• Restorative Dentistry and Endodontics
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• v.14 no.2
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• pp.49-64
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• 1989

The purpose of this study was to evaluate the effect of several materials on the healing process of apical wound. Sixteen mandibular premolars obtained from 4 healthy dogs were used for this study. Under general anesthesia, the pulpal chamber of each tooth was opened and the pulps were extirpated. The root canals were then instrumented with H-file and irrigated with physiologic saline solution ; the apices were purposely perforated and enlarged with the engine K-reamer. In the experimental groups, apical wounds were filled with one of calcium hydroxide, hydroxylapatite, and tricalcium phosphate materials, mixture of each materials and physiologic saline solution, with a lentulo spiral. In the control group, apical wounds were not filled with any material. All the root canals were filled by the lateral condensation technique with gutta-percha cone and ZOE sealer. The access opening of all the teeth were closed with amalgam. On the 10, 20, 40 and 60th day after experiment, experimental animals were sacrificed. Segments of jaws, each containing one tooth, were fixed in 10% formalin solution and decalcified in Plank-Rychlo solution. The specimens were embedded in paraffin and serially sectioned to an average thickness of $6{\mu}m$. The sections were stained by hematoxylin-eosin and Masson's trichrome stain method and examined under light microscope. The results were as follows : 1. In the experimental groups, the new bone formations were observed in apical wounds. 2. Fourty days later, apical wounds were healed by granulation tissue in the experimental groups, but were not healed by granulation tissue in the control group, and the healing process of experimental groups were more rapid than that of control group. 3. Sixty days later, chronic inflammation disappeared in the experimental groups, and the materials used showed biologic affinity to the periapical tissue. 4. In all the groups, the resorption of cementum appeared on the 10th and 20th day after experiment, and the deposition of cementum appeared on the 40th and 60th day after experiment, especially showing narrowness of apical foramen due to newly formed cementum in calcium hydroxide group. 5. Calcum hydroxide and tricalcium phosphate particles were gradually resolved, but hydroxylapatite particles were not resolved through the experimental period.

• The Journal of Korean Academy of Prosthodontics
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• v.45 no.5
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• pp.687-695
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• 2007

Statement of problem: The proper contact relation between adjacent teeth in each arch plays an important role in the stability and maintenance of the integrity of the dental arches. Proximal contact has been defined as the area of a tooth that is in close association, connection, or touch with an adjacent tooth in the same arch. Purpose: The aim of this study was to develop a digital device for measuring the proximal tooth contact tightness by pulling a thin stainless steel strip (2mm wide, 0.03mm thick) inserted between proximal tooth contact. Material and method: This device consists of measuring part, sensor part, motor part and body part. The stainless steel strip was connected to a stain gauge. The strain gauge was designed to convert the frictional force into a compressive force. This compressive force was detected as a electrical signal and the electrical signal was digitalized by a A/D converter. The digital signals were displayed by a micro-processor. The pulling speed was 8mm/s. Results: For testing reliability of the device in vivo, two healthy young adults (A, B) participated in this experiment. The tightness of proximal tooth contact between the second premolar and the first molar of mandible (subject A) and maxilla (subject B) was measured fifteen times for three days at rest. We double-checked the accuracy of the device with a Universal Testing Machine. Output signals from the Universal Testing Machine and the measuring device were compared. Regression analysis showed high linearity between these two signals. In vivo test, no significant differences were found between measurements. Conclusion: This device has shown to he capable of producing reliable and reproducible results in measuring proximal tooth contact. Therefore, it was considered that this device was appropriate to apply clinically.

