Objective: The goal in this study is to investigate the safety of a photodynamic antimicrobial chemotherapy (PACT) protocol, which we have found to be efficient against Porphyromonas gingivalis in a previous study of ours, in osteoblast cultures derived from rabbit mesenchymal stem cells.

PACT is a branch of photodynamic therapy which could provide a means of killing microorganisms in localized infections. PACT is based on the principle that a dye (photosensitizer) binds to the target cells and activated by light of a suitable wavelength. Following this activation, reactive agents such as singlet oxygen are produced which are extremely toxic to target cells and microorganisms. Main advantage of PACT is selectively eradicating target microorganisms while preserving surrounding tissues.

Material and methods: We used KTP laser (532 nm) and methylene blue as the light source and photosensitizer. Cell viability is assessed via MTS assays done in day 0, day 3 and day 6. SEM analysis is done for structure observation.

Results: KTP laser with methylene blue decreases cell growth when used both with 600 mW for 90 s and 400 mW for 150 s but cell number meets the original number in 6 days. Controls show that KTP laser or methylene blue do not have significant effects alone. SEM views show cell wall de-organisation in effected cells.

Conclusions: To conclude, although osteoblasts are effected by photoirradiation it may be mild and temporary or mitochondrial function may be delayed rather than cell death occurrence. Further studies may be necessary before in vivo experiments.

Conflict of interest: None declared.