A Computed Tomographic Study of the Distances Between the Maxillary Sinus Floor and the Apices of the Maxillary Posterior Teeth

By Eberhardt JA, Torabinehad M, Christiansen EL

Date: 01/1992
Journal: OOO


To find the mean distance of the maxillary posterior tooth apices to the sinus, and the lateral thickness of adjacent bone over these apices.


  • N= 12 autopsy and 38 live pts (medical CT previously prescribed) exclusion of patients with craniofacial trauma, deformity, etc.
  • CT scan measurements compared to macroscopic autopsy measurements (no significant difference found). Protrusion into the sinus given a negative value. Contralateral teeth averaged for each tooth type.


  • An inverse relationship exists between the thickness of bone BL and bone thickness superior to the apices of the teeth.
  • Apices furthest from sinus floor is of the first premolar (6-7 mm) getting progressively closer in more posterior teeth (second molar 0.5- 2 mm).
  • Buccal roots lie under 1- 4 mm buccal bone.
  • Palatal roots lie under 1- 3 mm palatal bone, except 1st premolar (5.5 mm).

Clinical Significance:

  • Distances from sinus floor will dictate the size of the crypt during surgical endodontics.
  • Lateral thickness of bone may indicate location of access with consideration of soft tissue reflection, hemorrhage control, and visibility.