Methods of examining the gnatic part of the face and determining the position of the lowest point of the apical basis according to Schwarz on a telerentgenogram

The methods of studying the gnathic part of the face on tele-radiographs remain relevant for the diagnosis of occlusal abnormalities in the vertical direction. In addition, it is not always possible to determine the position of the apical point of the lower incisor on tele-radiographs due to the overlapping of adjacent anatomical structures. The purpose of the work: To develop methods for studying the gnathic part of the face and determining the position of the apical base of the mandible according to Schwarz on a lateral tele-radiograph, and to evaluate their clinical significance. Material and methods: The study used the department's archival radiographs, of which 32 pictures were obtained from people with physiological variants of occlusion and 29 radiographs belonged to patients with abnormalities of occlusion in the vertical direction. Radiographs were analyzed in the PowerPoint program with the construction of diagnostic angles of the gnatic department of the face. From the upper point of the articular head (Cond), radial lines were drawn to the subnasal and supramenial skin points, which determined the size of the gnathic part of the face. A line was also drawn from the articular point through the apex of the root of the lower incisor. The projection of the apex of the incisor root on the bone (point B according to Schwarz) was determined based on the vertical size of the incisor. The average value of the indicator and its error (M ± m) were statistically determined, and the significance of the indicator was analyzed using the Student's t-test. Results and discussion: In lateral telexentographs of people with physiological occlusion, the angle of the gnathic part of the face was (20.09 ± 0.53)°. The angle formed by the condillary-supramental line and the condillary-apical line was 5°, and when it intersected with the conditional vertical of the lower incisor, it determined the position of the incisor's root apex. The distance from the cutting edge of the lower incisor to point B on the Schwarz scale corresponded to the height of the incisor. Conclusion: Thus, the proposed method for determining the lower apical point allows for more accurate analysis of Schwarz telex-radiographs for the differential diagnosis of gnathic and dental-alveolar forms of occlusion abnormalities. In addition, the subnasal-condylar-supramental angle of 20° characterized the optimal bite size and can be used to diagnose vertical occlusion abnormalities.