Correlations of basal cranial structures characteristics determined by Bjork and Jarabak methods with teleradiographic parameters of the upper and lower jaws and tooth location in young men and young women with orthognathic occlusion

The widespread use of methods of cephalometric analysis in practical orthodontics requires the adaptation of normative indicators for members of the local ethnic group. It is also important to study the relationships between cranial and odontometric parameters to understand the effects of these components on each other. The aim of the study was to establish the peculiarities of correlations between the characteristics of basal cranial structures determined by Bjork and Jarabak methods with teleradiographic parameters of the upper and lower jaws and the location of teeth in Ukrainian young men and young women with orthognathic occlusion. Teleradiography was performed in the mode of cephalometric examination of 49 young men (aged 17 to 21 years) and 76 young women (aged 16 to 20 years) who had a physiological bite as close as possible to orthognathic. Cephalometric analysis according to modifications of Jarabak J. R. Roth-Jarabak and Bjork A. CFT-Bjork methods, performed using OnyxCeph3TM software, 3DPro version, Image Instruments GmbH, Germany (software license No URSQ-1799). All indicators were divided into three groups according to Dmitriev M. O. (2017): the first group included metric characteristics of the skull, which are used as basic indicators in the methods of cephalometric analysis; to the second group dental-maxillary in which the skeleton has already been formed and which surgical methods can change the length, width, angles and positions of the upper and lower jaws; to the third group indicators that actually characterize the position of each individual tooth relative to each other, cranial structures and the profile of the soft tissues of the face. Correlation assessment was performed in the license package "Statistica 6.0" using the non-parametric Spearman method. As a result of the conducted researches in Ukrainian young men and young women with orthognathic occlusion the peculiarities of multiple correlations of characteristics of basal cranial structures determined by CFT-Bjork and Roth-Jarabak methods with teleradiographic parameters of upper and lower jaws and tooth location were established. Both the CFT-Bjork method and the Roth-Jarabak method have more reliable correlations in both young men and young women between the first and second groups (23.3 % for young men and 50.0 % for young women for CFT-Bjork and 48.4 % for young men and 41.1% for young women according to Roth-Jarabak) than between the indicators of the first and third groups (respectively 12.8 % for young men and 7.7 % for young women for CFT-Bjork and 22.5 % for young men and 12.5 % for young women for Roth-Jarabak). The expressed manifestations of sexual dimorphism of the received correlations between the indicators defined by CFT-Bjork and Roth-Jarabak methods both on quantity and force, and in some cases on a direction of correlations are established.


Introduction
The rapid development of orthodontics, which takes place both in Ukraine and abroad, is a logical consequence of the rapid spread of anomalies of the dental and maxillofacial system. For example, an analysis of 878 orthopantomograms at the Jeddah Dental Clinic (Saudi Arabia) showed that 45.1 % of patients had at least one dental abnormality. Among the anomalies such pathologies as congenital absence of teeth (25.7 %), retinal detachment (21.1 %) prevailed; curvatures of tooth roots (1.1 %) and excess teeth (0.3 %) were less common [1].
Dental examination of 25,186 Italians found 61 posterior excess teeth in 45 people. The frequency of detection of this phenomenon was higher in men (ratio of men and women 2.5:1). In 62.3 % this pathology was found on the upper jaw [8]. In another study conducted in Italy on a sample of 4006 people, data analysis showed that the prevalence of agenesis was 9 %. The most common was agenesis of the second premolars on the mandible (20.3 % in men and 18.1 % in women). Absence of one to five teeth was observed in 8.6 % of subjects [13].
In Turkey, the prevalence of dental anomalies among children was 2.0 %. As in previous studies, the prevalence of abnormalities was higher in boys than in girls [16]. A survey of 2,469 children in Nitte, India, found that the prevalence of hypodontia was 0.32 % and that of excess teeth was 0.24 %.
In another study conducted in India, the analysis of the obtained data showed that 27.7 % of the subjects had at least one odontological anomaly. Hypodontia, microdontia and hyperdontia were most frequently detected (10.4 %, 7.7 % and 6.3 %, respectively) [29].
Thus, there was a need to find and implement new diagnostic and therapeutic methods. The teleradiographic method of research deserves special attention, which considers cranial and dental-maxillary structures as one complex, which can also affect each other [2]. Numerous methods of analysis have been proposed by leading scientists in the field of odontology for the correct interpretation of the obtained data, each of which has its advantages and disadvantages, therefore the authors often consider several methods in their research combining their indicators [22,25].
However, the results of studies conducted by domestic researchers have shown that the methods of cephalometric analysis require adaptation for the Ukrainian population considering regional affiliation, gender and age [11,14,21,27].
The aim of the study was to establish the peculiarities of correlations between the characteristics of basal cranial structures determined by Bjork and Jarabak methods with teleradiographic parameters of the upper and lower jaws and the location of teeth in Ukrainian young men and young women with orthognathic occlusion.

