Victor M. Chuchkov

The timing, duration and quality of permanent teeth eruption are directly dependent on the morphological characteristics of dental tissues, whose formation is determined by the conditions of formation. The aim is a histomorphological study of the pulpodentin complex of a tooth during permanent teeth eruption in children and adolescents living under environmental and technogenic stress conditions. Materials and methods. The object of the study is the dental material of children and adolescents of Udmurtia at the age of 5 years (eruption beginning) and at the age of 14 years (eruption completed). The material was collected with the voluntary written consent of the child and his parents. Groups of children were formed based on the conditions of their residence in relatively prosperous settlements and areas with increased environmental and technogenic stress on the basis of data presented in the State Report «On the State of Sanitary and Epidemiological Welfare of the Population in the Udmurt Republic». Scientific research was approved by the Committee on Biomedical Ethics of the FSBEI of HE «Izhevsk State Medical Academy» under the Health Ministry of the Russian Federation (application № 391 dated 05.11.2013). Histological preparations of the pulpodentin complex were stained with hematoxylin and eosin, picrofuxin, photographed and subjected to a qualitative assessment. Results. The dental pulpodentin complex in children living under environmental and technogenic stress conditions at the time of permanent teeth eruption (5 years old) corresponded to the indicators of morphological maturity. Minor deviations were represented by single obliterated tubules, heterogeneity of the dentine layer, and the presence of fields with poorly calcified dentine. By the time when permanent teeth eruption was completed (14 years old), areas of reactive-altered dentin, zones of the basic substance dilution with a predominance of inter-tubular dentin, areas with alternating layers of mineralized dentin, uneven arrangement of dentine tubules, the presence of dilated blood microvessels with the phenomena of stasis of shaped elements were formed. Conclusions. Permanent teeth eruption in children and adolescents living under environmental and technogenic stress is accompanied by negative changes in the dental pulpodentin complex. Data on the peculiarities of pulp formation in adverse developmental conditions should be taken into account in pediatric dentistry in the treatment of children and developing the algorithm for preventive or corrective procedures.

BACKGROUND: Neuroinflammation is a key pathophysiological mechanism in age-related neurodegenerative diseases such as Parkinson's disease. Dihydroquercetin's water-soluble form (DHQ-WF) is considered a promising agent capable of inhibiting the neuroinflammatory process. Nevertheless, uncertainties persist regarding the cellular and molecular mechanisms governing its effects, taking into account nervous tissue's gliovascular organization. AIM: To study structural changes of microcirculatory vessels and functional responses of micro- and astroglial cells in the substantia nigra of young and old rats in response to intranigral injection of lipopolysaccharide (LPS) and subsequent oral administration of DHQ-WF. MATERIALS AND METHODS: Young (250–320 g) and old (390–450 g) Wistar rats were injected into the substantia nigra using a stereotaxic device with 2 μL of LPS solution at a concentration of 0.01 μL/mL (experimental groups; n=24) or 2 μL of sterile saline (control groups; n=12). Half of the animals in the experimental groups (6 animals of each age group) received 2 ml of a solution containing DHQ-WF ("Taxifolin aqua"; Advanced Technologies Ltd., Russia) at a concentration of 3 mg/mL by gavage daily for 8 weeks. At the end of the experiment, the animals were transcardially perfused with 4% paraformaldehyde, the brain was extracted and frozen on dry ice. Cryostat sections obtained on the cryotome were stained with FITC-labelled tomato lectin for the detection of vascular endothelium and antibodies against GFAP and CD-11β for the immunohistochemical detection of astrocytes and microglia, respectively. The length and number of vessels and their branches were counted using AngioTool software. The areas of glial cell bodies and their processes were measured using the morphometric software ImagePro Inside 8.0. RESULTS: 8 weeks after LPS administration into the substantia nigra (SN) of old rats, a significant excess of areas occupied by cell bodies and processes of microglial and astroglial cells, as well as the number of vessels on the standard plot, was found both in young animals that had experienced similar effects and in old control animals. Oral administration of DHQ-WF to rats significantly reduced LPS-induced glial activation in young and old animals. In addition, administration of DHQ-WF to old animals reduced the intensity of microvascular SN remodeling induced by LPS administration. CONCLUSIONS: Administration of LPS to the SN of rats of different ages causes neuroinflammation, which is maximally expressed in aged animals. In addition, LPS-induced microvessel angiogenesis is observed in aged animals. Administration of DHQ-WF for 8 weeks significantly reduces these LPS-induced changes, which allows us to consider it as a promising anti-neuroinflammatory agent.