to malignant transformation. Oral leukoplakia is a common premalignant lesion in oral mucosa and the incidence of cancer progression into SCC has been reported to be 0~43%. The genetic alterations of oncogenes, tumor suppressor genes and DNA repair genes occur during carcinogenesis. In order to evaluate the role of epithelial cells in the early stage of carcinogenesis, we analyzed the alterations of genetic heterogeneity in epithelial cells of oral leukoplakia samples, using Laser capture microdissection(LCM). The incidence rate of microsatellite instability(MSI) and loss of heterozygosity(LOH) were analysed from the DNA of epithelial cells from 16 leukoplakia samples using adjacent fibroblasts as a normal control. In this study, LOH was found in epithelial cells of all 16 cases of leukoplakias while MSI has been observed in 3 cases. Interestingly, the fibroblasts showed LOH and MSI in some cases, which was confirmed by DNA sequencing. Taken together, this study showed that leukoplakia has multiple genetic alterations in fibroblasts as well as in epithelial cells, suggesting that interaction between epithelial cells and fibroblasts might be involved in the early step of carcinogenesis.
The purpose of this study was to evaluate the role of integrin α3 and integrin β1 in the ameloblastomas. For this study, 10 specimens diagnosed as amoblastomas referred to the Department of Oral Pathology, School of Dentistry, Kyung Hee University, and 5 specimens of normal oral mucosa without any inflammatory changes were used as experimental and control groups, respectively. The ameloblastomas devided into follicular type, plexiform type, acanthomatous type, and granular cell type. All specimens; experimental and control group were fixed in 10% neutral formalin solution and embedded in paraffin, and then the serial tissue sections were made 5㎛ in thickness and processed for immunohistochemical observation. The specimens were incubated with primary antibody against integrin α3 or integrin β1, each was diluted at 1 : 100, followed by the Supersensitive non-biotin horse radish peroxidase detection system with DAB as chromogen. After counterstaining with Gill's hematoxylin stain method and mounted, and examined under the light microscope. Based on the intensity of the immunoreactivity, intensity of the immunity was scored no epithelial stain, weak or focal epithelial stain, moderate or focal intensive epithelial stain, intense generalized epithelial staining for the epithelial, and connective tissue component in ameloblastomas, and normal oral mucosa on each. Attained results as follows. Expression of integrin α3 in the oral mucosa, weak reaction was noted on the all layers of epithelium, and submucosa. Expression of integrin β1 in the oral mucosa, intense reaction on the superficial layer, moderate reaction in basal layer were shown. Expression of integrin α3 in ameloblastomas, it was noted that weak reaction on the ameloblast like cells in the all types and rarely in basement membrane. Expression of integrin β1 in ameloblastomas, intense reaction on the tumor cell ,and partly in the nuclei in follicular type was noted, And moderate reaction on the tumor cell in plexiform , acathomatous types, but weak reaction in granular cell type was shown. This results result suggest that integrin α3 may influenced negligibly, but the integrin β1 influenced significantly the development of the ameloblastomas considering the response is increased on the region with highly cellular activities
Angiogenesis is a process with a coordinated sequence of endothelial cell division, selective degradation of vascular basement membranes, and surrounding extracellular matrix with migration of theses cells that result in a new capillary growth from preexisting vessels. These processes are controlled by numerous different molecules. Among these, Vascular Endothelial Growth Factor(VEGF) is an endothelial cell-specific mitogen with a potent ability to induce microvessel permeability and angiogenesis. In this study, tissue samples of odontogenic keratocyst(10 cases), ameloblastoma(10 cases), adenomatoid odontogenic tumor(10 cases), calcifying epithelial odontogenic tumor(10 cases), ameloblastic carcinoma(2 cases) were obtained, and all specimen were routinely fixed in 10% formalin and embedded. Serial 5μm thick sections were cut from paraffin blocks. And the immunohistochemical staining, characteristics of VEGF about the cyst & tumor were observed & obtaned the results from this study. We presume that the growth of cyst is depends on not a differentiation but an epithelium & connective tissue. But, in odontogenic tumor, we presumed that the growth of tumor is influenced on inflammation & surrounding stimulus & vascular growth and supply. Therefore, it should be suggested that study on the growth of tumor and vascularity must be carrying out in this immunohistochemical study.
