[Cleaning effectiveness of two methods of instrumentation, manual and rotary; a microscopic study]

Root canal cleaning is the main purpose of canal instrumentation. Hand instruments leave more debris and smear layer on the root canal walls. The use of automated instruments is helpful in root canal cleaning. The aim of this study was comparison of hand NiTi instruments, rotary flexMaster and FKG race instruments in root canal cleaning. In this interventional and in vitro study, 75 single canal teeth with minimum curve were selected and divided into three groups of 25 teeth in each. The canals were prepared with hand NiTi file, FlexMaster and race instruments using crown down preparation technique, up to size 40. During preparation, the root canals were irrigated with 5m1 of 0 0.50% Naocl solution and at the end of instrumentation with 5 ml of normal saline. After splitting the roots longitudinally, the amount of the debris and smear layers were quantified on the basis of Hulsmann method, using a scanning electron microscope. The data were analyzed by Kruskal wallis test using SPSS statistical software. In general, flexMaster instruments left less debris than FKG race and NiTi hand instruments significantly [p<0.05]. This difference was significant in all three thirds of the canal. FlexMaster instruments left debris with the smallest size in the middle and coronal thirds of the canal but not the apical third. FlexMaster instruments left less smear layers just in the apical third of the canal significantly. No completely cleaned root canals were found with any of the three instruments. In general, FlexMaster instruments proved to have better canal cleaning in all three third of the root canal significantly

Radiographic and clinical evaluation of repair of furcal mechanical perforations in premolar teeth of dog using dark MTA, white MTA and Portland cement

One of the problems affecting the prognosis of the treatment is perforation which requires immediate and proper intervention. Dark MTA is applied as material of choice to repair perforations. The purpose of this study was to evaluate the repair of mechanical furcal perforations radiographically and clinically using white MTA and Portland cement and comparing them with dark MTA. In this experimental study, second to fourth mandibular and maxillary premolar teeth of five dogs received endodontic treatment following radiographic and clinical examinations. Then, the furcation area of the teeth was perforated and repaired with dark MTA in group 1, white MTA in group 2, Portland cement in group 3 and cotton pellet in group 4 [control]. Animals were controlled for 4 months and sacrificed using an overdose of Sodium thiopental intravenous injection after radiographic and clinical examinations. Chi-square test was used to compare groups for gingival attachment and presence of radiolucency. To compare these items between each two groups, Fisher's exact test was used. There was no statistically significant difference between dark MTA, white MTA and Portland cement groups in presence of radiolucency and gingival attachment. However, all the three groups were significantly different in radiolucency and gingival attachment from control group. Both white MTA and Portland cement revealed favourable results in repair of perforations and can be used as an alternative to dark MTA to repair perforations in the areas where esthetics is important and not important, respectively

[ invitro comparative study of marginal adaptation of two retrograde materials [Gray MTA and Portland cement] by SEM]

Total seal in the root apex for healing of periodontium is an important goal of endodontic surgery that is obtained by application of various kinds of retrograde materials. The purpose of this study was to evaluate and compare marginal adaptation of two retrograde materials [Gray MTA and Portland cement], using SEM. In this invitro study, 50 extracted single-rooted human teeth with mature apices, without decay, absorption or root fracture were selected. The canals were instrumented by rotary system and filled with gutta-percha and then 3 mm of the root-end was resected. Then a cavity was prepared at the root-end with 3 mm depth and 1 mm width. Next, the teeth were divided into two groups of 25 teeth each. Each group was filled with one of the retrograde materials [Gray MTA or Portland cement]. After that, the teeth were resected longitudinally to create buccal and lingual sections. Finally, the gap was determined and recorded in millimeter in two dimensions. The data were analyzed using Mann-Whitney test and Fisher's Exact test. The mean gap in Gray MTA and Portland cement were 211.6micron and 326.3 micron, respectively. The difference was not statistically significant. There was no significant difference in marginal adaptation between Gray MTA and Portland cement

[Comparison of chlorhexidine and sodium hypochlorite effect as intracanal irrigants on pain and swelling after root canal therapy in teeth with necrotic pulp]

