Determination of individual angular characteristics of the teeth positions according to the computer tomography in Ukrainian adolescents with orthognathic bite
Authors: Dmitriev М. О. , Volkov K. S. , Glushak A. A. , Kyrychenko Yu. V. , Balynska M. V. , Chugu T. V. , Kovalchuk О. І. 
Published: February 2019

The lack of the ability to determine the individual standard angle characteristics of the position of the teeth and the technical provision of their control often does not lead to the expected result and in each case requires individualization, the vision of which is based, as a rule, on the experience and intuition of the doctor. In order to solve such a situation, in addition to improving the positioning protocols of the non-removable equipment, the physician should be able to clearly identify the individual angular characteristics of the tooth-jaw system. The purpose of the study – by studying computer tomography and cephalometric indices and conducting direct stepwise regression analysis to develop in Ukrainian adolescents with orthognathic bite mathematical models of individual angular positions of teeth. Using the Veraviewepocs 3D device, Morita (Japan) at 38 young men (aged from 17 to 21) and 55 young women (aged from 16 to 20 years) with normal occlusion close to orthognathic bite received and analyzed dental tomograms and lateral teleroentgenograms. Cephalometric points and measurements were performed according to recommendations of A. M. Schwarz, J. McNamara, W. B. Downs, R. A. Holdway, G. P. F. Schmuth, C. C. Steiner and C. H. Tweed. Anatomical points were determined taking into account the recommendations of A. E. Athanasiou and S. I. Doroshenko and Y. A. Kulginsky. The simulation of CT indexes describing the position of individual teeth relative to each other, to the bone cranial structures and the profile of adolescents with orthognathic bite, depending on the metric characteristics of the skull, which are usually unchanged during surgical and orthodontic treatment, as well as the width, lengths, angles and positions of the upper and lower jaws that may be altered by orthodontic surgery done. The statistical processing of the obtained results was carried out in the license package “Statistica 6.0” using a direct stepwise regression analysis. It was found that in young men of 40 possible models, 23 were constructed with a determination coefficient R2 of 0.557 to 0.832, while in young women, only 8 models with a determination coefficient R2 of 0.581 to 0.832. Moreover, in the young men – of 10 possible 9 models of vestibular-tongue inclination of corresponding teeth (R2 from 0.557 to 0.832) were constructed; out of 10 possible 5 models of mesio-distal inclination of corresponding teeth (R2 from 0.558 to 0.769) constructed; of the possible 14 constructed 6 models of rotation of the corresponding teeth (R2 from 0.579 to 0.737); and in young women - there are only 5 models of vestibular-tongue inclination of the corresponding teeth (R2 from 0.603 to 0.665). In addition, in both young men and young women, models of the size of the inter-incision angle (R2 0.748 in young men and 0.581 in young women) were constructed, the magnitude of the angle of inclination of the lower canine in the jet plane (R2 respectively 0.729 and 0.793), and the magnitude of the inclination of the closure planes relative to the palatal plane (R2 respectively 0.808 and 0.832). In the analysis it was found that in young men, most frequently models included - indicator WITS (7.0%); angle GL_SNPOG (5.4%); distance S_E, angle ММ, angle NSBA (by 4.7%); angle AB_NPOG, angle N_POG_, distance N_SE, coefficient N_SP_SP, angle P_OR_N (by 3.9%). In young women, most frequently models included – angle N_POG_ (14.3%); angle AB_NPOG (10.2%); indicator WITS (8.2%); angle ММ, angle ANB, length of the branch of the mandible R_ASC (by 6.1%). Thus, in the work with the help of the method of step-by-step regression with inclusion, among Ukrainian adolescence, on the basis of peculiarities of computer-tomographic and teleroentgenography indices, reliable models of computer-tomographic individual linear angular characteristics of the position of teeth necessary for constructing the correct three-dimensional geometry of dental arches are developed and analyzed.