• Restorative Dentistry and Endodontics
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• v.31 no.2
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• pp.119-124
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• 2006

The purpose of this study was to evaluate the effect of newly developed endodontic root canal cleanser (MTAD) on the apical leakage of obturated root canal using an electrochemical method. Canals of 60 extracted single-rooted human teeth were prepared by using a crown-down technique with rotary nickel-titanium files. In Group 1 (positive control group) and 2 (negative centre) group), 5.25% NaOCl was used as a canal irrigant and no canal wall treatment was done. In group 3 only 5.25% NaOCl were used as canal irrigant, canal wall treatment and final rinse. In group 4, specimens were irrigated with 5.25% NaOCl, treated with 5 ml of 17% EDTA for 5 minutes and final rinsed with 5.25% NaOCl Specimens of group 5 were irrigated with 1 3% NaOCl and treated with 5 ml of MTAD for 5 minutes. All root canals are dried with paper points and obtuated with gutta-percha and AH plus as a sealer using a continuous wave of condensation technique except in the group 1. The electrical resistance between the standard and experimental electrodes in canals was measured over a period of 10 days. Rising of apical leakage with time was observed for all the groups. Group 4 and 5 showed lower apical leakage than group 3 but differences between the group 3, 4 and 5 were no statistical significance at any measurement time.

• Restorative Dentistry and Endodontics
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• v.34 no.3
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• pp.208-214
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• 2009

The purpose of this study was to compare the dye leakage of MTA (mineral trioxide aggregate) apical plug produced by two orthograde placement techniques (hand condensation technique and ultrasonically assisted hand condensation technique). To simulate straight canal, 60 transparent acrylic blocks with straight canal were fabricated. These transparent acrylic blocks were divided into 2 groups (Group C; hand condensation technique (HC) and Group U; ultrasonically assisted hand condensation technique (UAHC)) of 30 blocks with each MTA application method. Each group was divided into 2 subgroups (n=15) with different canal size of #70 (subgroup C70 and subgroup U70) and #120 (subgroup C120 and subgroup U120). After apical plug was created, a wet paper point was placed over the MTA plug and specimen was kept in a humid condition at room temperature to allow MTA to set. After 24 hours, remaining canal space was backfilled using Obtura II. All specimens were transferred to floral form socked by 0.2% rhodamine B solution and stored in 100% humidity at room temperature. After 48 hours, resin block specimens were washed and scanned using a scanner. The maximum length of micro leakage was measured from the scanned images of four surfaces of each resin block using Photoshop 6.0. Statistical analysis was performed with Mann-Whitney U test. Group U of UAHC had significantly lower leakage than Group C of HC in #70-size canal (subgroup U70) (p<0.05).

• Restorative Dentistry and Endodontics
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• v.22 no.2
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• pp.596-608
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• 1997

The purpose of this study was to compare the apical leakage and adaptation to the dentinal wall of a glass ionomer root canal cement(Ketac-Endo) with those of AH-26 and Tubli-Seal. 102 single-rooted teeth were insrumented with step-back technique and randomly divided into four groups according to kinds of root canal cements: Ketac-Endo, AH-26, Tubli-Seal, and no root canal cement. Four experimental groups were as follows; Group 1 : Filling with gutta-percha and Ketac-Endo Group 2 : Filling with gutta-percha and AH-26 Group 3 : Filling with gutta-percha and Tubli-Seal Group 4 : Filling with gutta-percha without root canal cement All the specimens were obturated with lateral condensation technique, and stored in 100% humidity for 4 days. 20 teeth in each group were placed in centrifuge tube filled with India ink, and then centrifuged for 20 minutes at 3,000 rpm. And they were evaluated for linear dye leakage using a stereoscope and analyzed by one-way ANOVA. 22 teeth were split longitudinally and evaluated the adaptation to the dentinal wall using scanning electron microscope(4 teeth in each group) and stereoscope(2 teeth in 1, 2, 3 group). The obtained results were as follows ; 1. In case of not used root canal cement(Group 4), there was showed much degree of dye penetration comparerd with used root canal cements (Group 1, 2, 3)(P<0.01). 2. In the case of used root canal cements(Group 1, 2, 3), there was no significant difference in linear leakage in groups(P>0.01). 3. In the case of used root canal cements(Group 1, 2, 3), there was showed intimate adaptation to the dentinal wall independent on kinds of root canal cements. 4. Fractured surfaces indicated failure of cohesion in Ketac-Endo, and failure of adhesion to dentine in AH-26 and Tubli-Seal. 5. According to similar apical leakage and adaptability to the dentinal wall to another root canal cements, it is possible to be used glass-ionomer cement as root canal cement.

