• Journal of Korean society of Dental Hygiene
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• v.16 no.3
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• pp.471-477
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• 2016

Objectives: Fluoride is widely used in the prevention and control of dental caries. The purpose of this study is to examine the biological effects of Sodium fluoride on the proliferation of oral normal cell in vitro(MDPC-23, HaCaT, HGF-1 cells). Methods: The proliferation of normal cells and the cyto-skeletal change of normal cells were assessed by WST-1 assay and F-actin stain assay. The statistical significances of the resulting data were analyzed using SPSS(Window 12.0). Results: The sodium fluoride(0-12 mM) treatment decreased the cell viability in a dose and time dependent manner: HaCaT(6 h): $100{\pm}0$, $98{\pm}0.39$, $82{\pm}2.68$, $75{\pm}0.83$, $69{\pm}1$, $67{\pm}1.42%$(p<0.005); HaCaT(24 h): $100{\pm}0$, $98{\pm}1.85$, $54{\pm}0.64$, $43{\pm}0.4$, $38{\pm}0.32$, $36{\pm}0.13%$(p<0.006), MDPC-23(6 h): $100{\pm}0$, $93{\pm}1.48$, $85{\pm}0.28$, $82{\pm}1.58$, $79{\pm}1.48$, $76{\pm}1.93%$(p<0.009); MDPC-23(24 h): $100{\pm}0$, $91{\pm}1.26$, $58{\pm}0.65$, $49{\pm}1$, $44{\pm}0.74$, $2{\pm}0.05%$(p<0.005), HGF-1(6 h): $100{\pm}0$, $97{\pm}2.93$, $89{\pm}5$, $71{\pm}5.42$, $58{\pm}4.82$, $43{\pm}3.47%$(p<0.009); HGF-1(24 h): $100{\pm}0$, $97{\pm}2.05$, $73{\pm}1.73$, $22{\pm}1.61$, $14{\pm}1.73$, $7{\pm}0.85%$(p<0.005). Thus, changes in cell morphology and disruption of filamentous(F)-actin organization were observed in higher concentration. Conclusions: These results suggest that higher concentrations of fluoride lead to a reduce the number of cells and morphology change of normal cell.

• Restorative Dentistry and Endodontics
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• v.32 no.5
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• pp.459-468
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• 2007

Protein microarray or protein chips is potentially powerful tools for analysis of protein-protein interactions. APin cDNA was previously identified and cloned from a rat odontoblast cDNA library. The purpose of this study was to investigate the APin-protein interactions during ameloblast differentiation. Protein microarray was carried with recombinant APin protein and MEF2, Aurora kinase A, BMPR-IB and EF-hand calcium binding protein were selected among 74 interacting proteins. Immortalized ameloblast cells (ALCs) were transfected with pCMV-APin construct and U6-APin siRNA construct. After transfection, the expression of the mRNAs for four proteins selected by protein micoarrays were assessed by RT-PCR. The results were as follows: 1. APin expression was increased and decreased markedly after its over-expression and inactivation, respectively. 2. Over-expression of the APin in the ALCs markedly down-regulated the expression of MEF2 and Aurora kinase A, whereas their expression remained unchanged by its inactivation. 3. Expression of BMPR-IB and EF-hand calcium binding protein were markedly increased by the over-expression of the APin in the ALCs, whereas expression of BMPR-IB remained unchanged and expression of EF-hand calcium binding protein was markedly decreased by its inactivation. These results suggest that APin plays an important role in ameloblast differentiation and mineralization by regulating the expression of MEF2, Aurora kinase A, BMPR-IB and EF-hand calcium binding protein.

• 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.

