• Restorative Dentistry and Endodontics
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• v.22 no.2
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• pp.739-750
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• 1997

Treatment of root perforation elicits special considerations due to its blood-contaminated circumstances. It is known that conventional dental restorative materials are all leaking. Calcium sulfate is the material which react with water to become chemically set. This study, therefore, was performed to develop a new compound containing calcium sulfate and to evaluate its physical and biological characteristics. Three materials were used, IRM, calcium sulfate, calcium sulfate-hydroxyapatite compound. The composition of the calcium sulfate-hydroxyapatite compound was basically 50 % of calcium sulfate and 50 % of hydroxyapatite mixed with guajacol. The materials were mixed in conventional way and underwent four physical test procedures, setting time, solubility test, compressive strength, and marginal leakage test. All materials were evaluated under the scanning electron microscope to examine the marginal sealing ability. Animal experiment was also performed to test the materials' tissue response. Twenty-four dog's premolars were tested with either furcation perforations or apical retro-fillings. From the results, we found that calcium sulfate possess the good marginal sealing ability. However, calcium sulfate creates many voids which is caused by crystal thrusting action when it reacts with water. It seemed that the voids caused disintegration of the material which eventually lead to tissue reaction. By compounding calcium sulfate and hydroxyapatite, we were able to obtain the better physical properties but it showed larger marginal gap between the material and the root surface. Within the six weeks observation period, both IRM and calcium sulfate-hydroxyapatite compound showed good tissue responses in animal experiment. It is concluded that calcium sulfate would be the material of choice in root perforation repair, but the physical property needs to be further improved.

• 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.

• Journal of the korean academy of Pediatric Dentistry
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• v.33 no.1
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• pp.131-138
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• 2006

A mixture of metronidazole, ciprofloxacin and minocycline(3Mix) in distilled water or in a root canal sealer were used to disinfect the infected endodontic and periapical lesions. It has been well acknowledged in recent literature that minocycline, a semisynthetic tetracycline derivative, causes discolorations in adult teeth and various other collagenous tissues. In these cases, pulp treatments were finished successfully using a combination of antibiotics but severe discolorations of the teeth were observed. Discolored non-vital posterior tooth was treated using the prosthodontic procedure. And anterior tooth was successfully treated using the walking bleach technique. Bleaching was performed by temporarily placing a mixture of sodium perborate and distilled water into the pulp chamber. There were significant esthetic improvement.

• Journal of the Korean Institute of Rural Architecture
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• v.16 no.4
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• pp.75-81
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• 2014

In this study, we have intended to provide the related construction manuals with technical materials and to reduce the defects in the on-site construction, with reviewing the adhesive properties of joint parts according to change of temperature and speed of hot-air sealer for the products that have been made of polyvinyl chloride(PVC) materials in the single waterproof sheet. The result from the experiment is shown as following. 1) Bond strength was shown as high as the welding speed became slower. For the hot-air welding velocity with 3~6m/min, a stable bond strength has been shown in the range of the hot-air welding temperature with $175{\sim}210^{\circ}C$, while it has been shown in the range of the hot-air welding temperature with $210^{\circ}C$, when the hot-air welding velocity is between 9~12m/min. 2) If the hot-air welding temperature is lower, the adhesive strength has been shown as higher in the section where the hot-air welding velocity is low, while the adhesive strength has been also shown as higher in the section where the velocity is fast as the hot-air welding temperature becomes higher. The highest bond strength has been shown in the velocity with 3m/min for the hot-air welding temperature with $140{\pm}10^{\circ}C$, which is rather low. At $175{\pm}10^{\circ}C$, a high bond strength has been shown in the velocity with 3~6m/min, while the high bond strength has been shown in the velocity with 6~9m/min at $210{\pm}10^{\circ}C$.

• Elastomers and Composites
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• v.39 no.1
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• pp.61-70
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• 2004

This work is about the development or asphalt sealant using the waste edible oil. Asphalt sealant has been used for crack filler and bridge deck joint sealer Several plasticizers such as aromatic or paraffin process oils, DOP, Bunker C fuel oil, and waste edible oil were compounded with the basic components such as asphalt(AP-5), a thermoplastic elastomer(SBS triblock copolymer), a tackifying agent(petroleum resin), and stabilizers. Penetration, softening point, ductility, and elongation by tensile adhesion of those asphalt sealant compounds were measured. Their properties were changed largely depending on both the type and content of plasticizers. Waste edible oil and DOP were the best plasticizers for the low temperature tensile adhesion characteristics. Penetration and elongation by tensile adhesion of asphalt sealant compounds increased with the increase of waste edible oil content and decreased with the increase of talc content. The manufacture of asphalt sealant with low penetration and excellent low temperature tensile adhesion was possible by the recipe optimization.

