A teaching model to illustrate the variation in size and shape of the maxillary sinus.

A technique to produce teaching models of the maxillary sinus is described. Dental impression material is injected into the maxillary sinus of a cadaver and subsequently dissected out. Using an impression and mould technique in a series of steps, a stone model of the maxillary sinus is produced. The shape, size and configuration of the model can be seen and the dimensions measured. A radiopaque impression material can be used so that the radiographic outline of the maxillary sinus on standard radiographic projections can be shown. Models of both dentate and edentulous patients can be used to show anatomical variation and the relationship to teeth and are useful in teaching both gross and radiographic anatomy. Since 10 out of 11 specimens had 3 walls leading to the apex from a 4-sided base, it would appear that the classical description of a 4-sided pyramidal shape to the maxillary sinus is relatively uncommon.