Bacterial colonization of titanium discs: a pilot study for evaluating implant surface deterioration

ABSTRACT

Background: Bacterial colonization of dental implant surfaces is considered the main aetiological factor in peri-implant diseases. Aim: To devise a protocol that will yield a consistent and viable biofilm on titanium specimens for the purpose of in vitro experimental investigation of microbially-induced surface deterioration and potential peri-implant therapy efficacy. Materials and Methods: Twelve Southern Implants grade 4 titanium discs, six with machined and six with moderately roughened surfaces were used in this study. Six discs were inoculated with Streptococcus oralis and incubated in brain- heart infusion under anaerobic conditions at 37o C 1, 2 and 3-days. Specimen surface characteristics were evaluated by scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). Energy dispersive x-ray analysis quantified the surface elemental composition of the discs. Qualitative and quantitative SEM analyses evaluated colonisation and consistency of biofilm formation. The pH of the media was determined following each incubation period. Results: There were significant differences in surface roughness between machined (Ra = 0.27μm, Sa = 1.01μm) and moderately roughened (Ra = 2.14μm, Sa= 1.34μm) surfaces. SEM revealed widespread surface irregularities (spikes, valleys and grooves) on the moderately roughened surfaces compared to the machined surfaces. pH measurements of the medium indicated an acidic level (pH = 4.4) after an initially neutral value (pH = 7.0). Colonisation of the disc surface was evident after 24 hours as a multilayered biofilm for both titanium surfaces. Conclusions: A protocol capable of yielding a consistent viable biofilm on titanium specimens has been devised. This can be used in future studies to investigate the effect of bacterial accumulation and the efficacy of peri-implant therapy on bacterial colonization on implant surfaces