Laser irradiation did not increase the proliferation or the differentiation of stem cells from normal and inflamed dental pulp.

OBJECTIVE: Low-level laser therapy (LLLT) has been reported to be responsible for promoting photostimulatory and photobiomodulatory effects in vivo and in vitro, stimulating cell growth, increasing cell metabolism, improving cell regeneration and invoking an anti-inflammatory response. This study was performed in order to investigate whether low-level laser therapy could increase the proliferation and differentiation potentials of hDPSC isolated from healthy dental pulps and from inflamed pulps.
DESIGN: Human dental pulp stem cells (hDPSC) were isolated from normal and inflamed dental pulps from different patients. STRO-1-positive cells were isolated and irradiated with a red low-level laser (660 nm) in four different energy fluences (0.05, 0.30, 7 and 42 J/cm(2)); the authors hypothesized that the first three fluences would promote biostimulatory effects, whereas the highest dose would induce antiproliferative effects. The two lower fluences were produced by irradiating the two higher fluences through a dentine disc, which was used to simulate a clinical condition. The proliferation and the cell odonto-osteogenic differentiation competence were compared.
RESULTS: No statistically significant differences were observed between the proliferation rates and the relative productions of mineralized nodules compared to the respective controls, either for hDPSC from normal or inflamed dental pulps.
CONCLUSIONS: The irradiation with low-level InGaAlP red low-level laser (660 nm) in four different energy fluences (0.05, 0.30, 7 and 42 J/cm(2)) potentiated neither proliferation nor odonto-osteogenic differentiation of hDPSC isolated from patients with normal and inflamed pulps.