Computed tomographic indices for maxillary sinus size in comparison with the sinus volume

To ascertain the normal range of maxillary sinus size and its changes with age on computed tomography (CT) and define convenient indices for sinus size, in addition, to examine the association of the height of the sinus floor with age and status of the dentition. The transverse and anteroposterior dimensions of the normal maxillary sinuses in 107 subjects were measured on axial CT and the relationship between these values and the sinus volume analysed. The height of the sinus floor was obtained by measuring the vertical distance from the anterior nasal spine to the sinus floor. The mean transverse and anteroposterior widths of the normal adult maxillary sinuses were 2.70 (s.d., 0.60) cm and 3.56 (s.d., 0.47) cm, respectively. There was a close correlation with sinus volume which could be predicted well from the multiple regression formula. These values increased up to the age of 20 y, but then decreased. There was no significant difference between subjects aged 50-79 years with and without maxillary premolars and molars. The width of the adult sinus correlated with the interzygomatic buttress distance and body weight. The mean height of the adult maxillary sinus floor was 0.37 (s.d., 0.44) cm inferior to the anterior nasal spine. It correlated negatively with sinus volume and fell with age up to 20 y, then rose again. In adults, it was not significantly influenced by the dentition status, and rose in proportion to the decrease in the interzygomatic buttress distance, and body height and weight. The transverse and anteroposterior widths of the maxillary sinus on axial CT are convenient indices for its size. The height of the sinus floor altered with changes in sinus volume, but was not directly influenced by the status of the dentition.