• Restorative Dentistry and Endodontics
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• v.23 no.2
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• pp.607-617
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• 1998

The purpose of this study was to evaluate the apical sealing ability of lateral condensation method, vertical condensation method, and MicroSeal obturation system. Sixty-four extracted anterior teeth were instrumented to #40 using Profile. Three groups of 20 teeth were obturated by lateral condensation technique, vertical condensation technique, and and MicroSeal obturation system. Control group were not obturated. Teeth were immersed in resorcinol-formaldehyde resin for 5 days at $4^{\circ}C$, and the resin was allowed to polymerize completely for 4 days at room temperature. Teeth were ground horizontally at 1,5mm(level 1), 2.5mm(level 2), and 3.5mm(level 3) from the anatomic apex and examined with a stereomicroscope at X40 magnification. The photographs were taken a at X40 magnification of the filling in each level and scanned. The leakage area, which was filled with the resin, was measured at each of the three levels. Each ratio of leakage was evaluated by calculating the ratio of thearea of the resin to the total area of the canal and was analyzed statistically. The results were as followed: 1. Vertical condensation group had significantly higher percentage of the area which was obturated by gutta percha than other two technique at each level. 2. At the level 1, there was the greatest leakage in the lateral condensation group, but there was no statistically significant(P>0.05) 3. At the level 2, there was the least leakage in the MicroSeal group, and the most leakage in the lateral condensation group. There was statistically significant difference between the MicroSeal group and the lateral condensation group(P<0.05). 4. At the level 3, there was least leakage in the vertical condensation group, and the most leakage in the lateral condensation group. There was statistically significant difference between the vertical condensation group and the lateral condensation group(P<0.05).

• Restorative Dentistry and Endodontics
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• v.23 no.2
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• pp.561-574
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• 1998

The purposes of this study were to observe the difference in the root canal wall after hand instrumentation or engine-driven Ni-Ti instrumentation under the scanning electron microscope, and to evaluate the apical leakage provided by continuous wave of canal filling technique with or without root canal sealer and smear layer. Twenty recently extracted human maxillary anterior teeth were instrumented with K-type files or engine-driven Ni-Ti files, Quantec series 2000$^{TM}$ and irrigated with 5.25% NaOCl alone or 15% EDT A and final flush of 5.25% NaOCl. After the instrumentation and flushing, teeth were split in half with a knife and a mallet. They were then examined with a scanning electron microscope Forty-four recently extracted human maxillary anterior teeth were divided into four groups with and without smear layer and then warm vertical canal filling using System-B with or without sealer. The extent of leakage was scored after immersion in India ink for 1 week. The results were as follows: 1. No significant difference of smear layer was observed between K-type file-instrumented group and engine-driven Ni-Ti file-instrumented group. 2. A group without smear layer showed significantly less apical leakage than a group with smear layer when sealer was used for the canal filling (p<0.01). 3. There was no significant difference between a group without sealer and smear layer and a group without sealer and with smear layer (p<0.01). 4. In groups without smear layer, a group with sealer showed significantly less apical leakage than a group without sealer (p<0.01). 5. When root canals were irrigated with NaOCl alone, a group with sealer showed significantly less apical leakage than a group without sealer (p<0.01).

• Proceedings of the KACD Conference
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• 2003.11a
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• pp.585-585
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• 2003

I. Objectives 17% EDTA is known as an effective solution to remove smear layer. When it's applicated for more than 1 minute, it shows dentinal erosion of intertubular and peritubular dentin. This study is to investigate the effect of dentinal tubule erosion with different time application of 17% EDTA solution on the apical leakage. II. Materials and Methods 35 recently extracted human teeth with single canal, straight root, and closed apex were used in this study. Crowns were removed and the pulp tissue remnants were removed with a barbed broach.(omitted)

• Restorative Dentistry and Endodontics
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• v.24 no.1
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• pp.166-179
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• 1999

Apical sealing is essential for the success of surgical endodontic treatment. Root-end cavity is apt to be contaminated with moisture or blood, and is not always easy to be dried completely. The purpose of this study was to evaluate the influence of dry methods of retrocavity on the apical seal in endodontic surgery. Apical seal was investigated through the evaluation of apical leakage and adaptation of filling material over the cavity wall. To investigate the influence of various dry methods on the apical leakage, 125 palatal roots of extracted human maxillary molar teeth were used. The clinical crown of each tooth was removed at 10 mm from the root apex using a slow-speed diamond saw and water spray. Root canals of the all the specimens were prepared with step-back technique and filled with gutta-percha by lateral condensation method. After removing of the coronal 2 mm of filling material, the access cavities were closed with Cavit$^{(R)}$. Two coats of nail polish were applied to the external surface of each root. Apical three millimeters of each root was resected perpendicular to the long axis of the root with a diamond saw. Class I retrograde cavities were prepared with ultrasonic instruments. Retrocavities were washed with physiologic saline solution and dried with various methods or contaminated with human blood. Retrocavities were filled either with IRM, Super EBA or composite resin. All the specimens were immersed in 2% methylene blue solution for 7 days in an incubator at $37^{\circ}C$. The teeth were dissolved in 14 ml of 35% nitric acid solution and the dye present within the root canal system was returned to solution. The leakage of dye was quantitatively measured via spectrophotometric method. The obtained data were analysed statistically using one-way ANOVA and Duncan's Multiple Range Test. To evaluate the influence of various dry methods on the adaptation of filling material over the cavity wall, 12 palatal roots of extracted human maxillary molar teeth were used. After all the roots were prepared and filled, and retrograde cavities were made and filled as above, roots were sectioned longitudinally. Filling-dentin interface of cut surfaces were examined by scanning electron microscope. The results were as follows: 1. Cavities dried with paper point or compressed air showed less leakage than those dried with cotton pellet in Super EBA filled cavity (p<0.05). However, there was no difference between paper point- and compressed air-dried cavities. 2. When cavities were dried with compressed air, dentin-bonded composite resin-filled cavities showed less apical leakage than IRM- or Super EBA-filled ones (p<0.05). 3. Regardless of the filling material, cavities contaminated with human blood showed significantly more apical leakage than those dried with compressed air after saline irrigation (p<0.05). 4. Outer half of the cavity showed larger dentin-filling interface gap than inner half did when cavities were filled with IRM or Super EBA. 5. In all the filling material groups, cavities contaminated with blood or dried with cotton pellets only showed larger defects at the base of the cavity than ones dried with paper points or compressed air.