• Journal of the Korean Academy of Esthetic Dentistry
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• v.27 no.2
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• pp.105-115
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• 2018

Not to recreate the final prosthesis is the shortest way to get a successful outcome. In the case of an aesthetic prosthesis, it is important not only the condition of the oral cavity but also the whole harmony in the face such as the interpupillary line and the smile line. But the dental technician creates the prosthesis only based on the oral model. So if you want to prevent the failure of the prosthesis due to discordance with the face, it is a good idea to use patient's facial photography and provisional restorations to reproduce facial features, shapes and aesthetics before switching to a final prosthesis. To prevent the failure of the final prosthesis, it is important to communicate among the patient, the technician and the doctor according to the model diagnosis, facial and oral photos. Then all the technicians will get satisfactory results. In addition, the technician have to understand the form of natural teeth, to analyze and reproduce colors, and to understand materials in order to produce a successful aesthetic prosthesis. From now on, I will explain two parts. At first, the communication in the dental office for the successful production of aesthetic prosthesis through the clinical case. And the second, my opinion for the successful aesthetic prosthesis.

• Imaging Science in Dentistry
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• v.54 no.1
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• pp.43-48
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• 2024

Purpose: Oral hygiene, maintained through plaque control, helps prevent periodontal disease and dental caries. This study was conducted to examine the accuracy of plaque detection with an intraoral scanner(IOS) compared to images captured with an optical camera. Materials and Methods: To examine the effect of color tone, artificial tooth resin samples were stained red, blue, and green, after which images were acquired with a digital single-lens reflex (DSLR) camera and an IOS device. Stained surface ratios were then determined and compared. Additionally, the deviation rate of the IOS relative to the DSLR camera was computed for each color. In the clinical study, following plaque staining with red disclosing solution, the staining was captured by the DSLR and IOS devices, and the stained area on each image was measured. Results: The stained surface ratios did not differ significantly between DSLR and IOS images for any color group. Additionally, the deviation rate did not vary significantly across colors. In the clinical test, the stained plaque appeared slightly lighter in color, and the delineation of the stained areas less distinct, on the IOS compared to the DSLR images. However, the stained surface ratio was significantly higher in the IOS than in the DSLR group. Conclusion: When employing IOS with dental plaque staining, the impact of color was minimal, suggesting that the traditional red stain remains suitable for plaque detection. IOS images appeared relatively blurred and enlarged relative to the true state of the teeth, due to inferior sharpness compared to camera images.

• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.3
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• pp.423-430
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• 2003

The teeth bleaching with bleaching agent is widely used at recent times. Until yet the exact mechanism of the bleaching agent isn't known but it is thought that is by the complex reduction-oxidation reaction of the decomposed free radical from bleaching agent through various ways. In other words, it is supposed that the teeth are whitened by agent's changing chemical structures of stain-causing materials. The purpose of this study is to exam the change of the dentinal character by bleaching agent and to evaluate the safety of this agent. For this study, after applying 10% carbamide peroxide to enamel of human premolar for 6 hours a day for 2 weeks we examined changes of surface morphology, microhardness, composition and contents of minirals in human dentin using SEM, microhardness tester, FT-Raman spectrometer and EPMA and got following results. There was no significant difference in surface morphologic change when we examined the effect of 10% carbamide peroxide which penetrated into dentin after applied on enamel surface comparing with result from specimen in distilled water No change was shown on the surface of peritubular and intertubular dentin within the nanometeric range. The microhardness between bleached teeth and teeth stored in distilled water showed no statistically significant difference FT-Raman spectra of dentin exhibited no change of the component in human dentin. Only the least change in peaks of organic and inorganic materials were detected in Raman intencity. The total content of mineral elements in dentin with no treatment, stored only in distilled water and stored in distilled water after bleaching were $98.73{\pm}1.89,\;98.56{\pm}2.11\;and\;97.47{\pm}2.51$ respectively. Also they showed no statistically significant difference. From above results, the effect of 10% carbamide peroxide bleaching on structure of dentin is very low and the results may confirm the safety of this bleaching agent.

