METHOD FOR PLANNING UPPER JAW POSITION IN ORTHOGNATHIC OPERATIONS Russian patent published in 2019 - IPC A61B6/14 

FIELD: medicine.

SUBSTANCE: invention relates to medicine. Method for planning position of upper jaw in orthognathic operations involves finding such position of upper jaw, in which continuation of occlusal plane passes along tangent to skull base, and the lower edge of the front incisors is located 1–3 mm below the edge of the superior lip and the base of the nose is spaced from the plane passing through the glabella at a distance equal to the distance from the plane Gb to the plane Tf. At that, when examining the patient, it is determined whether the edge of the central incisor of the upper jaw protrudes from under the lip of the upper lip with passive opening of the mouth, denoting the specified value as is – StS, then in DICOM viewer files, allowing to build a three-dimensional model with possibility of measuring distances, the following actions are performed: based on spiral or conical tomogram data, a three-dimensional head model is constructed, removing from the image the structures fixing the head. Thereafter, due to adjustment of contrast and saturation, the image is transformed into a mode of visualizing bone tissues, then skull positioning is performed in a lateral projection, wherein the lateral edges of the orbits and the condyloid processes of the lower jaw protrude as landmarks. To determine the head tilt, a side photograph is used or positioning is performed along the Frankfurt horizontal line, after which the image is transferred to the soft tissue mode, wherein the lines denote planes Ro, Tf, Gb, Sn, then image is transferred into mode of bone structures and occlusion plane OP is performed, then profile deficit PD' is calculated as difference of distances from Tf to Gb and from Gb to Sn, further mark the point is', which is the desired position of the edge of the central incisor of the upper jaw and located anterior of is at distance PD' and below it at a distance equal to 3-((age – 25):10) – (is – StS)), after which from the point is' the occlusive plane OP' is made tangentially to the occipital skull, and the following parameters are obtained, according to which the aesthetically optimal postoperative position of the upper jaw is uniquely determined: PD' is profile depth deficiency; is-is' is vertical displacement of upper jaw; angle between OP and OP' is angle of change of inclination of occlusal plane during operation; intersection of OP and OP' – point, relative to which rotation of upper jaw is to be performed, where: Ro – "girdle" plane, Tf – plane, passing through the upper border of the frontal perpendicular to the girdle plane, Gb – plane, passing through glabella perpendicular to girdle plane, Sn is a plane, passing through the base of the nose perpendicular to the girdle plane, OP – occlusion plane before surgery, PD' – profile depth deficit, is – lower edge of central incisor of upper jaw before operation, StS – lower edge of upper lip before operation, is – StS is the value of the patient's maxillary incisor central edge protrusion from under the upper lip lower edge with the passive opening of the mouth, is' is the desired position of the edge of the central incisor of the upper jaw, is – is' – the desired displacement of the upper jaw in the vertical, OP' is the desired position of the occlusal plane.

EFFECT: invention provides higher efficiency of finding the optimal postoperative position of the upper jaw of the patient during the operation planning.

1 cl, 1 ex, 6 dwg