• Restorative Dentistry and Endodontics
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• v.29 no.4
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• pp.365-369
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• 2004

The purpose of this study was to evaluate the apical sealing ability of Super-EBA, MTA and Dyract-flow as retrofilling materials. Forty-eight extracted human teeth with straight and single root canal were used in this study. The root canals were prepared to a #40 apical canal size and obturated with gutter-percha. Apicoectomies were performed and root end cavities were prepared to a depth of 3mm using an ultrasonic device. The root end cavities were filled with Super-EBA, MTA or Dyract-flow. Leakage was measured using an electrochemical technique for 4 weeks. According to this study, the results were as follows. 1. Increasing leakage with time was observed in all groups. 2. No significant difference was noted among the 3 groups with time (p =0.216). 3. No significant difference was noted among the 3 groups when measured within the same time interval (p =0.814). The results of this study suggest that the sealing ability of Dyract-flow is equal to that of Super-EBA and MTA, and Dyract-flow may be an alternative to other materials for root-end filling.

• Restorative Dentistry and Endodontics
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• v.20 no.2
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• pp.812-817
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• 1995

Endodontically treated teeth are usually restored for crown protection, aesthetics, and prevention of root canal recontamination. Restoration of these teeth, however, often requires intracanal posts. Various depths and techniques have been recommended for the preparation of post space. Therefore the purpose of this study was to evaluate the effect that pst preparation has on the coronal seal by linear dye penetration of root canals obturated by lateral condensation, vertical condensation, and thermafil techniques. Forty canals of roots of incisors and canines were cleaned and shaped with the use of a step-back technique. Thirty canals were obturated, 10 each with lateral, vertical, and thermafil techhniques. Five root canals were obturated without a root canal sealer and served as positive controls. Another five root canals were obturated, and their coronal half was sealed with sticky wax and served as negative controls. The apical 5 to 6mm of the filling materials were exposed to india ink for 48 hours. The depth of dye penetration was measured in all groups and statistically analyzed (ANOVA). The results were as follows. 1. The apical plugs in the thermafil groups had the highest degree of coronal dye leakage. 2. The group filled by vertical condensation technique had the lowest degree of coronal dye leakage. 3. No significant statistical difference was found in the amount of coronal dye leakage in canals filled by lateral condensation versus those filled by the veritcal condensation technique. 4. Significant statistical differences in coronal dye penetration were found between the canals filled by thermafil and those filled by the lateral or vertical condensation techniques (p<0.05).

• Restorative Dentistry and Endodontics
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• v.20 no.2
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• pp.780-788
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• 1995

The purpose of this study was to compare the apical seal following root canal shaping by different methods. From fourty extracted mandibular 1st and 2nd molars, fourty mesial roots whose canals have some degree of curvature were selected. The mesiobuccal root portion including mesiobuccal portion of a crown was sectioned in each molar. After access cavity preparation for the mesiobuccal canal, working length was determined with # 10 K-file. The sectioned roots were implanted in acrylic resin block and randomly divided into four groups. The canals of group I were shaped by step-down/balanced force, group II by stepdown/step-back, group III by step-back and group IV by conventional method. All of the shaped canals were obturated by Thermafil method and access cavities were filled with IRM. The roots were removed from acrylic resin block and placed in 100 % humidity for 7days. Except the root surfaces of apical 2mm, the root surfaces were nail-varnished 3 times. After the roots were placed in 700 torr vacuum pressure for 15 minutes, they were immersed in 2% methylene blue solution for 4 days. Nail varnishes were removed with acetone. After that, the roots were decalcified in 5 % nitric acid and dehydrated with alcohol series. Transparent specimens were made by methyl salicylate and the quality of apical seal was assessed by measuring the leakage linearly. The results were as follows. 1. The leakage in canals shaped by step-down/balanced force method was significantly less than that in canals shaped by step-back method(P<0.05) and was less but not statistically than that in canals shaped by step-down/step-back method (P>0.05). 2. The leakage in canals shaped by step-down/step-back method was less than that in canals shaped by step-back method, but there was no statistical significance(P>0.05). 3. The leakage in canals shaped by conventional method was significantly more than that in canals shaped by step-down/balanced force, step-down/step-back and step-back method (P<0.05).