• Journal of the korean academy of Pediatric Dentistry
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• v.44 no.3
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• pp.350-357
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• 2017

The purpose of this study was to evaluate the difference of differentiation potential in each passage of dental pulp stem cells from supernumerary tooth (sDPSCs). The sDPSCs were obtained from a healthy 6-year-old male patient under the guidelines and got the informed consent. Cells were cultured until passage number 16 and divided into two groups; 1 - 8 passages as a young group and 9 - 16 passages as an old group. It was taken $2.25{\pm}0.46days$ in a young group and $3.25{\pm}0.46days$ in an old group to propagate cells of each passage until confluence and there were statistically significant differences between two groups (p < 0.05). In every passage, cell morphology was observed with microscope and evaluated the capacity to form high levels of minerals by alizarin red solution staining after treating differentiation medium. Fibroblast-like, spindle shaped, elongated cells and a few nodules were found in uninduced cultures of passage number 1, 8 and 9. But at 16 passage culture, cell size became larger and broader and observed with more nodules. After inducing differentiation, mineralized nodules were detected at the first passage of 7th day culture whereas at the 8 passage culture, nodules were seen clearly at 14th day culture. In addition, the amount of mineralized nodules were remarkably decreased after passage 9. From the data presented in this study, it is recommended to use sDPSCs of passage number within 8 for utilizing as stem cells.

• Journal of the korean academy of Pediatric Dentistry
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• v.27 no.2
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• pp.333-343
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• 2000

The purpose of this study was to compare the effect of ferric sulfate and formocresol as pulp dressing agents in pulpotomized teeth of dogs. 40 teeth of 5 dogs, weighting 10kg. were used in this study. The animals were sacrificed at the intervals of 3, 7, 14, 28 and 56 days for histopathologic evaluation. The specimens were observed by the light microscope. The results were as follows : 1. Inflammatory response was observed in both groups, but pulp tissue of ferric sulfate group was showed lesser inflammatory degree and more rapid recovery than that of formocresol group. 2. In ferric sulfate group odontoblasts showed irregular arrangement pattern at initial stage and returned to regular pattern after 2 weeks. But in formocresol group. continued irregular pattern of odontoblast was observed during experimental period. 3. Reparative dentin was produced widely along the canal in one specimen of formocresol group at 8 weeks and dentinal bridge was formed in two specimens of ferric sulfate group at 8 weeks.

• Journal of the korean academy of Pediatric Dentistry
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• v.11 no.1
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• pp.169-179
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• 1984

The purpose of this study was to observe the effect of dental varnish applied with fluoride to dental pulp by comparing the groups of commercial fluoride product $Duraphat^{(R)}$, $Copalite^{(R)}$ after 1 Mole sodium fluoride application, Cavity $Sealer^{(R)}$ after 1 Mole sodium fluoride application with the control group not applied the dental varnish. After Cl V Cavity form was prepared on the buccal surface of the crowns with the total 75 teeth by using 5 dogs, average weight of 13.2Kg, dental varnish and silver analgram were placed. This study was performed by 3, 7, 21, 28, 56 days each. The dogs were sacrificed to extract the teeth, cut at the apical one fourth, and prepared histologic examination by fixing with 10% buffered formalin perfusion at sacrifice and decalcification in 10% nitric acid. The specimens were embedded in paraffin, stained with Hematoxylin and Eosin, and serially sectioned with 6 ${\mu}$width each. Microscopic evaluation of serial sections at the various time periods among the different groups revealed the following results: 1. In the control group, the marked change of the odontoblastic layer was showed on the 3 days group, and it was decreased gradually. Healing response, such as hyperplasia, was seen on the 28 days group and it was continued to the 56 days group. 2. In the experimental group with Cavity $Sealer,^{(R)}$ a slight hemorrhage was seen in the odontoblastic layer on the 3 days group, and the healing response with the hyperplasia of the odontoblast was showed on the 21, 28 days group. It was completely healed on the 56 days group. 3. In the Duraphat R group, a slight hemorrhage showed on the 3 days group and the disarrangement of the Odontoblastic layer was seen on the 7, 21, 28 days group. Odontoblasts showed hyperplasia on the 28 days group, and healed completely on the 56 days group. 4. In the $Copalite^{(R)}$ group, the 7 days group showed remarkable hemorrhage in the odontoblastic layer and stroma, and also it showed reticular degeneration with the disarrangement of the odontoblastic layer and congestion. Each group showed disarrangement. Healing ability of this group was greater than that of the control group, but less than that of the $Duraphat^{(R)}$ and Cavity $Sealer^{(R)}$ group.

