• Restorative Dentistry and Endodontics
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• v.19 no.2
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• pp.499-512
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• 1994

The purpose of this study was to evaluate the microleakage electrochemically using different retrograde filling materials, different root resection angle, and different cavity preparation instruments. 104 extracted single-rooted teeth were selected for this study. 100 teeth were used as experimental groups and four was used as controls. Anatomical crowns were resected, root canals were prepared, and the apical 2 mm of roots were removed. The experimental roots were randomly divided into five equal groups. Experimental groups : Group 1. no bevel, cavity preparation with ultrasonic instruments, amalgam filling Group 2. no bevel, cavity preparation with ultrasonic instruments, SuperEBA cement filling Group 3. no bevel, cavity preparation with ultrasonic instruments, desiccated ZOE filling Group 4. $45^{\circ}$ bevel, cavity preparation with ultrasonic instruments, amalgam filling Group 5. no bevel, cavity preparation with conventional bur, amalgam filling Microleakage was measured once a day for 30 days using electrochemical method and were analyzed statistically. The results were as follows : 1. The group with Super EBA cement filling showed the least marginal leakage from second to fourth day(p<0.05), there was no significant difference between the group with amalgam filling during eighth to eighteenth day(p>0.05), but after the nineteenth day here was a higher marginal leakage than the group with amalgam filling(p<0.05). 2. The group with desiccated ZOE filling demostrated that the highest marginal leakage, started on the eighth day(p<0.05). 3. The group using ultrasonic instrument showed lower marginal leakage than the group using bur until the nineteenth day(p<0.05), but there was no significant differnce with the group using bur after twentythird day(p>0.05). 4. The group without bevel showed lower marginal leakage than the group with bevel (p<0.05). 5. Whether bevel or nor had much more effect on marginal leakage than with cavity perparation instrument when the cavity was retrogrdefilled with amalgam(stepwise regression).

• Restorative Dentistry and Endodontics
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• v.18 no.1
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• pp.205-213
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• 1993

The purpose of the study was to evaluate the degree of the marginal leakage of esthetic restorative materials on root caries restoration. 120 cavities were prepared to $90^{\circ}$ butt joint on all margins on the crown and root portion, and divided into 4 groups. The four groups of cavity were filled with Amalgam(Dongmuyung Dental Alloy Co., Ltd, KOREA), Silux$^{(R)}$(3M Co., USA)-Scotch Bond 2$^{(R)}$(3M Co., USA), Silux$^{(R)}$-All Bond$^{(R)}$(BISCO USA), and GC Fuji II$^{(R)}$(G-C Co., JAPAN) respectively. The apical margin of the preparation was finished to leave a flash of restorative material. The coronal margin of the preparation was finished not to leave a flash of restorative material. All specimens were sectioned longitudinally with Isomet Low speed saw(Buether Ltd, USA). The degree of dye penetration was evaluated as the parameter of marginal leakage under the stereoscope. The results were as follows. 1. At the enamel and dentin/cementum margins, the margin were finished to leave a flash of material showed less marginal leakage than that were finished not to leave a flash of material (P<0.001). 2. The enamel margins showed less marginal leakage than the dentin/cementum margins(P<0.001). 3. There was no significant difference in the degree of the marginal leakage between Silux$^{(R)}$-Scotch Bond 2$^{(R)}$ group and Silux$^{(R)}$-All Bond$^{(R)}$ group.

• Restorative Dentistry and Endodontics
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• v.33 no.1
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• pp.66-75
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• 2008