Post endodontic treatment pain and swelling or both is named as Flare-up which is one of the problems after root canal therapy. This problem is particulary important in necrotic teeth because of infiltration of bacterial agents into the periapical region. Adequate and appropriate irrigation of canal removes intracanal microganisms, debris and infected agents from canal space and decreases the incidence of pain and swelling. Sodium hypochlorite is one of the most effective antibacterial irrigants which dissolves vital and non vital tissues. Chlorhexidine is another irrigant that has antibacterial characteristics. The aim of this study was comparison between the incidence of Flare-up after using chlorhexidine and sodium hypochlorite as irrigatns in root canal therapy of necrotic pulp. In this clinical trial study, 50 patients with single canal necrotic pulp without any symptoms were selected and were divided into two groups of 25. In any group, after isolation and access preparation, canals were prepared using rotary Race files. Canals were then irrigated with chlorhexidine 0.2% and sodium hypochlorite 2.5% and were finally obturated by lateral condensation. A questionnaire was given to the patients to fill the amount of their experienced pain using a visual analogue scale and swelling with a scale with 4 degrees. Patients were followed for 48 hours. The data were analyzed by Mann Whitney, Wilcoxon and Kruskal-Wallis tests. There was no significant difference between irrigant solutions in decreasing the amount of pain and swelling after endodontic treatment. No significant relationship was detected between amount of pain and swelling, and age and sex. Flare-up was observed more in maxilla compared to mandible. According to less toxicity effect of chlorhexidine, sodium hypochlorite can be replaced by chlorhexidine

[Evaluation of IL-1 beta secretion level by human osteoblast cells adjucent to white MTA, dark MTA, portland cement and IRM as a retrograde filling material]

Osteoblasts and ligament periodontal cells are the essential cells for wound repair after root-end resections and perforation repair. Osteoblast cells reaction in direct contact with filling materials play a critical role in wound repair after surgeries and perforation corrections. Cell attachment on material surfaces and cell secretory function is the primary phase for evaluation of normal cell function. The aim of this study was to morphologically evaluate osteoblast cells [MG-63] function and IL-1 beta secretory level adjacent to gray MTA, white MTA, Portland cement and IRM, as materials for root-end fillings and repairing perforations. Human osteoblast cells [MG-63] obtained from Iran Pasteur Institute. cell bank were grown in RPMI-1640 medium. The under study materials, following the company instructions, were mixed and seeded in 24, 1cmx1cm partition plates with the aproximate thickness of 1mm. The cells were added after the materials primary setting time. The cells were observed by a light microscope an day 1, 3 and 7. In the mentioned intervals, the cells supernants were collected and examined by ELISA and the amount of IL-1 beta in each specimen was measured in pg/ml. The turkey test was used for comparison of the data among different matreials and the Komogrov-Smirnov test was used for normalizing the resonses. The cells morphological outcomes illustrated that after 7 days, a large amount of osteoblasts adjacent to gray and white MTA had the good attachment and morpholigically expansion and flat. The cells adjacent to Portland cement were found round and mostly seperated from the surface, although some flat cells could be found among them. Adjacent to IRM, all the cells were round and seperated from the plate surface. The level amount of IL-1 beta secretion adjacent to gray and white MTA was significantly more than to IRM and Portland cement [P=0.00]. Adjacent to gray and white MTA, the amount of IL-1 beta secretion was not significantly different [P=0.77], also the IL-1 beta secretion level adjacent to Portland cement and IRM was not significantly different [P=0.187]. The currrent study result indicates that human osteoblasts adjacent to gray MTA and white MTA, in comparison to Portland cement and IRM, showed a more appropriate response. Therefore we recommend the use of MTA over the other materials. Regarding Portland cement more research needs to be done in order to reach a final conclusion

[Comparison of the remaining smear layer following use of manual and rotary instruments with various speeds]

Endodontic smear layer [SL] can reduce the apical seal and adaptation of gutta-percha to root canals [RCs]. Instruments with adequate flexibility and proper speed create less smear during RC preparation. The purpose of this in vitro study was to compare the amount of SL following canal preparation by hand and rotary instrumentation. Sixty freshly extracted single-rooted teeth with minimum curvatures were divided into two groups. All canals in group 1 were instrumented with SS-type K-files using a step-back technique. The remaining teeth constituting group 2 were divided into 3 subgroups and prepared by employing the GT profile system at rotational speeds of 1000, 8000, and 24000 rpm. In both groups, 2 teeth were selected as controls, which were placed in 17% EDTA for 15 minutes and then washed with 5.25% Naocl. All specimens were cut bucco-lingually, and evaluated under an electron microscope. Kruskal-Wallis and Man-Whitney U tests were used to compare the groups. A significant difference in the amount of SL was not observed between the three rotational speeds at the coronal portions of the RCs. These sections were cleaner in the 1000 and 24000 rpm groups. No significant difference was found between the two instrumentation techniques in the apical portions. The mean size of the smear plug was larger and showed a greater amount of attachment in group 1 as compared to group 2. Ni-Ti rotary instruments produced a thinner SL with less attachment to the root canal walls making it easy to remove with sufficient irrigation

