In 1863,the term odontoma was introduced by Paul Broca which he described as a tumor formed by overgrowth of transitory or complete dental tissue.The World Health Organization classified them under mixed benign odontogenic tumors because of their origin from epithelial and mesenchymal cells exhibiting different structures of dental tissue (enamel,dentin,cementum and pulp).There are two distinct  types:  compound  and  complex.  Compound  odontoma  is composed of all odontogenic tissue in an orderly fashion resulting in many teeth-like structures but with no morphological resemblance to normal teeth whereas a complex odontoma appears as an irregular mass with no similarity even to rudimentary teeth.
The pathogenesis of odontomas has not been completely established although the most accepted etiology is related to trauma, infection, growth pressure and genetic mutations in one or more genes that cause disturbances in the mechanism controlling tooth development.
Patients with compound odontoma are often asymptomatic. It is usually detected on routine radiography upon examination of an unerrupted tooth.Odontomas can occur anywhere in the jaws and are usually found associated with or within the alveolar process.
However,the presence of an odontoma in the maxillary sinus is very rare.We present a female patient with a compound odontoma in the maxillary sinus initially managed as nasal vestibulitis with maxillary sinusitis.