Dentist № 4 (51) – 2023, pp. 44-51                                                                                           SCIENTIFIC PUBLICATION

Changes of rat’s tooth germs at the beginning of enamel formation under the influence of low doses ionizing radiation

N.N. Cheshko

MD, PhD, Associate Professor, Belarusian State Medical University, Minsk, Belarus

https://doi.org/10.32993/dentist.2023.4(51).2

ABSTRACT
The aim of the study. To reveal microscopic and morphometric changes of rat tooth germs at the beginning of enamel formation period under general exposure of experimental animals to low doses of ionizing radiation.
Objects and methods. The study was carried out on albino rats of mongrel gregarious breeding. Pregnant female rats and their offspring were exposed to chronic irradiation at the Institute of Radiobiology of the National Academy of Sciences of the Republic of Belarus using “Gammarid-192/120 unit” at 110 mR/h power of exposition from the 1st day of pregnancy until the material was taken on the 3rd day after birth. The total dose absorbed by 3-day-old rats was 0.56 Gy. Samples for histological, histochemical and morphometric investigations were obtained from all the animals.
Results and discussion. In 3-day-old rats, a rather pronounced proliferation of specialized cells, odontoblasts and enameloblasts, was generally observed, although mitoses in all cells of tooth germs were rare. Under the influence of low doses of ionizing radiation, cell differentiation was delayed. Odontoblasts, like anameloblasts, were generally smaller in size, more hyperchromic, and randomly distributed. The dentin over the basophilic odontoblasts was uneven, wavy, and discontinuous. However, at this stage of odontgenesis, dentin formation with mineralization was generally well expressed, with a clear division into pre- and true dentin. The formation of enamel was behind the formation of dentin. Thin layers of enamel were revealed only with special methods of microscopic examination and in places of artificial tears in the sections. Atrophy of provisional structures – the pulp of the enamel organ, the outer enamel epithelium, and the basement membrane, which persisted longer in experimental animals – occurred simultaneously with the above mentioned changes.
Conclusion. The third day of rats’ postnatal life is a period of intensive formation of the tooth as an organ, despite the very weak mitotic activity of tooth germs cells.

Keywords: odontogenesis, ionizing radiation, low doses, rat

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Correspondence to:  Е-mail: cheshko.nelli@mail.ru