RU2819992C1 - Method for x-ray determination of value of distalisation of first molars of upper jaw - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: invention refers to medicine, namely to dentistry, particularly to orthodontics, and can be used in diagnosing abnormal position of teeth on upper jaw during occlusion of permanent teeth. Performing a three-dimensional X-ray examination of the dentoalveolar system of the patient to obtain an orthopantomogram of the jaws, on which a horizontal line and vertical lines perpendicular to it are built, passing through an apex of a mesiobuccal tuber of the first molar of the upper jaw and an anteriocuspidate fissure of the first molar of the lower jaw. At that, the horizontal line is built along the tops of the cusps of the lateral group of the teeth of the lower jaw, and the value by which it is necessary to distalize the first upper molars before closure according to the first Angle class, is determined by distance between points of intersection of vertical and horizontal lines.

EFFECT: method enables calculating the required amount of distalisation of the first upper molars relative to the first lower molars, before the beginning of the orthodontic treatment, taking into account not only the location of the crown part, but also their roots.

1 cl, 1 dwg, 2 ex

Description

The invention relates to the field of medicine, namely to dentistry, in particular to orthodontics. Can be used to diagnose abnormalities in the position of teeth in the upper jaw during the period of occlusion of permanent teeth.

There is a known method for determining the mesial shift depending on the sum of the mesiodistal dimensions of the lateral group of teeth (Gubanova, V.S. Diagnosis of the position of molars in three mutually perpendicular planes in dentofacial anomalies: dissertation of Candidate of Medical Sciences / V.S. Gubanova). An indicator of the sagittal position of the first upper molars is their position relative to the RPT line, as measured by dentition models.

To determine the mesial shift it is necessary:

1. Measure the distance from the distal surface of the upper molar to the point of intersection of the Schmut line and the dentition.

2. Compare the resulting distance with the sum of the mesiodistal dimensions of the lateral group of teeth.

Based on the result, a conclusion is drawn: about the degree of mesial shift on the side of interest of the upper dentition; about the preservation or loss of support during the process and/or at the end of orthodontic treatment.

The disadvantages of this method include the impossibility of accurately determining the required amount of distalization of the first upper molars and the complexity of performing this method.

The method of symmetroscopy is also known. Using this method, the location of the teeth is studied in the transversal and sagittal directions. Ortho-cross (orthodontic cross) is used for express diagnostics. It is a transparent plate on which a cross with millimeter divisions or a millimeter grid with divisions of 1-2 mm is applied. The plate is placed on a plaster model of the upper jaw, orienting the cross along the median palatal suture, and then the location of the teeth is studied in relation to the midline and transverse lines.

The disadvantages of this method include the possible incorrect comparison of the orthodontic cross with the median palatal suture.

As the closest analogue, the linear tetrasectoral analysis of orthopantomograms proposed by Dmitrienko D.S. was chosen, which is based on the distance between the points located on the middle lower points of the articular tubercles. On the left and right sides of the upper jaw, the orthopantomogram (OPTG) identifies four sectors of equal size (anterior, lateral, molar and retromolar). The boundaries of each segment correspond to the main anatomical landmarks for the location of key teeth (canines and first molars) and the boundaries of the retromolar region (Dissertation for the degree of Doctor of Medical Sciences “Optimization of modern methods of comprehensive examination and treatment of patients with a discrepancy between the sizes of permanent teeth and the parameters of the dentofacial arches” Dmitrienko D.S. - Volgograd - 2011). The main guideline of the proposed method is the distance between the points on the articular tubercles.

The disadvantages of the closest analogue include the well-known fact: the articular tubercles are not an anatomically stable landmark, since in diseases of the temporomandibular joint they are often deformed and in this case the use of this method is impossible.

The objective of the invention is an X-ray method for determining the required value for distalization of the upper first molars on a cone beam computed tomography (CBCT) section.

The proposed method has the following differences: the calculation of the required amount of distalization of the first upper molars is carried out on a CBCT (OPTG) section and the use of more stable anatomical landmarks.

The essence of the proposed method is as follows:

A three-dimensional X-ray examination of the patient's dental system is carried out, as a result of which an orthopantomogram of the jaws is obtained (Fig. 1). The method is based on anatomically significant and easily identifiable landmarks: the mesiobuccal cusp of the first upper molar, the anterotubercular fissure of the first lower molar, if correctly positioned, and a line running along the tops of the cusps of the lateral group of teeth.

On the OPTG, perpendiculars are lowered from the top of the mesiobuccal cusp of the first molar of the upper jaw and from the anterotubercular fissure of the first molar of the mandible to the selected line. Next, measure the distance between the points of intersection of the perpendiculars with a line drawn along the vertices of the cusps of the lateral group of teeth, and obtain the value by which it is necessary to distalize the first upper molars to obtain a closure according to the first Angle class.

The invention makes it possible to accurately calculate the required amount of distalization of the first upper molars, relative to the first lower molars, before starting orthodontic treatment, taking into account not only the location of the coronal part, but also their roots.

Examples of method implementation:

1. Patient L., 21 years old

Diagnosis: closure of the lateral groups of teeth according to the distal type. Supra- and vestibular position of the canines on the upper jaw.

One of the treatment goals is to move teeth 1.6 and 2.6 distally.

Treatment:

The required amount of distalization of teeth 1.6 and 2.6 was calculated using the method presented above: the distance between the points of lowered perpendiculars from the mesio-buccal cusp of tooth 1.6 and from the anterotubercular fissure of tooth 4.6 is 4.7 mm; the distance between the points of the lowered perpendiculars from the mesio-buccal cusp of tooth 2.6 and from the anterotubercular fissure of tooth 3.6 is 4.6 mm.

The result of distal movement after 7 months: tooth 1.6 moved by 4.7 mm, tooth 2.6 - by 4.6 mm. Teeth 1.6 and 4.6, 2.6 and 3.6 occlude according to Angle class 1.

2. Patient D., 23 years old

Diagnosis: closure of the lateral groups of teeth according to the distal type on the right. Supra- and vestibular position of the tooth 1.3.

One of the treatment objectives is to move tooth 1.6 distally.

Treatment:

The required amount of distalization of tooth 1.6 was calculated using the method presented above: the distance between the points of lowered perpendiculars from the mesio-buccal cusp of tooth 1.6 and from the anterotubercular fissure of tooth 4.6 is 5.2 mm.

Result of distal movement after 7 months: tooth 1.6 moved by 5.2 mm. Teeth 1.6 and 4.6 occlude according to Angle class 1.

Claims (1)

A method for radiometric determination of the amount of distalization of the first molars of the upper jaw, including a three-dimensional X-ray examination of the patient’s dental system to obtain an orthopantomogram of the jaws, on which a horizontal line and vertical lines perpendicular to it are constructed, passing through the apex of the mesiobuccal cusp of the first molar of the upper jaw and the anterotubercular fissure of the first molar of the lower jaw , in this case, a horizontal line is built along the tops of the cusps of the lateral group of teeth of the lower jaw, and the amount by which it is necessary to distalize the first upper molars before closure according to the first Angle class is determined by the distance between the points of intersection of the vertical and horizontal lines.