• Journal of Dental Rehabilitation and Applied Science
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• v.29 no.3
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• pp.209-223
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• 2013

This study was to evaluate the stress distributions of prefabricated, customized abutments and fixtures according to their material and shape by three-dimensional finite element analysis. And to investigate the fatigue life and fracture characteristics. Mandibular models were fabricated by reconstruction of the CT scan of patients with normal occlusion. A total of six finite element models were designed, a load of 100 N was applied on the buccal cusps vertically, and 30 degree obliquely. 10 specimens each were fabricated for the more clinically widely used 4 type abutments and were loaded according to ISO 14801. Differences in stress distribution patterns were not found according to the materials of the abutments and fixtures. But a slight difference in the stress level was detected. Customized abutment groups showed lower crown stress levels. One-piece zirconia implant showed the lowest bone stress levels. In the fatigue test, highest values were measured in group 7. Prefabricated abutments showed less variation of fatigue life (P<0.05). Use of customized abutments can improve the fracture resistance of restorations. Especially, use of customized zirconia abutments reinforced by titanium screw connecting parts is recommended.

• Journal of Periodontal and Implant Science
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• v.32 no.1
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• pp.129-142
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• 2002

Epithelial-mesenchymal interaction plays a important role in cell growth and differentiation. This interaction is already well known to have an importance during the organ development as well as cell growth and differentiation. However, in vitro experimental model is not well developed to reproduce in vivo cellular microenvironment which provide a epithelial-mesenchymal interaction. Because conventional monolayer culture lacks epithelial-mensenchymal interaction, cultivated cells have an morphologic, biochemical, and functional characteristics differ from in vivo tissue. Moreover, it's condition is not able to induce cellular differention due to submerged culture condition. Therefore, the aims of this study were to develop and evaualte the in vitro experimental model that maintains epithelial-mesenchymal interaction by organotypic raft culture, and to characterize biologic properties of three-dimensionally reconstituted oral keratinocytes by histological and immunohistochemical analysis. The results were as follow; 1. Gingival keratinocytes reconstituted by three-dimensional organotypic culture revealed similar morphologic characteristics to biopsied patient specimen showing stratification, hyperkeratinosis, matutation of epithelial architecture. 2. Connective tissue structure was matured, and there is no difference during stratification period of epithelial 3-dimensional culture. 3. The longer of air-exposure culture on three-dimensionally reconstituted cells, the more epithelial maturation, increased epithelial thickness and surface keratinization 4. In reconstitued mucosa, the whole epidermis was positively stained by anti-involucrin antibody, and there is no difference according to air-exposured culture period. 5. The Hsp was expressed in the epithelial layer of three-dimensionally cultured cells, especially basal layer of epidermis. The change of Hsp expression was not significant by culture stratification. 6. Connexin 43, marker of cell-cell communication was revealed mild immunodeposition in reconstitued epithelium, and there is no significant expression change during stratification. These results suggest that three-dimensional oragnotypic co-culture of normal gingival keratinocytes with dermal equivalent consisting type I collagen and gingival fibroblasts results in similar morphologic and immunohistochemical characteristics to in vivo patient specimens. And this culture system seems to provide adequate micro-environment for in vitro tissue reconstitution. Therefore, further study will be focused to study of in vitro gingivitis model, development of novel perioodntal disease therapeutics and epithelial-mensenchymal interaction.

• Journal of Periodontal and Implant Science
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• v.31 no.3
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• pp.611-623
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• 2001

