• Restorative Dentistry and Endodontics
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• v.9 no.1
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• pp.51-57
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• 1983

64 multi-rooted teeth (198 canals) were tested in vitro to evaluate the apical seal produced by the single cone filling and lateral condensation with sealer and without sealer. The obturated teeth were immersed in India ink, decalcified, and cleared. The degree of ink penetrated into the canal provided a measure of the apical seal. The results were as follows: 1. The lateral condensation with sealer provided statically less apical leakage than the other obturating techniques used in this study. 2. The single cone filling provided good apical sealing. 3. The lateral condensation without sealer provided most apical leakage than any other techniques used in this study. 4. The degree of apical leakage was not related to the visual appearence of the adaptation of the gutta percha filling in cleared teeth.

• The Journal of the Convergence on Culture Technology
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• v.8 no.2
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• pp.337-342
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• 2022

Although printing technology has recently been widely used in IT fields including displays and fuel cells, residual and thermal stress are generated by a manufacturing process of stacking the layers of the print head and result in the substrate deformation and nozzle plate crack, which may cause ink leaks or not be ejected onto a desired region. Therefore, in this paper, we propose a new design of thermal inkjet print head with a robust and reliable structure. Diverse types of inkjet print head such as a rib, pillar, support wall and individual feed hole are designed to reduce the deformation of the substrate and nozzle plate, and their feasibility is numerically investigated through FEA analysis. The numerical results show that the maximum stress and deformation of proposed print head dramatically drops to at least 40~50%, and it is confirmed that there is no nozzle plate cracks and ink leakage through the fabrication of pillar and support wall typed print head. Therefore, it is expected that the proposed head shape can be applied not only to ink ejection in the normal direction, but also to large-area printing technology.

• Restorative Dentistry and Endodontics
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• v.13 no.1
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• pp.113-120
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• 1988

The purpose of this study was to evaluate and compare the sealing ability of ZOE, FR and AH-26. Seventy two upper and lower anterior and premolor teeth were randomly selected and instrumented in a conventional method with K-file. After instrumentation and dry the canal, the teeth were divided into 3 groups and twenty four teeth in each group were filled with ZOE, FR, and AH-26 respectively. All the specimens were immersed into Indian Ink and decalcified in nitric acid and cleared in methyl salicylate. The apical leakage was evaluated by measuring the degree of ink penetration with caliper at the intervals of 1 day, 7 days and 14 days. The results were as follows; 1. In AH-26 and FR groups, there was increase in penetration related to increased time of immersion in the ink. 2. FR group showed the least penetration in 3 groups. 3. Statistics showed that there was no significant difference among the each sealer groups.

• Restorative Dentistry and Endodontics
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• v.20 no.2
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• pp.671-684
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• 1995

The purpose of this study was to compare the apical sealing ability, overfilling and obturation of lateral canals using two gutta-percha techniques: Thermafil obturators and cold lateral condensation. Eighty numbered epoxide blocks with one major and five lateral canals were divided into four experimental groups and obturated according to experimental groups. Four experimental groups were as follows: Group 1 : Filling with Thermafil plastic obturators and sealer(ThermaSeal) Group 2 : Filling with Thermafil plastic obturators only, without sealer(ThermaSeal) Group 3 : Fillng using lateral condensation with sealer(AH-26) Group 4 : Fillng using lateral condensation without sealer(AH-26) All the blocks were stored in 100% relative humidor at room temperature for 7 days. Each block was placed in centrifuge tube filled with India ink, and then centrifuged for 20 minutes at 3,000 rpm. Apical leakage was measured from the apical foramen to the most coronal level of dye penetration in millimeter under a stereoscope. The length of gutta-percha and sealer in each of the lateral canals was measured, too. The presence or absence of overfilling of gutta-percha and sealer was recorded. The data was analyzed by one-way ANOVA. The obtained results were as follows: l. Apical dye leakage was almost: not occurred in Group Willed with Thermafil and sealer) and Group 3(filled using lateral condensation with sealer), and there was no significant difference in linear leakage between two groups(p>0.01). 2. In both Thermafil and lateral condensation groups, linear leakage of Group I, 3(filled with sealer) was less than that of Group 2, 4(filled without sealer), and there was no significant difference in linear leakage between Group 1, 2, 3(p> 0.01). 3. Overfilling during obturation of Group 1, 2(filled with Thermafil) was more than Group 3, 4(filled using lateral condensation), and there was no significant difference between groups(p> 0.05). 4. Groups filled with Thermafil had significantly more gutta-percha than groups filled using lateral condensation in all lateral canals(p <0.01), the total length of gutta-percha and sealer found in all lateral canals were similar in Group 1 and Group 3.

