Determination of cephalometric parameters according to the COGS method, related to the profile of the soft tissues of the face depending on the types of faces in Ukrainian young men and young women with an orthognathic bite

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Introduction
Bite pathology is one of the most common in orthodontist practice. The results of the examination of almost 2,000 schoolchildren from Saudi Arabia revealed that 1,219 of them have a molar ratio of class I, 326 -class II and 154 -class III. Among the most common signs of malocclusion, the authors noted bulging teeth, an increase in the space between the teeth, overbite, crossbite, front open bite [2]. Another common pathology is the presence of supernumerary teeth. According to the literature, this pathology occurs in 0.3-0.8 % of people with non-permanent and 1.5-3.5 % of people with permanent dentition. It is also noted that this pathology occurs more often among men than women (the ratio of patients is 2:1, respectively) and more often on the upper jaw than the lower [3]. Manifestations of sexual and age-related dimorphism were also found when studying the prevalence of impacted teeth [16]. Agenesis of teeth occurs in 2.2-10.1 % of people and has a pronounced ethnic heterogeneity of distribution. It is most common among the white population of Australia, where it is found in 6.3 %, the least common among the white population of North America -3.9 % [5].
The cost of orthodontic treatment varies considerably depending on the method used and the country. In Finland, the average cost of providing orthodontic care to children and adolescents varies between 517-926 euros, in Great Britain it is 36-2941 euros [18].
The prevalence and diversity of orthodontic pathology, the high cost of its treatment have led to the rapid development of instrumental methods for both diagnosis and treatment of this pathology. One of the methods of treatment planning is cephalometric analysis, which became widespread and recognized in the first half of the 20th century [20,23].
The accuracy of cephalometric analysis of lateral teleroentgenograms is extremely high. Thus, when compared with direct craniometric measurement, the error is less than 1 mm. In general, when comparing the data, the Co-Gn, Go-Me, Co-ANS indicators had higher values in direct craniometry, while all other indicators had lower values [7]. Currently, scientific and technical progress allows, in addition, to use computer tomography data for cephalometric analysis. Nevertheless, the use of traditional lateral teleroentgenograms is almost in no way inferior in terms of informativeness and accuracy to data obtained by analyzing computer tomography data [13].
However, this method requires appropriate clinical research to be implemented in the practice of orthodontists.
The purpose of the study is to establish the peculiarities of cephalometric parameters according to the COGS method, related to the profile of the soft tissues of the face, in Ukrainian young men and young women with an orthognathic bite with different facial types.

Materials and methods
46 young men (YM) (aged 17 to 21) and 72 young women (YW) (aged 16 to 20) underwent a cephalometric study of lateral teleroentgenograms obtained using a Veraviewepocs 3D Morita dental cone-beam tomograph. All young men and women applied to the private dental clinic "Vinintermed" for a diagnostic examination, belonged in three generations to residents of Ukraine of the Caucasian race and had a physiological bite that was as close as possible to the orthognathic one. Committee on Bioethics of National Pirogov Memorial Medical University, Vinnytsya (protocol № 8 From 30.09.2021) found that the studies do not contradict the basic bioethical standards of the Declaration of Helsinki, the Council of Europe Convention on Human Rights and Biomedicine (1977), the relevant WHO regulations and laws of Ukraine.
Cephalometry was performed according to the COGS method [6]. The OnyxCeph 3 ™ software, version 3DPro, from Image Instruments GmbH, Germany (software license №URSQ-1799) was used for this analysis. The face type YM and YW is determined, respectively, by the value of Garson's morphological index [19].
The main cephalometric points and measurements according to the COGS method, including indicators of the structures of the soft profile of the face (   Statistical processing of the results was carried out in the license package "Statistica 6.0" using non-parametric estimation methods. Mean values and standard deviation were determined. The significance of the difference in values between independent quantitative values was determined using the Mann-Whitney U-test.

Results
The following distribution of young people according to the value of the Garson index was established: YM -5 with a very wide face, 22 with a wide face, 11 with an average face, 8 with a narrow face; YW -25 very wide face, 25 wide face, 10 medium face, 12 narrow face.
Tables 1 and 2 present the results of teleroentgenometric values according to the COGS method, related to the profile of the soft tissues of the face in boys or girls with an orthognathic bite with different types of faces.
Also, between YM and YW with different types of faces, the following gender differences in the indicators related to the profile of soft tissues of the face were established, namely, larger values: in YM, larger values of the distance Gl'-Sn (with wide, p<0.05 and the average face, p=0.057), the distance Gl'-Pog' (with the average face, p=0.062), as well as the angle Sn-Gn'-C (with wide face p<0.05); in YW larger values are the Sm-(Li-Pog') and Stms-I distances (with a very wide face, p=0.059, p=0.089), Sm-(Li-Pog') distances (with a wide face, p<0.001 and medium face, p<0.05), the Cotg-Sn-Ls angle (with a narrow face, p=0.083) and the Gl'-Sn/Sn-Me' ratio (with a wide face, p<0.05).

