Eun-Kyoung Pang

Yonsei University, Seoul, Seoul, South Korea

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Publications (7)12.62 Total impact

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    ABSTRACT: OBJECTIVES: The objective of this study was to elucidate the socket healing process and biodegradation of incorporating synthetic bone fillers followed by grafting of the fresh extraction socket. MATERIALS AND METHODS: Third premolars in four quadrants of eight beagle dogs were extracted and randomly treated with either one of hydroxyapatite (HA), biphasic calcium phosphate (BCP), β-tricalcium phosphate (β-TCP), or no graft (C). Histologic observations and histomorphometric analysis at three zones (apical, middle, and coronal) of the socket were performed. Socket area (S) and the proportions of newly formed bone (%NB), residual biomaterials (%RB), and fibrovascular connective tissue (%FCT) at 2, 4, and 8 weeks were measured. The numbers of osteoclast-like multinucleated cells (No.OC) were also determined at the three zones. RESULTS: %NB was significantly higher in control group compared with the grafted groups at all healing periods. %NB of HA and BCP increased with time, whereas %RB showed different patterns that decreased in BCP, unlike the minimal change observed in HA. %NB of β-TCP showed smallest portion compared with other grafted groups at 2 and 4 weeks, however, significantly increased at 8 weeks. %RB of β-TCP was less than HA and BCP at all healing periods. Numbers of multinucleated cells were greater in BCP and β-TCP, followed by HA and smallest in control group. CONCLUSIONS: Within the limit of this study, bone formation of the extraction socket was delayed in the sockets grafted with synthetic bone fillers and showed different healing process according to the biodegradation patterns.
    Clinical Oral Implants Research 09/2012; · 3.43 Impact Factor
  • Source
    The Journal of The Korean Academy of Periodontology. 01/2009; 39(3).
  • Source
    Deug-Han Kim, Ji-Youn Hong, Eun-Kyoung Pang
    The Journal of The Korean Academy of Periodontology. 01/2009; 39(3).
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    ABSTRACT: Beta tricalcium phosphate (beta-TCP) has been developed as one of the carriers of recombinant human bone morphogenetic protein (rhBMP). However, it is not known whether the particle size of beta-TCP is related to its resorption rate and the degree of bone formation. The purpose of this study was to evaluate the effect of using beta-TCP with different particle sizes on the ability of rhBMP-4 to enhance bone formation in the rat calvarial defect model. Calvarial, 8-mm-diameter, critical-size defects were created in 100 male Sprague-Dawley rats. Five groups of 20 animals each received either rhBMP-4 (2.5 microg) using beta-TCP with a particle size of 50 to 150 microm, rhBMP-4 (2.5 microg) using beta-TCP with a particle size of 150 to 500 microm, a beta-TCP control with a particle size of 50 to 150 microm, a beta-TCP control with a particle size of 150 to 500 microm, or a sham-surgery control, respectively, and were evaluated by measuring their histologic and histometric parameters following a 2- and 8-week healing interval. There were no significant differences in the defect closure, new bone area, or augmented area between either the two rhBMP-4/beta-TCP groups or between the two beta-TCP control groups at 2 and 8 weeks. rhBMP-4 combined with either small- or large-particle beta-TCP had a significant effect on the induction of bone formation compared to either a small- or large-particle beta-TCP control or a sham-surgery control. Within the parameters of this study, varying the particle size of beta-TCP did not seem to have a significant effect on bone formation.
    Journal of Periodontology 06/2006; 77(5):765-72. · 2.40 Impact Factor
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    ABSTRACT: The purpose of this study was to evaluate the effect of chitosan on human periodontal ligament fibroblasts (hPDLF) in vitro and on bone formation in rat calvarial defects in vivo. Fibroblast populations were obtained from individuals with a healthy periodontium and cultured in alpha minimum essential medium (MEM) for the control group. For the experimental groups, cells were cultured in alpha-MEM containing chitosan at concentrations of 0.01, 0.1, 1, or 2 mg/ml. The 3-(4,5-dimethyl-thiazole-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, reverse transcription-polymerase chain reaction (RT-PCR) and the assay of alkaline phosphatase (ALPase) activity were performed. Eight mm calvarial critical-sized defects were created in 30 male Sprague-Dawley rats. The animals were divided into three groups of 10 animals each. The defects were treated with either chitosan/absorbable collagen sponge (ACS) or ACS alone in the experimental groups or were left untreated (surgical controls). The animals were sacrificed at 2 or 8 weeks post-surgery and the treatment outcomes were evaluated using histological and histomorphometric parameters. The