Background. This study examined the effect of ethylenediaminetetraacetic acid (EDTA) and etidronic acid (HEDP) in retrograde cavities on the bond strength of MTA Angelus and NeoPutty. Methods. Sixty-six teeth with single roots and canals were decoronated and enlarged up to F3 using the ProTaper Universal file system. After removing the apical 3 mm within the scope of endodontic surgery procedures, retrograde cavities were prepared with ultrasonic tips. The teeth were divided into three main groups according to the irrigation solution used: saline, 17% EDTA, and 9% HEDP. Following the irrigation of retrograde cavities, each main group was further divided into two subgroups in terms of using MTA Angelus and NeoPutty as retrograde filling materials. Bond strength values of hydraulic cements were measured by the push-out test. Fracture modes were examined under a stereo microscope. Two dentin sections from each group were examined under scanning electron microscopy (SEM) to observe dentinal tubules. Two-way ANOVA and post hoc Tukey tests were used to analyze the data. Results. Irrigation solutions similarly affected the bond strength values of hydraulic cements (P=0. 115). MTA Angelus showed significantly higher values than NeoPutty in all the solution groups (P=0. 34). Adhesive and cohesive fracture modes were mostly observed in the MTA Angelus and NeoPutty groups, respectively. Conclusion. EDTA, HEDP, and saline had a similar effect on the bond strength of hydraulic cements. The higher bond values of MTA Angelus compared to NeoPutty could support its safe use in endodontic surgery procedures.

Apical surgery (AS) is considered as the last resort to save teeth which cannot be treated with a conventional endodontic approach. The main goal of apical surgery is to create a barrier between the root canal system and the peri-radicular tissues by means of a tight root-end filling after resection. However, failures in this treatment usually result in tooth loss. In such cases surgical re-treatment should be considered as a viable alternative. In this case series, successful ARs are presented that were performed on ten teeth in five patients referring for extraction after an unsuccessful apical surgery. It should be noted that if appropriate surgical and endodontic intervention is performed and adequate apical obturation is provided with retro-grade filling, teeth can be treated without extraction.

Introduction: Calcium aluminate a-aluminate (CAA) and wollastonite calcium α-aluminate (WOLCA) are new cements with sufficient biocompatibility and sealing ability. Radiopacity of these cements have not been evaluated. The aim of the present study was to determine the minimum amounts of two types of radiopacifiers necessary to incorporate into these two cements in order to achieve the necessary radiopacity in comparison with Pro-root MTA and Portland cement.Materials and Methods: In this experimental study, bismuth oxide and barium sulfate, with concentrations of 10% and 20%, were added to CAA and WOLCA as radiopacifiers and the radiopacity results were compared with that of Pro-root MTA as gold standard. Sixty Teflon ring specimens, measuring 10 mm in diameter and 1 mm in thickness, were prepared according to ISO standard of 6876, 2001. The specimens were divided into 12 groups of 5 and placed onto PSP cassette plates. The specimens were radiographed under exposure conditions of 63 kVp, 8 mA and 0.6 seconds. Data were analyzed by one-way ANOVA at a significance level of 0.95.Results: The materials exhibited radiopacity (in mm of aluminum) in the following descending order: Pro-root MTA, 0.8 gr of CAA+0.2 gr of bismuth oxide, 0.8 gr of WOLCA+0.2 gr of bismuth oxide, 0.9 gr of WOLCA+0.1 gr of bismuth oxide (p value<0.001).Conclusion: For appropriate radiopacity based on international standards, combination of 0.8 gr of CAA+0.2 gr of bismuth oxide, 0.8 gr of WOLCA+0.2 gr of bismuth oxide and 0.9 gr of WOLCA+ 0.1 gr of bismuth oxide are recommended.

Introduction: Different techniques and materials have been introduced over time to improve the quality of root canal treatment. This study aimed to compare the quality of root canal obturation using three root canal obturation techniques based on the existing void using cone beam computed tomography imaging techniques. Methods: Thirty-three single canal teeth were selected and the root canals were prepared. The roots were obturated with single-cone, lateral compaction with cold gutta-percha, and vertical compaction techniques. Afterward, the roots were scanned, and the presence of voids in the 1-, 3-, 5-, and 7-mm sections of the root apex was investigated, and then the area and volume of voids were calculated by Mimics 10. 01 software. Results: The highest percentage of voids presence in all groups was detected in the 7-mm section of the apex (60. 6%), while the lowest percentage was found in the 1-mm section of the apex (12. 1%). Conclusion: There was no significant difference between the three techniques evaluated in this study in terms of void size, void volume, and obturation quality. Voids were present in all samples. Considering the technique used to obturate the root canals, voids were different in terms of shape and volume.