Cyclosporin A is a cyclic polypeptide produced by the metabolism of fungi. It is widely used at present as immunosuppressive treatment following organ transplants. It is also used to deal with autoimmune diseases such as rheumatoid arthritis or type II diabetes. Gingival hyperplasia is one of the most frequent side-effects associated with the prescription of Cyclosporin A. The mechanisms involved in Cyclosporin A induced gingival hyperplasia are not yet clear. In vitro Cyclosporin A promotes proliferation of gingival fibroblasts, that Cyclosporin A act as a mitogen. Its action is based on mitosis of gingival fibroblasts regulated by cell cycle regulatory proteins. It was the purpose of the present study to examine the effects of Cyclosporin A on human gingival fibroblasts by means of biological and biochemical criteria. In this present study, we examined change of cell proliferation, cell activity, cell viability and cell cycle progression after application of Cyclosporin A. We also examined expression of cell cycle regulatory proteins by western blot analysis. Human gingival fibroblasts were cultured for 48 hours with application of Cyclosporin A at concentrations of 0.01, 0.1, 1, and 10 ng/ml. Cyclosporin A(1 ng/ml) significantly increased the cell activity of gingival fibroblast. Proliferation and viability of gingival fibroblasts were also increased in group treated with 1 ng/ml of Cyclosporin A compared to control group. In the cell cycle analysis, S phase was increased and G1 phase was decreased in the group treated with 1 ng/ml of Cyclosporin A. Cyclosporin A increased the expression of cdk4 and inhibited the expression of pRB and p21. These results suggest that 1 ng/ml of Cyclosporin A may increase the cell cycle progression of human gingival fibroblasts, and its mechanisms may increase the expression of cdk4 and decrease the expression of pRB and p21.

• Journal of Periodontal and Implant Science
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• v.31 no.3
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• pp.597-610
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• 2001

Normal gingival fibroblasts functioning is fundamental for the maintenance of periodontal connective tissue as well as wound healing. Nicotine have been found to affect DNA synthesis and cell proliferation, which appear to depend on the type of cells. This in vitro study was done to determine the effects of nicotine, a major component of tobacco, on cell proliferation, viability, activity, cell cycle distribution, and expression of cell cycle regulatory proteins in human gingival fibroblasts. Nicotine has been tested for 2 days or 4 days in 5 different concentrations; $0.1{\mu}g/ml$; $1{\mu}g/ml$; $10{\mu}g/ml$; $100{\mu}g/ml$; $1000{\mu}g/ml$. To assess cell proliferation and viability, viable and non-viable cells were counted by hemocytometer; to evaluate cellular activity, MTT assay was employed; to analyze cell cycle distribution, fluorescent propidium iodide-DNA complex were measured using fluorocytometer; to determine the expression of cell cycle regulatory proteins, western blot analysis was performed. After 2 days and 4 days incubation respectively, at concentrations of $1{\mu}g/ml$ - $1000{\mu}g/ml$, nicotine significantly inhibited proliferation comparing to non-supplemented controls. The cell viability was significantly decreased after 2 days and 4 days at concentrations of $1{\mu}g/ml$ - $1000{\mu}g/ml$ and at $10{\mu}g/ml$ - $1000{\mu}g/ml$ respectively. After 2 days and 4 days, the cellular activity was significantly decreased at concentrations of $10{\mu}g/ml$ - $1000{\mu}g/ml$. Treatment with $100{\mu}g/ml$ nicotine for 48 hours caused an increase in the proportion of G1-phase cells (from 46.41% to 53.46%) and a decrease in the proportion of S-phase cells (from 17.80% to 14.27%). The levels of cyclin $D_1$ and CDK 4 proteins in nicotine-treated fibroblasts were lower than that of controls, whereas the levels of p16 and pRB were higher than that of controls. These results suggest that the decrease of cell proliferation and lengthened Gap phases (G1) by nicotine may due to the increased expression of p16 and pRB as well as decreased expression of cyclin $D_1$ and CDK 4 in human gingival fibroblasts.

• Journal of Periodontal and Implant Science
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• v.32 no.1
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• pp.13-23
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• 2002

