EXPERIMENTAL STUDY OF THE ANIMALS MOUTH AREA SKIN CONDITION AFTER EXPOSURE TO DENTAL DIODE PHOTOPOLYMERIZERS
Authors: V.R. Shashmurina , V.M. Kiselev 
Published: July 2024

Aim of the study: studying the effect of light radiation from dental photopolymerizers on the soft tissues of the mouth area (regio oralis A01.2.01.018). Materials and methods. Experimental studies were carried out on 50 eight months male rats, randomly divided into 4 groups: 3 main (15 animals each), the fourth - control (5 animals). Under Zoletil anesthesia, the incisors of the lower jaw of experimental animals were exposed twice to light (wavelength 395 - 480 nm) from a dental photopolymerization device. Three photopolymerization modes were used: main group No. 1 – diode photopolymerizer with a luminous flux power of 1000 mW/cm2, main group No. 2 – diode photopolymerizer with a luminous flux power of 1400 mW/cm2; main group No. 3 – diode photopolymerizer with a luminous flux power of 3200 mW/cm2. Animals in the control group were not exposed to light radiation from dental photopolymerizers. After one, three and seven days, animals from groups No. 1 – 3, seven days – animals from the control group were subjected to ether anesthesia and removed from the experiment by decapitation. For pathomorphological studies, a fragment of skin from the mouth area was isolated. The material was fixed with a 15% aqueous neutral solution of formalin and embedded in paraffin. Histological sections were stained with hematoxylin and eosin, according to the van Gieson method, and Alcian blue; performed the CHIC reaction. The vascular bed and its elements were studied using the Gabu-Dybanu method. A standardized comparative microscopic study of skin tissue adjacent to the irradiation zone was carried out using the ZEISS Axio Imager A2 hardware and software complex at magnifications of 1:100 and 1:200. A descriptive method was used to evaluate the results obtained. Results. Microscopy of preparations of the skin of the lips of experimental animals allowed us to come to the conclusion that the primary reaction of tissues to the effects of light radiation from photopolymerizers is of the same type and does not depend on their technical characteristics. Hyperkeratosis and acanthosis of the epithelium, congestion of the microvasculature, the presence of edema and diffuse infiltration of the dermis were detected. Quantitative and qualitative changes in mast cells were observed - an increase in the degree of their degranulation and the number of process forms, which is a marker of tissue damage in response to irradiation. The described changes, which in general are pathomorphological signs of acute inflammation, were determined on the first and third days after irradiation. Further dynamics indicated a decrease in the described reactive changes by the third day when using the photopolymerization mode: wavelength 395 – 480 nm, power 1000 mW/cm2, exposure 10 sec. When using the photopolymerization mode: wavelength 395 - 480 nm, power 1400/3200 mW/cm2, exposure 3 seconds - by the seventh day of observation there was a positive dynamics in the relief of pathological processes, but signs of inflammation remained. Conclusion. Experimental data indicate the possible development of negative photochemical reactions in the skin of the lips after exposure to light from dental photopolymerizers during the treatment of patients with pathology of hard dental tissues. The results obtained can be used to substantiate the prevention of pathological processes in the tissues of the perioral area. Further in vitro, in vivo, and clinical studies are needed to determine the optimal irradiation intensity, irradiation time, and other aspects to ensure the safety and effectiveness of light curing agents.