Relevance. The goal of root canal instrumentation is elimination of bacteria and tissues and enlargement of canal diameter for optimal obturation. The aim of this study was to conduct a comparative analysis of most commonly used among Russian practitioners rotary systems for root canal instrumentation.

Aim. To determine the causes of an apical crack formation.

Materials and methods. Recently extracted teeth with one root were used in the research. They were divided into 4 groups: instrumented with ProTaper (Dentsply Maillefer), Mtwo (VDW), ProFile (Dentsply Maillefer) and hand stainless steel files.

Results. No cracks were observed after root canal instrumentation with hand files. Instrumentation with rotary nickeltitanium files caused apical cracks formation. The biggest amount of cracks was caused by ProTaper files (Dentsply Maillefer), the least amount of cracks was caused by Mtwo files (WDW).

Relevance of the research topic. The mandibular incisive nerve provides innervation to the mandibular anterior teeth and its damage can lead to neurological and pain symptoms. There is a possibility of damage to this nerve during endodontic treatment in the anterior mandible.

The aim is to study the location of the mandibular incisive canal relative to the root apices in the anterior mandible with cone-beam computer tomography (CBCT) scans.

Materials and methods. We selected and measured from the tops of the roots of the teeth to the mandibular incisive canal in 180 CBCT-scans of patients aged from 24 to 80 years (90 men and 90 women; average age 53.27 ± 6.8) on sagittal view.

Results. The average distance for all measurements from the mandibular incisive canal to the root apices was 7.2 ± 2.4 mm. The lowest distance was noted in the first premolar region on the left (1.4 mm), and the greatest the canine region on the same side (15.1 mm). There were no statistically significant differences between age and gender, between the sides, as well as in the area of different groups of teeth.

Conclusion. Despite the fact that the risk of damage to this structure is quite small, it still exists and clinicians should not ignore this feature.

Relevance. The prevalence of precancerous diseases in the structure of the pathology of the oral mucosa in patients of the Russian Federation is quite high (up to 35%) and has no tendency to decrease, which actualizes the search for more effective methods of complex treatment and rehabilitation to improve the patient's quality of life and prevention of malignancy.

Aim. To present a comparative assessment of the effectiveness of conservative surgical dental treatment in combination with restorative rehabilitation of patients with oral lichen planus.

Materials and methods. The study assessed the effectiveness of complex conservative surgical treatment and prosthodontic rehabilitation of patients with the most frequently detected form of oral precancer lichen planus.

Results. Based on a comprehensive assessment of objective and subjective indicators, the feasibility and advantages of an integrated approach to the treatment and rehabilitation of patients with lichen planus are substantiated, including the local use of highly active topical steroids / calcineurin inhibitors, electrocoagulation of hyperkeratosis sites until stable remission with subsequent prosthetic treatment using biocompatible materials, rational designs, atraumatic techniques, including implant dental prosthetics.

Conclusion. Conducting a rational prosthodontic rehabilitation upon completion of the conservative-surgical treatment stage provided a 6.5-month longer remission of the disease compared with the control group.

Relevance. Focal enamel demineralization is one of the significant problems of dentistry, given that the initial stages are manifested by demineralization, rapidly progressing in the absence of timely adequate therapy.

Aim. To substantiate the feasibility of using the microinvasive method of treating focal enamel demineralization in orthodontic patients based on multilevel analysis of the enamel microstructure using modern clinical and high-precision experimental studies.

Material and methods. Enamel artificial caries was modeled on the vestibular surface of 42 teeth using an original technique, as well as special hardware and instrumentation.

Results. When analyzing the SEM data, an inhomogeneous rough enamel microrelief with the presence of numerous depressions, depressions, and characteristic ridges was established. SEM certification of the longitudinal section of the tooth showed that with an increase of 217 times in the section of artificial caries, enamel destruction zones are determined from 200 to 450 μm deep, most often in the shape of a triangle, with the apex facing the enamel-dentine border.

Conclusion. The results of a multilevel (macro-, meso- and microscopic) analysis of the structure and micromechanical properties of enamel in the focus of demineralization made it possible to assess the validity of the developed experimental methods for artificial caries of enamel, to obtain voluminous information about the structural and functional disorders developing in it, to justify the expediency of the pathogenetic use of the microinvasive infiltration treatment method.

