Anatomical study of the maxillary tuberosity in Japanese men.

The placement of dental implants in the molar region of the maxilla is often difficult because of the presence of the maxillary sinus. It has recently been postulated that the pillar of bone consisting of the maxillary tuberosity, the pterygoid process of the sphenoid bone, and the pyramidal process of the palatine bone, which is located at the posterior part of the maxilla, is suitable for fixing implants in the maxilla. In this study, we morphometrically examined the figure of the pillar of bone in dentate and edentulous maxillary bone specimens. The posterior part of the maxilla, including the pterygoid process of the sphenoid bone and pyramidal process of the palatine bone was embedded in polyester resin. Serial transverse sections 500 microns thick were prepared, and soft X-ray photographs were taken. Three-dimensional images of the pillar of bone were reconstructed from the contour in the soft X-ray images, and the height inclination angles, and volume of the pillar were measured. In dentulous specimens, the imaginary approximation line of the center of the gravity of the pillar of bone in the posterior part of the maxilla was inclined antero-posteriorly at an angle of 76.5 +/- 3.0 degrees from the anterior to posterior direction against the Frankfurt horizontal plane and bucco-palatally at 17.2 +/- 2.7 degrees to the medial direction against the sagittal plane. In edentulous specimens, the pillar of bone was inclined antero-posteriorly at 67.3 +/- 5.0 degrees against the Frankfurt horizontal plane and bucco-palatally at 14.1 +/- 2.1 degrees against the sagittal plane. The volume of the pillar of bone was greater in edentulous specimens than those in the dentulous specimens. The present results will enable setting up a standard for implant surgery dentulous specimens.