Clinical and radiological assessment of mesial occlusion associated with congenital skeletal abnormalities of the jaw bones

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Introduction. Sagittal occlusion abnormalities, in particular mesial occlusion, are becoming more and more common at orthodontic appointments. This pathology accounts for about a quarter of all orthodontic patients. The progression in the prevalence of mesial occlusion occurs due to untimely treatment, insufficient diagnosis, the presence of bad habits, teratogenic factors during pregnancy, as well as due to the lack of a unified weak system for providing specialized medical care to such patients.
Mesial occlusion, depending on the morphological etiology, has two forms: dental alveolar and skeletal.
The skeletal form of mesial occlusion is formed from birth to adolescence. At the same time, the differences between the dental and skeletal forms are not clinically revealed.
The growth of the mandible can stimulate its forward extension in case of skeletal anomaly of mesial occlusion
The aim of the work is to evaluate the cephalometric and anthropometric parameters of individuals with skeletal form of mesial occlusion of the dentition
Materials and methods of research.
Clinical, X-ray, anthropometric, mathematical, and statistical methods were used to conduct the study. The clinical method included the collection of complaints, anamnesis, external examination of the face to determine the symmetry of the face, profile type, proportionality of the face and facial features, examination of the oral cavity to identify anomalies of occlusion, the size and position of the dentition and jaw bones, the location of the frenules of the upper and lower lip, tongue. The parameters of length, width, height, depth, as well as the proportionality of different parts of the head were evaluated by the anthropometric research method.
The study involved 11 patients aged 12 to 18 years, who were divided into two groups based on the completeness of the formation of the facial skeleton.
The study was carried out at the Voronezh Region budgetary healthcare institution "Voronezh Children's Clinical Dental Polyclinic No. 2" at the Department of Pediatric Dentistry with Orthodontics.
Inclusion criteria: mesial occlusion, micrognathia of the upper jaw, retrognathia of the upper jaw, macrognathia of the lower jaw, prognathia of the lower jaw, retrognathia of the lower jaw in combination with retrognathia of the upper jaw, lack of completed orthodontic treatment in the anamnesis.
Exclusion criteria: a history of completed orthodontic treatment, dental alveolar and articular forms of mesial occlusion.
Photographs of patients obtained with their consent were used as material for anthropometric diagnostics. Telerentgenograms were calculated manually and in the OrtoCeph program using the Tweed method. The Microsoft Excel program was used to collect, store and organize the information received, as well as for its subsequent mathematical and statistical processing.
The results of the study.
According to the results of the analysis of telerentgenograms in the lateral projection of the subjects, a decrease in the angles of SNA and ANB was revealed compared to the norm in all probants, which indicates a retroposition of the upper jaw and the third skeletal class, respectively. The average values of the SNA angle are 79o, ANB is -3.2O.
The SNB angle in 2 (20.5%) patients turned out to be less than normal, which indicates retrognathia of the mandible, in the rest - more than normal (79.5%) - prognathia of the mandible, the average values of the SNB angle were 82.1 O.
In all patients, the SNPog angle exceeding the value of the SNB angle indicates the anterior position of the chin.
We revealed a significant deviation from the norm of the Beta angle, the average values of which turned out to be 49.3o, which indicates a pronounced third skeletal class.
The Wits number, which determines the disproportion of the development of the apical bases of the jaws, ranged from -6 to -20, the average values were -11.
When determining the index of facial height, it was found that half of the patients (50.5%) had a vertical type of facial skeleton growth (increased anterior height and decreased posterior), 32.4% of the subjects had a horizontal type of growth with an increase in posterior and a decrease in anterior facial height, and 17.1% had a normal type of facial skeleton growth.
To determine the type of growth of the facial skeleton, the Bjork angle was also analyzed, which in 50.5% of cases was greater than 396 degrees, in 17.1% - normal, and in 32.4% - less than normal.
Also, anteinclination of the upper jaw was detected in 60.9% of the probants, retroinclination of the upper jaw was detected in 39.1%, and the average values of the NSL-NL angle were 8.3 degrees.
Determination of the inclination of the mandible relative to the plane of the base of the skull NSe showed that only one patient (10.1%) had the norm, the remaining 90.9% had retroinclination of the mandible, the average values of the angle NSL-ML were 42.4O.
The mandibular angle, showing the mutual inclination of the upper and lower jaw, indicated normal in only 1 case (10.1%), and hyperdivergence in the remaining patients (89.9%).
The average values of the gonial angle are 134.2 O.
