An odontogenic infection is an infection that originates within a tooth or in the closely surrounding tissues. The term is derived from odonto- (from ancient Greek odous - "tooth") and -genic (from Greek genos - "birth"). Odontogenic infections may remain localized to the region where they started, or spread into adjacent or distant areas.
It is estimated that 90-95% of all orofacial infections originate from the teeth or their supporting structures. Furthermore, about 70% of odontogenic infections occur as periapical inflammation, i.e. acute periapical periodontitis or a periapical abscess. The next most common form of odontogenic infection is the periodontal abscess.
Odontogenic sinusitis
Sinusitis is inflammation of the paranasal air sinuses. Infections associated with teeth may be responsible for approximately 20% of cases of maxillary sinusitis. The cause of this situation is usually a periapical or periodontal infection of a maxillary posterior tooth, where the inflammatory exudate has eroded through the bone superiorly to drain into the maxillary sinus. Once an odontogenic infection involves the maxillary sinus, it is possible that it may then spread to the orbit or to the ethmoid sinus.