Microbial Colonization on Seven Different Titanium Surfaces

Objectives: This study assessed the microbial adherence and colonization on 7 differently processed titanium surfaces using a multispecies biofilm model.

Methods: Six-species biofilms were formed anaerobically on sterilized, saliva-preconditioned titanium discs (diameter 5mm). Material surfaces were chosen as follows: machined, stained, acid etched or sandblasted/acid-etched. Samples of the latter two materials were also available in a chemically modified form with increased wet-ability characteristics. Surface roughness and contact angles of all materials were determined and the discs were then incubated anaerobically for 16.5 h. Initial microbial adherence was evaluated after 20 min incubation and further colonization after 2, 4, 8, and 16.5 h using non-selective and selective culture techniques. Mean CFU and standard deviations at different time points were determined and compared using one-way analysis of variance (ANOVA; Scheffé test). Level of significance was set at 95%.

Results: Chemically modified and activated surfaces showed the highest, machined surfaces the lowest microbial colonization with a difference of more than 2 log steps after 16.5 h (P<0.05). Machined implant surfaces with mean surface roughness above or below the suggested threshold values of 0.2 µm showed comparable biofilm formation. The strongest initial adherence among the 6 microorganisms applied for biofilm formation was exhibited by Veillonella dispar and Candida albicans. Within the differently crafted titanium surfaces, inter-microbial adherence discrepancies were very similar to those described for total CFU. Differences in affinity of Actinomyces naeslundii for these surfaces were more distinct. Fusobacterium nucleatum remained with one exception below detection level.

Conclusion: Both surface roughness and wet-ability influenced biofilm formation under the conditions described. Using this model it is now possible to assess microbial adherence and colonization on a wide spectrum of biomaterials. In particular surface coatings and treatments having an antimicrobial effect are open to experimental scrutiny.

Supported in part by Straumann AG, Basel, Switzerland.