• Restorative Dentistry and Endodontics
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• v.35 no.1
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• pp.5-12
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• 2010

The purpose of this study was to evaluate the pulp tissue reaction to direct pulp capping of mechanically exposed beagle dogs' pulp with several capping materials. A total of 36 teeth of 2 healthy beagle dongs were used. The mechanically exposed pulps were capped with one of the followings: (1) Mineral Trioxide Aggregate (MTA: $ProRoot^{(R)}$ MTA. Dentsply, Tulsa, USA), (2) Clearfil SE Bond (Dentin adhesive system: Kuraray, Osaka, Japan), (3) Ultra-Blend (Photo-polymerized Calcium hydroxide: Ultradent, South Jordan, USA), (4) Dycal (Quick setting Calcium hydroxide: LD Caulk Co., Milford, USA) at 7, 30, and 90 days before sacrificing. The cavities were restored with Z350 flowable composite resin (3M ESPE, St. Paul. MN, USA). After the beagle dogs were sacrificed, the extracted teeth were fixed, decalcified, prepared for histological examination and stained with HE stain. The pulpal tissue responses to direct pulp capping materials were assessed. In MTA calcium hydroxide, and photo-polymerized calcium hydroxide groups, initial mild inflammatory cell infiltration, newly formed odontoblast-like cell layer and hard tissue bridge formation were observed. Compared with dentin adhesive system, these materials were biocompatible and good for pulp tissue regeneration. In dentin adhesive system group, severe inflammatory cell infiltration, pulp tissue degeneration and pulp tissue necrosis were observed. It seemed evident that application of dentin adhesive system in direct pulp capping of beagle dog teeth cannot lead to acceptable repair of the pulp tissue with dentine bridge formation.

• Journal of Periodontal and Implant Science
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• v.25 no.3
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• pp.497-517
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• 1995

The cells associated with normal defense mechanism in inflammation release free oxygen radicals, hydroxy radicals, and various protease, all of which can damage the surrounding cells(fibroblasts) and matrix molecules(collagen). The objective of this study was to evaluate the effects of "scavenger" enzyme, superoxide dismutase(SOD). to periodontal ligament (PDL) cells. Human PDL cells were cultured from the teeth extracted for non-periodontal reason. Cultured PDL cells in vitro were treated with SOD and LPS according to dosage and culture times. Cellular activity was exaimed by Microtitration(MTT) assay. The quantitative expression of cellular proliferation by proliferating cell nuclear antigen(PCNA), collagen type I and fibronectin by indirect immunocytochemically stain in PDL cells were done. The results were as follows: 1. As only SOD treated group at 2 and 3 days, PDL cell activity was significantly increased at more than 150U(P<0.05). 2. When LPS(0.5, $5{\mu}g/m{\ell}$) and SOD(more than 150U) were added together, it was significantly increased than LPS only treated and control groups at 2 days(P<0.05). 3. When LPS($5{\mu}g/m{\ell}$) and SOD(150, 300U) were added together, PCNA index was significantly increased than LPS only treated and control groups at 2 and 3 days(P<0.05). 4. When LPS($5{\mu}g/m{\ell}$) and SOD(150U) were added together, collagen type I was significantly increased than LPS only treated and control groups at 3 days(P<0.05). 5.When LPS($5{\mu}g/m{\ell}$) and SOD(300U) were added together, fibronectin was significantly increased than LPS only treated and control groups at 3 days(P<0.05). On the above the results, the SOD in association with collagen type I, fibonectin, and PCNA may afford biological protection to oxy-radicals that were typically liberated during normal inflammatory response. Thus, the exogenous application of SOD may be effective in sthe treatment of the localized breakdown associated with chronic periodontal disease.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.1
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• pp.11-17
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• 2008

The purpose of this study was to investigate early histological changes and calcitonin gene-related peptide (CGRP) expression in the dental pulp of the rat after Er:YAG laser preparation. Occlusal cavities were prepared in the upper first molars using either Er:YAG laser and conventional bur. At 48 hours after cavity preparation, the teeth were processed for hematoxylin-eosin stain and CGRP immunohistochemistry. The results were as follows : 1. The cavity floor by Er:YAG laser preparation was more irregular shape compared with those by bur preparation and there are some cracks in the directions of dentinal tubules. 2. There were more inflammatory cell infiltration and disruption of odontoblast in the dental pulp by Er:YAG laser preparation in comparison with the dental pulp by bur preparation. 3. CGRP expression in the pulp tissue by both Er:YAG laser and bur preparations were increased and higher than in the normal pulp. The expression pattern of CGRP was more strong in the pulp by Er:YAG laser preparation. These results indicate that Er:YAG laser is useful in the operative dentistry such as caries removal and cavity preparation if properly applied.

