In complex dental treatments, a preliminary virtual plan (VP) can minimise the probability of errors and increase the predictability of the achieved result. Digital technologies and artificial intelligence open more opportunities for such planning, as they can be applied at the early stages of clinical examination to develop a simultaneous VP of all stages of treatment. The present clinical case describes a one-stage entire VP combining all the stages of treatment: gnathological, orthodontic, and prosthetic rehabilitation, until the final result. This approach avoids the accumulation errors associated with multistage VP, in which one stage of planning follows the end of a previous stage. One-step VP also allows demonstrating to the patients the expected results of the restoration, which increases their motivation to initiate the treatment.

ЦЕЛЬ ИССЛЕДОВАНИЯ Оптимизация методики 3D-анализа параметров височно-нижнечелюстного сустава (ВНЧС), анализ причин возможных погрешностей. МАТЕРИАЛ И МЕТОДЫ Представлена методика 3D-анализа ширины суставной щели, размеров мыщелка, высоты и наклона дистального ската суставного бугорка в компьютерной программе Avantis3D (Россия) по данным компьютерной томографии. Проведена оценка точности (прецизионности) определения параметров ВНЧС при повторных ручных коррекциях контуров мыщелков и суставных ямок, при смещении центра секторов измерения ширины суставной щели, в зависимости от алгоритмов определения продольной оси мыщелков, а также от точки начала отсчета секторов измерения. РЕЗУЛЬТАТЫ Исследование показало, что любое искусственное смещение центра секторов измерения ширины суставной щели, который совпадает с продольной осью мыщелка, приводит к существенному изменению показателей. В связи с этим особое значение приобретает точное и независимое от человеческого фактора построение продольной оси мыщелков. Наибольшая неточность и вариабельность результатов измерения параметров ВНЧС, как показало исследование, связана с возможной ручной коррекцией контуров поверхностей мыщелков и суставных ямок. Исследование не обнаружило заметной разницы в показателях в случае начала отсчета секторов измерения от вершины суставного бугорка или от линии параллельной франкфуртской горизонтали. Определены оптимальные настройки разработанной методики. С ее использованием определены средние значения параметров ВНЧС для пациентов с условной «нормой», а также для пациентов с дисфункцией ВНЧС. Между группами обнаружена заметная и статистически значимая разница только для ширины верхней и задней трети суставной щели. ЗАКЛЮЧЕНИЕ Обоснованы средние значения параметров ширины суставной щели, которые могут быть положены в основу виртуального задания реконструктивной позиции нижней челюсти для ортопедического или ортодонтического лечения.

Purpose: To compare the aspect of the reproduction accuracy in studied methods of determination of the (CR) of jaws using the digital research methods. The methods used were bilateral manipulation by P.E. Dawson, frontal deprogrammer, leaf gauge, and intraoral device for recording of Gothic arch angle. Methods: To determine the reproduction accuracy of the centric relation of jaws, we examined 5 patients with intact dentition in a prosthetic dentistry clinic (first class in Angle’s system). For each method, 20 registrations of the centric jaw relation were carried out by one operator. The breaks between definitions were 30 minutes. A total of 400 CR recording operations were carried out (400 records of CR). In order to study the reproducibility of CR determination methods, 200 recorded mandible positions were analyzed by means of an analog-to-digital method (a macro kit Canon 650D, Canon 60 mm macro IS USM f2.8, Canon macro ring MR-14 EX and the computer program Adobe Photoshop) to assess the first occlusal contact obtained in the CR of jaws, while the other 200 were analyzed by means of a digital method (the computer program Avantis for 3D modeling, Prime as a laboratory 3D scanner (DOF), and Trios as an intraoral scanner (3Shape)) to assess the spatial position of the mandible in the CR. Statistical analysis was carried out using STATISTICA-10. In all statistical analysis procedures, the critical significance level p was assumed to be 0.05. Results: In the study of the data by means of the computer program Avanti 3D, the reproducibility of the mandible position in the CR reached 0.119 ± 0.012 mm for frontal deprogrammer, 0.225 ± 0.028, p ≤ 0.05 for bilateral manipulation by Dawson P.E., 0.207 ± 0.02, p ≤ 0.05 for leaf gauge, and 0.120 ± 0,013, p ≤ 0.05 using an intraoral device for recording the Gothic arch angle. The analog-to-digital method showed an identical tendency for reproduction of the mandible position. Conclusions: The digital analysis we made using the Avantis 3D program showed, with high confidence, that the maximum reproducibility of the CR position was reached by using our own design frontal deprogrammer and the device for recording Gothic arch angle.

To increase the efficiency of diagnosis and orthodontic treatment of patients with temporomandibular joint dysfunction based on the study of the relationship between the features of the position of the heads of the lower jaw and various face types in patients aged 25 to 44 years according to cone beam computed tomography. We examined 100 people who were divided into two main groups (50 males, 50 females). To study the formed groups index method for diagnosing facial types according to Isar was used. The facial indicator was determined: the percentage of physiognomic height to the morphological width of the face. The structural features and relative positions of the TMJ bone structures in patients with TMJ dysfunction in various face types were studied in the Avantis 3D computer program. It was noted that the upper position of the lower jaw heads in women and men with a narrow type of face was observed in 50% and 40% of cases, respectively; the distal position of the lower jaw heads in women and men with a wide type of face was observed in 50% and 42.3% of cases, respectively. The results of the study indicate that there is a relationship between different types of face and the position of the lower jaw heads in the lower jaw, which should be considered in comprehensive treatment planning. The most at risk of temporal dysfunction is the TMJ of a woman with a narrow type of face, in which dominates the upper position of the lower jaw heads and a woman with a wide type of face with the distal position of the lower jaw heads. Before orthodontic treatment it is necessary to investigate the position of the TMJ heads with the help of CBCT and make a mandatory correction before the beginning of orthodontic treatment.

The aim is to study of the accuracy of the virtual reposition of the mandible (LF) by comparing the virtual and real position of the LF heads, as well as the analysis of factors contributing to the occurrence of errors. An experimental model of a human skull with a movable LF was made of radiopaque material. The resulting computed tomogram (CT) of the upper and lower jaws and temporomandibular joint (TMJ) was combined with dental scans of dental rows and CT scans and a report on the position of the heads of the LF was obtained. Then the LF was shifted to another position and this position was fixed. Optical bite recorders were obtained using an intraoral scanner. An experimental model with a fixed new position of the LF was placed in a tomograph and repeated CT was obtained. In the program, according to optical registers, a virtual reposition of the LF was carried out. The correspondence of the virtual and real position of the mandibular heads was compared. The absolute difference of glenoid fossa space between the actual and virtual reconstruction was 0.542±0.3354 mm in the anterior joint section (M±δ, M - average mean, δ - standard deviation); for the upper joint section - 0.309±0.2246 mm; and 0.260±0.1862 mm for the posterior section. The integral indicator of surface coincidence (q) when the virtual and actual position are directly compared was 0.296±0.1254 (s.u.). The total margin of error depends on the following factors: repeated scanning error (teeth arches and bite scans), repeated CBCT error, a combination of scan and CBCT error, a combination of teeth arch scan and bite scan error, error of TMJ separation. The latter two factors were the most significant.

Представлены обзор современных данных по применению 3D-печати в стоматологии, принцип действия 3D-принтеров по металлам, приведены сравнительные данные по качеству и точности конечного продукта 3D-печати металлом. Указаны возможности и перспективы применения 3D-печати металлом в стоматологии.