[The results of the study of the focus of initial caries of human tooth enamel in vitro using atomic force microscopy]

OBJECTIVE

Identify structural disorders of the surface of the enamel of a human tooth during the development of the carious process in the «white spot» stage using atomic force microscopy (AFM).

MATERIAL AND METODS

The studies were carried out on 10 molar samples in areas with initial caries in the white spot stage. 6 areas of initial caries were scanned using the atomic force microscope Cetus Light (Nano Scan Technology, Russia) in semi-contact mode. Criteria were proposed for comparing the results of AFM scanning of tooth enamel surface samples and, based on them, the nature of the main structural disorders of the enamel surface in the affected area was determined.

RESULTS

For all the samples studied, the healthy enamel surface was smoother compared to the enamel in the area of the clinically visible «white spot» and in the immediate vicinity of it. The heterogeneity of the enamel surface in the center of the white spot» for all the samples studied was at least 60% higher than at the edge of the process. It was revealed that the heterogeneity of the surface outside the clinically visible white spot at a distance of less than 1 mm from its perimeter is at least 30% higher than that of healthy tissue of the same tooth. It is shown that the heterogeneity of the enamel surface in the center of the caries area in the white spot stage is at least 4 times greater than the heterogeneity of the surface of the healthy enamel of the same tooth, which indicates its demineralization.

CONCLUSION

The established features of the spread of the initial carious process can be used in clinical practice for the diagnosis and dynamic observation of the processes of enamel demineralization.

The role of Herpes Simplex Virus type 1 in oral diseases in children

Relevance. Herpes virus infections are the most common and poorly controllable viral infections. There are many difficulties in herpetic lesion verification and treatment in dental practice.

Purpose. The study aimed to present the results of a foreign publication investigation on the role of herpes simplex virus type 1 in the development of oral diseases in children.

Material and methods. Foreign scientific articles about the oral HSV-1 infections published from 2018 to 2022 formed the basis for the study. The study searched the publications on PubMed and Google Scholar bases.

Results. The article presents the newest data on the prevalence, clinical characteristics and diagnosis of oral HSV infection in children. Primary herpetic gingivostomatitis (PHGS), chronic recurrent herpetic gingivostomatitis, chronic recurrent herpes labialis are the main clinical presentations of herpes infection diagnosed in a dental practice. Primary herpetic gingivostomatitis is very common in children aged six months to fve years and occurs in newborns from 2 to 43 days of life. Modern virology success can improve diagnosis and treatment of oral herpetic lesions.

Conclusion. Primary herpetic gingivostomatitis is an acute infectious disease that requires the joint attention of a general practitioner and a dentist to ensure comprehensive treatment.

[Total nasal defect reconstruction with nasal prosthesis. Two case reports]

Total nasal defects after injures or surgical interventions can negatively affect patient's quality of life. Maxillofacial prosthesis is a contemporarily and reliable solution. This method gives us opportunity to restore missing tissues and helps patients to overcome social and psychological difficulties. In this article we demonstrated advantages and disadvantages of the method in two clinical cases. The application of magnetic and adhesive retention in different cases is described. Also, we outlined clinical and technological steps of maxillofacial prosthesis manufacture. Modified procedure of impression obtaining is offered.

[Tatiana Strelyukhina is an outstanding dentist, scientist, researcher (on the occasion of the 100th anniversary)]

The purpose of the work is to present materials on the history of Russian dentistry in connection with the 100th anniversary of an outstanding scientist, clinician, one of the patriarchs of Russian dentistry, a veteran of the great Patriotic war, associate Professor Tatyana Strelyukhina who was at the origins of the specialty and was among the first to create domestic dental materials science.

[Ultrastructural changes of human dental hard tissues during orthodontic treatment with fixed appliances]

The aim of the study was to evaluate ultrastructural changes of dental enamel after fixation of orthodontic appliances, initial influence of orthodontic forces and removal of braces. Five intact permanent tooth extracted for orthodontic reasons were included in the experimental study. Scanning probe microscopy was conducted in 4 random enamel points in each tooth (20 points overall) in semi-contact mode with standard 10 nm probes. The study showed ultrastructural enamel changes such as nanofractures up to 1 mm along the braces locks. The changes correlated with surface morphological features and teeth anatomy and may play an important role in dental decay and non-carious lesions occurring in the course of orthodontic treatment.

[Evaluation of dental hard tissues by means of atomic force microscopy]

The paper presents modified method of teeth slice preparation for evaluating enamel and dentin morphological structure by means of atomic force microscopy (AFM). The method allows measuring directly and describing hydroxyappatite crystals on nanolevel. Structural properties of dental hard tissues were determined and comparative characteristic of form and density of enamel prisms particles with similar morphological inorganic elements of dentin were specified.

[Peculiarities of the morphological structure of the inorganic component of human dental enamel and dentin at nano-level]

Using the polished sections of 20 permanent human molars and premolars, the regimes of probe atomic force microscopy were assessed that permit the definition of the size, shape, spatial configuration of the structure-forming hydroxyapatite crystals of enamel and dentin inorganic component. It was found that the major part of enamel crystals had the size of 40-60 nm and were more flattened. Dentin crystal average size was equal to 60-80 nm. Microspaces between them had the shape of rotational ellipsoid sized 120 nm by 60 nm.

[Changes in the masticatory muscles, periodontal tissues and the pharyngeal ring in Wistar rats subjected to chronic psychophysical stress]

Experimental study, performed in 120 male Wistar rats, using histological and morphometric methods, has demonstrated changes of the oral tissues in response to chronic psychophysical stress (dosed swimming). Masticatory muscle showed the foci of non-infectious inflammation, dystrophic changes of muscle fibers and contractures. Periodontal ligament demonstrated the disturbances of microcirculation, with the pronounced congestion of the venous portion, local hemorrhages, changes in the orientation of collagen bundles and their deformation. In the tissues of the pharyngeal ring, the reduction in the number of lymphocytes was detected, as well as a progressing loosening of connective tissue, and a decrease in the number of non-degranulated mast cells as compared to similar parameters in the control group. The intensity of these manifestations was dependent on the level of physical load and individual adaptation capacity of an animal. The changes of the oral tissues detected in this study, may become an etiopathogenetic basis for the development of chronic inflammatory periodontal disease.