In most cases (79.8%), protrusion of the upper incisors was revealed both relative to the base of the skull and relative to the plane of the upper jaw NL, in one patient (10.1%) the position of the upper incisors relative to the base of the skull is normal, and relative to the upper jaw - in protrusion, in another patient (10.1%) - retrusion relative to the base of the skull and protrusion relative to the plane of the upper jaw.
The retraction of the incisors of the mandible relative to the plane of the mandible was revealed in 100% of cases.
The incisor angle in all the subjects turned out to be higher than normal, which indicates a biretrusion of the incisors of the upper and lower jaw.
Upper macrognathia was detected in 17.1% of patients, lower - in 83.9%, upper normognathia - also in 17.1% of the subjects, upper micrognathia - 65.8%, and lower micrognathia - in 17.1% of cases.
At the same time, the combination of anomalies in the size of teeth was as follows: in 50.5% of cases, upper micrognathia and lower macrognathia, 17.1% of cases - upper and lower macrognathia, upper and lower micrognathia, as well as upper normognathia and lower macrognathia.
The statistical data of the conducted research are shown in Table 1 in more detail.
Myagkova N.V., analyzing telerentgenograms in persons with gnatic mesial occlusion, used, along with the above, other parameters: projection of the upper jaw to TVL, projection of the lower jaw to TVL, overjet, overbite, anterior height of the lower jaw Md1tip-Me,, height of the lower third of the face, height of the upper jaw, mandible height, A-Co, Gn-Co [1].
G.Zegan et al. evaluated telerentgenograms using 14 parameters, such as angles SNB, SND, FMA, IMPA, MeGoOcP, Mand1-MeGo, NSAr, ArGoMe, NGoMe, SNPog; lengths Ao-Bo, lu-NPog; Holdway coefficients, AFH; angle NGoAr, Ls-NsPog distance and S-Ar ratio:Ar-Go. This study showed the absence of sexual characteristics of mesial occlusion [2].
In our opinion, the most common and frequently used method of evaluating telerentgenograms is precisely the Tweed method.
According to Yu.A. Gioeva, there is no correlation of values between the Wits number, angle I-I and the type of growth of the facial skeleton. Consequently, it does not affect the position of points A and B, as well as the position of the incisors relative to each other [3].
L.G. Ulyanova considers such a parameter as the distance from the pterygoid vertical to the distal surface of the upper molar, which increased by more than 50% during treatment, to be the most relevant [4].
Evid identified from 3 to 14 classes based on the analysis of SNA, SNB, Ar-Go-Me angles. He revealed the ethnic features of the clinical picture of mesial occlusion. Thus, he divided people of Asian origin into 8.5 classes, and Caucasians into 3.5. This study indicates the important role of the phenotype in the development of mesial occlusion [5].
We have determined that in individuals with a neutral growth type, jaw development occurs anteriorly and downwards relative to the NSe plane. With the vertical type of growth, the rotation of the lower jaw is observed counterclockwise and its movement posteriorly. The horizontal type of growth, sideways, leads to the movement of the lower jaw anteriorly and its hourly rotation.
Based on this study, it was found that for effective planning of orthodontic treatment based on the nature of the direction of growth of the jaw bones, such parameters as the index of face height, total Bjork angle, NSL-ML angle, basal angle, Beta angle are of the greatest importance.
In the treatment of patients with mesial occlusion and neutral growth type, it is necessary to monitor the angle I-ML, length GoGn; with horizontal growth type - angle NSL-NL, SNB, I-NSL, I-NL, length A1Snp; with vertical growth type - angle NSL-ML, I-ML, anterior height NMe. In all cases of treatment, the total Bjork angle in dynamics is necessarily measured.
To prevent recurrence of dental anomalies after the end of orthodontic and surgical treatment, attention is paid to the length of the body of the lower jaw, the posterior height of the face, the length of the anterior part of the base of the skull during anterior rotation; to the basal angle, the angle NSL-ML - during posterior rotation.
Conclusion.
When drawing up a treatment plan for patients with mesial occlusion due to skeletal abnormalities, it must be remembered that the vertical type of growth of the facial skeleton contributes to a favorable prognosis of treatment, and the horizontal type of growth, on the contrary, can create difficulties in correcting mesial occlusion. These circumstances should be taken into account when planning methods and means to achieve proper occlusion of the dentition.

About the authors

Irina Igorevna Utrobina

Voronezh State Medical University named after N. N. Burdenko

Email: utrobina10@mail.ru
ORCID iD: 0000-0002-6610-8909
SPIN-code: 2791-4284

Student

Russian Federation, 10 Studencheskaya Street, 394036 Voronezh, Russian Federation

Mikhail Eduardovich Kovalenko

Voronezh State Medical University named after N.N. Burdenko

Author for correspondence.
Email: m.kovalenko@vrngmu.ru

Candidate of Medical Sciences

Russian Federation, 394036, Voronezh region, Voronezh, st. Student, d. 10.

References

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