Relevance. Many dentists in their clinical practice use a two-time adhesion protocol, which does not always follow the manufacturer's instructions, believing that they achieve improved adhesion of the filling material to the tooth tissues. To solve the problems associated with increasing the compressive strength of adhesive materials, a single-bottle adhesive system was developed based on the technology of organically modified ceramics (Admira Bond, VOCO GmbH Germany). Despite the fact that the Admira Bond adhesive system is already used in practical dentistry, its adhesion to hard tooth tissues and the characteristics of the hybrid zone when used according to the manufacturer’s instructions and the protocol providing for double application of the adhesive for restoration of the tooth have not been sufficiently studied.

Aim. To study the structure of the hybrid zone using a scanning electron microscope using an Admira Bond adhesive system based on Ormoker.

Materials and methods. Using a remote survey on the frequency of use of various adhesive protocols, identify the most commonly used and compare the selected protocols on samples of longitudinal sections of teeth using a Tescan Mira LMU scanning electron microscope.

Results. I n a s ample p repared b y t he a dhesive p rotocol o f d ouble a pplication o f a dhesive, t he t hickness o f t he hybridization zone is 1 μm. The distribution of adhesive over the dentin surface is uneven. The adhesive system was infiltrated into the filling material.

Conclusions. When using the protocol according to the manufacturer's instructions, a higher quality of hybridization, uniformity of structure and uniform distribution of the Admira Bond adhesive system based on Ormoker on the dentin surface are noted than when using the protocol of double application. This confirms that deviation from the manufacturer's recommended protocol for using Admira Bond adhesive system based on Ormoker, reliably leads to a deterioration in the adhesion strength of the filling material to the dentin of the tooth.

Relevance. Persistence of microorganisms in the root canal system of teeth with apical periodontitis negatively affects the success of treatment and the expected response to it. Improving the process of root canal irrigation can form a basis for the development of new scientifically grounded methods for effective treatment of the root canal system.

Aim. To increase the effectiveness of the treatment of chronic apical periodontitis through improving the method of root canal irrigation.

Materials and methods. 180 patients with chronic apical periodontitis were examined and treated. The survey sample was divided into 2 groups: the main group of 90 patients treated with the use of vacuum-jet irrigation; the control group of 90 patients submitted to the standard irrigation procedure with the use of an endodontic syringe with sonic activation. The study included patients subject to the primary endodontic intervention (98 people), and patients subject to the medically indicated repeated endodontic treatment (82 people). The case follow-up lasted for 24 months. The effectiveness of the treatment was evaluated according to clinical, anamnestic and radiological criteria.

Results. No aggravation of the process was identified in 86.7% of patients of the control group during the 2-year followup. Remission was achieved by only 76.9% of the control group patients who had undergone repeated intervention. In the main study group, remission for over 24 months was identified in 97.8% of individuals. According to the PAI index, a lytic lesion in the periapical area reactivated within 24 months in 94.3% of the main group patients, which exceeds the control group's rate by 2.7 times.

Relevance. The use of skeletal support in orthodontics led to the use of elastic traction and mini-implants for upper jaw traction in class III treatment, however, when planning the placement, clinicians did not take into account the anatomical structures of individual areas, that could lead to iatrogenic damage to the endodontium and periodontium.

The aim of this study is a three-dimensional assessment of the relative position of the roots of mandibular canines and incisors when planning treatment for anomalies of class III occlusion using mini-implants.

Materials and methods. We examined 27 cone beam computed tomography (CBCT) scans in patients aged 20 to 36 years. First, the divergence angle of the longitudinal axes of the canines and lateral incisors was measured on coronary sections of CBCT. Then, according to the bisector of the angle from the anatomical cervix of the tooth, the distances between the roots were measured at the following points: 3 mm, 5 mm, 8 mm and 10 mm. Similar measurements were performed between the central incisors.

Results. The average divergence angle between the lateral incisor / canine on the right was 13.8 ± 2.82 degrees, between the lateral incisor / canine on the right 14.68 ± 2.68 degrees and 10.76 ± 2.47 degrees. The average distance between the lateral incisor / canine totaled 2.45 ± 0.4 mm at a level of 5 mm, at a level of 8 mm this distance is 2.9 ± 0.5 mm, and at a level of 10 mm – 3.26 ± 0. 6 mm.

