Regression models of individual teleradiographic indicators according to Ricketts method in Ukrainian young men and young women with different face types
Authors: Drachevska I. Yu. 
Published: September 2021

Annotation. Anomalies of the dental-jaw system are one of the most difficult challenges of modern orthodontics, and accordingly require the use of modern and evidence-based therapy. To predict the results of treatment and proper planning of orthodontic interventions, a reliable tool in the hands of an orthodontist is cephalometric analysis by the Ricketts method. An important step in the successful implementation of this method of analysis is to conduct a study taking into account ethnicity, age, sex and the influence of facial type on teleradiographic indicators calculated by this method. The aim of the study is to build and analyze regression models of teleradiographic indicators used in the Ricketts method for Ukrainian young men and young women with orthognathic occlusion with different face types. Ricketts teleradiography was performed for 49 young men and 76 young women with orthognathic occlusion. Cephalometric analysis was performed using OnyxCeph³™ software, 3DPro version, Image Instruments GmbH, Germany (software license URSQ-1799). The division into facial types was performed by determining the morphological index of Garson. All indicators were divided into three groups: the first group included the main cephalometric points and measurements used in modern cephalometric analyzes Schwartz, Ricketts, Steiner, Roth-Jarabak, Burstone and Bjork and are parameters that usually do not change during surgery and orthodontic treatment; to the second group – metric dental-jaw characteristics by the Ricketts method by which surgical methods can change the length, width, angles and position of the jaws; to the third group – indicators according to the Ricketts method which characterize the position of each individual tooth relative to each other, cranial structures and the profile of the soft tissues of the face. Regression models of individual teleradiographic indicators are built using the license package "Statistica 6.0". Only reliable models with a coefficient of determination higher than 0.6 were subject to analysis. Of the 13 possible facial features, 9 models of teleradiographic indicators (R² = from 0.691 to 0.834) were included to the second group, depending on the indicators of the first group, and 9 (R² = from 0.640 to 0.910) of the 15 possible models of indicators were included to the third group depending on the indicators of the first and second groups. In young men with a wide type of face, the constructed models of indicators included to the second group, depending on the indicators of the first group, most often include the distance Ar-Go (20.7 %), angle POr-NBa (13.8 %), distances N-S and S-E and the ratio N-S:S-Ar' (10.3 % each); and to the models of indicators included in the third group depending on the indicators of the first and second groups – the angle N-CF-A (12.8 %), the distance Ar-Go (10.3 %), the distances N-CC and A-NPog and angle ANS- Xi-Pm, POr-ANSPNS and DC-Xi-Pm (7.7 % each). In young women with a very wide type of face out of 13 possible built only 2 models of teleradiographic indicators (R² = 0.691 and 0.834) which were included to the second group depending on the indicators of the first group and 5 (R² = from 0.628 to 0.919) of 15 possible models of indicators which entered the third group depending on the indicators of the first and second groups. In young women with a very wide type of face, the constructed models of indicators included in the third group, depending on the indicators of the first and second groups, most often include the distance Xi-Pm (18.2 %), as well as the distance P-PTV and angles MeGo-NPog and POr-CFXi (9.1 % each). In young women with a wide type of face from 13 possible 5 models of teleradiographic indicators (R² = from 0.606 to 0.854) which were included in the second group depending on indicators of the first group and 7 (R² = from 0.607 to 0.888) from 15 possible models of indicators which were entered to the third group depending on the indicators of the first and second groups. In young women with a wide type of face, the constructed models of indicators included in the second group, depending on the indicators of the first group, most often include the distance Ar-Go (28.6 %) and the angle POr-NBa and the ratio S-ar:ar-Go (14.3 %), and to the models of indicators included in the third group depending on the indicators of the first and second groups – the distances A-NPog and Xi-Pm and the angle NBa-PtG (10.3 % each).