Biofilm formation on cpTi, Ti-6Al-4V and PEKK abutment surfaces: An in vitro study

OBJECTIVE: Bacterial adhesion and biofilm formation on abutments are critical factors in peri-implant tissue inflammation. Aim of this in vitro study was to compare biofilm development on three abutment materials: machined commercially pure titanium (cpTi), titanium alloy (Ti-6Al-4V), and polyetherketoneketone (PEKK). METHODS: CpTi, Ti-6Al-4V, and PEKK disks were characterized with a color 3D laser scanning microscope (Sa, Sz, Sdr, Ssk). Streptococcus oralis, Aggregatibacter actinomycetemcomitans, Fusobacterium nucleatum, and Porphyromonas gingivalis were cultivated individually, then combined to establish a multispecies biofilm. Sterile disks were preconditioned with artificial saliva, then incubated in bacterial culture under anaerobic conditions for 5 days. Disk incubated in medium were used as control. Following proteinase K digestion, DNA was extracted from adherent microorganisms, and species quantification was performed using quantitative polymerase chain reaction (qPCR) (n = 9 disks per group with bacteria and n = 3 with medium only as control). Scanning electron microscopy (SEM) and Alcian blue staining were used to investigate biofilm morphology. Data were analyzed using Kruskal-Wallis test, followed by Wilcoxon post hoc test with Bonferroni correction, where appropriate. RESULTS: All disks displayed smooth surface (mean Sa < 0.4 µm). PEKK disks exhibited significantly higher Sa, Sz, and Sdr values than cpTi and Ti-6Al-4V (p < 0.001), while no significant differences were observed for Ssk. qPCR analysis revealed no statistically significant differences in absolute copy number among materials for any bacterial species (p > 0.05). None of the four bacterial strains were detected in the controls. SEM and Alcian blue staining results further confirmed biofilm formation in all test groups. SIGNIFICANCE: Within the limitations of the present experimental in vitro model, comparable multispecies biofilm development was observed on all abutment materials.