This study examined the influence of the apical sizes on the sealing ability of a root canal filling. Thirty-six single rooted teeth with a single canal were divided into 3 groups (n = 12) and instrumented with either the $Profile^{(R)}$ or $LightSpeed^{(R)}$ system to achieve three different apical sizes (master apical file [MAF] of #25, #40, or #60). The teeth were filled with gutta perch a using a modified continuous wave technique. The level of microleakage was determined by immersing ten teeth from each group into India ink for 1 week followed by clearing with nitric acid, ethyl-alcohol, and methylsalicylate. The microleakage was measured using vernier calipers. The data was analyzed statistically using Kruskal-Wallis one-way ANOVA and a Student-Newman-Keuls Method. Two teeth from each group were sectioned horizontally at 1, 2, 3 and 4 mm from the apex in order to observe a cross section. The apical size was significantly (p < .05) influenced the level of microleakage. In the Student-Newman-Deuls Method, MAF sizes of #25 and #40; and MAF sizes of #25 and #60, respectively showed a statistically significant difference. There was no significant difference between #40 and #60. In most cross sections, oval-shaped canals were observed, and the irregularity of the internal surface increased with decreasing apical size. There was also an increase in the area of recess, which is the area where the canal space is not filled with either gutta-percha or sealer. When the root canals are filled using a modified continuous wave technique, canal filling with more consistent and predictable outcome may be expected as the apical preparation size is increased.

• Restorative Dentistry and Endodontics
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• v.11 no.1
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• pp.27-32
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• 1985

The purpose of this study was to examine the influence of canal irrigants and smear layer on the property of apical seal. Fourty-five canals from human teeth were randomly selected and divided into 5 groups according to the irrigants used in conjunction with instrumentation. The irrigants were RC-prep in combination with Naocl, Citric acid, Naocl, Naocl in combination with $H_2O_2$, and normal saline solution. After instrumention and dry the canal with paper point, the canals were obturated by lateral condensation of Zinc-oxide eugenol sealer and gutta percha cone. All the specimens were immersed in 2% methylene blue dye solution for 7 days and the depth of dye penetration into the canals was evaluated by macros cope. The following results were obtained. 1. All the canals experimented showed varying degree of dye penetration. 2. There was no significant difference in depth of dye penetration between the groups known to be effective and ineffective in the removal of the smear layer. 3. The canals irrigated with NaOCl alone showed the highest dye penetration and mean leakage was 7.7 mm. 4. In the canals irrigated with RC-prep in combination with Naocl and citric acid, the mean dye penetration was 5.5 mm and 4.8 mm respectively, and the canals irrigated with NaOCl in combination with $H_2O_2$ and normal saline solution revealed mean dye penetration of 3.9 mm.

• Restorative Dentistry and Endodontics
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• v.21 no.2
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• pp.628-634
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• 1996

The purpose of this study was to investigate the effect of moisture on apical sealing properties of root canal. Fifty five single rooted human teeth were selected from maxillary and mandibular teeth. After removing crown portion at the cemento-enamel junction, all teeth were routinely prepared with step-back method. And then, the canals were dried with paper point and the teeth were randomly divided into 3 groups of 15 teeth each, and remaining 10 teeth were used as positive and negative control teeth : Group 1 were irrigated with 1ml of 95% alcohol and dried with air and paper point. Group 2 and 3 were intentionally contaminated with 0.05ml of 3.5% NaOCl or saliva, respectively. All the teeth were obturated with sealapex and gutta percha cone by lateral condensation technique, and covered with two coat of nail varnish after 48 hours of obturation. The teeth were immersed in india ink for 1 week and cleaned with methyl salicylate and then the degree of dye penetration were measured with stereomicroscope. The data were analyzed statistically by one-way ANOVA. The results were as follows : 1. All experimental groups showed varying degrees of dye penetration, and the mean degree of dye penetration was 0.1mm to 0.7mm. 2. Saliva contamination group(group 3) showed the highest amount of dye penetration, followed by NaOCl contamination group, then alcohol dried group, but there was no significant difference among three experimental groups. * This results suggest that there was no significant differences of apical leakage after canal obturation between alcohol dried canal and moisture present canals and the use of alcohol instead of paper point is unnecessary to dry the canals prior to canal filling. But other factors such as bacterial contamination and sealer discoloration by moisture must be considered in application of this results to clinical practice.