Materials and methods
Teleradiography in the mode of cephalometric examination was performed using a dental cone-beam tomograph Veraviewepocs 3D Morita (Japan) for 49 young men (YM) (aged 17 to 21 years) and 76 young women (YW) (aged 16 to 20 years) who had a physiological bite as close as possible to orthognathic (further orthognathic) which is determined by 11 points by Bushan M. G. and others. [6]. Cephalometric analysis according to modifications of the methods Jarabak J. R. [15] -Roth-Jarabak and Bjork A. [5] -CFT-Bjork, performed using OnyxCeph 3 ™ software, 3DPro version, Image Instruments GmbH, Germany (software license № URSQ -1799).
Cephalometric points were determined according to the recommendations of Phulari B. S. [23] and Doroshenko S. I. and Kulginsky E. A. [12].
The main cephalometric points and measurements according to the CFT-Bjork method: distance Ii-Is (known as Overbite by CFT-Bjork) -the distance from the point Is to Ii in the vertical plane, characterizes the inter-cut overlap in the vertical plane (mm); distance Ii-NCL (Lower Lip Protrusion, also known as Li-NsPog' by Roth-Jarabak) -the distance from the point Li to the line Ns-Pog`, characterizes the position of the lower lip (mm); distance Is-NCL (also known as: Upper Lip Protrusion and Ls-NsPog' by Roth-Jarabak) -the distance from the point Ls to the line Ns-Pog`, characterizes the position of the upper lip (mm); Is-Olf distance (also known as: Max-Incisor Extrusion 1u-OcP, Max. Incisor to Occl. Plane) -the distance between the point Is and the closing plane (POcp), characterizes the vertical location of the cutting edge of the medial incisor (mm); Overjet distance (CFT-Bjork analysis) -the distance from the point Is to Ii in the sagittal plane, characterizes the inter-cutter distance in the sagittal plane (mm); Wits distance (CFT-Bjork analysis) -the distance between the projections of points A and B on the closing plane (POcp), characterizes the linear ratio of the lower and upper jaws along the folding plane (mm); angle A-N-B (also known as: ss-n-sm, Jaw Relation)formed by lines A-N and N-B, characterizes the position of the jaws to each other (°); angle A-N-Pog (also known as: ss-n-pg, Jaw Relation to Pog, NAPog, Angle of Convexity) -formed by lines A-N and N-Pog, characterizes the intermaxillary position in the sagittal plane (°); CL/ML angle (also known as Mandibular alveolar The main cephalometric points and measurements according to the Roth-Jarabak method: Ar-Go distance (also known as: Ramus Length, the length of the lower jaw branch) -the distance from the Ar point to the tGo point, which characterizes the length of the lower jaw branch (mm); distance Go_Me (also known as: Body (Mandibular) Length) -the distance from the point tGo to the point Me, characterizes the length of the body of the mandible (mm); Li-NsPog' distance (also known as: Facial aesthetic line Lower lip, Distance of Lower Lip to Esthetic Line) -the distance from the Li point to the Ns-Pog line, characterizes the position of the lower lip relative to the "Aesthetic line"the Ns-Pog` line (mm). It should be noted that, unlike the original Jarabak analysis, the Roth-Jarabak analysis does not use a specific A-point which is placed 2 mm in front of the apex of the middle maxillary incisor, but uses the more common Downs A-point.
Indicators in this study were divided into three groups according to Dmitriev M. O. [10]. The first group includes metric characteristics of the skull, which are used as basic indicators in the methods of cephalometric analysis; to the second group -dental-maxillary in which the skeleton has already been formed and which surgical methods can Correlation assessment was performed in the license package "Statistica 6.0" using the non-parametric Spearman method.

