• Restorative Dentistry and Endodontics
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• v.6 no.1
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• pp.7-16
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• 1980

The author observed the periodontal tissue reactions to the root canal sealers after root perforations were made intentionally in dogs. The perforations were made on 74 teeth from 7 dogs. The experiments were performed in two different modes of procedure: In Group I, the perforations were made through the root canal to the alveolar bone. In Group II, the perforations were made from site of alveolar bone to the root canals. The perforated canals in Group I were filled with gutta-percha and root canal cements; Calxyl (Calcium Hydroxide in Ringer's solution), Zinc Oxide -Eugenol cement (Z.O.E.), Kerr sealer (Rickert's paste) and AH 26 (Epoxy Resin preparations). The perforated canals in Group II were sealed with Calxyl, Z.O.E, Kerr sealer and AH26. Histologic examinations of periodontal tissue reactions were observed at various time intervals. The results were as follows; l. Cementum deposition on the perforated root surface in Group II cases showed slightly earlier than that of Group I. Healing tendency of injured alveolar bone in Group II was greater than that of Group I. 2. According to the time increase after experiment, the cementum deposition on the site of perforated dentin in Group II with intact pulp was notably thickened. Secondary dentin deposition on the root canal surface where the dentinal tubles were cut was also found in similar pattern. 3. In the cases of perforated canals sealed with Calxyl both in Group I and Group II, It revealed the earliest cementum-deposition among 4 different root canal cements. In the cases of perforated canals sealed with Kerr sealer and AH26, the cementum-deposition on the root surface was not found. 4. Proliferation of epithelium around the perforated area was first seen at 5-week cases in Group I, and at 3-week cases in Group II. 5. In all cases, dentin resorption on the site of perforated root surface was always occured.

• Restorative Dentistry and Endodontics
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• v.38 no.3
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• pp.172-177
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• 2013

The mesiobuccal root of the maxillary molars is well known to pose a hindrance during endodontic therapy. Presented here is a case of a maxillary left second molar where three canals were located in its mesiobuccal root with the use of visual and diagnostic aids. Difficulties encountered during the process of unveiling the tooth's internal anatomy were discussed. The dilemmas encountered pertained to the root canal configuration, the nomenclature of the extra canals, and the justification for the presence of a third canal. The root canal configuration of 3-2-1 was confirmed for the mesiobuccal root using information gained from clinical, radiographic, and multidetector computed tomography (MDCT) scan findings. This case demonstrates the need for efforts to locate extra canals in the mesiobuccal root of the maxillary molars as their internal anatomy remains a mystery.

• Restorative Dentistry and Endodontics
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• v.39 no.4
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• pp.258-264
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• 2014

Objectives: This in vitro study aimed to investigate the ability of Candida albicans (C. albicans) and Enterococcus faecalis (E. faecalis) to penetrate dentinal tubules of instrumented and retreated root canal surface of split human teeth. Materials and Methods: Sixty intact extracted human single-rooted teeth were divided into 4 groups, negative control, positive control without canal instrumentation, instrumented, and retreated. Root canals in the instrumented group were enlarged with endodontic instruments, while root canals in the retreated group were enlarged, filled, and then removed the canal filling materials. The teeth were split longitudinally after canal preparation in 3 groups except the negative control group. The teeth were inoculated with both microorganisms separately and in combination. Teeth specimens were examined by scanning electron microscopy (SEM), and the depth of penetration into the dentinal tubules was assessed using the SMILE view software (JEOL Ltd). Results: Penetration of C. albicans and E. faecalis into the dentinal tubules was observed in all 3 groups, although penetration was partially restricted by dentin debris of tubules in the instrumented group and remnants of canal filling materials in the retreated group. In all 3 groups, E. faecalis penetrated deeper into the dentinal tubules by way of cell division than C. albicans which built colonies and penetrated by means of hyphae. Conclusions: Microorganisms can easily penetrate dentinal tubules of root canals with different appearance based on the microorganism size and status of dentinal tubules.