Discussion
When comparing Ukrainian YM or YW with an orthognathic bite with different facial types of indicators  related to the profile of facial soft tissues according to the COGS method, more pronounced differences are established between YW with different facial types, namely (see Table 2): in YW with a very wide face, significantly smaller values or trends of the Gl'-Sn-Pog' angle and the Sn-Gn'/H-Gn' ratio (compared to the medium and narrow face types), the Cotg-Sn-Ls angle, and Ls-(Sn-Pog') distances (compared to the average face type); in YW with a wide face, there is a tendency for larger Ls-(Sn-Pog') distance values (compared to the average face type) and a tendency for smaller Stms-I distance values (compared to the average face type); YW with narrow face have significantly greater, or trends toward, greater values of Gl'-Sn distance (compared to medium face type), Sn-Gn'/H-Gn' ratio (compared to wide face type), Gl'-Sn/Sn-Me' ratio (compared to the medium face type), as well as a significantly smaller value of the Sm-(Li-Pog') distance (compared to the wide face type).
Between Ukrainian YM with different types of faces, a significantly smaller number of reliable, or trends, indicators of differences related to the profile of the soft tissues of the face according to the COGS method were established (see Table 1): in YM with a very wide face, there is a tendency towards larger values of the Gl'-Pog' distance (compared to the Notes: here and in the following table, M±σ -sample mean ± standard deviation; р (1-2, 1-3, 1-4, 2-3, 2-4, 3-4) -the validity of the differences in scores between the corresponding face types in YM or YW. average face type) and a tendency towards smaller values of the Sn-Gn'/H-Gn' ratio and the Stms-I distance (compared to average face type); in broad-faced YM, a tendency towards higher Sn-Stms/ Stmi-Me ratio values (compared to the average face type) and a tendency towards lower values of the Gl'-Sn/Sn-Me' ratio (compared to the average face type); in YM with a narrow face, significantly higher, or a trend towards higher values of the value of the ratio of Gl'-Sn/Sn-Me' (compared to very wide and wide face types).
Minor manifestations of sexual dimorphism of indicators related to the profile of the soft tissues of the face were also established, namely: larger values, in most cases in YM with wide and medium face types -values of Gl'-Sn distances, Gl'-Pog' distances (only with an average face type), Sn-Gn'-C angle (only with a wide face type); and in YW -values of Sm-(Li-Pog') and Stms-I distances (with very wide face type), Sm-(Li-Pog') distance (with wide and medium face types), Cotg-Sn-Ls angle (with narrow face type) and Gl'-Sn/Sn-Me' ratio (with wide face type).
COGS analysis is an excellent tool that is actively used for the assessment and planning of orthodontic treatment, which involves various types of surgical interventions, such as osteotomies, genioplasty and other interventions on the maxillo-dental apparatus [8,11,12,15].
In a previous study, we analyzed COGS cephalometric parameters that characterize the position of individual teeth in boys and girls with an orthognathic bite and different facial types. As a result, pronounced manifestations of sexual dimorphism were found for both linear and angular indicators, namely, YW have higher values of the OP-HP angle, and YM have higher values of most linear dimensions [14].
Indeed, taking into account as many parameters as possible is important when conducting cephalometric studies. Yes, the type of face affects the position of the hyoid bone. Significant differences were found for SNB, ANB and NSH indicators in different groups [1].
It is also important to take into account the age of the examined persons. Bergman R. T. with co-authors [4] investigated changes in the soft tissue structures of the face of persons aged 6 to 18 years using COGS analysis. In particular, with age, such indicators as the lower face height, the thickness of the upper and lower lips, the length of the upper lip and the lower lip-chin length increase, the interlabial gap and the contour of the furrow of the lower jaw decrease. Some indicators do not change with age: the angle of the face profile, the nasolabial angle, the upper and lower protrusion of the lips.
The existence of sex differences in terms of indicators of soft tissue structures of the face is also a proven fact. In men, higher values of the thickness of the soft tissues of the face were found in representatives of the maxillofacial class I, II and III. The most significant differences were found for the index of the furrow of the upper lip (t=3.772; p<0.001) [17].
And of course, the ethnic component is important. A group of researchers [9] revealed soft tissue cephalometric indicators that are different (p<0.05) for Nigerians, Ghanaians and Senegalese: length of the upper lip, Liesthetic line, angle of the tip of the nose, N-Pr-Pg, Pg-Ls, B-N pogonion and pogonion-mandibular angle. In addition, such indicators as the nasolabial angle, mentolabial angle, depth of the nose, general convexity of the soft tissues of the face are excellent for the mentioned nationalities and Europeans.
Differences were also found for the Japanese population, which, compared to the European population, has higher average face projection values [22].