الفهرس 
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Abstract
Recent reports have indicated that angiogenesis and mast cells possibly affects the biologic behavior of the lesions. The aim of this study was to determine the density of microvessels and mast cells in odontogenic cysts. The relationship between microvessels and MCs was evaluated to assess the role of MCs and angiogenesis in growth of odontogenic cysts. This will make the concept of contribution of angiogenesis and MCs to the growth and pathogenesis of the odontogenic cysts more clear and may help for planning future nonsurgical treatment strategies targeting MCs. In this work, the study samples included 45 paraffin blocks of odontogenic cysts, three groups of cysts were considered (RC, DC and OKC, 15 cases of each type). Cysts were evaluated for the angiogenic activities and presence of MCs in their connective tissue capsule. Odontogenic keratocysts and dentigerous cysts were subdivided into inflamed and not inflamed cysts, according to the presence or absence of inflammatory cells in connective tissue wall. Four micrometer thick tissue sections were stained through standard immunohistochemistry for identification of CD 105 antigen. The staining procedures was done according to the instructions of the manufacturer. Histochemical stain (Toluidine blue) was used for clarification of mast cells. For angiogenesis and MC counting, the sections were scanned at 200X magnifications. Hot spot fields (the fields most populated by microvessels and MCs) were identified and five representative high power fields at 400X magnification were analyzed in each section. The mean of five fields was considered as the total count for each sample. Scores of overall MVD and MCD were represented as mean density/mm2 ± SD for quantitative variables using SPSS (Statistical package for Social Siences) software. Comparisons among the experimental groups were done using One-way analysis of variance test (ANOVA) (p˂0.05). To compare the number of microvessels and MCs between inflamed and non-inflamed DCs and OKCs, independent t-test was used. Pearson correlation coefficient test was used to determine the correlation between MVD and MCD. Vascular endothelial cells, stained by CD105, were clearly identified by their brown cytoplasmic staining. On the other hand, mast cells stained by toluidine blue, were stained purple in their cytoplasm and the rest of the section stained blue. Results revealed that, RC and OKC showed the highest mean numbers of microvessels and MCs with statistically significant difference when compared to DCs. The inflamed OKCs and DCs contained more microvessels and MCs compared to their non inflamed counterparts. A positive correlation between the numbers of microvessels and MCs was observed but not statistically significant. The conclusion of the present study was: 1. Increase in angiogenesis of OKC confirms that aggressive lesions require a larger number of blood vessels and highlights the concept of unique clinical behavior of this cyst. 2. In OKCs and DCs cysts, the MVD is closely related to of the inflammatory infiltrate. 3. Mast cells are imperative in the pathogenesis of odontogenic cysts. 4. Mast cells have a role in promoting the growth of odontogenic cysts, particularly OKC. Recommendations: 1. Further investigations on large scale of odontogenic lesions are required to make the role of mast cells and angiogenesis in odontogenic cysts more clear. 2. Targeting of mast cells may be useful for treatment of odontogenic cysts. 3. Management of angiogenesis may help in controlling the growth of OKCs.