Using of digital technologies at biomechanical modelling of orthodontic tooth movement

Dental anomalies (malocclusion, crooked teeth, etc.) are a common problem. Due to them, violations of the aesthetics of the face, blood supply to the brain, respiration, posture, facial expressions, pronunciation of words, digestion and etc. are possible. Correction of dental anomalies consists in moving the teeth to a new position corresponding to the physiological norm under the influence of the orthodontic load (bracket system, elastopositioner, etc.). The main question in orthodontic treatment is the determination of such load (value, direction, place of application). This work continues a series of publications by authors dedicated to solving this question. Earlier, the concept of “center of resistance of a tooth” was introduced and determined. Using this consept, it is possible to study the initial movement of the tooth within the framework of the bone hole. In accordance with the introduced conditions for the existence of this point, it turned out that the "center of resistance of a tooth" does not exist always. Therefore, the authors proposed a new concept of “region of resistance of a tooth” determined by sets of translational action lines and a pair of rotation axes. The purpose of this work is to study them, namely, the conditions for the existence of these lines, the relative position and, on the basis of this, to demonstrate the classification of the types of tooth resistance region.