V.A. Krasnov

The aim of this research is to examine the morphometric parameters of lower third molars at different stages of eruption and across different age groups, as well as the prevalence of retention in the study participants with undifferentiated connective tissue dysplasia. Material and methods. The research included 327 women with and without undifferentiated connective tissue dysplasia (UCTD). Morphometric parameters were assessed using CBCT data obtained using Planmeca ProMax 3D s (Finland) with the OnDemand 3D software. The study examined the inclination of the lower third molars, mesiodistal and vestibulolingual dimensions, the crown length of the teeth, and the average crown length of the lower molar arch. Results. An analysis of the topographic position of the lower third molars revealed that medial inclination occurs in 32.4% of cases with UCTD and in 41.7% of cases without UCTD. Among the examined patients with UCTD, the following types of inclination were prevalent among positional anomalies: buccal (19% of cases), lingual (16.9%), and distoangular (15.5%). In patients with UCTD, horizontal inclination of the lower third molars was observed in 11.3% of cases. Among patients without UCTD, buccal (20.5% of cases) and distoangular (9.7%) types of inclination of the examined teeth predominate. It is important to note the high number of cases among examinees without UCTD who had a vertical inclination of the lower third molars (17.9% of cases); however, this number is lower among individuals with UCTD (2.8% of cases, p<0.001). Conclusions. A study of the position of the lower eighth teeth revealed that the following types of inclination predominate in patients with UCTD: medial, buccal, lingual, and distoangular. An analysis of the mean module in the lateral quadrant of the mandible revealed a decrease in this index for the lower sixth and seventh teeth with age in individuals with UCTD, which confirms the findings regarding a reduction in the primary massiveness of the first and second molars in UCTD.

The aim is to describe the connective tissue mechanism of lower third molar eruption in normal conditions and in cases of connective tissue dysplasia, to develop and test a technology to support medical decision-making in assessing the risk of lower third molar eruption diseases and purulent-septic complications. Materials and Methods. The study involved 327 women who underwent clinical, radiological, microscopic, morphological, and biochemical examinations to determine the presence and degree of connective tissue dysplasia and to develop a description of the mechanism of lower third molar eruption. For clinical testing of the decision support technology, two groups of patients were selected: those with CTD (n=20) and those without CTD (n=20) diagnosed with acute pericoronitis, in whom the presence of clinical symptoms was assessed in the early postoperative period. Results. A conceptual description of the mechanism of eruption of lower third molars in connective tissue dysplasia was provided, which made it possible to develop and test a technology for supporting medical decision-making and criteria for establishing the risk of purulent-septic complications in cases of impaired eruption of lower third molars. The application of medical decision-making technology in the clinic for patients with connective tissue dysplasia made it possible to reduce pain syndrome by 1-2 days, general symptoms of intoxication by 3-4 days, and local manifestations by 5-6 days, which in many respects achieved a clinical effect similar to that in the control group (examined without CTD) in many respects, as well as preventing the development of purulent-septic complications in the early postoperative period. Conclusions. The developed mechanisms and technologies are aimed at understanding the causes of impaired eruption of lower third molars and provide a methodology for managing patients with this condition for timely diagnosis and prevention of purulent-septic complications.

Цель работы — оценить зрелость твердых тканей нижних третьих моляров, находящихся на различных стадиях прорезывания, при дисплазии соединительной ткани (ДСТ), опираясь на результаты микроскопических и биохимических методов. В исследовании приняли участие 84 женщины в возрастных группах 14—17, 18—21, 22—26, 27—31, 32—36 лет с ДСТ и без нее, у которых по ортодонтическим или неотложным показаниям удаляли зубы 3.8, 4.8, находящиеся на разных стадиях прорезывания. После подготовки по собственным методикам образцов дентина, эмали и эмалево-дентинного соединения проводили микроскопическое исследование с помощью растрового электронного микроскопа Jeol JCM-5700, оценивали морфологию твердых тканей зуба на продольном срезе, а также выполняли биохимическое исследование методом ИК-спектроскопии, определяли на всех этапах положение и интенсивность полос поглощения (ПП). Между возрастными группами при ДСТ выявлены статистически значимые отличия в поверхностном отделе: в возрастной группе 22—26 лет на стадиях зачатка (p=0,0001), до уровня десны (p=0,02), до уровня коронки второго моляра (p=0,002); в возрастной группе 14—17 лет на стадии прорезывания до уровня коронки второго моляра (p=0,02). В глубоком отделе отличия уставлены только в возрасте 14—17 лет на стадии до уровня коронки второго моляра (p=0,02). Интенсивность ПП фосфатов (967 см−1) снижается при ДСТ на всех стадиях прорезывания, кроме стадии зачатка, однако именно в этой стадии также снижается интенсивность ПП 1050 см−1, что в целом свидетельствует о снижении содержания минеральной составляющей твердых тканей зубов при ДСТ. Интенсивность ПП коллагена (1202 и 1249 см−1) при ДСТ растет в дентине и снижается в эмали. Результаты микроскопического и биохимического исследования твердых тканей нижних третьих моляров показывают, что наличие коллагеновых волокон в дентине влияет на биохимические и механические свойства эмали через эмалево-дентинное соединение за счет прочного сцепления и правильной упаковки коллагеновых фибрилл. Purpose of the work is to evaluate the maturity of the hard tissues of the lower third molars at different stages of eruption in connective tissue dysplasia, based on the results of microscopic and biochemical methods. . The study involved 84 women in the age groups 14—17, 18—21, 22—26, 27—31, 32—36 years with and without connective tissue dysplasia who had teeth 38, 48, which were at different stages of eruption, extracted for orthodontic or emergency indications. After preparation of dentin, enamel and enamel-dentin junction samples according to our own methods, microscopic examination was carried out using a scanning electron microscope Jeol JCM-5700, the morphology of dental hard tissues was evaluated on a longitudinal section, as well as biochemical examination by IR spectroscopy, the position and intensity of absorption bands (AB) were determined at all stages. . Statistically significant differences between age groups in CTD were found in the superficial section: in the age group 22—26 years at the stages of rudiment (p=0.0001), up to the gingival level (p=0.02), up to the level of the crown of the second molar (p=0.002); in the age group 14—17 years at the stage of eruption up to the level of the crown of the second molar (p=0.0200). In the deep section, differences were established only at the age of 14—17 years at the stage up to the level of the crown of the second molar (p=0.0200). The intensity of AB phosphate (967 cm−1) decreases in CTD at all stages of eruption except for the rudimentary stage, but it is at this stage that the intensity of AB 1050 cm−1 also decreases, which generally indicates a decrease in the mineral content of dental hard tissues in CTD. The AB intensity of collagen (1202 and 1249 cm−1) in CTD increases in dentin and decreases in enamel. . The results of microscopic and biochemical examination of the hard tissues of lower third molars show that the presence of collagen fibers in dentin affects the biochemical and mechanical properties of enamel through enamel-dentin junction, due to strong adhesion and proper packing of collagen fibrils.