Cementomas result from the odontotic epithelial-mesenchymal complex and are located mainly in the area of large and small molar teeth of the mandible. There was an extremely rare cement location in the analyzed clinical cases. In the first case, cementoma of the frontal sinus spread into the ethmoidal sinus and eye socket in a female patient aged 38 years. The tumor is manifested by right frontalorbital pain and exophthalmos. There were no problems in removing the tumor and repairing the defect of the skull base. The second case was an extensive tumor in a 11-year-old child, which involves the maxillary, ethmoidal, and sphenoidal sinuses, by damaging the bones of the skull base. Tumor removal gave rise to an extensive defect of the skull base which the dura mater protruded through. In this case the important stage was closure of the defect of the dura mater and that of the skull base with the dura mater protruding through. This defect could be successfully closed with a pedicle musculoperiosteal flap of the musculus temporalis by fixation with sutures and fibrinthrombin glue.