• Restorative Dentistry and Endodontics
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• 제17권2호
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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.

• Restorative Dentistry and Endodontics
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• 제24권2호
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• pp.356-363
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• 1999

The purpose of this study was to compare the apical sealing effect of Microseal obturation technique with lateral condensation technique in 26 recently extracted single rooted teeth. The root canals were instrumented using step-back technique and obturated with laterally condensed gutta-percha or Microseal. Teeth were suspended in methylene blue dye for 2 days and then longitudinary splited. The apical microleakage and the adaptability of gutta-percha to the root canal wall were examined under a stereomicroscope at ${\times}20$ magnification. The results were as follows: 1. The mean leakage was 1.38${\pm}$1.18 mm for laterally condensed gutta-percha group, and 0.71${\pm}$0.57 mm for Microseal gutta-percha group. But there was no statistical difference between two groups. 2. In Microseal gutta-percha group, they showed no gap between the master cone and Microseal gutta-percha, and showed homogeneous mass. 3. In contrast, laterally condensed gutta-percha group showed some gaps not only between gutta-percha cones, but also between gutta-percha cones and the canal walls, and the gaps were filled with some sealer. And also this group showed some amout of sealer on the root canal walls, Within the limits of the results of this experiment, Microseal gutta-percha obturation technique demonstrated relatively favorable apical sealing effect and shorter obturation time. Thus, it is thought that this obturation technique is a acceptable method for clinical use but further studies on this matter should be conducted.

• Restorative Dentistry and Endodontics
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• 제20권2호
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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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• 제18권1호
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• pp.156-172
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• 1993

The purpose of this study was to evaluate for the cytotoxicity of root canal sealers - Tubliseal, N2, AH26, and Sealapex - on fibroblasts cultivated from human periodontal ligament. Succinate dehydrogenase activity test and $^{51}Cr$ release test were performed to evaluate the shortterm cytotoxicity. According to l,3 and 6 days vital cell count and $^{14}C$-leucine incorporation rate to fibroblasts were evaluated. The results of this study were as follows: 1. In the test of SDH activity by millipore filter method, Sealapex showed mild cytotoxicity but Tubliseal, N2 and AH26 showed severe cytotoxicity. 2. In $^{51}Cr$ release test, Tubliseal was the most cytotoxic sealer tested, and rank ordered the relative cytotoxicity of the other sealers tested as follows: AH26, N2, Sealapex. 3. In the test of viable cell count, cytotoxicity in Tubliseal was continued because vital cell number reduced with time. Because vital cell was not showed in N2 and AH26 at 1 day, it was recognized that N2 and AH26 exhibited severe cytotoxicity. In Sealapex, vital cell number increased remarkably with time, so it showed that cytotoxicity decreased with time. 4. In $^{14}C$-leucine incorporation rate test, protein sythesis was not produced in Tubliseal, N2 and AH26 after 3 days, it showed that cytotoxicity in Tubliseal, N2 and AH26 was severe. Although protein synthesis in Sealapex decreased with time, it continued after 6 days. Therefore Sealapex has been exhibited mild cytotoxicity.

• Restorative Dentistry and Endodontics
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• 제18권1호
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• pp.133-143
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• 1993

The aim of this study was to establish reproducible method for measurements of radiopacity and to investigate the level of radiopacity of root canal sealers. The experiments were performed in two parts. In the first part, densitometric readings were performed using an aluminum step wedge as a reference at variable voltages and exposure times. Then standard curves for the aluminum step wedge were compared to comprehend the effect of voltage and exposure time. In the second part, on the basis of these results, appropriate conditions for exposure were adopted for standardized measurements of radiopacity. Under standardized set of conditions, densitometric measurements of ten root canal sealers and one gutta-percha point were performed and the levels of radiopacity referable to an equivalent thickness of aluminum were compared. The following results were obtained : 1. At 50 and 60 kVp, increasing the exposure time caused a decrease in the slope of the standard curve for the aluminum step wedge. However, at 70 kVp increasing the exposure time causing a parallel shift of the standard curve to the right. 2. At constant exposure time, increasing the voltage caused a decrease in the slope of the standard curve. 3. The radiopacity of root canal sealers and a gutta-percha point varied between 2.43 mm Al and 9.20 mm Al equivalent. 4. All the root canal sealers had radiopacities more than dentin, and the radiopacity of the gutta-percha point was approximately 5 times as much as that of dentin in terms of equivalent thickness of aluminum. 5. The AH26 had radiopacity more than the gutta-percha point, and the radiopacities of ZOE, Vitapex, Canals, Kerr PCS, Nogenol were similar to that of the gutta-percha point, and Tubliseal, Apatite II, Apatite III, Silapex were less radiopaque than the gutta-percha point.