Conclusion. The mini-implant placement in mandibula in the area between the roots of lateral incisors and canines should be carried out more apically from the anatomical cervix of the tooth more than 8 mm.

Relevance. In case of failure of primary therapy of root canals the modern endodontiya gives to doctors various opportunities of treatment allowing to avoid a tooth extraction. In article the reasons of failure of standard endodontic treatment are considered.

Aim. Recommendations and diagnostic criteria for the choice of a technique of repeated intervention are discussed: orthograde therapy, apical surgical treatment, a tooth extraction or dynamic observation of a clinical situation. The clinical cases in article illustrate process of making decision on the choice of tactics of treatment in various clinical situations.

Aim. Estimation o f possibility of dentin materials u sing Raman spectroscopy for their further possible use for preparation of bone-substitute materials in surgical dentistry and implantology.

Materials and methods. The subjects of the study were 16 samples of dentin material of different size taken from teeth extracted because of orthodontic indications. The teeth were preliminarily treated with the 3% solution of sodium hypochlorite, 3% solution of hydrogen peroxide, then enamel, cement, affected tissues were thoroughly removed and the samples were formed using the diamond drill with water cooling system. All the samples were divided in two groups: group 1 – dentin surface after removal of enamel and cloak dentin (near-pulp dentine) and group 2 – dentin surface after removal of enamel and cement, surface layer of dentin (cloak dentin). The research was made using the Raman spectroscopy method.

Results. It is shown that the researched biological subjects have similar spectral composition. Therefore all dentin of pulpal area of intact teeth can be used for preparing bone-plasty materials for using in dentistry.

Relevance. Use of materials based on the calcium silicate (CSM) in dentistry became popular with the advent of the Mineral trioxide aggregate (MTA) in 1993 as root filler. However in the market of dental services constantly new materials appear which are convenient in use, and also have the best properties, than predecessors. Recently BiodentineTM was provided as "the first universal, biologically active and biocompatible material for replacement of the damaged dentine". Producers claim that BiodentineTM has much shorter time of a curing unlike other silicate cements, such as (MTA) and also has the best mechanical and operational properties. This review of the literature is directed to comparative assessment of physical and chemical, biological ProRoot MTA TM and Biodentine TM properties.

The original implant treatment protocols required a patient to have a waiting period of several months after implant placement. Patients had to use removable dentures during this period. In this case report, novel patient rehabilitation protocols are used, that include immediate implant placement, socket augmentation, early loading in the first maxillary right premolar site, as well as the recession plastic surgery in left maxillary canine with a minimum number of visits.

Relevance. Today, many practitioners encounter paresthesia of the inferior alveolar nerve after surgical procedures. This literature review was aimed at finding possible treatment options for paresthesia and identifying their effectiveness.

In accidents, anterior teeth frequently get injured. In such cases composite restoration can be used as a minimally invasive approach. For a predictable result, it is recommended to use a wax-up and a silicon index as guides to create the correct shape of the incisal. The right matrix system helps reproduce the approximal surface. For an aesthetic outcome, an anatomic layering technique should be used to create the correct optical effects of a natural tooth. Finally, finishing and polishing is responsible for the surface texture and life-like reflection.

Lesions of class II are the most common types of dental caries. The complexity of the diagnosis of contact lesions, the presence of a lot of nuances in the restoration of contact walls determines the high relevance of this issue today. A male patient, 21 years old came to dental clinic of Department of Cariesology and Endodontics MSUMD complaining on the pain on the right upper molars area, constant food partical jamming and unacceptable state of previous restorations. After the analysis of clinical situation and inspection was done the carious process was observed in the 24-27 tooth area. I decided to remove the old restorations, to restore the natural morphology of occlusal surfaces with using Ceram-X. Duo composite material and Palodent V3 matrix system.

Individual manufacturing of post and core systems using CAD-CAM technology allows to quickly and efficiently adapt these structures in the root canal. Today, there are a number of materials, one of which is fiberglass, that is intended for milling. The aim of this literature review is to assess fracture resistance of endodontically treated and reconstructed using fiberglass post and cores using CAD / CAM based on available publications.