[Success rate of retreated teeth with periapical lesions: a clinical and radiographic evaluation]

As for other dental treatments, root canal therapy may lead to failure. Correction of these conditions will be faced with problems and complexities, particulary if any periapical lesion is peresent. The aim of this study was to evaluate the success rate of retreament in teeth with apical lesions. In this descriptive study 60 teeth with failed root canal therapy which had been retreated by an endodontist were reevaluated clinically and radiographically between 6 to 12 monthis after retreatment. Clinical examinations were performed by a clinician and comparison with the primary symptoms, recorded in patiants file, was obtained. Periapical radiographs were prepared by parallel technique and E speed film with the same proccessing conditions. Periapicel lesion size was evaluated and comparison was made before and 6-12 month after retreament, using photoshop software [version7] .The data were analyzed by chi-square test and agreemental tables. Statistically, there was no correlation between variables and success rate. The success and failure percentage of retreatment was 81.7% and 5%, respectively and 13.3% of cases were uncertain. The most success rate was observed in group of 31-40 years old [95%], keeping in mind that most patients were in this age group. The least success was in group over 50 years old. According to this study, the high success rate could be expected in retreatment of teeth with periapical lesion

[Evaluation of apical microleakage in cavity preparation with different dimension for retrograde filling]

Several materials are recommended for retrofilling. One of the best materials that have ever been suggested is MTA [Mineral Tioxide Aggregate]. Many studies have confirmed the biocompatibility, proper marginal adaptation and sealability of this agent. The purpose of this study was the evaluation of apical evaluation of apical microleakge in cavity preparation with different dimension for retrograde. In this study, we examined the influence of cavity dimension on sealability of MTA. We selected sixty roots with a single canal. After cleaning and shaping, the canals were obturated with guta-percha and canal sealer by lateral condensation technique. Samples were divided into 5 groups: two positive and negative control groups and three experimental groups. Cavity preparation was performed for all experimental groups with the following methods: A: 1.5mm depth and 0.6mm width B: 3mm depth and 0.6mm width C: 3mm depth and 1.5mm width After cavity preparation, MTA powder was placed in each cavity and wet cotton adjacent to them for 24 hours. Then the samples were placed in Incubator [37 degree C and 100% wet] for 72 hours. Subsequently dye penetration examination was performed; dye leakage was measured by stereomicroscope. We used T-test for statistical analysis. After statistical analysis these results were achived: 1. Increase depth from 1.5mm to 3mm reduce the amount of leakage. 2. No significant difference between leakage of cavities with different width was found [P-value>0.05]. It's better to prepare cavities for retrograde filling with more depth and less width

[In vitro comparison of apical sealing ability of apatite root sealer and AH26 sealer]

Studies have shown the effect of sealers used with master cones in order to gain better apical multi dimensional sealing. This goal is considered to be effective in treatment prognosis and blocking micro-organisms and limiting their activities. Applicable sealers should have advantages such as little dissolution and proper adaptation to periapical tissue. Calcium phosphate and hydroxy apatite are compounds that have shown significant effect in recovery of osseous lesions. The aim of this study was to apply a mixture of these materials as sealer, named Apatite Root Sealer, with gutta percha in root canals and compare its micro leakage with AH26 sealer. Materials and method: In this experimental study 26 extracted single-root human adult teeth, with same size and without curve were selected. The apical third of roots were prepared by step-back technique and Race rotary files [6%] up to MAF# 40 and the coronal two thirds were prepared by gates gliddens. The canals were irrigated with sodium hypochlorite 5.25%. The teeth were divided in two test groups of 10 and two control groups of three teeth. Group A: Canals were filled with gutta percha and Apatite Root Sealer. Group B: Canals were filled with gutta percha and AH26 sealer. The access cavities were sealed with Glass ionomer and then samples were placed in incubator at 37°C and 100% humidity for about 48 hours. After sealing the roots with two layers of nail polish and sticky wax except for the two mm of apical area, the teeth were placed in silver nitrate 50% for six hours and then rinsed and exposed to florescent light before floating in developing solution for about two hours. Specimens were sectioned longitudinally from buccal to lingual and examined under a stereomicroscope by 0.1 mm accuracy. The dye penetration level was measured and analyzed using T-student statistical test. Measuring the samples showed that dye penetration in Apatite root sealer group was more than AH26 group, which was significantly comparative [p<0.001]. Since the resin-based sealer [AH26] was more trustworthy and effective in achieving apical seal in comparison to the Apatite root sealer, its application is more recommended