• Restorative Dentistry and Endodontics
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• v.30 no.1
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• pp.7-15
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• 2005

The purpose of this study was to compare the sealing ability of root canal obturation with or without the use of dentin adhesive system. Forty extracted human teeth with one canal were selected and decoronated. The teeth were divided into two Groups. The obturation procedure of Group 1 was the same as that of Group 2 with the exception of dentin adhesive system. Group 2 were obturated with dentin adhesive system, AH-26, and gutta-percha. After obturation, the teeth were immersed in methylene blue solution for 84 hours. The teeth were sectioned horizontally at 1.5 mm (Level 1), 2.0 mm (Level 2) 2.5 mm (Level 3) from the root apex using a low speed microtome. Distance of dye-penetrated surface and total dentinal surface were measured using SigmaScan Pro 5.0, and the ratio of dye-penetrated distance to the total dentinal distance was analyzed statistically by Mann-Whitney U-test. 1. In both groups, the mean leakage ratio was decreased cervically. 2. At level 1, there was no significant difference between group 1 and group 2 (p > 0.05). 3. At level 2 and 3, group 1 showed significantly higher mean leakage ratio than group 2 (p < 0.05). The results suggest that using dentin adhesive system in root canal obturation procedure reduces the apical microleakage.

• Restorative Dentistry and Endodontics
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• v.25 no.3
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• pp.381-389
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• 2000

Lateral condensation with gutta-percha and sealer has been shown to provide an excellent apical seal; however, the lateral condensation technique has demonstrated less favorable apical leakage results in curved canals when compared with straight canals. Placement of endodontic spreaders to within 1 to 2mm of the root canal working length has been advocated for optimum gutta-percha obturation. Due to their stiffness, stainless-steel(SS) spreaders will often fail to achieve this position in curved canals. Newly marketed nickel-titanium(NT) spreaders may offer an advantage in this regard due to the increased flexibility of these instruments. The purpose of this study was to evaluate the effect of NT finger spreader on the sealing ability in lateral condensation technique, compared with conventional SS finger spreader. Twenty four standardized resin models simulating curved canals(30 degree) were randomly placed into 2 groups and instrumented to a #30 master apical file size with Ni-Ti Profile .04 taper series using step down technique. Each groups was obturated with standardized gutta-percha cone by standard lateral condensation technique using SS finger spreader, NT finger spreader. And then, each model was sectioned horizontally with microtome at 1, 2, 3, 4, 5mm levels from the apex. At each of 5 levels, ratio of the area of gutta-percha was obtained by calculating the area of gutta-percha to the total area of the canal. The data collected were then analyzed statistically using a t test for independent samples. The results as follows ; 1. The total mean ratio of area of gutta-percha was 89.20${\pm}$7.00(%) for SS spreader group. 92.20${\pm}$5.17(%) for NT spreader group. There was statistically significant difference between each group(p<0.05). 2. At 3mm level, the mean ratio of area of gutta-percha was 88.32${\pm}$5.41(%) for SS spreader group, 95.25${\pm}$2.60(%) for NT spreader group. There was statistically significant difference between each group(p<0.05). At 1,2,4mm levels, NT spreader group showed greater mean ratio of area of gutta-percha than SS spreader group, too. But there was no statistically significant difference. 3. At 5mm level, the mean ratio of area of gutta-percha was 91.83${\pm}$3.42(%) for SS spreader group, 87.91${\pm}$3.68(%) for NT spreader group. There was statistically significant difference between each group(p<0.05). This study concluded that the NT spreader demonstrated somewhat favorable apical sealing effect than SS spreader in prepared curved canals. The clinical use of NT spreaders may enhance our ability to create better apical seals in curved canals, but further studies in this area will help clarify some of the remaining areas with which practitioners are concerned, such as compaction forces exerted by NT spreaders.