• Restorative Dentistry and Endodontics
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• v.19 no.1
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• pp.205-216
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• 1994

The purpose of this study is to evaluate of apical plug materials for the contral of extrusion and sealing ability of high-temperature thermoplasticized gutta-percha in plastic root canal blocks. Seventy seven plastic blocks with canal preformed were instrumented with # 50K file 1 mm beyond apical foramen. Blocks were randomly divided into 5 groups of 15 blocks each. Group 1 was filled by high-temperature thermoplasticized gutta-percha only. The another 4 groups were placed with apical plug materials each other and then remaining space was back filled with high temperature thermoplasticized gutta-percha Apical plug materials were used as follows; Group 2: Thermoplasticized gutta-percha (Thermoplasticized gutta-percha group) Group 3 :. Calcium hydroxide powder (Calcium hydroxide group) Group 4 : Silver point (Silver point group) Group 5 : Gutta-percha cone softened by chloroform (Gutta-percha cone group) All the blocks were stored in 100 % relative humidor at room temperature for 14 days. Filling material extruded was removed carefully and then weighed in analytic balance. Each block was placed in centrifuge tube filled with India ink, and then centrifuged for 20 minutes at 3,000 rpm. Apical leakage was measured from the apical foramen to the most coronal level of dye leakage in millimeter by two examiners under a stereoscope. The data were analysed statistically by Student's t-test The obtained results were as follows; 1. The amounts of material extruded through the foramen decreased in all of groups used apical plug materials (P<0.01). 2. Silver point group and gutta-percha cone group were similar linear leakage to high-temperature thermoplasticised gutta-percha technique only (P>0..5). 3. Calcium hydroxide group and thermoplasticized gutta-percha group showed more liner leakage than high-temperature thermoplasticized gutta-percha only (P<0.01, P<0.05). 4. High-temperature thermoplasticized gutta-percha technique with silver point and gutta-percha cone as apical plugs showed less linear leakage and less extrusion of filling material.

• The Journal of Advanced Prosthodontics
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• v.3 no.4
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• pp.186-189
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• 2011

PURPOSE. Porcelain fused to metal (PFM) crowns provide the best treatment option for teeth that have a large or defective restoration. More than 20% of teeth with PFM crowns or bridges require non-surgical root canal treatment (NSRCT). This may be due to the effect of restorative procedures and the possible leakage of bacteria and or their by-products, which leads to the demise of the tooth pulp. Thus, this study was planned to compare the ability of the restorative materials to seal perforated PFM specimens. MATERIALS AND METHODS. The study evaluates the ability of amalgam, composite or compomer restorative materials to close perforated PFM specimen's in-vitro. Ninety PFM specimens were constructed using Ni-Cr alloys and feldspathic porcelain, and then they were divided into 3 groups: amalgam (A), composite + Exite adhesive bond (B) and compomer + Syntac adhesive bond (C). All the PFM samples were embedded in an acrylic block to provide complete sealing of the hole from the bottom side. After the aging period, each group was further divided into 3 equal subgroups according to the thermocycling period (one week for 70 cycles, one month for 300 cycles and three months for 900 cycles). Each subgroup was put into containers containing dye (Pelikan INK), one maintained at $5^{\circ}C$ and the other at $55^{\circ}C$, each cycle for 30 sec time. The data obtained was analyzed by SPSS, 2006 using one way ANOVA test and student t-test and significant difference level at (P<.01). RESULTS. The depth of dye penetration was measured at the interfaces of PFM and filling materials using Co-ordinate Vernier Microscope. The lowest levels of the dye penetration for the three groups, as well as subgroups were during the first week. The values of dye leakage had significantly increased by time intervals in subgroups A and C. CONCLUSION. It was seen that amalgam showed higher leakage than composite while compomer showed the lowest level of leakage.

• 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.16 no.1
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• pp.121-132
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• 1991

The purpose of the study was to evaluate the marginal sealing effect of composite resin inlays according to the luting techniques and compare them to the conventional direct resin filling technique. 90 cavities of class V were prepared on the buccal surface of 90 extracted molar teeth, which were divided into four groups. Cavities of control group were directly filled with Scotchbond 2 and P - 50, and those of composite resin inlay groups were luted with one of the followings: Adhesive bond followed by Adhesive cement, All bond followed by Adhesive cement, Fuji - ionomer type L All the specimens were immersed in India ink dye solution for 7 days at $37^{\circ}C$ incubator after thermocycling between $5^{\circ}C$ and $60^{\circ}C$ and longitudinally sectioned with diamond disk inot two parts All the specimens were observed at the occlusal and gingival margins and statistical analysis was performed. The results were as follows: 1. Groups filled with composite resin inlay showed less marginal leakage than the group directly filled(p<0.01). 2. There was no significant difference in marginal leakage between composite resin inlay groups luted with Adhesive bond followed by Adhesive cement and the group luted with All bond followed by Adhesive cement(p>0.05). 3. At occlusal margins, Composite resin inlay group luted with Adhesive bond followed by Adhesive cement showed less marginal leakage than the group luted with Fuii ionomer type I(p<0.01). At gingival margins, composite resin inlay group luted with All bond followed by Adhesive cement showed less marignal leakage than the group luted with Fuji ionomer type I(P<0.01).

• Journal of the Korean Vacuum Society
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• v.20 no.2
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• pp.146-154
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• 2011

The adhesive-tape of a liquid leak film sensor including the alarm system is developed. The sensing film is composed of three layers such as base film layer, conductive line layer, and protection film layer. The thickness of film is 300~500 um, the width is 3.55 cm, and the unit length is 200 m. On the conductive line layer, three conducting lines and one resistive line are formulated by the electronic printing method with a conducting ink of silver-nano size. When a liquid leaks for the electricity to be conducted between the conductive line and the resistive line, the position of leakage is monitored by measuring the voltage varied according to the change of resistance between two lines. The error range of sensing position of 200 m film sensor is ${\pm}1m$.

• 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).