• Restorative Dentistry and Endodontics
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• v.17 no.1
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• pp.55-68
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• 1992

Periapical lesions are developed as a result of inflammatory response to irritants from root canal system. Clinicians remove these irritants from root canal system and seal the root canal space to induce healing of the periapical lesions. Immunopathologic responses may play an important role in development and progression of periapical lesions and periapical lesions contain immunocompetent cells. The purposes of the present study were to analys and to compare the distribution of the immunocompetent cells in the human periapical lesions according to the stage of endodontic treatment using indirect immunoperoxdase technique. Obtained 94 human periapical lesions were devided into four groups: Group 1 : no endodontic treatment(28 samples) Group 2 : root canal enlarged and irrigated(28 samples) Group 3 : root canal filled(29 samples) Group 4: unknown(9 samples) Monoclonal antibodies to examine target cells were UCHL-1 for T lymphocytes(1 : 200, Dakopatt, Denmark), L26 for B lymphocytes(1 : 200, Dakopatt, Denmark), OPD4 for helper T lymphocytes(l : 200, Dakopatt, Denmark) and alpha-1-antichymotrypsin for macrophages(l : 2000, Dakopatt, Denmark). The following results were obtained : 1. All the periapical lesions studied were infiltrated by T lymphocytes, plasma cells, B lymphocytes, and macrophages. T lymphocytes were more infiltrated than B lymphocytes, and B lymphocytes and macrophages were less infiltrated than T lymphocytes and plasma cells(P<0.05 : Oneway ANOVA test). 2. In untreated group and canal irrigated and enlarged group of all the periapical lesions, helper T lymphocytes were predominently infiltrated(P>0.05 : Oneway ANOVA test). 3. In canal filled groups of all lesions except periapical cyst, plasma cells were predominently infiltrated. But, in canal filled group of periapical cyst, helper T lymphocytes were the predominent cells(P>0.05 : Oneway ANOVA test). The above results shows that the immunologic responses play important role in pathogenesis of periapical lesions and the immunologic response involved undergoes certain changes after endodontic therapy.

• Restorative Dentistry and Endodontics
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• v.9 no.1
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• pp.107-114
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• 1983

The purpose of this study was to observe the effect of cleansing action of irrigation solutions which was 3% $H_2O_2$ and 5% NaOCl, and 15% EDTA solution on the root canal wall. After treatment with the irrigant, each sample was dehydrated, and coated with 200~250${\circ}$A of gold, and observations were made with the use of scanning electron microscope. The results were as follows: 1. In the root canal walls irrigated with 3% $H_2O_2$ and 5% NaOCl solution without instrumentation after extirpation through barbed broach, the predentin of root canal wall was found scarely affected, and the wall was shown retaining network structure and fibrous organic matters. 2. When 15% EDTA was applied as irrigants for 60, 90 and 120 seconds after instrumentation, there was no signigicant difference of the cleansing effect of the elapsed times which were 90 and 120 seconds on the root canal wall, but in the applied time which was 120 seconds, the canal wall was the cleanest. Therefore it was thought that the most suitable application time of 15% EDTA as the irigants was 120 seconds.

• Journal of the korean academy of Pediatric Dentistry
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• v.43 no.4
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• pp.467-472
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• 2016

Successful root canal treatment can be obtained by the removal of microorganisms from the pulpal space of the root canal system through biomechanical technique with instruments and irrigation. Due to the difference in the dimension of the pulpal structure such as thin wall of the root, large portion of chamber, the primary teeth should be considered in a different way of approach. Traditionally, fluids have been dispensed passively into the root canals for improve the cleansing. The use of sodium hypochlorite as an irrigant in root canal treatment is widespread and common, because it meets requirements for the ideal irrigants.

• Journal of Korean Dental Science
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• v.2 no.1
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• pp.11-18
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• 2009

The purpose of this study was to investigate the possibility to reduce the toxicity of oil based root canal sealers containing calcium hydroxide using MTT & agar overlay assays. Thus some formulations of traditional root canal sealers were replaced with oil-soluble solvents and experimental root canal sealers manufactured. In MTT assay, Cell viability of all experimental sealers in addition with oil soluble solvents were observed significantly higher than both control groups, especially according to replace zinc and/or calcium ion components. Also agar overlay assay was appeared moderate to no cell responses into modifying both zinc and/or calcium ion components and oil soluble solvent weight. Authors found the reducing effect of cell toxicity through significant role of oil soluble solvent factor into root canal sealer containing calcium hydroxide.

