Summary:
The need for accurate preoperative planning has led dental science in
the development of imaging techniques for accurate and detailed imaging
evaluation.
The purpose of this research is a) to summarize the operating principles
of computed tomography and cone beam CT and b) to determine the accuracy and
reliability of linear measurements of the dimensions of the alveolar bone in
cross sectional slices, as they arise from the application of different
inclinations of axial slices.
10 maxillas and 10 mandibles from patients who underwent dental computed
tomography in the preoperative imaging evaluation for implant placement were
used. The selection criteria were: a) The patients to be all partially
edentulous and b) the edentulous areas to be completely free from pathological
lesions. The reconstruction of axial slices was made by using two different
inclinations: A) MAXILLA: 1) in a direction parallel to the occlusal plane 2)
in a direction parallel to the plane of the palate. B) MANDIBLE: 1) in a
direction parallel to the occlusal plane, 2) in a direction parallel to the
tangent of the lower edge of the body of the mandible. From each
reconstruction, cross sectional slices were created, perpendicular to the
longitudinal axis of the jaw, spaced by 1mm and with a thickness of 1mm. Then
linear measurements of bone height were made for each reconstruction at fixed
points. Linear measurements were made by two observers, at constant study
conditions, in random order and in two different times.
After statistical control t (t-test) was performed, for the upper jaw the
resulting difference on linear measurements was found to be not statistically
significant (t = 0.896 with p> 0.05) while for the lower jaw the resulting
difference on linear measurements was found to be statistically significant
(t=3.379 with p <0.01) for each measurement point respectively.
The conclusions of this research are:
• A change of the inclination of axial slices can have a significant
impact on linear measurements performed on cross sectional slices, especially
in the lower jaw.
• For the maxilla, linear measurements performed in each anatomical
region do not differ statistically significantly between the two different
inclinations.
• For the mandible, linear measurements performed in each anatomical
region can differ statistically very significantly between the two different
inclinations.
• The individualization of treatment plan indicates the safest practice
in the selection of the appropriate inclination of reconstruction of axial
slices, thus creating accurate linear measurements of the dimensions of the
alveolar bone in cross sectional slices.
Keywords:
CBCT, Cone beam, Linear measurements, Volumetric analysis, Inclination of reconstruction