Considering the great potential of iron chelators at inhibiting the proliferation of tumor cells, in order to determine the molecular and biological basis for the effects of iron chelator in oral cancer, we investigated the effects of iron chelator, desferrioxamine (DFO), on the gene profiling analysis of immortalized human oral keratinocytes (IHOK), and oral cancer cells (HN12), using the cDNA microarray. We identified 46 clones cDNA exhibiting more than 2 fold overexpression in DFO treated IHOK and HN12 cells, and 94 cDNA reveal more than 2 fold down-regulated expression. Examination of gene expression that differs between DFO treated vs. control IHOK and HN12 cells apprear to be related to : cell cycle regulator, cell growth and apoptosis, signal transduction and stress. p21 for cell cell cycle factor was upregualted, and cyclin-cdk gene was decreased expression, so we observed cell cycle arrest in DFO treated IHOK and HN12 cells. In tumor growth, we have identified downregulation of hemidesmosomal protein (bullous pemphigoid antigen 1) and epiregulin expression in DFO treated IHOK and oral cancer cells. Signal transducers including mitogen-activated protein kinase-activated protein kinase 5, serine/thereonine kinase 6 were downregulated with DFO treated cells, suggesting the DFO regulates the p38 MAP kianse pathway in immortalized and maignant oral keratincytes. In conclusion, we have demonstrated the high-throughput utility of cDNA array hybridization in parallel to the gene expression analysis to identify genes that are expressed differentially in DFO treated with immortalized and malignant oral keratinocytes. The differentially expressed genes identified here should be informative in DFO-induced anti-cancer effects.
Demineralized Freeze Dried Bone(DFDB) graft material have been used for reconstruction of large bony defects or augmentation of thin alveolar ridge during implantation of titanium fixtures. But at present osteogenic effect of DFDB do not overcome the capacity of autogenic bone graft. Thus many investigators had applicated various bioactive substance to DFDB to enhance the ability of osteogenesis of DFDB. In this study, mixture of grafting material was made from fibrin glue(F) and DFDB(D)(group 1: F+D), fibrin glue, DFDB and rhBMP-2(B) (group 2: F+D+B), fibrin glue, DFDB, polylactic- co-glycolic acid(PLGA)(P) and rhBMP-2(goup 3: F+D+B+P), fibrin glue, DFDB, PLGA, rhBMP-2 and autogenic osteoblasts( O)(group 4: F+D+B+P+O), and fibrin glue, DFDB, autogenic osteoblasts (group 5: F+D+O). During first surgical procedure, extraction of molar teeth was performed at male Biggle dog's mandible, and collected bone marrow tissue from tibia at same Biggle dog. Collected bone marrow tissue was cultured and differentiated into osteoblasts in vitro, and stored in nitrogen bottle. After four months, titanium fixture was implanted with prepared graft material to Biggle dog's mandible. After four and eight weeks respectively, experimental dog was sacrificed. Obtained tissues were prepared for examination by using resin embedded ground section method. Prepared sections were evaluated with transmitted and polarized microscope, and areas of osteoid and cacified bone were calculated with IPTK 5.0( image processing tool kit version 5.0). Resultant data was statistically analyzed by SPSS 13.0 software. Results of this study showed that autogenic osteoblats had more enhancing capacity of bone formation than rhBMP-2, but PLGA inhibited bone forming potential of bony tissue.
The purpose of this study was to observe the histopathologic reaction in vital bone to various surface treated implants. For this purpose, ten New Zealand Albino rabbits, weighing 3.3 to 4kg were used as experimental animals. All the experimental groups divided into five groups; 1) Machined surface as control, 2) RBM(resorbable blast media), 3) RBM etched nitric acid solution, 4) RBM etched sodium hydroxide solution, 5) RBM etched acid, alkali, and heat treated group on each. All the surfaces of implants were examined under the scannning electron microscope to distinguish the differences between each experimental groups compare to that on the control group. All the rabbits were implanted into the tibial metaphyses of rabbits. On the 4th and 8th week after implantations, all the experimental rabbits were sacrificed. All the tissues containing each implanted materials were fixed in ethyl alcohol, and embedded in spurr resin as usual manner, sectioned in 10μm or more thickness, grinded, stained with the Villanuevaʼs osteochrome bone stain method and examined histopatholgically. For the fluorescence microscopic examination, three kind of fluorescence dyes, Oxytetracycline, Alizarin-Complexone, and Xylenol-Orange were injected to put into the bone to implant interface produced polychromatic fluorescence labelling on the 1st week, 2nd week, and 5th week on each. On the 8th week after experiments, the animals sacrificed, and the tissues containing the implants were taken, fixed in ethyl alcohol and embedded in spurr resin, sectioned, grounded 10um in thickness and examined under the fluorescence microscope. Following results were obtained; On the scanning electron microscopic examination of the implants, dull cracks, continuous linear indentations were revealed on the machined surface implant, irregular multiple leaflike eruptions on the RBM, and more sharp porous indentation with multiple complicated c rack s on the RBM acid etched surface, and more dull margins on complicated porous indentation on the RBM alkalic etched surface and more dull and less indented particles were noted on the RBM, acid, alkalic etched, heat treated surface, On the histopathologic examination, on the 4th week after experiment, complete osseointegation was noted between the implant and cortical bone on the collar and the apex lesion. and in parts, small newly formed bone spicules directly attached to the screws, and osteoid tissues were revealed in marrow tissues, in all experimental groups. On the histopathologic examination, on the 8th week after experiment, osseointegration is more increased compare to that on the 4th week group, the amount of bone trabeculae and osteoid tissues directly fused to screw of implants were markedly increased. On fluorescence examination, band or linear shape was witnessed on the boarder of compact bone and marrow tissues, and on bone trabeculae according to the formed age. and precipitated as granular and globular shape on the haversian canals. These results indicate that the surface treated method used for the present study render the implants compatible to bone tissue but the tissue compartibility is not different among the surface treated implants.
