Cementoma is an odontogenic tumor

Tumor

A tumor or tumour is commonly used as a synonym for a neoplasm that appears enlarged in size. Tumor is not synonymous with cancer...

 of cementum

Cementum

Cementum is a specialized calcified substance covering the root of a tooth. Cementum is excreted by cells called cementoblasts within the root of the tooth and is thickest at the root apex. These cementoblasts develop from undifferentiated mesenchymal cells in the connective tissue of the dental...

.It occurs in usually after root development is finished but before the age of 25. It is found most commonly in the mandible in the region of the lower molar teeth. It causes distortion of its sourrounding areas but is a usually painless growth , at least initially. Considerable thickening of the cementum can often be observed. A periapical form is also recognized.