• The Journal of the Korean dental association
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• v.14 no.10
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• pp.845-849
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• 1976

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.171-172
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• 2006

Most existing studies for stress analysis of teeth have employed small number of teeth, and used big element size using F-E models. Therefore, the results are not accuracy enough for showing the internal stress variation. 15 males' and 13 females' mandibular first premolar are employed for internal structure's study of teeth and small element size for a FE model are used. According to these processes, stress distribution of internal parts of teeth are well shown, and the stresses are varied a lot between enamel layer and dentine layer, but there is little variation on pulp chamber.

• The Journal of the Korean dental association
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• v.11 no.3
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• pp.185-189
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• 1973

Dental amalgam in the clinic practice of dentistry is one of the most important materials. Mercury, one of the component of this alloy, is emitted in the form of vapor after filling as long as 5 days Silver particles penetrate into the dentine deeply along the tubles underneath cavity floor. To determine the permeability of mercury in the teeth following experiments were performed. Class 5 cavities total 40 from 10 dogs were prepared on upper and lower canines and amalgam alloys which contain about 10uCi of radioactive mercury were inserted. The animals were sacrificed 7 days after the experiments and the teeth were decalcified, sectioned and autoradiographed by means of emulsion and stained by H & E. Following are the results obtained from this experiments. 1. Blackened silver grains were found along the dentinal tubules underneath the cavity floor. Beyond the border of dentine and pulp chamber grains were seen in odontoblastic layer (Fig. 1, 2, 3, 4) 2. Underneath the odontoblastic layer, the pulp tissue showed almost normal appearance except slight dilatation of blood vessel.

• Proceedings of the KACD Conference
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• 2003.11a
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• pp.587-589
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• 2003

I. Objectives The purpose of this study was to evaluate the effects of EDTA on microhardness of roor canal dentine according to different working time. II. Materials and Methods Forty recently extracted, intact single root teeth were used. Debris and soft tissue remnants on the root surface were cleaned with scaler and stored in saline at $4^{\circ}C$ until used. All selected roots were similar in size and shape. 1. Preparation of teeth. The crown of the teeth were removed at the level of the CEJ, using a water-cooled diamond bur.(omitted)

• Proceedings of the KACD Conference
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• 2002.11a
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• pp.684-684
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• 2002

No Abstract, See Full Text

• Journal of Periodontal and Implant Science
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• v.39 no.1
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• pp.87-94
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• 2009

Purpose: The aim of this study was to compare the effectiveness of hydroxyapatite containing toothpaste with positive control toothpastes in reducing dentine hypersensitivity. Materials and methods: This clinical trial was a double-blind, randomized, parallel group comparison of two, namely hydroxyapatite containing toothpaste and strontium chloride containing toothpaste. A total of 55 subjects were included in this study. The subjects were given randomly assigned one of the two toothpastes after received tooth brushing instruction at baseline. Some clinical indices(PI, GI, PD), verbal rating score(VRS) for sensitivity to stimulus, the effect in relieving sensitivity and visual analogue scale(VAS) for sensitivity at baseline, week 2, week 4 and week 8 were assessed. All data were evaluated by intention-to-treat analysis. Results: Overall, PI and GI scores were significantly reduced compare baseline in all groups(p<0.05). In addition, there was significant difference in PI at 4 weeks and in GI at 4, 8 weeks between groups. The proportions of subjects relieved sensitivity were 70.4% in experimental group and 57.1% in control group at 8 weeks respectively. The VRS for sensitivity to three kinds of stimuli and VAS for sensitivity decreased according to time, there was no overall difference between two groups(p>0.05). Conclusion: This study demonstrated that the new hydroxyapatite containing toothpaste was similarly effective in reducing dentine hypersensitivity with pre-existing benchmark toothpaste.

• Restorative Dentistry and Endodontics
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• v.39 no.2
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• pp.120-125
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• 2014

Use of an apical plug in management of cases with open apices has gained popularity in recent years. Biodentine, a new calcium silicate-based material has recently been introduced as a dentine substitute, whenever original dentine is damaged. This case report describes single visit apexification in a maxillary central incisor with necrotic pulp and open apex using Biodentine as an apical barrier, and a synthetic collagen material as an internal matrix. Following canal cleaning and shaping, calcium hydroxide was placed as an intracanal medicament for 1 mon. This was followed by placement of small piece of absorbable collagen membrane beyond the root apex to serve as matrix. An apical plug of Biodentine of 5 mm thickness was placed against the matrix using pre-fitted hand pluggers. The remainder of canal was back-filled with thermoplasticized gutta-percha and access cavity was restored with composite resin followed by all-ceramic crown. One year follow-up revealed restored aesthetics and function, absence of clinical signs and symptoms, resolution of periapical rarefaction, and a thin layer of calcific tissue formed apical to the Biodentine barrier. The positive clinical outcome in this case is encouraging for the use of Biodentine as an apical plug in single visit apexification procedures.