The ultimate goal of periodontal therapy is directed to arresting the progression of the disease, and regenerating the fibrous attachment. In order to achieve such treatment aim, the plaque and calculus must be eliminated and the physiological conditions of the root surface must be changed to facilitate the attachment and migration of the new fibroblasts, The method of changing the proper root surface conditions to promote the healing of periodontal tissue involves mechanical procedures, such as scaling and root planing, and chemical procedures such as tetracycline-HCl. However, the formation of a long junctional epithelium was most frequently observed type of healing. Thus, the aim of this study was to examine in vitro the influence of surface conditioning of dentin by TC-HCl on human gingival epithelial cell attachment. Human gingival epithelial cells were obtained from healthy retromolar pad area(under the age 23 years). Seventy two teeth extracted from severe periodontitis were used as study material. To evaluate the epithelial cell attachment to dentin, the prepared specimen was divided to four groups. For the control group, only scaling and root planing were carried out, and for the test group, 1 to 3, the concentration of the TC-HCl was 50, 125 and 250mg/ml respectively. After cell cultivation time of 1-, 3-. 24 hour, for the indirect quantitative assessment of gingival epithelial cell attached to dentin sample, the absorbance of epithelial cell unattached to dentin was measured. The results were as follows; 1. There was no statistically significant difference between scaling and root planing group and TC-HCl 50mg/ml 125mg/ml and 250mg/ml group about absorbance of unattached epithelial cell to dentin sample(p>0.5). 2. As time passes, the absorbance of unattached gingival epithelial cell to dentin sample was decreased statistically significant(p<0.05). 3. There was no statistically significant difference among the TC-HCl group(p>0.05) We concluded that there was similar effect on gingival epithelial cell attachment between TC-HCl conditioning on root surface and only scaling and root planing treatment

• Journal of Periodontal and Implant Science
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• v.36 no.4
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• pp.849-861
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• 2006

타이타늄은 기계적 특성이 우수하고 생체적합성이 뛰어나 의료용 장비의 주 재료로 사용되고 있으며 타이타늄 보다 기계적 특성이 더 우수한 타이타늄 합금들(주로 Ti-6Al-4V와 Ti-6Al-7Nb 합금)도 개발되어 치과와 의료용 임플란트로 사용되고 있다. 그러나 타이타늄 합금 성분들 중 알루미늄 (aluminum)과 바나디움(vanadium)은 인체에 노출되면 세포손상과 신경계에 문제를 일으킬 수 있다. 따라서 인체에 독성이 없으면서 기계적 성질과 생체적합성이 우수한 타이타늄 합금의 개발이 필요하다. 최근 인체에 독성이 없는 성분들이 함유된 새로운 ${\beta}$ - 형태의 타이타늄 합금들이 개발되고 있는데, ${\beta}$ - 타이타늄 합금은 그 기계적 성질이 기존의 ${\alpha}+{\beta}$ 타이타늄 합금에 비해 우수하다고 알려져 있다. 최근 새로운 ${\beta}$ - 타이타늄 합금이 전남대학교 부설 타이타늄 연구소에서 개발되었다. 이 연구는 새로 개발된 ${\beta}$ - 타이타늄 합금의 생채 적합성을 세포 증식도, 알카리 인산 분해 효소 활성과 유전자 증폭을 통해 알아보고자 하였다. 그 결과는 다음과 같다; 1. Titanium-6aluminum-4vanadium (Ti-6Al-4V) 합금 표면애서의 세포 증식율은 Titanium-Titanium8Tantalum-3Niobium (Ti-8Ta-3Nb) 합금과 순수 타이타늄 표면에 비해 유의하게 낮았다(p<0.00l). Ti-8Ta-3Nb 합금 표면에서의 증식도는 순수 타이타늄 표면과 유사하였다. 2. Ti-8Ta-3Nb 합금과 순수 타이타늄에서 배양된 세포이 알카리 인산 분해 효소의 활성도는 Ti-6Al-4V 합금에서의 것보다 유의하게 높았다 (p<0.001). 3. 유전자 증폭 분석 결과, Ti-8Ta-3Nb 합금과 순수 타이타늄에서 collagen type I과 bone sialoprotein mRNA 가 유사한 수준으로 발현되었다. 이상의 결과는 생체 적합성 측면에서 Ti-8Ta-3Nb 합금과 순수 타이타늄의 차이가 없음을 보여주며 따라서 Ti-8Ta-3Nb 합금이 의학 및 치의학 영역에서 새로운 임프란트 재료로 사용될 수 있음을 의미한다.

