Adhesion of oral microbiota to structural materials for manufacturing aligners

With the growing demand for correction of individual tooth position anomalies, there is an active implementation of digital technologies and the development of new photopolymer materials for the production of aligners. This necessitates a systematic study of their structural characteristics. It is known that the creation of additional retention points in the oral cavity due to aligners contributes to the formation of a bacterial biofilm, the rate of formation of which depends, among other things, on the properties of the materials. The aim of the study was to study the adhesive activity of oral microbiota representatives to structural materials for aligners manufactured using various methods. Materials and methods. The 3D printing material Graphy Direct Aligner (South Korea) and thermoforming materials Zendura (USA), Biolon (Germany), and Duran (Germany) were studied. Eighteen identically sized samples of 10 mm in diameter (area 78.5 mm2) were fabricated from each of these materials. Cultures of C. albicans, C. kruzei, Str. pyogenes, S. aureus, and Str. salivarius were stained with gentian violet and incubated in the sample plate for 1, 3, and 6 hours. The optical density of the dye solution, eluted with alcohol from the cell walls of microbes adhered to the sample surface, was then measured. Samples without the addition of a microbial suspension, stained in the same manner, served as a control. Results. It was established that the listed microorganisms have different rates of adhesion to structural materials. In addition, species specificity of microorganisms is observed: S. aureus demonstrated universal adhesive activity, Candida spp. — a variable reaction, which must be taken into account when selecting a material. Conclusion. Species specificity of microorganisms was revealed, requiring an individual approach to the selection of material for the manufacture of aligners. The results of the study highlight the need for further study of the physicochemical characteristics of materials and their impact on the oral microbiota. Zendura is recommended for use in patients with an increased risk of inflammatory diseases, while the use of Graphy may be associated with a higher risk of microbial adhesion.