• Journal of the korean academy of Pediatric Dentistry
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• v.37 no.3
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• pp.275-287
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• 2010

Deep caries may induce pulpitis and the pulpal tissue interacts with microbial invasion. The immune response to protect the pulpal tissue can be mediated by cellular signal molecules produced by the pulpal cells. The understanding of these processes is important to find future therapeutic method for the diseased pulp. The pulp tissue from sound teeth was set as control group (n=30) and the pulp tissue from decayed teeth was set as test group (n=30). Total RNA was extracted from the pulp of each group and it was used for cDNA microarray and reverse transcriptase-polymerase chain reaction(RT-PCR). The expression of TGF-${\beta}1$ was studied by immunohistochemistry. The results were as follows: 1. cDNA microarray analysis identified 520 genes with 6-fold or greater difference in expression level with 143 genes more abundant in health and 377 genes more abundant in disease. 2. The RT-PCR analysis was done for randomly selected 14 genes and the results supported the result of cDNA microarray assay. 3. TGF-${\beta}1$ was highly expressed in the carious pulp and it was found in odontoblast by immunohistochemistry. In conclusion, many cytokines were found to be significantly changed their expression in the diseased pulp(/M/>1.6).

• Anatomy & Biological Anthropology
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• v.26 no.1
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• pp.41-49
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• 2013

Dental epithelial and mesenchymal cells that form the teeth undergo dynamic changes in cell cycle during tooth development and morphogenesis. Although proliferation has been known as a key event during odontogenesis, the cell cycle phases and their relations with the complicated molecular mechanisms of tooth development are not fully understood yet. This study comparatively examined the expression patterns of Ki-67, cyclin A, and cyclin D1 during tooth development in the mouse incisor and molar in order to identify the cell-cycle characteristics during odontogenesis. We found that Ki-67 and cyclin A were expressed in the proliferating cells in the dental epithelial and mesenchymal tissues at the bud, cap and bell stages. Cycln D1 showed distinct expression in the incisor odontoblast region and the enamel knot, in which Ki-67 nor cyclin A was expressed. Our results provide specific information on the cell cycle phases during tooth development that may provide clues to relate them with the complex odontogenic mechanisms. Furthermore, we suggest that our findings enlightened the previous studies on the incisor odontoblasts and the enamel knot during tooth development.

• The korean journal of orthodontics
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• v.31 no.2 s.85
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• pp.249-259
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• 2001

This study was designed to evaluate the expression of heat shock protein in tooth and surrounding tissue during the experimental movement of rat incisors, by LSAB(labelled streptavidine biotin) immunohistochemical staining for heat shock protein. Twenty seven Sprague-Dawley rats were divided into a control group(3 rats), and 6 experimental groups(24 rats), to which 75g of force was applied from helical springs across the maxillary incisors. Rats of experimental groups were sacrificed at 0.5, 1, 4, 7, 14 and 28 days after force application, respectively. And the periodontal tissues of a control group and experimental groups were studied immunohistochemically. The results were as follows : 1. In control group, the expression of HSP47 was rare in gingiva, dentin and cementum, and mild in periodontal ligament and alveolar bone. But it was more evident than that of HSP70. 2. The expression of HSP47 or HSP70 was rare or mild in dentin, cementum and odontoblast of experimental group, regardless of the duration of force application, which was not different from that of control group. 3. In experimental group, the expression of HSP47 got to the highest degree in periodontal ligament and alveolar bone at 4 days after force application, and then decreased. And the expression was more evident in the pressure side than in the tension side of periodontal ligament 4. The expression of HSP70 began to increase at 12 hours after force application and got to the highest degree at 4 days, in the capillary of pulp and periodontal ligament. And the expression was more evident in the pressure side than in the tension side of periodontal ligament 5. The expression of HSP70 in alveolar bone of experimental group was rare, which was similar to that of control group.

• 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.