• Restorative Dentistry and Endodontics
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• v.30 no.3
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• pp.149-157
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• 2005

Mechanical removals in decayed teeth have been performed using drill and sharp hand instruments. These methods have some disadvantages such as pain, local anesthesia and overextended cavities Therefore chemo-mechanical excavation of dentin carious lesions has been introduced. The purpose of this study was to evaluate the efficacy of traditional mechanical methods using burs and chemo-mechanical methods (Carisolv) of caries dentin. Mechanical caries removal was carried with low speed round bur Chemo-mechanical caries excavation was performed with Carisolv (Medi-team), using the Carisolv hand instruments. The mean time to remove caries with two different methods was evaluated and the data analyzed with SPSS software (ver 11.5) by t-test (p < 0.05). For histomorphometry of caries removal were also carried with mechanical or chemo-mechanical (Carisolv) methods from 20 extracted caries permanent molars. Complete caries removal was verified with a $\#$23 sharp explorers, Caries Detector (Kuraray Co. Japan), and standard apical radiography. 1. Chemo-mechanical method was taken more times than mechanical method (1.5 fold) (p < 0.05) 2. Excavation for caries took more time for molar lesion than premolar lesion, and the least time was taken to remove the caries in incisor lesion (p < 0.05). 3. There were no significant differences to remove the caries between the maxilla and mandible (p > 0.05). 4. The remaining carious dentin was detected after the ckemo-mechanical removal of the carious dentin, and no smear layer were seen after the mechanical and chemo-mechanical removal of the carious dentin.

• Journal of Periodontal and Implant Science
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• v.32 no.1
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• pp.89-112
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• 2002

The earliest reports of the use of electrical energy to directly stimulate bone healing seem to be in 1853 from England, the techniques involved the introduction of direct current into the non-united fracture site percutaneously via metallic needles, with subsequent healing of the defect. One endpoint of the periodontal therapy is to generate structure lost by periodontal diseases. Several procedural advances may support regeneration of attachment, however, regeneration of alveolar bone does not occur consistently. Therefore, factors which stimulate bone repair are areas for research in periodontal reconstructive therapy. Effects of cytokines or growth factors on bone repair are examples of such areas. Another one is electrical current which occurs in bone naturally, so that such bone may be particularly susceptible to electrical therapy. The purposes of this study were to observe the effects of electrical stimulation on the normal periodontium, to determine whether the electricity is the useful means for periodontal regeneration or not. Forty rats weighted about 100 gram were used and divided into 4 groups, the first group, there was no electrical stimulation with the connection of electrodes only. In the second group, there was stimulated by the 10 mA during 10 minutes per a day, in the third group was stimulated by the 25 mA , and the fourth by the 50 mA. At 3, 5, 10 and 15 days post-appliance , two rats in each group were serially sacrificed. and the maxillae and the mandible processed to paraffin, and the specimens were prepared with Hematoxylin-Eosin stain for the light microscopic evaluation. The results of this study were as follows : 1. There was the distinct reversal line on the lingual alveolar crest, whereas a little changes in the labial alveolarcrest to the duration and amount of currents. 2. In 50 mA group, the cells were highly concentrated at the apex of anterior teeth, and was observed the necrotic tissue. In posterior root apex, the hypercementosis was appeared, and newly formed cementum layer has been increased continuously with the time. 3. The periodontal ligament fiber and Sharpey's fiber were arranged in order, and the bone trabeculae were increased as the experiment proceeded by, relatively the bone marrows were decreased. 4. In the pulp tissue, the blood vessels were increased with blood congestion in the experimetal specimens remarkably, and the dentinal tubules were obstructed . 5. The osteoblasts in alveolar bone proper had been showed highly activity, and also observed the formation of bone trabeculea. In the conclusion, it was suggested that the electrical stimulation has influence on the periodontium and the pulp tissue. However, there might be the injurious effects.