Biofilm-forming activity of Enterococcus faecalis on basic materials of removable dental prosthetic bases

BACKGROUND: According to a number of authors, Enterococcus faecalis is characterised by low biofilm-forming ability on polymeric plastics. Such a feature of enterococci allows them to be considered marker strains in determining the resistance of plastics used in dentistry to microbial colonisation. This determines the need to study the aspects of interaction between clinical strains of Enterococcus faecalis and the main structural polymeric materials used for the manufacture of the bases of removable dental prostheses.

AIM: To study the biofilm-forming activity of Enterococcus faecalis strains isolated from the oral cavity on the basic materials of bases of removable dental prosthetic structures.

METHODS: The study included individuals with dental defects (code K08.1 according to the International Classification of Diseases). In order to assess the oral microbiota, isolate clinical strains of Enterococcus faecalis, and cultivate the on the following materials: hot-curing acrylic material Etacryl-02, thermoinjection polymer Deflex Acrynel, and thermoplastic monomer-free material Perflex T-Crystal, biomaterial was collected from patients of the observation groups from the central apex area of dental defects using swab probes. Statistical analysis was performed using the Shapiro–Wilk test, Student’s t-test, and χ²-test.

RESULTS: Bacterial film formation was most pronounced on the acrylic material hot curing acrylic material (coefficient of biofilm-forming activity ranged from 16.7 to 30.6). The same index was in the range of 4.6–10.1 when studied on thermoplastic monomer-free material, and for thermoinjection polymer — 1.2–2.7. It was found that 12.5% of Enterococcus faecalis strains formed an intensive biofilm on thermoplastic monomer-free material and hot curing acrylic material simultaneously, 25% — on thermoinjection polymer and hot curing acrylic material. A quarter of strains practically did not form biofilm on thermoplastic monomer-free material and thermoinjection polymer simultaneously, the remaining 37.5% of strains formed moderately pronounced bacterial film on all three variants of materials.

CONCLUSION: Enterococcus faecalis can be classified as a marker microorganism for investigating the resistance of dental prosthetic base materials to microbial colonization. At the stage of prosthetic planning, enterococci should be detected in the oral cavity for rational polymer selection.