Results
The results of the evaluation of the correlations between the indicators of the first group by the method of CFT-Bjork or Roth-Jarabak with the indicators of the second and third groups are presented in tables 1 and 2.

Discussion
Manifestations of sexual dimorphism were detected in the study of teleradiograms by the Bjork-Jarabak method of 100 people living in Bangladesh. According to the analysis of the data, men have in comparison with women the values of the saddle angle, gonial angle, body length of the lower jaw, incisor angle and anterior height of the face. In general, it was also found that the indicators for both №41, Page 52-59 men and women differed significantly from the normative indicators for Bjork-Jarabak [3].
Differences in cephalometric parameters according to Bjork-Jarabak were found for the population of Saudi Arabia. Thus, the largest differences were found for the length of the anterior and posterior part of the face, the height of the branch and the length of the mandible, the length of the anterior and posterior cranial part [4].
Jarabak cephalometric standards have been established for Pakistanis. Differences with the control sample were found for such indicators as upper and lower gonial angle, saddle angle (p<0.001), anterior facial height, posterior facial height, anterior and posterior skull base (p<0.05) [17].
In another study conducted on a Pakistani sample of individuals, however, using Bjork-Jarabak analyzes, the authors found no differences among virtually all indicators except joint angle and PFH/AFH ratio [20].
Features of cephalometric indicators according to Jarabak are established for the population of Nepal. Statistically significant differences were found for 10 of the 30 studied indicators. In addition, manifestations of sexual dimorphism were detected for 11 of the 30 studied parameters [24].
Processing of cephalometric analysis data by Bjork 122 Polish adolescents revealed the relationship between odontometric parameters and indicators of facial soft tissues [19].
P. Vasanthan and others [28] estimated the height of teeth in malocclusions using cephalometric analysis by Bjork. To conduct this work, the authors analyzed the indicators before and after treatment. Statistically significant results were obtained for the height of the teeth of the mandible measured from the plane of the mandible and the plane CSm.
Interdependencies between cranial structures and odontometric parameters using cephalometric analysis by Downs, Steinner, Bjork, Ricketts and McNamara were found when working with the Brazilian population sample [7,18].
A correlation between Bjork growth rates and skeletal model prediction was found by Davidovitch M. and coauthors [9]. It was found that only LAFH correlated with age in all study groups.
In Ii-Is 0.12 0.01 -0.14 -0.14 -0.08 0.14    Thus, the established features of correlations of characteristics of basal cranial structures determined by CFT-Bj ork and Roth-Jarabak methods with teleradiographic parameters of the upper and lower jaws and the location of teeth in Ukrainian YM and YW with orthognathic occlusion will allow more reasonable and correct interpretation of the data. teleradiograms by these methods.

Conclusion
1. In Ukrainian YM and YW with orthognathic occlusion, qualitative and quantitative features of correlations of characteristics of basal cranial structures determined by CFT-Bj ork and Roth-Jarabak methods with teleradiographic parameters of upper and lower jaws and tooth location were established.
2. Manifestations of sexual dimorphism of correlations between the indicators determined by the methods of CFT-Bjork and Roth-Jarabak both in number and strength, and in the direction of correlations was established.