Development of a non-radiographic cephalometric system

Abstract

The purpose of the present study was to develop a three-dimensional (3D) non-radiographic cephalometric system based on Simon's three planes. In pursuit of cephalometry without irradiation of patients, readiness of data and simplicity of the system, a portable 3D computer-aided, contact-method cephalometric system, equipped with newly developed cephalometric software for chairside use, was developed. The feasibility of its clinical use was examined based on comparison of the measurements obtained with those from conventional radiographic cephalometry on a human dry skull, as well as on three living subjects. From a total of nine measurements, a statistically significant difference was seen in six measurements: FMPA, U1/FH, FMIA, ANB, IMPA, and A-Np for the dry skull; in four measurements: FPA, FMPA, U1/FH, and Pog-Np for subject A; in five measurements: FMPA, U1/FH, FMIA, AN/FH, and A-Np for subject B; and in seven measurements: FMA, FMPA, U1/FH, FMIA, ANB, IMPA, and AN/FH for subject C. A clinically significant difference was found only in one measurement, U1/FH for the dry skull, in four measurements FPA, FMPA, U1/FH, and Pog-Np for subject A, in one measurement AN/FH for subject B, and in three measurements U1/FH, FMIA, and AN/FH for subject C. While demonstrating workability as a chairside tool and whilst there is a need for further refinement in measurement accuracy, this newly developed cephalometric system shows potential applicability, not only in the clinic as an auxiliary to or as a substitute for existing radiographic cephalometry, but also outside the clinic as an epidemiological tool.

Reproducibility of Linear Measurements Performed with 3-D Cone Beam Computed Tomography: Scan Reconstructions in Region of Pterygomaxillary Junction

“…Nagasaka et al [22] proved that the more closely located the two landmarks are, the greater the measurement error may appear. Kanazawa et al [5] and Ueki et al [9] revealed that increased thickness of the pterygomaxillary junction predisposes it to fractures on the greater palatine foramen.…”

Cone-beam computed tomography for assessment of palatal displaced canine position: A methodological study

“…18,19 No significant differences were found for intra-or interexaminer measurements, but higher interexaminer error was observed, as has also been shown in previous studies. [20][21][22] Canine cusp tip to dental arch and canine apex to dental arch had somewhat higher measuring errors compared to the rest of the linear measurements in both intra-and interexaminer measurements. This can be explained by the following geometric principle that Nagasaka et al 22 illustrated in his study: the distance between landmarks influences the magnitude of measuring errors of linear measurements.…”

“…[20][21][22] Canine cusp tip to dental arch and canine apex to dental arch had somewhat higher measuring errors compared to the rest of the linear measurements in both intra-and interexaminer measurements. This can be explained by the following geometric principle that Nagasaka et al 22 illustrated in his study: the distance between landmarks influences the magnitude of measuring errors of linear measurements. They showed that the closer two landmarks are, the greater the linear measurement error tends to be.…”

“…They showed that the closer two landmarks are, the greater the linear measurement error tends to be. 22 As mentioned in the ''Materials and Methods'' section, CBCT images from 20 patients on three different occasions were measured instead of measuring 60 images on one occasion, since that was the original design of the study. This might have resulted in a greater variation of canine apex development or position of the canine cusp tip, which can be another explanation for the somewhat higher errors in these variables.…”

Orientation of the occlusal plane in a Class I adult population

“…23 If the points which make up the plane are close together, the plane is more difficult to locate accurately, such as in the case of the occlusal plane. 24,25 When identifying the occlusal plane, one must also overcome the obstacle of bilateral images which can lead to problems with the reproducibility of the occlusal plane. 26 Plane identification is difficult even under ideal conditions, which in the case of the occlusal plane can lead to variation in interpretation of the cant between different tracings of the same film as much as 3 .…”