Introduction: In cases of limited access to the surgical site, an alternative approach is to obturate the canal prior to surgery. Endodontic surgery is subsequently performed by root-end resection without retro-cavity preparation. This in vitro study was designed to compare the sealing ability of resected roots filled with either mineral trioxide aggregate (MTA) or calcium enriched mixture (CEM) cement. Materials and Methods: Seventy maxillary anterior teeth were selected. Following canal preparation, the teeth were randomly divided into four experimental (n=15) and two control (n=5) groups. In Group 1, CEM cement was placed into the apical 6-mm of the canal. The remainder of the canal was filled with gutta-percha/AH26 and 3-mm root-ends were resected. In Group 2: the teeth were treated as described above except that MTA was used instead of CEM cement. Group 3: The canals were obturated with gutta-percha/AH26. After root-end resection, retro cavities were prepared and filled with CEM cement. Group 4: The teeth were treated as described for group 3 except that MTA was used instead of CEM cement. The root apices of teeth were then placed in India ink, and maximum dye penetration was measured with a stereomicroscope. Nested ANOVA and Independent samples t-test were used to evaluate the statistical significance.Results: The mean dye leakage values for groups 1 to 4 were 402.6, 526.4, 141.0, and 177.4, respectively. The retrofilled groups had less microleakage compared to the resected materials; in the CEM cement groups this was statistically significant (P<0.05), i.e. root-end resection had no significant influence on the sealing ability of MTA, but significantly increased the microleakage of CEM cement (P=0.017). Overall, CEM cement showed less microleakage compared to MTA, however the difference was not significant.Conclusion: Within the limitations of this dye leakage study, we can conclude that if limited access prohibits retrofill placement, MTA or CEM cement can be used to fill the canal prior to root-end resection; as they have similar sealing ability. However, further laboratory and clinical studies are required to evaluate this alternative method.

Introduction: The goal of apical surgery is to eliminate the root apex, apical lesions and promote tissue repair. In apical surgery, the root is resected at an angle of 45, 60 or 90 degree. In many cases, it is not possible to resect the root at 90-degree bevel and prepare a root-end cavity with 4-mm depth. The aim of this study was to evaluate the simultaneous effect of apical resection angle and depth of the retrograde filling with mineral trioxide aggregate (MTA) on apical microleakage. Methods and Materials: Root ends were resected at 45 degree, 60 degree and 90 degree bevels in 110 extracted human single root permanent teeth. For each apical surgery, root-end cavities were filled with MTA to depths of 2 mm, 3 mm and 4 mm. Root end-filled teeth were mounted in fluid filtration device. The evaluation was conducted after 24-h, 1 week, 1 month, 2 months and 3 months. Each group included 10 samples. Also 20 roots were used as positive and negative control samples, in the negatives the entire root surface was coated with 2 layers of nail varnish and positives were unfilled root-end preparation. Statistical analysis consisted of the Kruskal-Wallis test and Pairwise comparison. Results: There were no significant differences in apical microleakage after 24 h and 1 week in the experimental groups. In the 3rd month, samples with 90° bevel and 4-mm-thick MTA showed significant statistical differences with all samples with 45° and 60° bevels and depths of 2-and 3-mm-thick MTA (P<0. 05). Conclusions: This in vitro study showed that when the resection angle is 90° , retrograde depth does not affect microleakage, but resection angles other than 90° , require 4 mm-retrograde depth to be sealed.