• Journal of Periodontal and Implant Science
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• v.35 no.4
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• pp.1053-1071
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• 2005

To find out the suppressive effect of natural extract Curcuma xanthorrhiza on $IL-1{\beta}$ and MMP-2 derived from periodontal ligament cells through in vitro study and to confirm its effect on plaque and gingivitis through clinical study, Curcuma xanthorrhiza containing toothpaste was used and following results were produced. 1. In vitro study, type IV collagenase MMP-2 production was inhibited dose-dependently in the group treated with Curcuma xanthorrhiza compared to the control group. 2. In vitro study, the production of $IL-l{\beta}$ which is one of the inflammatory mediators associated with periodontitis was inhibited dose-dependently in the group treated with Curcuma xanthorrhiza. 3. On the third week, the plaque index of the groups treated with or without Curcuma xanthorrhiza containing toothpastes were both increased significantly compared to the baseline(p<0.05). 4. On the third week, the gingival index of the group treated with Curcuma xanthorrhiza containing toothpaste was not significantly different from baseline. However, the group treated without Curcuma xanthorrhiza containing toothpaste showed a significant increase of gingival index at shielded area(p<0.05). 5. The gingival index of the group without Curcuma xanthorrhiza containing toothpaste showed a significant increase in the sites without tooth brushing when compared to sites with tooth brushing(p<0.05). However. there was no significant difference for the group with Curcuma xanthorrhiza containing toothpaste in sites either with or without tooth brushing. 6. The Bleeding on probing for the group without Curcuma xanthorrhiza containing toothpaste showed no significant difference even when tooth brushing was done. However, for the group with Curcuma xanthorrhiza containing toothpaste, bleeding on probing was significantly reduced compared to baseline when tooth brushing was done(p<0.05).

• Journal of Periodontal and Implant Science
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• v.48 no.1
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• pp.34-46
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• 2018

Purpose: The purpose of this study was to evaluate the effects of 1,25-dihydroxyvitamin $D_3$ on the proliferation, differentiation, and matrix mineralization of MC3T3-E1 osteoblast-like cells in vitro. Methods: MC3T3-E1 osteoblastic cells and 1,25-dihydroxyvitamin $D_3$ were prepared. Cytotoxic effects and osteogenic differentiation were evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, alkaline phosphatase (ALP) activity assay, ALP staining, alizarin red S staining, and reverse transcription-polymerase chain reaction (RT-PCR) for osteogenic differentiation markers such as ALP, collagen type I (Col-I), osteocalcin (OCN), vitamin D receptor (VDR), and glyceraldehyde 3-phosphate dehydrogenase. Results: The MTT assay showed that 1,25-dihydroxyvitamin $D_3$ did not inhibit cell growth and that the rate of cell proliferation was higher than in the positive control group at all concentrations. ALP activity was also higher than in the positive control group at low concentrations of 1,25-dihydroxyvitamin $D_3$ ($10^{-10}$, $10^{-12}$, and $10^{-14}M$). RT-PCR showed that the gene expression levels of ALP, Col-I, OCN, and vitamin D receptor (VDR) were higher at a low concentration of 1,25-dihydroxyvitamin $D_3$ ($10^{-12}M$). Alizarin red S staining after treatment with 1,25-dihydroxyvitamin $D_3$ ($10^{-12}M$) showed no significant differences in the overall degree of calcification. In contrast to the positive control group, formation of bone nodules was induced in the early stages of cell differentiation. Conclusions: We suggest that 1,25-dihydroxyvitamin $D_3$ positively affects cell differentiation and matrix mineralization. Therefore, it may function as a stimulating factor in osteoblastic bone formation and can be used as an additive in bone regeneration treatment.

• Journal of Periodontal and Implant Science
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• v.36 no.2
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• pp.385-396
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• 2006

