Krox-25, a Kruppel type zinc finger protein, may play an important role for the morphogenesis of tooth in ectomesenchymal interaction between enamel epithelium and odontogenic mesenchyme. The interrupted expression of Krox-25 by antisense inhibition is supposed to affect the abnormal development of tooth germ similar to the deranged proliferation of odontogenic tumors. This study was performed to know the histomorphogenetic effect of Krox-25 antisense inhibition in tooth germs of mouse embryos and to understand the abnormal expressions of Krox-25 in different odontogenic tumors which proliferate in aberrant direction of ecto-mesenchymal interaction. Total 95 tooth germs obtained from pregnant mice in the 13th day of fertilization were cultured with antisense oligonucleotides targeting mouse Krox-25 gene, and their histological patterns were compared with those of different odontogenic tumors, i.e., ameloblastic fibro-odontoma (n=5), ameloblastoma (n=8), and ameloblastic carcinoma (n=2). Resultantly, the cultured tooth germs treated with antisense oligodeoxynucleotides produced primitive dentine and enamel by odontoblasts and ameloblasts, respectively, but they aberrantly grew and formed abnormal tooth organs. Especially, the harmonious growth of enamel and dentine formation was greatly deranged by the antisense inhibition in the organ culture system. These findings were much similar to the abnormal growth of odontogenic tumors. The relatively well differentiated enamel epithelium of ameloblastic fibro-odontoma showed irregularly strong reaction of Krox-25, while the poorly differentiated enamel epithelium of ameloblastic carcinoma showed weak reaction. These data suggest that Krox-25 may play important roles for the histomorphogenesis of tooth germ by signaling the ecto-mesenchymal interaction between odontoblasts and ameloblasts in normal tooth germ development of mouse embryos as well as in cytodifferentiation of odontogenic tumors.

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.

World Health Organization(WHO) revised the classification of neoplasms and other tumours related to odontogenic apparatus in 1992. The aim of this study was to classify the odontogenic tumors of Korean according to the WHO Histologic classification. A total of 271 cases were reviewed for the study which were diagnosed as odontogenic tumors at the department of Oral Pathology, Yonsei University College of Dentistry for the period from Jan. 1997 to March 2003. Clinical and pathology reports were reviewed & radiographic feature were examined. The following results were obtained : 1. Among 271 cases, 269 cases(99.3%) were diagnosed as benign odontogenic tumors, and the remaining 2 cases(0.7%) were malignant tumors, which were diagnosed as odontogenic ghost cell carcinoma and squamous cell carcinoma ex odontogenic cyst. 2. Four cases were not able to classify into the WHO classification. All of them were belonged to mixed odontogenic tumors; two cases of adenomatoid odontogenic tumor with calcifying epithelial odontogenic tumor, one case of adenomatoid odontogenic tumor with odontoma, odotogenic cyst and one case of ameloblastoma with immature odontoma. 3. The most frequent odontogenic tumour was odontoma(45.2%), followed by ameloblastoma (29.2%), odontogenic fibroma(9.2%) 4. One case of atypical amelobalstoma and one case of calcifying odontogenic cyst with ameloblastic fibroma were not able to subclassify histologically. 5. Male to female ratio of odontogenic tumors was 1.2:!. Odontogenic tumors mainly occured in the first and second decade, occurred twice as much as in the mandible than in the maxilla 6. The odontogenic tumors was discovered by routine oral x-ray examination, whereas the chief complaint of ameloblastoma were swelling, pain. 7. Ameloblastoma, adenomatoid odontogenic tumor, calcifying odontogenic cyst and odontoma were related to the impacted teeth and tooth displacement. The root resorption was frequently observed in ameloblastoma and calcifying odontogenic cyst.