chitosan-induced proliferative responses of the hPDLF reached a plateau at a concentration of 0.1 mg/ml (P <0.05). When the hPDLF were stimulated with 0.1 mg/ml chitosan, both the mRNA expression of type I collagen and the ALP activity were significantly up-regulated (P <0.05). The surgical implantation of chitosan/ACS enhanced the new bone formation at 8 weeks post-surgery and the amount of new bone formation of the chitosan/ACS group was significantly greater than that of both the ACS alone group and the surgical control group (P <0.01). The new bone area and defect closure in the chitosan/ACS group were significantly greater than those in the ACS control and sham surgery control groups at 8 weeks (P <0.01). However, the chitosan/ ACS group exhibited significantly less bone density than both the ACS control and the sham surgery control group at 8 weeks (P <0.01). Chitosan (0.1 mg/ml) enhanced the type I collagen synthesis and facilitated the differentiation into osteogenic cells. Chitosan reconstituted with ACS has a significant potential to accelerate the regeneration of bone in rat calvarial critical size defects.
    Journal of Periodontology 09/2005; 76(9):1526-33. · 2.40 Impact Factor
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    ABSTRACT: Bone morphogenetic proteins (BMPs) are being evaluated for periodontal and bone regenerative therapy. The objective of this study was to evaluate the effect of recombinant human bone morphogenetic protein-4 (rhBMP-4) dose on local bone formation in a rat calvaria defect model. Calvarial, 8 mm diameter, critical-size osteotomy defects were created in 140 male Sprague-Dawley rats. Seven groups of 20 animals each received either 1) rhBMP-4 (2.5 microg) in an absorbable collagen sponge (ACS) carrier, 2) rhBMP-4 (5 microg)/ACS, 3) rhBMP-4 (2.5 microg) in a beta-tricalcium phosphate (beta-TCP) carrier, 4) rhBMP-4 (5 microg)/beta-TCP, 5) ACS or 6) beta-TCP carrier controls, or 7) a sham-surgery control, and were evaluated by histologic and histometric parameters following a 2- or 8-week healing interval (10 animals/group/healing interval). Surgical implantation of rhBMP-4/ACS and rhBMP-4/beta-TCP resulted in enhanced local bone formation at both 2 and 8 weeks. Within the dose range examined, rhBMP-4 did not exhibit an appreciable dose-dependent response. Defect closure was not significantly different between the rhBMP-4/ACS and rhBMP-4/beta-TCP groups. New bone area of the rhBMP-4/ beta-TCP group was significantly greater than that of the rhBMP-4/ ACS group; however, bone density in the rhBMP-4/ACS group was significantly greater than that in the rhBMP-4/beta-TCP group at 8 weeks (P < 0.05). rhBMP-4 combined with ACS or beta-TCP has a significant potential to induce bone formation in the rat calvaria defect model. Within the selected rhBMP-4 dose range and observation interval, there appeared to be no meaningful differences in bone formation.
    Journal of Periodontology 11/2004; 75(10):1364-70. · 2.40 Impact Factor
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    ABSTRACT: Alveolar bone resorption is a characteristic feature of periodontal diseases and involves the removal of both the mineral and organic constituents of the bone matrix, which is caused by either multinucleated osteoclast cells or matrix metalloproteinases (MMPs). The gram-negative bacterium, Porphyromonas gingivalis has been reported to stimulate the activity and expression of several groups of MMPs, whereas (-)-epigallocatechin gallate (EGCG), the main constituent of green tea polyphenols, has been reported to have inhibitory effects on the activity and expression of MMPs. In the present study, we investigated the effects of the green tea polyphenol, EGCG, on the gene expression of osteoblast-derived MMP-2, -9 and -13, stimulated by P. gingivalis, and on the formation of osteoclasts. The effect of EGCG on the gene expression of MMPs was examined by treating mouse calvarial primary osteoblastic cells with EGCG (20 microM) in the presence of sonicated P. gingivalis extracts. The transcription levels of MMP-2, -9 and -13 were assessed by reverse transcription-polymerase chain reaction (RT-PCR). The effect of EGCG on osteoclast formation was confirmed by tartrate-resistant acid phosphatase (TRAP) staining in a co-culture system of mouse bone marrow cells and calvarial primary osteoblastic cells. Treatment with the sonicated P. gingivalis extracts stimulated the expression of MMP-9 mRNA and this effect was significantly reduced by EGCG, whereas the transcription levels of MMP-2 and MMP-13 were not affected by either the sonicated P. gingivalis extracts or EGCG. In addition, EGCG significantly inhibited osteoclast formation in the co-culture system at a concentration of 20 microM. These findings suggest that EGCG may prevent the alveolar bone resorption that occurs in periodontal diseases by inhibiting the expression of MMP-9 in osteoblasts and the formation of osteoclasts.
    Journal of Periodontal Research 11/2004; 39(5):300-7. · 1.99 Impact Factor