Titanium surface modification and its effect on the adherence of Porphyromonas gingivalis:: an in vitro study

Aim: Titanium dental implants are an important treatment option in the replacement of missing teeth. Implant failures can, however, occur and may be promoted by the loss of tissue as a result of local bacterial infection (peri-implantitis). Objectives: Bacterial adherence to implant surfaces is believed to be influenced by material surface roughness and surface-free energy parameters. Consequently, the aim of this study was to modify these properties of titanium and identify what effect these modifications had on subsequent bacterial adherence. Materials and methods: In this study, 16 titanium samples of different roughness (R-a 34.57-449.42 nm) were prepared using specific polishing procedures. A further six samples were chemically altered by argon plasma discharge treatment and immersion in silane solutions to produce different surface hydrophobicities. An in vitro adhesion assay using Porphyromonas gingivalis was used to assess the effect of modification on bacterial adherence. Results: A significant reduction in adhesion to materials categorised as being 'very smooth' (R-a 34.57 +/- 5.79 nm) was evident. This reduction did not occur with 'smooth' (R-a 155.00 +/- 33.36 nm), 'rough' (R-a 223.24 +/- 9.86 nm) or 'very rough' (R-a 449.42 +/- 32.97 nm) surfaces. Changing material surface hydrophobicity was also not found to effect bacterial adhesion. Conclusions: Adhesion of P. gingivalis to titanium was inhibited at surface roughness levels below those generally encountered for implant collars/abutments (R-a 350 nm). Considerations of these findings may be beneficial in the production of titanium implants in order to reduce bacterial colonisation.