Statement of Problem: Due to the anatomic complextieis of C-shaped canals, using an obturation technique capable of filling the irregular isthmus in the root canal system seems to be necessary.Purpose: The aim of this study was to compare the efficacy of three different root canal obturation techniques used for filling the irregular root canal system in C-shaped teeth.Materials and method: The study was perfomed on 30 human extracted molar teeth which were radiographically and anatomically recognized as having C-shaped canals. All root canals were prepared in the same way and the samples were divided into 3 groups, each of 10 teeth. The root canals in group I were filled by cold lateral condensation technique (CL). Teeth in group II were filled by means of warm lateral condensation technique (WL) and those in group III were filled by means of warm vertical condensation technique (WV). All teeth were demineralized and then cleared with methylsalicilate. Images were taken from both longitudinal and cross-sectional feature of the cleared teeth by a digital camera connected to a stereomicroscope. The filling quality of the main canals and the isthmus between them was evaluated by three independent endodontists. The data were statistically analyzed by chisquare, one way and two way ANOVA and t-test.Results: In longitudinal photographs, the highest percentage of good filling quality (80%) was observed in the WV group and was significantly more acceptable than WL group (p<0.05). The lowest percentage of good filling quality was observed in the isthmus area of the canals (46.7%) which was significantly less than other areas (p<0.05). Cross- sectional photographs demonstrated no significant difference between the percentage of isthmuses filled with the filling material and the two areas of the canals in the three obturation techniques (p>0.05).Conclusion :The results indicated that none of the suggested techniques could successfully fill the root canal space, but the warm vertical and cold lateral condensation techniques were more acceptable than warm lateral condensation technique.

Background: There is some concern that root resection may alter the surface features and crack formation of the previously set orthograde material. The aim of this in vitro study was to evaluate the crack formation in orthograde mineral trioxide aggregate (MTA) and calcium‑, enriched mixture (CEM) plugs after root resection. Materials and Methods: This in vitro study was conducted on 170 extracted human maxillary anterior teeth. The teeth were randomly divided three experimental (n = 50) and control (n = 20) groups. In Group 1, after root canal treatment, half of the roots were cut with a bur, and the other half with an ultrasonic cutter. In Groups 2 and 3, after the 4‑, mm CEM and MTA plugs were placed and set, the root ends of half of the samples were cut with a bur and the other half by an ultrasonic cutter. The prevalence of cracks in the dentin and orthograde apical plugs of MTA and CEM was then assessed by scanning electron microscopy. Data were analyzed using the McNemar’, s, Chi‑, square, and Fisher’, s exact tests at P ≤,0. 05 level of significance. Results: In general, the prevalence of crack in dentin in Groups 2 and 3 was significantly higher than in the plug (P < 0. 05). There was no significant difference in the prevalence of dentin crack in the studied groups (P > 0. 05). The prevalence of crack in dentin was lower when the bur was used to cut off the end of the root, although the difference was not significant. The prevalence of crack in the plug was similar in CEM and MTA. Conclusion: Based on the results of this study, the prevalence of crack in dentin is always significantly higher than its prevalence in the plug, and the prevalence of crack in the plug was similar in CEM and MTA,then, when there is an orthograde access to the root canal and surgery is likely in future, MTA and CEM can be placed in an orthograde technique and it just resects the root during surgery.

Introduction: Apical surgery aims to eradicate the apical part of the root and the lesion to enhance the healing. The sealing ability of retrograde filling material is an essential factor affecting the success rate of the surgery. Mineral trioxide aggregate (MTA) is the gold standard of retrograde filling materials, with approved sealing capability and biocompatibility. Newly introduced root repair material with an approved antibacterial effect similar to MTA is Nano-fast cement (NFC) which should be investigated for its sealing ability. This study aimed to evaluate the sealing ability of NFC vs. MTA. Materials and Methods: Root apices of 48 single-rooted teeth were resected at 90 degrees and were prepared at 3 mm depth. The teeth were randomly divided into 2 experimental groups (n=21), negative control group (n=3), and positive control group (n= 3). MTA and NFC plugs were condensed as retrograde filling material. The samples were evaluated by a modified fluid filtration device for 1 hour. The measurement was conducted at 24 h, 1, and 3 months. Data were analyzed by Friedman Test and Kruskal-Wallis test. Results: According to the results, NFC at 3-months interval showed the least microleakage, and MTA had the highest at the baseline. However, the results between the two groups were not statistically significant in all intervals. NFC reached the ideal sealing ability within 1 month, which was reached for MTA after 3 months. Conclusions: The results of this in vitro study showed that the microleakage value of NFC is comparable to MTA. In light of current findings, NFC shows characteristics of a suitable calcium silicate-based cement. Further clinical researches are needed to introduce the NFC as retrograde apical plug or for other endodontic applications.