86 THE NOSE AND PARANASAL SINUSES CYSTS OF THE MAXILLARY SINUS Cysts of the maxillary sinus are usually of dental origin and are called dental cysts. If the cyst contains a tooth it is termed a dentigerous cyst. The cause of a dental cyst lies in the periodontium or periosteum of a diseased upper premolar or molar tooth. The cyst enters the antrum through its floor and gradually enlarges until it may distend the sinus cavity by pressure on its walls. Dental cysts may occur at any age. Fig. 40. Cyst almost filling the maxillary antrum of a child. SYMPTOMS. The cyst may be entirely painless, giving rise to no symptoms and being discovered accidentally. Infection within the cyst causes toothache^ and pain in the infra-orbital region. Similarly, distension of the sinus produces local pain. CLINICAL FEATURES. Clinical examination may be negative if the cyst is small. When the antrum becomes enlarged there may be a fullness of the inferior meatus or even of the hard palate, and palpation of the gingivolabial fold gives a sensation of crackling elasticity. Radiography will show a spherical dense area in the floor of the maxillary sinus if the cyst is small (Fig. 40). When the cyst fills the antrum there is a homogeneous opacity, and if it contains a tooth this will be seen on radiography (Fig. 41). TREATMENT. Proof puncture of the affected antrum will produce clear greenish or amber-coloured fluid which may issue through the cannula when the trocar is withdrawn. The rest of the contents may be aspirated into a syringe through a blunt-pointed needle inserted through the cannula. This in itself may cure the condition if dental attention is given to the unhealthy tooth. If the cyst is large or infected, or if it should contain a tooth, a Caldwell-Luc operation is performed and the entire cyst removed.