<prompt> Which one of the following is NOT true of Ameloblastoma -Most common odontogenic tumourGenerally benignCommon in 3rd to 5th decadeArises from mesenchymal tissue  <response>: AmeloblastomaAmeloblastoma is the most common benign odontogenic tumor.It is benign but locally invasive.It is common in the 3rd to 5th decades of life.Preferential sites are the mandible in the molar-ramus area and maxilla.The tumor is epithelial in origin - arises from the dental epithelium of enamel.Tumor with a histologic resemblance to ameloblastoma can occur occasionally in the long bone, like adamantinoma of the tibia. 