• Journal of Chest Surgery
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• v.37 no.2
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• pp.166-172
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• 2004

When compare with blebectomy or bullaectomy simply and pleurodesis together in treatment of primary spontaneous pnevmthorax, the later has been realized as the method that can reduce the recurrent rate after surgical operation. Therefore, in this study, we compared the merits and demerits of the clinical result of chemical pleurodesis that use Talcum powder in pleurodesis and mechanical pleurodesis that use apical pleurectomy and analyzed the reappearance rate etc. Material and Method: The Pleurodesis through the apical pleurectomy and talc powder insufflation had been used as secondary procedure after blebectomy of spontaneous pneumothorax from January 1, 2000 to June 30, 2002. This study consisted of a retrospective review of 68 patients who were treated with apical pleurectomy, and 84 patients treated with talc powder insufflation. We compaired the apical pleurectomy and talc powder insufflation in terms of age, sex, cause of operation, number of used autosuture staple, tine duration of procedure after blebectomy, severity of pain and complication after operation, postoperative air leakage period, duration of chest tube insertion, hospitalization, and recurrence rate of pneumothorax. Result: Time required for secondary procedure was longer in apical pleurectomy than talc powder insufflation. Postoperative pain was more severe in talc powder insufflation than apical pleurectomy. Otherwise there was no significant difference between two methods. Conclusion: Although Talc powder insufflation is more convenient than apical pleurectomy, the difference is not large and, the severity of postoperative pain is worse in talc powder insufflation. Therefore apical pleurectomy can be recommended for the secondary surgical procedure after blebectomy of primary spontaneous pneumothorax can be recommended.

• Restorative Dentistry and Endodontics
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• v.25 no.4
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• pp.527-535
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• 2000

The purpose of this study was to evaluate effects of smear layer and dentin primers on the sealing ability of root canals. 126 extracted human teeth with single, straight canals and mature apices were used. The Samples were first classified into six groups as follows: presence of smear layer; absence of smear layer; Scotchbond Bond Multi-Purpose; All Bond 2; Mac Bond 2; Clearfil Liner Bond 2. A Positive control was also established. All teeth except the control group were then obturated with thermoplasticized gutta-percha and AH26. Electrochemical and dye penetration technique were later used to evaluate the degree of micro leakage through the root canal. Seventy teeth were then immersed in a 1% potassium chloride solution and An external power supply(DC 10 V) was then applied to the circuit for the electrochemical microleakage test. The degree of Microleakage was determined over period of 28 days before being evaluated. In total, 48 teeth were submitted to the dye infiltration technique. All specimen were suspended in 2% methylene blue dye for 1 week before being longitudinally split. The degree of dye infiltration was measured under a stereo microscope at ${\times}10$ magnification and evaluated. The results were as follows: 1. Apical microleakage increased throughout the test period in all group and one group having a smear layer showed a dramatic increase under electrochemical test (p<0.05). In the group having smear layer, the degree of apical microleakage was the highest, and the micro leakage was much higher than in the smear layer removed group in electrochemical test (p<0.05). Scotchbond Multi-Purpose, All Bond 2, Mac Bond 2 and Clearfil Liner Bond 2 showed lower micro leakage than one group having smear layer. The All Bond 2 and Clearfil Liner Bond 2 treated groups showed the lowest microleakage in electrochemical test (p<0.05). 2. There was no significant difference between the experimental groups in dye penetration technique. These results suggested that the removal of the smear layer from root canal and concomitantly the application of dentin primer into root canal could improve the sealing ability of root canal obturation.

• Restorative Dentistry and Endodontics
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• v.17 no.2
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• pp.343-354
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• 1992

The purpose of this study was to analyze the relationship between linear and volumetric measurements of apical dye penetration in canals obturated by various kinds of methods. The canals of 108 roots without crown were conventionally prepared and randomly assigned to four group. The canals of group I a2 were obturated by lateral condensation with sealer, group II a2 by thermoplasticized low-temperature ($70^{\circ}C$) gutta-percha with sealer, group III by Thermafil endodntic obturation with sealer and group IV by injection-molded thermop-lasticized guttapercha One mm of root apex was exposed to a 2 % methylene blue solution at $7^{\circ}C$or 10 days, and the quality of apical seals was assessed by measuring the leakage linearly and volumetrically. The obtained results were as follows: In linear measurements, group II showed significanty less leakage than group III, I and group III also showed less than group N, but no statistically significant difference was demonstrated between the others. In volumetric measurements, group II showed significantly less leakage than group I and II, and no significant differnce from group III. There was a weak significant correlation between the linear measurement and the volumetric measurement(r=0.3391, P<0.001).