For the regeneration of periodontal tissues, the microenvironment for new attachment of connective tissue fibers should be provided, At this point of view, cementum formation in root surface plays a key role for this new attachment. This study was performed to figure out which factor promotes differentiation of cementoblast Considering anatomical structure of tooth, we selected the cells which may affect the differentiation of cementoblast - Ameloblast, OD11&MDPC23 for odontoblasts, NIH3T3 for fibroblsts and MG63 for osteoblasts. And OCCM30 was selected for cementoblast cell line. Then, the cell lines were cultured respectively and transferred the conditioned media to OCCM30. To evaluate the result, Alizarin red S stain was proceeded for evaluation of mineralization. The subjected mRNA genes are bone sialoprotein(BSP), alkaline phosphate(ALP) , osteocalcin(OC), type I collagen(Col I), osteonectin(SPARC ; secreted protein acidic and rich in cysteine). Expression of the gene were analysed by RT-PCR, The results were as follows: 1. For alizarin red S staining, control OCCM30 didn't show any mineralized red nodules until 14 days. But red nodules started to appear from about 4 days in MDPC-OCCM30 & OD11-OCCM30. 2. For results of RT-PCR, ESP mRNAs of control-OCCM30 and others were expressed from 14 days, but in MDPC23-OCCM30 & OD11-OCCM30 from 4 days. Like this, the gene expression of MDPC23-OCCM30 & OD11-OCCM30 were detected much earlier than others. 3. For confirmation of odontoblast effect on cementoblast, conditioned media of osteoblasts(MG63) which is mineralized by producing matrix vesicles didn't affect on the mineralized nodule formation of cementoblasts(OCCM30). This suggest the possibility that cementoblast mineralization is regulated by specific factor in dentin matrix protein rather than matrix vesicles. Therefore, we proved that the dentin/odontoblast promotes differentiation/mineralization of cementoblasts. This new approach might hole promise as diverse possibilities for the regeneration of tissues after periodontal disease.

• Journal of Periodontal and Implant Science
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• v.35 no.2
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• pp.345-357
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• 2005

Prostaglandin plays a significant role in the local control of bone metabolism associated with periodontal disease. ${\Delta}^{12}-PGJ_2$ is a natural $PGD_2$ metabolite that is formed in vivo in the presence of plasma. It is known for ${\Delta}^{12}-PGJ_2$ to stimulate calcification in osteoblastic cells. Bone morphogenetic protein(BMP) stimulated osteoblastic differentiation in various types of cells and greatly enhanced healing of bony defects. The purpose of this study was to evaluate the effect of rhEMP-2 on ${\Delta}^{12}-PGJ_2$ induced osteoblastic differentiation and mineralization in vitro. A human osteosarcoma cells line Saos-2 were cultured. In the test groups, 10-7M of ${\Delta}^{12}-PGJ_2$ or mixture of 10-8M of ${\Delta}^{12}-PGJ_2$ and 100ng/ml of rhBMP-2 or 100ng/ml of rhEMP-2 were added to culture media. After 1 day, 2 days and 4 days of culture period, the cell number was measured. Alkaline phosphatase activity was measure at 3 days. Reverse transcription polymerase chain reaction(RT-PCR) was performed to determine the expression of mRNA of bone matrix protein at 8 hours, 1 day and 7 days. The ability to produce mineralized nodules in rat osteoblasts(MC3T3-E1) was evaluated at 21 days. The results were as follows : 1. rhEMP-2 or mixture of rhBMP-2 and ${\Delta}^{12}-PGJ_2$ inhibited cell proliferation of human osteosarcoma cells. 2. rhEMP-2 or mixture of rhBMP-2 and ${\Delta}^{12}-PGJ_2$ stimulated alkaline phosphatase activity significantly higher than ${\Delta}^{12}-PGJ_2$ alone. 3. rhBMP-2 or mixture of rhEMP-2 and ${\Delta}^{12}-PGJ_2$ stimulated mineralization compared to ${\Delta}^{12}-PGJ_2$ alone. 4. mRNA of alkaline phosphatase, BMP-2, cbfa 1, Type I collagen were detected in the group treated with ${\Delta}^{12}-PGJ_2$/rhBMP-2, rhBMP-2 alone, ${\Delta}^{12}-PGJ_2$ alone. These results show that mixture of ${\Delta}^{12}-PGJ_2$ and rhBMP-2 causes more bone formation than ${\Delta}^{12}-PGJ_2$ alone while the bone formation effects of mixture of ${\Delta}^{12}-PGJ_2$ and rhBMP-2 are less than those of rhBMP-2 alone. Further researches would be necessary to clarify the interactions of these agents.