Cementum is a hard connective tissue, produced by cementoblasts during tooth root formation, which provides for the attachment of the periodontal ligament to the roots and surrounding alveolar bone. Establishment of this attachment is an important event in the regeneration of lost periodontal tissues. We examined whether or not odontoblast conditioned media(CM) have a regulatory influence on the differentiation and mineralization of cementoblasts(murine cementoblastic cell line, OCCM-30) in vitro. To identify the effect of odontoblast conditioned media and dentin non collagenous proteins (dNCPs) on cementoblast differentiation and mineralization, we treated CM and dNCPs to cementoblast then differentiated the cells for 14 days. To evaluate the formation of mineralized nodules alizarin-red S staining was performed at 0,4,7 and 14 days. Expression of cementum matrix genes was measured by RT-PCR. Mineralization of cementoblasts was accelerated with CM from odontoblastic MDPC-23 and OD-11. The expression of BSP, ALP, and OC mRNA in cementoblastic OCCM-30 cells was facilitated by the MDPC-23 and OD-11 cells. The extracted dNCPs had little influence on the proliferation, cell cycle modification, and chemotaxis of OCCM-30 cells. Although the dNCPs did not exhibit chemotactic activities for cementoblasts, the dNCPs promoted the differentiation and mineralization of cementoblasts. In conclusion, the dentin matrix protein, or the secreted products of odontoblast, facilitates cementoblast differentiation and mineralization. This represents a new approach and suggests another avenue for cementum regeneration.
Currently, implants are widely used in dental and medical fields. Especially dental implants are widely used for reconstruction of oral and maxillofacial defects. Many researcher's had studied for raising the osseointegration through various method. It was reported high success rate. Also they study the enhancing the speed of bone remodelling and osseointegration. Low level laser therapy is introduced one of the methods to accelerate the speed of bone remodelling and osseointegration. The purpose of this study was to evaluate the effect of diode laser irradiation about to raise ossoeintegration. Twenty four New Zealand white rabbits which were about 3Kg were used for experiment. Two implants were implanted same side of rabbits tibia. Diode laser was irradiated 1cm diameter, 0.5 watt power, 1 minute duration at periphery of one of implants. Eight rab b its were sacrificed every 2, 4, 8 weeks, made undecalcified sample. We investigated in the undecalcified samples histological and histomorphometrc analysis by light microscope. The results were as follows. 2 weeks, 4 weeks, 8 weeks experimental groups which were showed rapid bone remodelling than control groups. They showed many difference especially in early healing time. Bone Implant contact rate were 47% in 2 weeks experimental group. 28% in 2 weeks control groups, 82% in 4 weeks experimental groups, 62% in 4 weeks control groups, 98% in 8 weeks experimental groups and 84% in 8 weeks control groups then experimental groups show statistically significant difference(p＜0.05). Bone remodelling area rate inside the implant threads were 49% in 2 weeks experimental groups. 31% in 2 weeks control groups, 90% in 4 weeks experimental groups, 82% in 4 weeks control groups, 99% in 8 weeks experimental groups and 97% in 8 weeks control groups then 2,4 weeks experimental groups show statistically significant difference(p＜0.05). Implant-bone contact length rate and bone remodelling area rate were no significant difference of linear regression equation of control and experimental groups then bone remodelling were different at early healing time but there were no differences of time changes. According to above results, one of the low level lasers diode laser irradiation was effected on the volume of new bone formation in implant interface and between the implants threads. Low level laser irradiation were helpful for initial stage of bone remodelling.