• Journal of the Korean Society of Visualization
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• v.14 no.1
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• pp.40-45
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• 2016

Elimination of the smear layer and bacteria in the root canal is the most important in the endodontic treatment, and various irrigation devices have been developed. Nevertheless, it is hard to eliminate the smear layer and bacteria completely. In this paper, a micro bubble irrigation system has been developed for the root canal cleaning of tooth. Micro bubbles are generated when pressurized fluids passing through a porous material inside a hand-piece nozzle, and the bubbly flows excited by ultrasonic vibration are observed using a high-speed camera and a microscope. The results show that the diameter and number of bubbles increases with the applied pressure, and there found an optimum excitation frequency in order to minimize the bubble size. From in-vitro tests, it is also verified that the developed bubble irrigation system has the ability of antibacterial and infection removal. Thus, this biocompatible system would be well suited for root canal cleaning.

• Restorative Dentistry and Endodontics
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• v.14 no.1
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• pp.161-171
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• 1989

The purpose of this study was to evaluate and compare the sealing ability of ZOE, FR and Sealapex, as a root canal sealer. Ninety six extracted anterior or premolar human teeth with single root were instrumented by using conventional method. After instrumentation, the teeth were divided into three groups and thirty two teeth in each group were filled as follows: ZOE group: ZOE cement as a root canal sealer in combination with guttapercha cone FR group: FR root canal sealer in combination with guttapercha cone Sealapex group: Sealapex root canal sealer in combination with guttapercha cone $^{45}Ca$ in the form of calcium chloride, was employed as the tracer in this study and produce the auto-radiograph. The depth of isotope penetration into the root canal was evaluated by method by Yates and Hembree at the intervals of 1 day, 7 days, 14 days and 30 days. The following conclusions were derived from the results obtained; 1. After 1 day, ZOE group exhibited the greatest penetration degree of radioisotope (p < 0.05). 2. After 14 days, there was some difference of the radioisotope penetration between each group, but its difference was not significant statistically. 3. After 30 days Sealapex group exhibited the least penetration degree of radioisotope (p < 0.025). 4. In ZOE and Sealapex groups, there was no change of the degree of radioisotope penetration with time.

• Restorative Dentistry and Endodontics
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• v.17 no.2
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• pp.365-382
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• 1992

The purpose of this study was to evaluate the adaptation of filling material to the dentinal walls of root canals with and without smear layer. Fifty extracted upper and lower anterior teeth were selected, and the root canals were instrumented with K - files 1mm short of the apical foramen by step - back method. The teeth were randomly divided into two groups of 25 each : in the group I, smear layers were not removed, and in the group II, smear layers were removed by 15% EDTA solution. Again the two groups 25 teeth were randomly divided into unfilled contol group and filling groups(lateral, ultrasonic, ULTRAFIL, McSpadden compaction group). Upon completion of root canal filling, the teeth were grooved on the both the labial and lingual surfaces and then split with mallet and chisel. Each specimens were examined with JSM - 840 Scanning Electron Microscope (JEOL., Japan). The results were as follows : 1. In the contol group, dentinal tubules of group I couldn't be distinguished in the canal wall, but those of group II appeared to be open and patent. 2. In the filling groups of group I, the tubular penetration of the sealer or gutta percha couldn't be seen, but in the filling groups of group II, it could be seen except McSpadden compaction group. 3. In the filling groups, ULTRAFIL group showed the best adaptation of filling material to root canal wall among the group I, and lateral and ultrasonic condensation group showed the best adaptation of filling material among the group II. McSpadden compaction group showed the worst adaptation in group I, II. 4. Generally, the group II showed better adapation of filling material to root canal wall than the group I.