Methods: A total of 30 maxillary first molars and 30 maxillary second molars from 17 patients were examined with CBCT. For each root the shortest distance to the maxillary sinus was determined in sagittal, coronal and axial planes, using in-built measurement tools. Means, standard deviations, minimum and maximum values and frequency of root protrusion were calculated for all roots.

Results: The distance between sinus floor and root tip was longest for the first molar mesiobuccal root and shortest for the second molar distobuccal root.

Conclusions: Knowledge of the anatomical relationship between the maxillary sinus floor and the maxillary posterior teeth root tips is important for the preoperative treatment planning of maxillary posterior teeth.

Keywords: CBCT, Maxillary molar roots, Maxillary sinus, Endodontic implications