• Restorative Dentistry and Endodontics
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• 제12권2호
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• pp.65-72
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• 1987

The purpose of this study was to examine the influence of several root canal sealers on the discoloration of internal surface after root canal obstruction. Twenty four sound human premolars, extracted for orthodontic or prosthodontic purposes, were randomly selected and divided into eight groups. Extracted premolars were prepared, and the following seven materials were introduced into the pulp cavities: AH 26, Fuji ionomer (Type I) cement, N2, Oxypara "Murakami", Kerr sealer, PCA sealer, and G-C's Propac ZOE cement. After 7 weeks of incubation; the discolored tooth crowns were hemisectioned, and the internal staining patterns were examined. Then, with an association of observed values the mean intensity scores and percentage of coverage scores of the internal staining patterns in teeth attained by two observers using for Chisquare test were analyzed. The results were as follows: 1. All the experimental premolar's crown showed various ranged discoloration of internal surface. 2. There was no significance between the association scores of two observers participated into this experiments:% coverage scores (P > 0.05) and intensity (P > 0.05) 3. The crowns filled with PCA sealer, AH 26, and Fuji ionomer cement was visible within a depth of one third of dentin. (P> 0.05) 4. For N2, Kerr sealer, and G-C's Propac cement, A slight dentinal staining was recorded, which penetrated up to half way into the dentin. (P> 0.05) 5. It was noticed that the teeth filled with Oxypara "Murakami" were discolored more than two thirds of the dentinal layer. 6. On the control group, there was no discoloration.

• Restorative Dentistry and Endodontics
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• 제23권1호
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• pp.346-356
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• 1998

The purpose of this study was to evaluate the sealing ability of various canal filling methods. Palatal roots of ninety extracted human maxillary molar teeth were resected at cementoenamel junction. Eighty of them were randomly assigned to four experimental groups, ten were served as positive and negative controls. All canals were prepared to # 40 using Profile. Experimental groups were obturated by lateral condensation technique, Thermafil technique, Continuous Wave of Condensation Technique, and down-pack & back-fill technique of Obtura-II, each with root canal sealer. Control groups 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 then ground horizontally at 1.5mm(level 1), 2.5mm(level 2), 3.5 mm(level 3) from the anatomical apex and examined with a stereomicroscope at ${\times}40$ magnification. The gap between the canal wall and the filling material, which was filled with the resin, was measured at each of the three levels. Each ratio of leakage was obtained by calculating the ratio of the area of the resin to the total area of the canal and was analyzed statistically (Rank-sum test). The results were as follows : 1. At the level 1, there was the greatest leakage in the Thermafil group and Obtura-II group, and the difference between the Obtura-II group and Continuous Wave of Condensation Technique group was statistically significant(p<0.05). 2. At the level 2, there was the least leakage in the Continuous Wave of Condensation Technique group, but there was no statistically significant difference between each group (p>0.05). 3. At the level 3, there was no statistically significant difference between each group(p>0.05).

• Restorative Dentistry and Endodontics
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• 제21권2호
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• pp.517-529
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• 1996

The purpose of this study was to evaluate the apical sealing ability of the Thermafil endodontic obturation technique and to compare it with lateral condensation technique. 42 straight canals from extracted human anterior teeth and 42 curved canals(> $25^{\circ}$) from maxillary and mandibular molar teeth were selected. And 80 of them were divided into four groups, 20 canals respectively. The teeth in prior two groups had straight canals and the other two groups had curved canals. The rest of four canals served as positive and negative controls. After resecting anatomical crowns, all canals were prepared using a standard step-back technique. Lateral condensation was used to obturate two groups, one group of straight ones the other curved. And Thermafil obturators were also used in the same two groups. Obturated teeth were infiltrated by India ink for a week, decalcified and cleared with 5% nitric acid and methyl salicylate. The apical leakage and the frequency of filled lateral and accessory canals were measured with stereomicroscope and also apical extrusion of sealer and gutta-percha and obturation time were checked and the data were analyzed statistically(one-way ANOVA, t-test, Chi-square test). The results were as follows : 1. There was no significant difference in the degree of dye penetration between Thermafil and lateral condensation groups(p>0.05). 2. Apical extrusion of sealer and gutta-percha occurred significantly more often with Thermafil obturators in straight canals(p<0.05), but not significantly different in curved canals(p>0.05). 3. Canal obturation time with Thermafil obturators was significantly faster than lateral condensation (p<0.05). 4. The Thermafil groups showed a higher frequency of filled lateral and accessory canals than in the lateral condensation groups. But the difference was not statistically significant (p>0.05).

