Cone-Beam Computed Tomography-Based Three-Dimensional McNamara Cephalometric Analysis.

This article introduces a method that extends the McNamara cephalometric analysis to produce 3-dimensional (3D) measurement values from cone-beam computed tomography images. In the extended method, the cephalometric landmarks are represented by 3D points; the bilateral cephalometric landmarks are identified on both sides of the skull; the cephalometric lines, with the exception of the facial axis, are represented by 3D lines; the cephalometric planes, with the exception of the facial plane, are represented by planes; the effective mandibular length, the effective midfacial length, and the lower anterior facial height are measured as 3D point-to-point distances; the nasion perpendicular to point A, the pogonion to nasion perpendicular, the upper incisor to point A vertical, and the lower incisor to point A-pogonion line are measured each as components of a vector; the facial axis angle is measured as a line-to-plane angle; and the mandibular plane angle is measured as a plane-to-plane angle. As a result, the method provides real effective lengths of the maxilla and mandible on both sides of the skull; real height of the lower anterior face; directed distances from the point A to the nasion perpendicular, from the pogonion to the nasion perpendicular, from the left and right upper incisor to the point A vertical, and from the left and right lower incisor to the point A-pogonion line for both the lateral and posteroanterior views of the skull; and real angles of the facial axis and the mandibular plane.

Influence of different setups of the Frankfort horizontal plane on 3-dimensional cephalometric measurements.

Introduction: The Frankfort horizontal (FH) is a plane that intersects both porions and the left orbitale. However, other combinations of points have also been used to define this plane in 3-dimensional cephalometry. These variations are based on the hypothesis that they do not affect the cephalometric analysis.

Automatic repositioning of jaw segments for three-dimensional virtual treatment planning of orthognathic surgery.

Purpose: To develop a computer-based method for automating the repositioning of jaw segments in the skull during three-dimensional virtual treatment planning of orthognathic surgery. The method speeds up the planning phase of the orthognathic procedure, releasing surgeons from laborious and time-consuming tasks.

Materials And Methods: The method finds the optimal positions for the maxilla, mandibular body, and bony chin in the skull.