COMPARATIVE EVALUATION OF ADHESIVE ABILITY OF MICROORGANISMS TO THERMOPLASTIC AND ACRYLIC BASE POLYMERS FOR REMOVABLE DENTAL PROSTHESES POLISHED WITH DIFFERENT PASTES
Authors: Makeyev V.F. , Hunovskyi Ya.R. 
Published: June 2022

The ability of microorganisms to penetrate into the thickness of the material directly depends on the surface quality and structure of the material. In order to counteract the adhesion and colonization of microorganisms, it is essential to obtain the smoothest possible surface of the prosthetic structure with low values of roughness and free surface energy. Non-compliance with the technique of manufacturing removable orthopedic structures with the formation of roughness, pores, and lack of proper care for the prosthesis promotes the adhesion of microorganisms and their penetration into the base of the dental prosthesis.

The aim of the study. Comparative evaluation of the adhesion of test microorganisms (Staphylococcus aureus АТCC 6538, Escherichia coli ATCC 25922, Candida albicans АТСС 10231, Enterococcus faecalis IMB В-7497) on the surfaces of samples of acrylic and thermoplastic polymers treated with different polishing pastes.

Materials and methods. Four types of samples are used in the study to assess the adhesive ability of microorganisms from thermoplastic material "Vertex ™ ThermoSens" and polymethylacrylate copolymer "Villacryl H Plus" which are treated with polishing paste — "Blue Shine." As well as from the thermoplastic material "Vertex ™ ThermoSens," from polymethylacrylate copolymer "Villacryl H Plus" which are treated with universal polishing paste "Vertex ™ ThermoGloss."

A suspension of test strains was prepared according to the optical turbidity standard at the rate of 1x109 CFU / cm3 to determine the adhesive ability of polymer samples from daily crops grown on TCA (for bacteria) for 24 hours and 48 hours for Candida albicans grown on Saburo agar. The test samples were then placed in sterile containers; 10 ml of test culture suspension was added to each of them and cultured at 37°C with appropriate test strains of microorganisms. The adhesion of microorganisms to samples of base polymeric materials treated with various polishing pastes was evaluated.

Results. An in vitro study shows that thermoplastic materials, in contrast to the acrylic plastics used in the experiment, have less ability to colonize the pathogenic microflora on their surface. Each base material, depending on the physicochemical parameters, has a distinctive qualitative and quantitative profile of adhesion of microbial flora. The obtained data allow to conclude that samples of polymeric materials for prosthesis bases differ significantly in the degree of adhesion of bacteria and fungi of the genus Candida, which depends on the surface structure of the material, polishing method, choice of polishing pastes, which accordingly determines differences in colonization resistance to the formation of microbial biofilms when using the polymer in clinical conditions.

Conclusions. Consequently, the study results are important for critical evaluation of the quality of polishing thermoplastic and acrylic materials for the bases of removable dentures in terms of contamination on their surface of pathogenic microorganisms. The degree of contamination of acrylic and thermoplastic polymeric materials used for the manufacture of removable dentures will depend not only on their structural integrity and timing but also on the body's reaction to them, the development of inflammation, and allergic reactions.