Assessment of the relationship between the maxillary molars and adjacent structures using cone beam computed tomography

Abstract

Purpose: This study investigated the relationship between the roots of the maxillary molars and the maxillary sinus using cone beam computed tomography (CBCT), and measured the distances between the roots of the maxillary molars and the sinus floor as well as the thickness of the bone between the root and the alveolar cortical plate.

Materials and methods: The study sample consisted of 83 patients with normally erupted bilateral maxillary first and second molars. A total of 332 maxillary molars were examined using CBCT images. The vertical relationship of each root with the maxillary sinus was classified into four types on CBCT cross-sectional images. The distance between the sinus floor and root and the bone thickness between the root and alveolar cortical plate were measured.

Results: In the buccal roots of the maxillary molars, a root protruding into the sinus occurred most frequently. A root projecting laterally along the sinus cavity was most common in the palatal roots of the maxillary first molars. The mesiobuccal roots of the maxillary second molar were closest to the sinus. The mesiobuccal roots of the first molars were closest to the cortical plate.

Conclusion: The relationship between the roots of the maxillary molars and the sinus differed between the buccal and palatal roots. A root protruding into the sinus occurred more frequent in the buccal roots of the maxillary molars. The mesiobuccal root of the maxillary second molar was closest to the maxillary sinus floor and farthest from the alveolar cortical plate.

Keywords: Bone and Bones; Cone-Beam Computed Tomography; Maxillary Sinus; Molar.

Fig. 1

CBCT images show 4 types of vertical relationships between the root of the maxillary molars and the sinus floor. A. Type 0, the root is separate from the sinus floor. B. Type 1, the root is in contact with the sinus floor. C. Type 2, the root is projecting laterally along the sinus cavity, but is outside the sinus borders. D. Type 3, the root is projecting into the sinus cavity.

Fig. 2

The illustrations show 3 types of the horizontal relationships between the root of the maxillary molars and the sinus floor. Type B, the lowest point of the maxillary sinus floor is located on the buccal side. Type BP, the lowest point of the sinus floor is located between the buccal and palatal roots. Type P, the lowest point of the sinus floor is located on the palatal side of the palatal root.

Fig. 3

The distance between the root apex and the sinus floor is measured using CBCT cross-sectional images. Apices extending below the floor of the sinus are assigned positive values (A), whereas those above the sinus floor are assigned negative values (B).

Fig. 4

The minimum bone thickness between the root and the alveolar cortical plate is measured using CBCT cross-sectional images. For the buccal roots, the distance to the buccal cortical plate is obtained (A), and for the palatal roots, the distance to the palatal cortical plate is measured (B).