dr. mahdi tabrizizadeh

 To perform a successful endodontic treatment, sufficient knowledge about the number of root canals and their morphology is essential. Missed normal variations may burden this treatment. This study aimed to evaluate the presence of the second canal in the roots of mandibular central and lateral incisors in an Iranian population by employing CBCT images. This cross-sectional study recruited 180 CBCT image of mandible to evaluate the number of roots as well as the number and types of root canals. Data for each sample were collected in a data collection form set and analyzed by chi-square test using SPSS17 software. A total of 681 permanent mandibular incisors were assessed. All samples had one root. Most of the samples (70.3%) had only one canal (type 1 Vertucci classification). The frequency of dual-canal in samples was 29.7%; the prevalence of dual-canal in mandibular lateral teeth (35%) was more than the mandibular central teeth (23.9%, p< 0.05). Following type 1 canal, type 3 (15.7%), type 5 (12.9%), type 4 (0.7%), and type 2 (0.3%) canals had the highest frequencies respectively. Based on this study, presence of a second canal in mandibular lateral teeth (35%) is more common than in mandibular central teeth (23.9 %). The most common canal type observed was type 1 (according to Vertucci classification) followed by type 3.

 Sealing ability is one of the most important factors for successful endodontic treatment. Some studies have shown that the powder to liquid ratio can influence the properties of dental materials. Subsequently, this may happen for those used for sealing in endodontics. The purpose of this research was to assess the microleakage of calcium-enriched mixture cement (CEM cement) apical plug in different powder to liquid ratio. Ninety-six extracted human single root and single canal teeth were decoronated. Working length was determined using ≠15 k-file. Canal preparation was performed using step back method. Samples were divided into 3 groups randomly. CEM cement was placed into the canal with 1.13, 2.27 and 3.40 powder to liquid ratio in the group 1, 2 and 3, respectively. After complete setting of CEM cement, the micro leakage value was evaluated using fluid filtration method. Data were analyzed using ANOVA and Scheffe tests. The bubble movement in three groups showed a statistically significant difference (p< 0.001). Minimum and maximum bubble movements were observed in the group with powder to liquid ratios of 3.40 and 1.13 respectively. Increased CEM Cement powder to liquid ratio will increase the sealing ability of this material as apical plug. Considering the conditions of this study, the powder to liquid ratio of 3:40 provided the best sealing ability.

 Intra-bone lesions are common in lesions, among them periapical lesions have a higher incidence. Todays, all direct digital imaging systems provide various types of image processing techniques. The purpose of this study is to investigate the effects of different digital image processing techniques on the diagnosis of bony defects.  In this experimental study, 50 sheep inferior half-jawbones were used. Lesions were created by round bars with numbers 1/4, 1/2, 1, 2 and 4. Digital images were obtained by edge enhance, sharpening, invert gray scale processing method and unprocessed investigated by two radiologists and in case of disagreement them observers by third observer. The method of recording the results was definitive diagnosis of lesion number 1, misdiagnosis number 2 and possible diagnosis number 3 .The results were analyzed by chi-square and Fisher's exact tests. Percent of diagnostic sensitivity in unprocessed Images (71.8%) and images processed with Sharpen filter (71.4%) were significantly higher than images processed with invert grayscale (68.5%) and edge Enhancer (53%).(p<0.001) To detect bone lesions, unprocessed and processed digital images with Sharpen filters have higher diagnostic accuracy.

File Fracture is one of the most common problems during root canal treatment which can affect treatment procedure and prognosis, so it is important to diagnose and prevent it. The aim of this study was to evaluate and compare the diagnostic value of cone-beam computed tomography (CBCT) and digital periapical radiography for detection of separated instrument retained inside the canal. Methods and Materials: Ninety single-rooted extracted human teeth were selected and randomly divided into 3 groups (n=30). Group 1, separated file #10 at the 2-mm apical third of the root canal; group 2, separated file #35 at the 2-mm apical third of the root canal; and group 3, without a broken file (control group). The teeth were instrumented to size #30 and were shaped to size #55 and then the canals were obturated up to separated instrument, or the working length for the teeth without a separated instrument, with lateral condensation technique. After that all teeth were placed in dry skull, digital radiography and CBCT was taken. After data collection, data was analyzed using SPSS software by means of sensitivity, specificity, positive and negative predictive values, and frequency tables. Sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy of digital periapical radiography in detection of a fractured file #10 in the canal was 96.7% and 63.3%, 76.7%, 73.1%, 67.6%, 70%, for CBCT, respectively. Sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy of digital periapical radiography in detection of a fracture file #35 in the canal was 93.3%, 96.7%, 96.6%, 93.5% and 95%, and 36.7%, 76.7%, 61.1%, 54.8%, 56.66%, for CBCT, respectively. Sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy of digital periapical radiography was better than the CBCT technique in both sizes of broken files.