[ vitro evaluation of the presence of second canal in distal root of first and second mandibular molars]

The human tooth have a lot of anatomical variation and adequate information of root canal anatomy is an important factor in successfull root canal therapy. The purpose of this study was evaluation incidence of second canal in distal root of inandibular first and second molars. In this descriptive invitro study, 100 extracted human extrated first and second mandibular molar used then; distal roots resected from CEJ. After removal the pulp tissue, teeth stored in 30% hydrogen peroxid for 48 hours. Root canal system was studied with dye penetration and serial horizontal sectioning methods. There were 16% and 18% two canals in distal root of mandibular first and second mandibular molars. Different type of canals in distal root of first mandibular molars were observed as follow: 10% type IV and 6% type II. Different type of canals in distal root of second mandibular molars were as follow: 2% type IV, 2% type III, and 14% type II. With attention to the results of this study about incidence of second canal in distal root of mandibular molars careful exploration is necessary for finding of extra canals

influence of instrument application frequency on apical extrusion of debris in three instrumentation techniques

Various kinds of hand-held or rotary techniques are used for mechanical preparation of the canal. The purpose of this study was to assess the influence of the number of applications on apical extrusion of debris in conventional and two rotary instrumentation techniques [Profile, Flex Master]. In this in vitro study, 75 extracted single-rooted human mandibular premolars with curvature between 0-10 degrees were selected and divided into three groups of 25 teeth each. All teeth were shortened to length of 15 mm by cutting the crown. Group H was prepared by hand step back technique, group P was prepared by profile system and group F was prepared by Flex Master system. The number of applications was according to manufacturer recommendation. For collection of debris, vials of distilled water were used that were weighed before preparation by 0.0001 weighing machine. At the end of canal preparation, vials were completely dried and weighed again. The difference between the weights of vials in two stages was the weight of debris extruded from apical foramen. The mean weight of debris in various numbers of applications within each system was compared by one-way variance analysis. Comparing the various numbers of applications in each system, it was noted that only in profile group, with increasing the number of applications, the quantity of debris extrusion was reduced. Unused profile instruments induce more extrusion of debris from apical foramen, rather than used ones

comparison of apically extruded debris between conventional and 2 rotary instrumentation techniques according to the number of applications [An in vitro study]

Various kinds of hand or rotary techniques are used for mechanical preparation of the root canal. The aim of this study was to assess the influence of the number of applications of conventional and two rotary instrumentation techniques [Profile, FlexMaster] on the apical extrusion of debris. In this study, 73 single rooted mandibular premolars with curvatures between 0 to 10 degrees were divided into three groups. Groups H, P and F were prepared by the hand step-back, Profile and FlexMaster techniques, respectively. Preweighed vials [0.0001 precision] containing distilled water were used to collect debris. After canal preparation, the vials were completely dried and weighed again. The weight of the debit extruded from the apical foramen was calculated by assessing the difference between the weights of the vials, before and after canal preparation. One-way ANOVA was used to compare the mean weight differences of the debris between the number of applications of the three different techniques. The weight of the debris varied significantly according to the number of times the Profile technique was applied [n=6], i.e. the quantity of debris decreased with increased application. A statistically significant difference was not observed between the number of applications using the other studied techniques. New Profile instruments induce more extrusion of debris from the apical foramen as compared to previously used instruments

[Evaluation of adhesion and morphology of human osteoblasts to white MTA/Gray MTA and IRM as root end filling materials by scanning electron microscopy]

Osteoblast and periodontal ligament cells are major cells for wound healing after root end resection. The interaction of osteoblast with directly contact filling materials could plays a critical role in healing of surgical lesion. Adhesion and spreading of cells on material surface are the initial phase for cellular function. The purpose of the present study was the evaluation of morphology and attachment of human osteoblasts in presence of Gray MTA, white MTA and IRM as root end filling material. This study was a descriptive study the human osteoblasts [MG-63 cell line] were prepared from Iranian Pasteur Institute; Cellular Bank, were grown in PRMI 1640 medium. The testing materials were mixed according to the manufacture's instruction, inserted into the wells of 24-well flat-bottomed plate, and condensed to disk of 1mm thickness and 1×1mm diameter. Cells were added to the materials after two weeks. During 1,3,7 days intervals, the disk of materials along with cells were grown on their surface, examined by a scanning electron microscopy. First day: After first day cells in presence of white and gray MTA showed adhesion and normal morphology, in presence of IRM were totally round. Third day: After third day osteoblasts adjacent to white and gray MTA were flat with adhesion to both materials. In presence of IRM they were round and with no attachment. Seventh day: In seventh day cells appeared with adhesion and normal morphology. Adjacent to IRM cells were round with no attachment. The results indicate that human osteoblasts have a favorable response to gray and white MTA compared with IRM

