied systems and sections from the apex

Increase in pH value on external root surface following intracanal application of materials is a treatment approach for external root resorption. The goal of present in vitro study was to compare pH changes in external simulated root defects after intracanal biodentine and modified portland cement dressing(MPC) insertion.
In this in vitro study twenty-four bilaterally matched pairs of human teeth with single root were randomly assigned to two experimental groups (20 matched pairs of teeth for Biodentine and MPC) and control group (four matched pairs of teeth for calcium hydroxide and saline. The buccal root surface cavity preparation measuring 0.7mm depth and 1.4mm width were made and then root were prepared using Race rotary files system to apical size 40, 0.08 taper. The pH changes of the experimental and control groups were measured immediately before, after placement of materials at different intervals of 24 hours, 1, 2, 3, 4 and 8 weeks. A repeated measures analysis of variance was used for comparing changes in pH in version 22 SPSS software at the significant level of 0.05.
Significant pH changes occurred over time in the Biodentine and MPC groups (P with respect to these results, study we can take advantage of MPC and Biodentine for treating external root resorption.

The purpose of this in vitro study was to compare the canal transportation and centering ability of Twisted File (TF) to that of Reciproc system. Methods and Materials: Forty noncalcified roots with mature apices, minimum length of 19 mm and an apical curvature of 15-30 degrees (according to Schneider’s method), from freshly extracted mandibular and maxillary teeth, were selected for this study. Samples were randomly divided into two groups (n=20) and canal preparation with either TF or Reciproc was performed according to manufacturers'' instruction. Pre- and post-instrumentation cone-beam computed tomography (CBCT) images were captured and the extent of canal transportation and centering ability of the files were calculated, using the NNT Viewer software and Photoshop CS5, at levels of 3, 4, and 5 mm from the apex. The Mann-Whitney U test was used to analyze the statistical significance between the two groups. One fracture occurred in the TF group. TF produced more transportation than Reciproc in both mesiodistal and buccolingual directions; however, the difference between the two systems were not statistically significant except for the TF group at 5-mm distance from the working length, where the difference was significant(P>0.05). Both file systems were able keep the original curvature of the canal and thus can be considered safe for clinical application.

Use of rotary Nickel-Titanium (NiTi) instruments for endodontic preparation has introduced a new era in endodontic practice, but this issue has undergone dramatic modifications in order to achieve improved shaping abilities. Cone-beam computed tomo-graphy (CBCT) has made it possible to accurately evaluate geometrical changes following canal preparation.This study was carried out to compare canal centering ability and transportation of Twisted File and BioRaCe rotary systems by means of cone-beam computed tomography. Thirty root canals from freshly extracted mandibular and maxil-lary teeth were selected. Teeth were mounted and scanned before and after preparation by CBCT at different apical levels. Specimens were divided into 2 groups of 15. In the first group Twisted File and in the second, BioRaCe was used for canal preparation. Canal transportation and centering ability after preparation were assessed by NNT Viewer and Photoshop CS4 software. Statistical analysis was performed using t-test and two-way ANOVA. All samples showed deviations from the original axes of the canals. No significant differences were detected between the two rotary NiTi instruments for canal centering abili-ty in all sections. Regarding canal transportation however, a significant difference was seen in the BioRaCe group at 7.5mm from the apex. Under the conditions of this in vitro study, Twisted File and BioRaCe rotary NiTi files retained original canal geometry.

The aim of this study was to evaluate the accuracy of two electronic apex locators (Smarpex and NovApex) in detecting apical perforation. After access cavity preparations, the working length was determined by the first examiner before and after perforation with a stereomicroscope by introducing a K-file size 10 into the canal and size 25 K-file up to the perforation site, respectively. The specimens were embedded in a 17-well plastic box containing alginate. The root canals were irrigated with chlorhexidine 0.2% (CHX) through a 27-gauge needle. Two examiners measured the root canal length twice and the mean value was calculated. The data were analyzed using Kolmogorov-Smirnov and ANOVA tests. The results obtained with each Electronic Apex Locator were compared with the corresponding control length. The statistical analysis showed reliable accuracies in detecting the perforation site for the two experimental electronic apex locators (60% and 80% for NovApex and Smarpex, respectively). Although no significant difference was shown between Smarpex and NovApex, these results suggest that electronic apex locators can effectively and reproducibly detect root canal perforations.

Pulpectomy of primary teeth is commonly carried out with hand files and broaches; a tricky and time consuming procedure. The purpose of this in vitro study was to compare the cleaning efficacy and time taken for instrumentation of deciduous molars using hand K-files and Flex Master rotary system. In this study, 68 canals of 23 extracted primary molars with at least two third intact roots and 7-12 mm length were selected. After preparing an access cavity, K-file size #15 was introduced into the root canal and India ink was injected with an insulin syringe. Sixty samples were randomly divided in to experimental groups in group I (n=30), root canals were prepared with hand K-files; in group II (n=30), rotary Flex Master files were used for instrumentation, and in group III 8 remained samples were considered as negative controls. After clearing and root sectioning, the removal of India ink from cervical, middle, and apical thirds was scored. Data was analyzed using student''s T-test and Mann-Whitney U test. There was no significant difference between experimental groups cleaning efficacy at the cervical, middle and apical root canal thirds. Only the coronal third scored higher in the hand instrumented group (P<0.001). Instrumentation with Flex Master rotary files was significantly less time consuming (P<0.001). Although there was no difference in cleanliness efficacy at the apical and middle thirds, the coronal third was more effectively cleaned with hand files. Predictably, time efficiency was a significant advantage with rotary technique.

The aim of this study was to determine the effect of different luting agents on fracture resistance of endodontically treated teeth restored with casting post. In this experimental study, forty extracted human maxillary central incisors teeth with the mean length of 23mm were randomly assigned in to four groups. All the studied teeth were caries free without any crack. After root canal treatment, the specimens were stored in 100% relative humidity at 37°C for 72h, and were decoronated 2mm above cementoenamel junction. The teeth in group1, 2, 3, and 4 received casting post and core and they were cemented with Zinc phosphate, Panavia F, Fuji Glass Ionomer, and Rely X, respectively. All teeth received 1.5 mm shoulder finishing line and 0.5mm bevel. Samples were then restored with complete coverage crowns and were loaded with an Instron universal testing machine. The cross-head speed was 0/02 cm/min and specimens were loaded with load values (Newton) computed at a speed of 1000 point/min, until the fracture happened. Loads were applied with 135 degree at middle lingual surfaces of the samples. Fracture loads were recorded. Data were analyzed by the one-way ANOVA test. There was no significant difference between the fracture resistances of four test groups. According to the results of this in vitro study, the type of luting cement had no influence on the fracture resistance of teeth.