Background and Objective: Although many helpful procedures are used in pathology for the prognosis of aggressive behavior of lesions, but their morphometric values were not detected. The purpose of the present study was to detect and compare the morphometric characteristics of KCOT and dentigerous cyst and to determine whether morphometric evaluation is a valuable and helpful method in the prognosis of aggressive behavior of these odontogenic lesions. Materials and Methods: This cross- sectional study was done on 40 paraffin blocks of above odontogenic lesions from the archive of Dentistry Faculty. After hematoxylin-eosin staining, special software was used for determination of mean nuclear and cytoplasmic area, nuclear to cytoplasmic ratio (N/C) in each layer and all layers of odontogenic epithelium, mean microvessel density (MVD) and number of inflammatory cells, the epithelial thickness, and ferret ratio (F,R) in these odontogenic lesions. Results: Mean nuclear and cytoplasmic area, N.C ratio in all layer of KCOT was 9551.1± 4543.1μm2, 20140.4 ± 7729.8 μm2, 0.47± 0.1 and in dentigerous cyst was 5166.9 ± 3082 μm2, 12232.1± 6191.8 μm2, and 0.4±0.9. Mean epithelial thickness, number of inflammatory cells and MVD, F.R in KCOT was higher than detigerous cyst (p < 0.001). Conclusion: From high nuclear to cytoplasmic ratio and high MVD, it is suggested that histomorphometry should be a helpful method in the prognosis of aggressive behavior of the above odontogenic lesions.
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