The concentration of methylene blue (MB) photosensitizer could affect the eradication efficacy of antimicrobial photodynamic therapy (aPDT) in the treatment of contaminated implants， which is linked to the osseointegration of the implant. This was the first report of evaluating osteoblast functions on the contaminated SLA (sandblasting， large-grit and acid-etching) Ti alloy surfaces after the concentration-dependent use of MB-aPDT. Totally 1，164 SLA discs were randomly distributed for the analyses of antibacterial efficacy and osteoblast functions. Gram-negative (Aggregatibacter actinomycetemcomitans; A. actinomycetemcomitans) or Gram-positive (Streptococcus mutans; S. mutans) adhered on disc samples was subjected to aPDT with different MB concentrations (200， 250， 300， 350， and 400?μg/mL) using 660?nm diode laser with maximum output 80?mW for 1?min irradiation (4.8?J/cm). Bactericidal effect was examined by viability， morphology， and lipopolysaccharide (LPS) assays. The disinfected disc surfaces by MB-aPDT to support osteoblast-like MG63 attachment， proliferation， differentiation， and mineralization were assessed for the predetermined culture time intervals. The statistical differences between the means were performed using a one-way analysis of variance (ANOVA) with a post hoc Scheffe test. The results of the morphology observation and bacterial survival examination consistently indicated a remarkably lower quantity of bacterial colonies on biofilm-contaminated surfaces after the aPDT treatment with higher MB concentration. Similarly， the higher MB concentration in aPDT resulted in the lower LPS amounts remaining on the A. actinomycetemcomitans-contaminated surfaces. Intriguingly， the expression of osteoblast cultured on disinfected surfaces using aPDT with higher MB concentration was comparable to the control without contamination. Within the limits of this in vitro model， this formulation of 400?μg/mL MB used in aPDT may be not only the lethal concentration against the 2 bacteria-contaminated implants， but it could also enhance the osteoblast functions on the contaminated implants. Nevertheless， the efficacy in the clinical practice for peri-implantitis therapy remains to be studied.