The aim of this study was to evaluate the effect of the morphology of titanium implant surfaces on dental plaque biofilm formation and the antimicrobial effects of mouthrinses on dental plaque biofilms regarding these titanium surfaces by using an open biofilm model. The average surface roughness (RA) of three types of titanium surfaces (Smooth, hydroxyapatite (HA), sandblast large grit and acid-etching (SLA)) were tested by atomic force microscope (AFM). Subgingival plaques were collected and cultured on titanium surfaces for 4 hours to 2 weeks. After treatment with mouthrinses, characterization of dental plaque biofilms was tested by field-emission SEM (FESEM) and confocal laser scanning microscopy (CLSM). The results of AFM and SEM showed that the surface roughness and biofilm thickness of HA and SLA surfaces were significantly higher than those of smooth surface. In addition, it was revealed that the mouthrinses were effective on the killing of young dental plaque biofilms, while the more mature biofilm (14-day-old) exhibited a stronger resistance to mouthrinses used in this study. In conclusion, the roughness of titanium surfaces can affect the dental plaque biofilm formation and Colgate Plax and Listerine COOL MINT are effective mouthrinses to kill dental plaques at the early stage of biofilm growth on the titanium implant surfaces.