Multiple methods for evaluating microleakage have been introduced over the years, but there has been no agreement as to which technique will give more accurate results. The aim of this study was to compare the accuracy and results of fluid filtration and marginal adaptation methods for mineral trioxide aggregate (MTA) and calcium-enriched mixture (CEM) cement apical plugs.
Methods and Materials: A total of 250 single-rooted human teeth were collected. The teeth were decoronated, the root canals were prepared and open apex condition was stimulated by passing #1 to 4 Peeso Reamer drills from apical foramen. Five teeth were selected as the positive and negative controls and the rest of the samples were randomly allocated to two groups of MTA and CEM cement plugs. In each group, apical plug was placed into the canal. After the apical plugs were completely set, microleakage and marginal adaptation of the samples were evaluated using fluid filtration method and scanning electron microscopy (SEM), respectively. The obtained results were analyzed by independent-samples t test.
Gap between plug and dentin walls and air bubbles displacement was higher in MTA group compared to the CEM cement group, though this difference between MTA group and CEM cement group was not statistically significant.
According to the obtained results, it seems that there is a direct relationship between the two methods of microleakage assessment.

The aim of this study was to compare the marginal adaptation of mineral trioxide aggregate (MTA) and calcium-enriched mixture(CEM) cement apical plugs in open apex teeth in dry, blood- and saliva-contaminated canals.
Methods and Materials: A total of 120 human extracted single-rooted teeth were used. The teeth were decoronated and canals were cleaned and shaped up to #80 K-Files. After simulating open apex condition, samples were randomly divided into two groups (Group 1: MTA plug and group 2 CEM cement plug) and each group was then further divided into 3 subgroups (dry canal, blood- and saliva-contaminated canals). MTA and CEM cement apical plugs were placed into the canal. After full setting of apical plug, immediate marginal adaptation of the samples was assessed by electronic microscope. The data were analyzed using the two-way analysis of variance.
There was no statistically difference between the average marginal gap in MTA and CEM cement groups in three different conditions. The average gap in dry canal was significantly lower than canal contaminated with blood and saliva.
It seems that marginal adaptations of MTA and CEM apical plug was not significantly different in various conditions and the two materials can be used successfully in this method.

Calcium hydroxide (CH) is one of the most common intracanal medications. Corticosteroids (CS) are used in endodontics because of their anti-inflammatory activity. This study aimed to evaluate the antimicrobial effect of CH+betamethasone and CH+saline against Enterococcus faecalis (E. faecalis) using agar diffusion test and measuring the microbial zone of inhibition (ZOI). Methods and Materials: Four plates containing Mueller-Hinton broth and E. faecalis culture media, were prepared. In each plate, 5 holes (5×3 mm) were created and a creamy mixture of CH+betamethasone was inserted into the holes (10 holes for each material). Two holes with ampicillin disks and two empty holes were used as negative and positive controls, respectively. Plates were incubated for 24 h and then the diameter of microbial ZOI was measured. The pH of each mixture was measured by pH meter. Data were analyzed using the Mann-Whitney U test. The mean diameter of ZOI for CH+betamethasone and CH+saline was 3.4 and 3 mm, respectively. The difference was not significant (P=0.143). The pH was 12.5 for CH+saline and 12.3 CH+betamethasone, respectively. The mixture of CH+betamethasone had good antimicrobial effects against E. faecalis. Further studies are needed to confirm the value of this mixture in clinical settings.

