Location of the upper first premolars relative to the Bimler stess-axis in variants of physiological occlusion and features of the chin protrusion

The issues of determining the methods of orthodontic treatment with and without tooth extraction remain relevant to this day. A special place is occupied by methods with the removal of the first premolars, and the orientation to the position of the Bimler stess-axis is perhaps the only criterion for determining the method of extraction therapy. However, we have not found any information about the position of the Bimler line, taking into account the individuality of the dentition-jaw system. Purpose. To determine the location of the upper first premolars relative to the Bimler stess-axis in different trusal variants of the dentoalveolar arches and latitudinal parameters of the chin protrusion. Material and methods. The study was retrospective, with distribution into groups that took into account variants of physiological protrusion and incisor retrusion, as well as latitudinal variants of the chin protrusion, along the posterior protrusion of which the Bimler strass axis passed. Using the computer program PowerPoint, a circle was inscribed on the photo of the teleradiograph, which passed through the anterior and posterior occlusal points and the upper point of the articular head. From the center of the circle to the posterior convexity of the contour of the chin symphysis, the Bimler strass axis was drawn. The position of the first upper premolars relative to the landmark was visually assessed. Results and discussion. It was noted that with the protrusive position of the incisors, in people with physiological occlusion, there was a displacement of the first premolars anterior to the Bimler stress axis. At the same time, the location of the first upper premolars behind or on the Bimler line, in people with retrusin-type arches, is not a contraindication to extraction treatments. The width of the chin protrusion influenced the position of the Bimler stress axis. Conclusion. In the course of the study, it was found that in the mesotrusal type of dental arches, in people with wide chin variants, the location of the Bimler stress axis behind the upper premolars is not a sign of their mesial displacement relative to the structures of the skull. The same is noted for the protrusive type of arches, regardless of the width of the chin protrusion. The data obtained can be decisive in the diagnosis of anomalies and the choice of extraction and non-extraction methods of treatment.