[The effect of adding mannitol to lidocaine on the anesthesia of teeth with inflamed pulp in cat]

Achieving complete anesthesia in the presence of inflammed pulp is one of the main problems in root canal therapy, and researchers are trying to find a more efficient anesthetic drug for these cases. The main goal of this study was to compare the analgesic effect of lidocaine and lidocaine mixed with mannitol in teeth with inflamed pulp. By using an electrophysiological method the anesthetic effect of lidocaine and lidocaine - mannitol injections on 24 mandibular canine teeth belonging to 12 cats were compared. At the first stage, right and left canines were exposed to the oral cavity for about 3 days in order to induce pulp inflammation. At the second stage, the inferior alveolar canal was exposed by a surgical flap and the extraction of the covering bone. Then recording electrodes were connected to the inferior alveolar nerve and stimulating electrodes were connected to the canine's teeth. The teeth were stimulated by increasing the voltage with a stimulator. The lowest voltage that produced the highest amplitude of the neurological wave was considered as the main voltage of the study and neurograms were recorded before and after drug injections in each tooth. Lidocaine and lidocaine - mannitol were used alternatively for each side of the mandible. Mann Whitney test was used for data analysis. Based on the obtained results there is no significant difference between the two anesthetic agents in decreasing the amplitude of the neurological wave

[Invitro study of apical micro-leakage of three materials: gray MTA, white MTA and Portland cement]

Retrograde surgery is a method to correct failures in endodontics, for which various materials are used. The purpose of this study was comparative evaluation of the amount microleakages of three retrograde cements: gray MTA, white MTA and Portland cement. In this experimintal study, 57 single root human extracted teeth with matu] apices, were selected. After cutting crowns, teeth were prepared with manual file [step back technique], they were obturated with gutta-percha and AH26 sealer laterally. Then roots devided into three experiment groups with 15 teeth in each group and 2 positive and negative control groups with 6 teeth in each group After a 45° bevel, 3mm apical cavities were prepared and then each one was filled with one of the three cements. The coronal part of the roots sealed with amalgam. After nail varnishing on the root surface [except their apical 1mm of each root]. All roots were immersed in 2% methylen-blue dye for 72 hrs. Then they were split and linear dye-penetration was measured by stereomicroscope. The data were analyzed statistical using one way ANOVA test.Statistic analysis of the data showed no significant difference between the three retrograde cemen Gray MTA [4.520mm] white MTA [4.826mm] and Portland cement [4.826mm].According to results, the use of Portland cement as a retrograde cement seems to be promising clinically. In vivo studies focusing on Portland cement are recommended

Histopathological study of periapical inflammation following preparation of the root canal with conventional and profile rotary instrumentation in teeth of cats

Various factors are involved in causing inflammation following root canal treatment. Controlling these factors may relieve the related pain. One of these factors is extrusion of debris beyond the apex. Although debris extrusion happens in all instrumentation techniques, researchers have declared that in coronal flaring technique, there is minimum debris extrusion. The purpose of this study was to evaluate and compare the inflammation of periapical area following root canal therapy, using conventional and profile rotary instrumentation in cats' teeth, from a histopathological point of view. This experimental study conducted on thirty Persian one year old cats. Three groups of samples were chosen and treated with different methods. First group were prepared by step-back instrumentation technique using stainless steel K-type files. Second group were prepared by crown down technique using Ni-Ti files. Third group were prepared using profile GT rotary system at 150-rpm speed. Animals were subjected to vital perfusion at 8, 24 and 48 hour intervals after instrumentation. The canine teeth were separated from the jaw along with some of the supporting structures. Then decalcification and laboratory processing were carried out and samples were evaluated histologically. Collected data were analyzed using Kruskal-Wallis test. The results showed that in vital teeth with no evidence of periapical pathosis, the inflammation following various instrumentation methods was not statistically different. In vital teeth, the periapical inflammation following various methods of instrumentation is not statistically different

histologic evaluation of rat connective tissue reaction to three different gutta-percha cones [ariadent, roeko and diadent]