Vertical root fracture (VRF) is the longitudinal fracture of the root in endodontically treated teeth. Considering the limitations of two-dimensional radiographic images in detection of VRF and introduction of cone-beam computed tomography (CBCT), this study was designed to find the sensitivity, specificity and accuracy of CBCT and periapical (PA) radiography in detection of VRFs. Methods and Materials: This was a cross-sectional in vitro study on 80 extracted human single canal teeth including 40 maxillary and 40 mandibular teeth. After standardized endodontic treatment of the roots, VRF was induced in half of the teeth in each group, and other half were left without fracture. Teeth were inserted in dry maxillary and mandibular alveoli. PA radiographs and CBCT images were taken from the specimens. Data were analyzed with SPSS software. The McNemar test was used to evaluate the sensitivity, specificity and accuracy of images, and kappa coefficient was used to assess the degree of agreement between the observers. The level of significance was set at 0.05. Sensitivity and specificity values of CBCT were 97.5% and 95%, respectively. However, for PA radiography the sensitivity and specificity were 67.5% and 92.5%, in order of appearance. Accuracy of CBCT (96.25%) and PA radiography (80%) in both jaws were significantly different (P=0.022). Two methods were not significantly different when testing specificity (P=0.298). This study showed that the sensitivity and accuracy of CBCT in detection of vertical root fracture are higher than periapical radiography. CBCT can be recommended to be used in detection of vertical root fractures.

The purpose of this study was to evaluate the effect of spreader penetration depth and its alloy on apical microleakage using lateral compaction method. For conducting this in vitro lab study, 68 extracted maxillary central incisors were instrumented using the step-back method, and randomly divided into the following four experimental groups: A) stainless steel (S.S) spreader with penetration to the working length B) Nickel-titanium (Ni-Ti) spreader with penetration to the working length C) S. S spreader with penetration 1mm short of working length D) Ni-Ti sprader with penetration 1mm short of working length. Microleakage evaluation was conducted using dye penetration method. Data were statistically analysed by Two-Way ANOVA test. The data showed that the least dye penetration happened in group D. There were significant differences in mean microleakage among the groups (P=0.002). Conclucsion:According the results of this study, it seems that spreader alloyand its penetration may have a role in the amount of apical microleakage. However, before recommending Ni-Ti spreaders, further in vivo and in vitro studies should be carried out.

Endodontic treatment in pulpless immature teeth is challenging due to the lack of an apical stop. Insertion of an apical plug is an alternative to conventional long-term apexification with calcium hydroxide. The aim of this study was to compare the apical microleakage of mineral trioxide aggregate (MTA) and calcium-enriched mixture (CEM) cement as apical plugs with three different obturation techniques. Methods and Materials: This experimental study was conducted on 130 single rooted human teeth with one canal. Samples were randomly divided into 2 experimental groups (n=60) and two negative and positive control groups containing 5 samples each. After cleaning and shaping, an open apex configuration was prepared in all samples. MTA or CEM cement apical plugs with 5 mm thicknesses were placed. Then, each group was divided to 4 subgroups and the remaining space of root canals were filled with either lateral compaction or thermoplasticized injectable gutta-percha or was obturated by filling the entire canal with apical plug material. In one remaining subgroup the canal space was left unfilled. Microleakage was measured by the fluid filtration method and results were analyzed by means of the two-way ANOVA test. There were no significant differences between microleakage of MTA and CEM cement apical plugs (P=0.92). The difference between three obturation methods was not significant, either (P=0.39). MTA and CEM cement have similar sealing ability as apical plugs and no significant difference was found in microleakage of the three groups.

Accessibility to all sites of root canal and its mechanical and chemical cleaning is mandatory for successful root canal therapy. The presence of isthmus is a major hindrance to complete root canal accessibility.. The purpose of the present study was to determine the relative frequency and type of isthmuses in the apical region of mesial root of the first mandibular molar extracted in Yazd.. In this descriptive-laboratory study, 100 mandibular first molar teeth were collected. The mesial roots were excised at the cervical region and three horizontal sections perpendicular to the longitudinal axis of the root were secured with 1-, 3-, and 5-mm distances upwards from apex region of the roots. The incised surfaces were stained using India ink and viewed under stereomicroscope with a magnifying power of ×60 and photographed. The obtained images were studied regarding the presence or absence of isthmuses and the various anatomical forms of isthmuses were recorded based on Hsu & Kim taxonomy.. Isthmus was present in 54% of teeth. The greatest frequency of isthmuses was observed in the 5 mm from the apex. The type V isthmus was the most prevalent isthmuses between all levels of roots.. The frequency of isthmuses in the mesial root of mandibular first molars was high. The results of clinical and surgical endodontic procedures may be affected by this aspect of root canal anatomy..

