Relationship of maxillary posterior roots to the maxillary sinus and cortical bone: a cone beam computed tomographic study.

This study evaluated the relationship between the apices of maxillary posterior teeth (second premolar, first molar, and second molar) and the maxillary sinus floor (MSF) and maxillary cortical bone (MCB). Cone beam computed tomographic (CBCT) scanning was used to analyze 1660 roots from 678 teeth and determine the shortest distance between the root apex and MSF and between the root apex and buccal and palatal cortices of maxillary bone. The root apices were classified based on their relationship to the MSF: type 1, the root apex protruded into the maxillary sinus; type 2, the root apex was from 0 mm (touching the MSF) to 1 mm below the MSF; and type 3, the root apex was greater than 1 mm below the MSF. As the age of the subjects increased (older than 40 years), there was a significantly greater proximity of the teeth to the MCB (P < 0.05) and less proximity of second molars to the MSF (P = 0.005). First and second molars each presented a high prevalence of root apices that protruded into the maxillary sinus (type 1), 47.8% and 43.8%, respectively. Second premolars were more frequently classified as type 3 (71.7%) than first and second molars. The mesiobuccal root of the maxillary second molar was the root closest to the MSF, while the maxillary first molar was the tooth closest to the MCB.