Regarding the manufacture of different gutta-percha cones and the importance of apical seal in a successful root canal therapy, this experimental study was designed to compare the invivo effects of Ariadent gutta-percha with Roeko and Diadent. In this exprimental invivo study, 29 mature Albinus rats [mean weight 202/77 gr] were selected. Four intradermal incisions were made in the dorsal part of each rat. In three incised areas, a piece of each gutta-percha was placed and one of the four incised areas was assumed as the negative control. Animals were sacrificed at 15, 30 and 60 day intervals and then specimens were taken from subcutaneous connective tissues of rats. All of the specimens were prepared histologically and stained using H and E staining method, histological assessment was based on the number of inflammatory cells. Data were analysed using One-Way ANOVA and Duncan test with 95% confidence level through SPSS software. The results revealed that Ariadent gutta-percha in 15 day interval was more reaction inducing than Roeko and Diadem but in 30 and 60 day intervals, tissue biocompatibility of Ariadent was the same as Roeko and Diadent. Iranian Ariadent gutta-percha can be considered as a substitute for other foreign gutta-percha cones

[ clinical study of the effects of oral administration of betamethasone on the incidence of post treatment endodontic pain]

Introduction: one of the complications following root canal therapy in some patients is the post treatment endodontic pain. The purpose of this study was to evaluate the effects of oral administration of a single dose of betamethasone prior to treatment on the incidence of post - treatment endodontic pain

Materials and Methods: in this study, 100 patients with single canal teeth with vital pulps undergoing root canal therapy were selected. One hour before treatment, patients were randomly given either 4mg of betamethasone or a placebo identical in appearance to the test drug. Root canal therapy was accomplished with the current standardized technique and evaluated for the incidence of pain, using the visual analog scale approach 2, 4, 6, 8, 10, 12, 24, 36 and 48 hours after the treatment

Results: the results of this study indicated that oral administration of betamethasone in comparison with placebo at all periods significantly reduced post treatment endodontic pain

Conclusion: according to the above findings, oral administration of a single dose of prophylactic betamethasone could significantly reduce post treatment endodontic pain in vital teeth

[Histological evaluation of pulpal status in patients with periodontal diseases]

Introduction: the close relationship between endodontics and periodontics is firmly established. Many authors claimed that pulpal inflammation might occur following periodontal diseases. The purpose of this study was histological evaluation of pulp in teeth with periodontitis

Materials and Methods: 32 single root teeth with periodontal diseases and without any caries and restoration selected for extraction were used in this study. Extractions were done after special clinical and radiographical examination. Samples were fixed in 10% formalin and then decalcified by EDTA for three months. Six micron sections were prepared and stained by H and E. Pulp status was evaluated histologically under light microscope

Results: showed that the amount of inflammatory cells was directly related with mobility and pocked depth. Atrophy in pulpal vessels as well as calcific feature were found in samples with deeper pocket

Conclusion: the findings imply that pulp is significantly affected by periodontal diseases. This should be a carefully considered factor when dental treatment is planned

[ invitro investigation on the incidence of apical leakage after using calcium hydroxide as an intracanal dressing]

Background and aim: nowadays Calcium hydroxide is used as a dressing for canal sterilization and repair progression of apical lesions. The aim of this study was to determine the incidence of apical leakage after susing Calcium hydroxide as an intracanal dressing and filling the canal with gutta percha and AH,, sealer

Materials and Methods: the crowns of fifty-eight single-root extracted human teeth were resected and then divided into three test groups and two control groups [test groups=15teeth, positive control =3 teeth, negative control=10 teeth]. The canal of each tooth was prepared using step-back technique up to 50= k-file and MAF=30 in groups A and C, MAF = 30 in-group B. The teeth of groups B and C were filled with Calcium hydroxide for one week and then the paste was removed by 35$ file and irrigated with normal salin in group B and sodium hypochlorite in group C. Then canals of test groups and negative control were obturated with gutta percha and AH, sealer using lateral condensation technique. Following this, teeth were centrifuged in India ink before floating in it for three days. Specimens were sectioned vertically and examined under a stereomicroscope to measure dye - penetration level. The results were analyzed using ANOVA statistical test

Results: dye - penetration of group C in which calcium hydroxide. paste had been removed with sodium hypochlorite was less than two other groups, however, no statistically significant difference was found between three experimental groups of A, B and C in dyepenetration

Conclusion: it can be concluded that using calcium hydroxide for canal sterilization has no effect on the level of apical leakage