Biofilm formation on the surface of modern implant abutment materials

Objective: To investigate the formation of biofilms on the surface of materials applied for the fabrication of implant abutments.

Material and methods: Specimens were prepared from the implant abutment materials titanium, zirconia, and polyetheretherketone (PEEK); specimens made from polymethylmethacrylate (PMMA) were used for reference. All specimens were polished to high gloss using silicon carbide paper; surface roughness was determined using profilometry, and surface free energy was calculated from contact angle measurements. After the simulation of salivary pellicle formation, multispecies biofilm formation was initiated by exposing the specimens to a suspension of Streptococcus gordonii, Streptococcus mutans, Actinomyces naeslundii, and Candida albicans for either 20 or 44 h. Viable microbial biomass adherent to the specimens (n = 10 per material and incubation time) and the percentage of dead microorganisms in the different biofilms (n = 5, accordingly) were determined.

Results: Significantly lower surface roughness was identified for PEEK and PMMA than for zirconia and titanium (P < 0.001); surface free energy was significantly lower for zirconia than for PEEK (P = 0.038). Significantly higher viable biomass and a significantly higher percentage of dead microorganisms were identified after 44 h than after 20 h of biofilm formation (P < 0.001, respectively); after 20 h, PEEK surfaces harbored significantly lower viable biomass than the surfaces of the other materials (P < 0.0125). After 44 h, significant differences were identified in the percentage of dead microorganisms organized in the biofilms on the different materials (P = 0.012).

Conclusions: Within the limitations of a laboratory study, the results suggest that biofilm formation on the surface of PEEK is equal or lower than on the surface of conventionally applied abutment materials such as zirconia and titanium. However, clinical studies are necessary to corroborate these preliminary results.