Clinical study of the biofilm of implant-supported complete dentures in healthy patients.

Objective: The purpose of this study was to quantify the area covered by biofilm and identify bacteria and yeasts present in mandibular acrylic resin full-arch implant-supported fixed prostheses.

Background: Biofilm control of implant-supported fixed prosthesis is hampered by their design, and it can cause oral and systemic problems, mainly in immunocompromised patients like the elder. Knowledge about microbiota reinforces the awareness about the need for periodic professional cleaning maintenance.

Materials And Methods: Twenty prostheses were unscrewed, washed in 0.89% sodium chloride, stained with eosin 1% and photographed. The area covered by biofilm was digitally delimited and quantified. Biofilm samples were collected, diluted up to 1:10 , seeded in chromogenic agar media and incubated for 48 hours, at 37°C, for counting of colony-forming units (CFU/mL). DNA hybridization was performed to complement the identification and quantification of microorganisms. Data were analyzed using Mann-Whitney test, Spearman correlation and Fisher's exact test (α = .05).

Results: An average of 62% of the gingival surface of the prostheses was covered by biofilm. Enterococcus spp. (5.82 ± 1.38 log CFU/mL) and Staphylococcus aureus (5.75 ± 2.02 log CFU/mL) showed higher prevalence in cultures. Patients with five implants had less biofilm compared to those with four implants (P = .031) but had higher Escherichia coli counts (P = .039). In DNA hybridization, Streptococcus pneumoniae, Veillonella parvula and Fusobacterium nucleatum presented higher quantification and were present in all the samples; patients over 65 years old contained more Candida tropicalis (P = .049); prostheses on five implants presented lower quantification for several species.

Conclusion: Biofilm was present on all prostheses, containing potentially pathogenic microorganisms. The number of implants may play a role in quantification of biofilm and in microorganism counts.