• Restorative Dentistry and Endodontics
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• 제21권2호
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• pp.677-687
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• 1996

This study was conducted to evaluate the tissue responses histologically to three root canal cements : Sealapex, AH-26, and zinc oxide-eugenol cement. Twelve white female Sprague-Dawley rats, weighing between 350 and 400 gm, were anesthetized with an intraperitoneal injection of Ketamine hydrochloride(0.4 ml). After shaving the sites selected(left and right scapular areas, left and right pelvic areas), the animal's backs were scrubed with soap and water, and sterilized with absolute alcohol. Each material was mixed to a thin consistency to flow out easily through a 24-guage needle, and loaded into a sterile, disposable plastic 1-ml syringe. All of the rats were injected subcutaneously with 0.1 ml of the three test sealers. Normal saline was used as a control. Animals were sacrificed after 48hr, 1, 4, and 12 weeks by overanesthetization using jars containing anesthetic ether. The tested sites were surgically removed with the surrounding tissue and fixed with 10% formalin. After 48 hours specimens were embedded in paraffin, sectioned to an average thickness of $6{\mu}m$ thick, stained with hematoxylin-eosin. The slides were examined under the light microscope. The results were obtained as follows 1. All material except the control showed various degree of inflammation on 48 hr. 2. Sealapex : In early stage, severe inflammatory cell infiltration was observed. At the 4th weeks observation, graunlomatous tissue with macrophage and foreing body giant cells containing many dark particles in their cytoplasm was observed. 3. AH-26 : Mild inflammatoy reaction was observed with AH-26 throughout the experimental period. 4. Zinc oxide-eugenol cement : Severe inflammatory cell infiltration, necrosis along the material, edema could be seen in early stage. Zinc oxide-eugenol cement maintained a moderate/severe reaction throughout the experimental period.

• 대한소아치과학회지
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• 제28권2호
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• pp.207-218
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• 2001

본 실험은 수산화칼슘계 근관 충전제가 파골 세포의 분화 및 활성에 미치는 직접적인 억제 효과의 유무를 고찰하고자 chick embryo tibia의 골수로부터 추출한 파골 세포의 전구세포와 0.1, 0.01, $0.05{\mu}g/ml$로 희석된 네가지 실험 물질인 $Ca(OH)_2$ powder, Vitapex$^{(R)}$, Metapaste$^{(R)}$, pulpdent$^{(R)}$를 사용하였다. 파골세포의 분화 및 활성에 미치는 억제 효과를 관찰하고자 분화된 파골 세포의 수와 흡수와 면적이 측정되고 이들 약제의 효과가 세포독성에 의한 결과인지를 알아보고자 U2OS 골아세포에 대한 MTT assay를 시행하여 다음과 같은 결론을 얻었다. 1. 파골세포의 분화에 대한 억제 효과는 다음과 같은 순서로 분화된 파골세포의 수가 통계학적으로 유의한 증가를 보였다.: Metapaste$^{(R)}$, $Ca(OH)_2$ powder, Vitapex$^{(R)}$. 하지만, 모든 농도에서 분화된 파골세포의 수가 증가한 pulpdent$^{(R)}$ 군에서는 통계학적으로 유의한 차이를 나타내지는 않았다. 2. 통계학적으로 분화된 파골세포 수의 감소가 유의한 결과를 나타낸 $0.1{\mu}g/ml$로 희석된 세가지 실험 물질인 $Ca(OH)_2$ powder, Vitapex$^{(R)}$, Metapaste$^{(R)}$ 가운데, Vitapex$^{(R)}$ 군만이 대조군에 비해 유의한 세포독성을 나타내고 다른 두 집단은 유의한 결과를 보이지 않았다. 또한, 0.2% DMSO군은 통계학적으로 유의한 세포독성을 나타내었다. 3. $0.1{\mu}g/ml$로 희석된 세가지 실험 물질인 $Ca(OH)_2$ powder, Vitapex$^{(R)}$, Metapaste$^{(R)}$과 대조군에서 흡수와의 양상과 면적을 관찰해 보면, $Ca(OH)_2$ powder군을 제외하고 대조군과 실험군사이에 유의한 차이를 나타내었고, 0.2% DMSO군도 통계학적으로 유의한 감소를 보였다. 이상의 결과를 볼때, 수산화칼슘은 파골 세포 분화 및 활성의 직접적인 억제 작용에 기인한 경조직 흡수의 억제에 관여하는 것으로 사료된다.