• The korean journal of orthodontics
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• v.1 no.1
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• pp.15-20
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• 1970

The author investigated on the responses of pulp and dentine following tooth movements. The material consisted of fifty-four intact teeth from twenty-seven adult white rats. The half of the teeth were employed as controls and the other half served as experimental group. These teeth were moved with forces ranging from 30 grams to 120 grams for from 3 to 7 days. All these were extracted immediately after the force was relieved. The main pulp changes in the experiment were vacuolization of the pulp tissue and circulatory disturbances. The magnitude of the force had an important role. In addition to these changes, the resorption in dentine and cementum was observed, which was related to the magnitude of the force and the duration of experiment.

• International Journal of Oral Biology
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• v.33 no.4
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• pp.187-195
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• 2008

Reparative dentine formation requires newly differentiated odontoblast-like cells. Therefore, identification of the molecule that stimulates the odontogenic differentiation of precursor cells in the tooth pulp will be helpful for the development of strategies to repair damaged pulp. In this study, we examined the effect of N-acetylcysteine (NAC) on the odontogenic differentiation of MDPC-23 cells, a mouse odontoblast-like cell line derived from dental papilla, and primary cultured rat dental papilla cells (RDPCs). NAC (1-30 mM) suppressed production of reactive oxygen species in MDPC-23 cells in a dose-dependent manner. Although 5 to 20 mM NAC did not alter MDPC-23 cell proliferation, 1 or 30 mM NAC significantly inhibited it. NAC enhanced mineralized nodule formation and the expression of several odontoblast differentiation-associated genes in both RDPCs and MDPC-23. This NAC stimulatory effect was significant, even at concentrations lower than 1 mM. However, NAC did not stimulate expression of bone morphogenetic protein-2, -4, or -7, which are known to enhance odontogenic differentiation. Since reactive oxygen species are also involved in the pulp toxicity of resin-based restorative materials, these results suggest that NAC may be a promising candidate for supplementation of dental restorative materials in order to enhance reparative dentine formation.

• The Journal of Korean Academy of Prosthodontics
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• v.17 no.1
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• pp.23-34
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• 1979

In this study, the adhesive strength of three commercial polycarboxylate cements to ten types of dental casting alloys, such as gold, palladium, silver, indium, copper, nickel, chromium, and human enamel and dentine were measured and compared with that of a conventional zinc phosphate cement. The $8.0mm{\times}3.0mm$ cylindrical alloy specimens were made by casting. The enamel specimens were prepared from the labial surface of human upper incisor, and the dentine specimens were prepared from the occulusal surface of the human molar respectively. Sound extracted human teeth, which had been kept in a fresh condition since, extraction, were mounted in a wax box with a cold-curing acrylic resin to expose the flattened area. The mounted teeth were then placed in a Specimen Cutter (Technicut) and were cut down under a water spray, and then the flat area on the all specimens were ground by hand with 400 and 600 grit wet silicone carbide paper. Two such specimens were then cemented together face-to-face with freshly mixed cement, and moderate finger pressure was applied to squeeze the cement to a thin and uniform film. All cemented specimens were then kept in a thermostatic humidor cabinet regulated at $23{\pm}2^{\circ}C.$ and more than 95 per cent relative humidity and tested after 24 hours and 1 week. Link chain was attached to each alloy specimen to reduce the rigidity of the jig assembly, and then all the specimens were mounted in the grips of the Instron Universal Testing Machine, and a tensile load was delivered to the adhering surface at a cross head speed of 0.20 mm/min. The loads to which the specimens were subjected were recorded on a chart moving at 0.50 mm/min. The adhesive strength was determined by measuring the load when the specimen separated from the cement block and by dividing the load by the area. The test was performed in a room at $23{\pm}2^{\circ}C.$ and $50{\pm}10$ per cent relative humidity. A minimum of five specimens were tested each material and those which deviated more than 15 per cent from the mean were discarded and new specimens prepared. From the experiments, the following results were obtained. 1) It was found that the adhesive strength of the polycarboxylate cement to all alloys tested was considerably greater than that of the zinc phosphate cement. 2) The adhesive strength of the polycarboxylate cements was superior to the non precious alloys, such as the copper, indium, nickel and chromium alloys, but it was inferior to the precious gold, silver and palladium alloys. 3) Surface treatment of the alloy was found to be an important factor in achieving adhesion. It appears that a polycarboxylate cement will adhere better to a smooth surface than to a rough one. This contrasts with zinc phosphate cements, where a rough helps mechanical interlocking. 4) The adhesion of the polycarboxylate cement with enamel was found superior to its adhesion with dentine.