• Restorative Dentistry and Endodontics
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• v.43 no.2
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• pp.23.1-23.9
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• 2018

Objectives: This study evaluated the effect of ultrasonic agitation of mineral trioxide aggregate (MTA), calcium silicate-based cement (CSC), and Sealer 26 (S26) on adaptation at the cement/dentin interface and push-out bond strength. Materials and Methods: Sixty maxillary canines were divided into 6 groups (n = 10): MTA, S26, and CSC, with or without ultrasonic activation (US). After obturation, the apical portions of the teeth were sectioned, and retrograde cavities were prepared and filled with cement by hand condensation. In the US groups, the cement was activated for 60 seconds: 30 seconds in the mesio-distal direction and 30 seconds in the buccal-lingual direction, using a mini Irrisonic insert coupled with the ultrasound transducer. After the materials set, 1.5-mm thick sections were obtained from the apexes. The presence of gaps and the bond between cement and dentin were analyzed using low-vacuum scanning electron microscopy. Push-out bond strength was measured using a universal testing machine. Results: Ultrasonic agitation increased the interfacial adaptation of the cements. The S26 US group showed a higher adaptation value than MTA (p < 0.05). US improved the push-out bond strength for all the cements (p < 0.05). Conclusions: The US of retrograde filling cements enhanced the bond to the dentin wall of the root-end filling materials tested.

• Restorative Dentistry and Endodontics
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• v.24 no.2
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• pp.286-298
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• 1999

The endodontic-periodontic combined lesions have been difficult to get correct diagnosis and predictable treatment. This study was to make the experimental endodontic-periodontic combined defects in dogs for the study of the periodontal regeneration and to evaluate the efficacy of the enamel matrix protein and e-PTFE membrane in the experimental endodontic-periodontic combined defects. 5 mongrel dogs were used. The pulp chambers were opened and the plaque was inserted into the chambers to induce the periapical lesions on the mandibular second, third and fourth premolars of the dogs. 1 month later, the root canal treatments were done with gutta perch a and ZOE sealer. On the day of surgery, the periapical defects were standardized by trephine bur. The buccal dehiscence defects were made by the dental bur and bone chisels. The apicoectomy with retrofilling was done. The prepared roots were randomly selected for test and control groups. In the experimental groups, the enamel matrix derivative and e-PTFE membrane were used. Nothing was placed on the control group. Fluroscent labelling was used to evaluate the bone formation. After 4 and 12 weeks, the dogs were sacrificed and undecalcified sections were prepared and stained with toluidine blue. Those histologic sections were examined by fluorescent microscopy and light microscopy. The results were as follows. 1. In the control group, new bone was formed in the periapical defects and scarcely in the buccal dehiscence defects. New cementum was not detected at 4 and 12 weeks. 2. In the experimental groups, new bone, new cementum and periodontal ligament were found in the periapical and buccal dehiscence defects. The relative amount and the quality of the new bone, new cementum and periodontal ligament tissue that had formed on the experimental groups were superior to those of the control group. 3. The current observation implicated that e-PTFE membrane and enamel matrix protein could be the effective tools for the guided tissue regeneration of the endo-perio combined defects.

• 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.18 no.1
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• pp.197-204
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• 1993

This study was conducted to evaluate and compare the apical leakage in the following retrofilling techniques after apical resection; No apical cavity preparation and no retrofilling(control group), Amalgam(group I) or silver glass ionomer cement(group II) retrofilling after apical cavity preparation with mini contra-angle and bur, Amalgam(group III) or silver glass ionomer cement(group N) retrofilling after apical cavity preparation with ultrasonic micro endo tip. Extracted ninety upper anterior and lower canine teeth were fixed in skull simulators and root canals were prepared with step-back method and obturated with gutta-percha and zinc oxide eugenol sealer. Obturated roots were resected 2mm from apical ends and apical cavities of 1mm width and 2mm depth were prepared and retrofilled by above mentioned methods. After application of nail varnish on all surface except resected surface, apical 1/3 of the roots were placed in 1% methylene blue solution for 3 days. After longutudinal sectioning to expose central parts of filled materials, depths of penetrated dye were measured by measuring microscope and were analyzed statistically. The results were as follows. 1. Having no relation with instruments used in apical cavity preparation, amalgam retrofilling groups(group I and II) showed less apical leakage which was not significant statistically than no retrofilling group(control group) (P<0.05), but silver glass ionomer cement retrofilling gruoups(group II and IV) showed significantly less apical leakage than no retrofilling group(control group) (P<0.01). 2. In the groups retrofilled with the same material, the apical leakage in cavities prepared with ultrasonic micro endo tip (group III and IV) was less than that in cavities prepared with mini contra-angle and bur(group I and II), but not significant statistically(P>0.05). 3. When apical cavities were prepared with same instrument. the egroups retrofilled with silver glass ionomer cement(group II and IV) showed significantly less apical leakage than the groups retrofilled with amalgam(group I and III)(<0.01).

• Restorative Dentistry and Endodontics
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• v.18 no.1
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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.