Detailed awareness of the root canal anatomy and configuration of the pulp canal is an essential and basic procedure in endodontic therapy. Root canals are left untreated because of the dentists' inability to identify them, particularly in the teeth that have anatomical variations or additional root canals. Therefore, the aim of this study was to investigate the prevalence of the extracted maxillary first premolars with three root canals in Yazd.

In order to conduct this descriptive cross-sectional study, 180 extracted maxillary first premolars were gathered from Yazd dental clinics. In fact, the teeth were first examined for the number of the roots. Then, the standard access cavity was prepared and, the number of canals was examined by endodontic probe and file. Moreover, the roots were horizontally sectioned at 3 different levels and types of canals were determined according to Vertucci ’s classification.

18 (10%) teeth had one root canal, 160 (88.9%) teeth possessed two root canals and only 2 (1.1%) teeth had three root canals. 35 (19.5%) teeth owned single root, and 143 teeth (79.4%) had two roots and only 2 (1.1%) teeth had three roots. The canal patterns were classified as type I (11.42%), type III (25.71%), type IV (60%), type VIII (2.85%) according to vertucci’s classification.

According to prevalence of multiple canals in maxillary first premolar teeth, precise examining of pulp chamber floor and taking radiographs in different angles are recommended.

The seal provided by a root canal filling may be compromised by post space preparation. The aim of this study was to compare coronal microleakage around cast posts and prefabricated pins. Thirty-eight extracted single-rooted, maxillary human teeth were prepared with step back method and filled with gutta-percha and sealer. After removing 8 mm of coronal gutta-percha with peeso-reamer drills #2 in twenty canals, the teeth were divided into three groups: cast post & core, prefabricated pin, and gutta-percha (without any post or pin). After thermocycling, the samples were immersed in India ink for seven days. Finally, the specimens were cleared and the coronal microleakage of dye was then measured by the stereomicroscope. The data were analyzed by One-way ANOVA and Tukey HSD tests. According to the results, the mean dye penetration in cast posts, pins, and group without post or pin was 3.3 (0.39), 5.2 (0.47), and 7.2 (0.15) mm, respectively. There was no statistically significant difference between the groups (P>0.05). Considering the importance of adequate filling of crown for prevention of microleakage, the method for coronal filling must be selected with caution. According to the results of this study, no significant difference between microleakage of cast posts and prefabricated pins was observed.

Diagnosis of periapical pathology is of paramount importance in enabling the clinician to provide immediate and appropriate dental treatment. Both intraoral digital radiography and film radiography are used to detect periapical pathology. The purpose of this study was to compare the accuracy of digital radiographic imaging with conventional radiography in detecting chemically created lesions. For conducting this experimental study one cow cadaver mandibular Jaw was used. After building four 1×1cm2 pools at first molar areas, 35% Hydrochloric acid solution used to create chemically lesions. The designed time for chemically lesions was 4, 12, 24 and 36 hrs following acid exposure. Then, 1 digital and 1 conventional image with E-Speed film was taken from each half-jaw and images evaluated by five examiners. Wilcoxon signed Ranks test used for statistical analysis. The results of this study showed that diagnosis were more precise in detecting lesions with RVG than conventional radiography. This difference was statistically significant (p<0.05). Regarding the acceptable quality of digital radiographs comparing to conventional radiographs we suggest using this method for detecting bone lesions.

The effect of smear layer on dentinal tubules is remarkable in endodontic treatments. The aim of this study was measuring the range of dye penetration in dentinal tubules with and without smear layer.

