Abstract: Objective: To study the effects of surface treatments commonly used in clinic on the adhesion of Porphyroman gingivalis (Pg), Fusobacterium nucleatum (Fn), and Streptococcus sanguis (Ss). Methods: Titanium discs were divided into three groups for surface modification: electrodeposited hydroxyapatite (HA) group, micro-arc oxidation (MAO) group, and sandblasted with large-grit and acid-etched (SLA) group. The surface properties were tested. Fn, Ss, and Pg were cultured on three groups of titanium discs for 4 days, respectively. The colony forming unit (CFU) method, thiazole blue (MTT) method, and scanning electron microscopy (SEM) were used to observe bacterial adhesion. Results: (1) SEM observation showed that there were a large number of irregular rod-like structures on the surface of HA group, crater-like structures on the surface of MAO with aperture ranging from 0.1 to 1 micron, and irregular depressions on the surface of SLA with different sizes and sharp edges. Ra values of surface roughness in three groups was: SLA group < HA group < MAO group; (2) Fn biofilm was the lowest in SLA group, with statistical difference from the other two groups (P<0.05); The activity of Ss biofilm on three groups of titanium discs was the highest in HA group and the lowest in SLA group, but there was no significant difference among three groups (P>0.05). Pg biofilm had the highest activity on titanium plate in MAO group, with statistical difference from the other two groups (P<0.01). (3) SEM observation showed that the bacterial activity was related to the morphological structure of implant surface. Conclusion: The adhesion of bacteria to implant surface is affected by surface morphology, which is related to roughness and physical configuration. For three kinds of bacteria, SLA had the least bacterial adhesion.

Key words: titanium implant, surface modification, bacterial biofilm