New Biofilm Model to Evaluate Microbial Colonization on Titanium Surfaces

Objectives: The purpose of the study was to validate a new biofilm model for assessing microbial adherence and colonization on 7 differently processed titanium surfaces. In most former studies, only the adherence of non-growing bacteria on titanium surfaces but not the inevitable following microbial growth was measured. Methods: The previously described Zurich multi-species biofilm model was applied. Biofilms were formed for 16.5 h on sterilized, saliva-preconditioned titanium discs (Diameter 5 mm) of different wet-ability and roughness. To find growth conditions discriminating between the differently machined titanium surfaces, biofilms were incubated anaerobically in saliva/FUM (70:30) for the entire 16.5 h (N=3) or fed twice (N=9) for 45 min with saliva/FUM (30:70) at times 0 and 8 h. In between feeding periods the biofilms were incubated in saliva. Initial microbial adherence was evaluated after 20 min and further colonization after 2, 4, 8, and 16.5 h using non-selective culture techniques. Results: Initial adherence on different titanium surfaces incubated continuously in saliva/FUM (70:30) was in a narrow range between 5.3E3-3.5E4 CFU/disc. After 2 h the numbers of microorganisms had increased on all discs (Range: 1.1E5-1.6E6). After 4 h, and even more after 8 h, microbial density was augmented further, leveling-out the initial adherence differences. When biofilms were fed twice only, initial adherence was as described above. After 4 h significant microbial detachment was observed, after 8 h the shedding was compensated by growth that continued up to 16.5 h. Variation between the 3 experiments (3x3 discs) was small. In part, statistically significant differences between the variably machined titanium discs were observed (Pf<0.05). Conclusion: A reliable biofilm model allowing testing of both the initial microbial adherence and the ensuing colonization on biomaterials was developed.

This study was supported in part by Straumann AG, Basel, Switzerland