Thirty extracted human teeth used in this study. At first, segments e prepared with 5 mm length from each tooth's root and then their canals widened by a 1/4 mm diameter bur, so that the smear layer appeared. The external, superior and inferior surfaces of the segments covered by 2 layers of nail varnish. The segments divided to 2 groups of 15 samples. The first group samples immersed in 17% EDTA for 2 minutes and then in 5.25% NaOCl for 20 minutes to remove the smear layer. After that the samples immersed in 2% basic fushin for 24 hours. The second group samples immersed in 2% basic fushin without removing the smear layer. After water rinse,all samples sectioned horizontally from middle of the root and photographs was taken of each samples surfaces. After transmitting the photographs to a computer, the percentage of the dye penetration into dentinal tubules of each sample calculated by Photoshop software.

Due to results, the range of dye penetration in dentine tubules of the teeth with and without smear layer had no statistically significant difference (P-Value=0.120).

According to the result, smear layer removal have no effect on dentin permeability to dye penetration and dentin sclerosis is an important factor in this subject. Performing studies on the teeth with certain age and using other methods such as microbial permeability evaluation are needed.

Calcium hydroxide has a pronounced antimicrobial activity against most of the bacterial species found in the root canal and now is widely used as an intracanal medicament in endodontic therapy. The aim of this study was to evaluate the antimicrobial effect of different calcium hydroxide preparations with Normal saline, Lidocaine 2%, Chlorhexedin 2% and 0/2%, Iodine Potassium Iodide 2% and Glycerin on Entrococcus faecalis with direct exposure method. For conducting this experimental in-vitro study 375 sterile paper points were contaminated with the microbial suspension of Entrococcus faecalis. The samples were placed in sterile dishes and covered with creamy mixture of six different calcium hydroxide preparations. After 1, 3, and 7 days the paper points were immersed in test tubes containing BHI. Microbial growth was evaluated by turbidity in culture mediums. Data obtained showed that all of tested materials had perfect antimicrobial action but only in calcium hydroxide with Chlorhexidine 2% and 0.2% groups perfect antimicrobial action and no microbial growth was observed after 24 hours. Regarding the results of this study it is concluded that the vehicle of calcium hydroxide has not any significant effect on its antimicrobial activity, however, more studies on the effect of vehicles of chemical properties of calcium hydroxide such as its diffusion in similar conditions of root canal system, are needed.

Antibacterial effect of the sealers which are used in root canal therapy is a factor which increases the rate of success in root canal therapy. The aim of this study was to compare the antibacterial effect of three sealers (ZOE, AH26, Dorifill) on two bacterial species, staphylococcus aureuse and streptococcus mutans immediately after mixing and one week after mixing. Methods & Materials: For conducting this experimental study the bacteria were provided in isolated microbial species and a standard concentration from bacteria were cultured on the blood agar media with muller-Hinton base. The 5 millimeter diameter wells in the central area of the plate were punched. The fresh mixture of the mentioned sealer were put in the wells. The same process was performed on the sealers one week after mixing. After 24 hours incubation the diameters of the inhibitory zones in 4 directions were measured with boley - gauge. The results showed that the fresh mixture of AH26 for both bacterial species was significantly more effective than the others (P=0.001). One week after mixing for both species ZOE was significantly more effective than AH26 and AH 26 was significantly more effective than Dorifill (P=0.001). With regard to acceptable antibacterial effects of these three sealers performing studies about other properties of these sealers specially ZOE, is suggested.

The goal of this Cross-Sectional study was assessment of the rate of fear in different dental situations on 231 patients referring to dental school of Shahid Sadooghi University of Yazd.Method & Material: All of necessary information was gathered by the means of a questionnaire containing questions about demographic varieties and 19 different dental situations. In this study rate of fear of patients was obtained by the method of visual analogue scale. The results of this study showed that 134 (57/3%) patients had low to moderate fear, 85 (36.8%) patients had moderate to sever fear and 12 (5.19%) patients had very sever fear. The most rate of fear was from surgery, root canal therapy, extraction and observation of needle. The assessment of information showed that there was significant statistical relationship between fear and sex and unfavorable experiences. But there wasn’t any significant statistical relationship between fear and age and number of appointments. With considering of these results we advise that dentists increase their information about fear and the ways to reduce it.