Laser and LED photobiomodulation effects in osteogenic or regular medium on rat calvaria osteoblasts obtained by newly forming bone technique.

The purposes of this study are to evaluate the effects of photobiomodulation (PBM) with laser and LED on rat calvaria osteoblasts (rGO lineage), cultured in osteogenic (OST) or regular (REG) medium, after induction of a quiescent state and to test if PBM is capable of osteogenic induction and if there is a sum of effects when combining OST medium with PBM. Before irradiation, the cells were put in a quiescent state (1% FBS) 24 h, when red (AlGaInP-660 nm) and infrared laser (GaAlAs-808 nm) and LED (637 ± 15 nm) were applied. The groups were as follows: red laser (RL3-5 J/cm2, 3 s and RL5-8.3 J/cm2, 5 s, 1.66 W/cm2); infrared laser (IrL3-5 J/cm2, 3 s and IrL5-8.3 J/cm2, 5 s); LED (LED3-3 s and LED5-5 s, 0.02 J/cm2, 0.885 W/cm2); positive (C+, 10% FBS) and negative control (C-, 1% FBS). For alkaline phosphatase (ALP) and mineralization assays, the cells were cultured in REG (DMEM 10% FBS) and OST medium (DMEM 10% FBS, 50 µg/mL ascorbic acid, 10 mM ß-glycerophosphate). Statistical analysis was performed using ANOVA and Tukey's tests (p < 0.05). RL5 and LED5 increased proliferation, in vitro wound closure, ALP, and mineralization in rGO cells (p < 0.05). PBM with red laser and LED induced mineralization by itself, without osteogenic medium, not observed for infrared laser (p < 0.05). A sum of effects was observed in osteogenic medium and PBM by infrared, red laser, and LED (5 s). Red laser and LED increased proliferation, migration, and secretory phases in rGO cells in a dose-dependent manner. PBM with red laser and LED promotes osteogenic induction by itself. PBM with infrared laser and osteogenic medium potentializes mineralization.

Comparison of the effect of root surface modification with citric acid, EDTA, and aPDT on adhesion and proliferation of human gingival fibroblasts and osteoblasts: an in vitro study.

Root demineralization is used in Periodontics as an adjuvant for mechanical treatment. The aim of this study was to evaluate the effects of root surface modification with mechanic, chemical, and photodynamic treatments on adhesion and proliferation of human gingival fibroblasts and osteoblasts. Root fragments were treated by scaling and root planing (C-control group), EDTA (pH 7), citric acid plus tetracycline (CA-pH 1), and antimicrobial photodynamic therapy (aPDT) with toluidine blue O and red laser (pH 4). Cells were seeded (104 cells/well, 6th passage) on root fragments of each experimental group and cultured for 24, 48, and 72 h. Cells were counted in scanning electron microscopy images by a calibrated examiner. For fibroblasts, the highest number of cells were present at 72-h period (p < 0.05). EDTA group showed a very low number of cells in relation to CA group (p < 0.05). CA and aPDT group presented higher number of cells in all periods, but without differences between other treatment groups (p > 0.05). For osteoblasts, there was a significant increase in cell numbers for aPDT group at 72 h (p < 0.05). In conclusion, aPDT treatment provided a positive stimulus to osteoblast growth, while for fibroblasts, aPDT and CA had a tendency for higher cell growth.

Laser and light-emitting diode effects on pre-osteoblast growth and differentiation.

The acceleration of bone regeneration by low-intensity laser irradiation may hold potential benefits in clinical therapy in orthopedics and dentistry. The purpose of this study is to compare the effects of light-emitting diode (LED) and laser on pre-osteoblast MC3T3 proliferation and differentiation. Cells were irradiated with red, infrared, and LED (3 and 5 J/cm(2)). Lasers had a power density of 1 W/cm(2) and irradiation time of 2 and 5 s. LED had a power density of 60 mW/cm(2) and irradiation time of 50 and 83 s. Control group did not receive irradiation. Cell growth was assessed by a colorimetric test (MTT) (24, 48, 72, and 96 h), and cell differentiation was evaluated by alkaline phosphatase (ALP) quantification after growth in osteogenic medium (72 and 96 h and 7 and 14 days). At 24 h, the cell growth was enhanced 3.6 times by LED (5 J/cm(2)), 6.8 times by red laser (3 J/cm(2)), and 10.1 times by red laser (5 J/cm(2)) in relation to control group (p < 0.05). At the other periods, there was no influence of irradiation on cell growth (p > 0.05). The production of ALP was not influenced by irradiation at any period of time (p > 0.05). Low-intensity laser and LED have similar effects on stimulation of cell growth, but no effect on cell differentiation.

Laser phototherapy at high energy densities do not stimulate pre-osteoblast growth and differentiation.

OBJECTIVE: The aim of this study is to evaluate the effects of red and infrared lasers at high energy densities on pre-osteoblast MC3T3 proliferation and differentiation. BACKGROUND DATA: The acceleration of bone regeneration by low intensity laser irradiation may hold potential benefits in clinical therapy in orthopedics and dentistry. MATERIALS AND METHODS: Cells were irradiated with red (660 nm) and infrared (780 nm) lasers (90 and 150 J/cm2, 40 mW). The control group did not receive irradiation. Cell growth was assessed by a colorimetric test (MTT) (24, 48, 72, 96 h) and cell differentiation was evaluated by alkaline phosphatase (ALP) quantification after growth in osteogenic medium (72, 96 h; 7, 14 days). RESULTS: None of the irradiation groups had an enhancement in cell growth (p<0.05). The production of ALP was not influenced by irradiation at any period of time (p>0.05). CONCLUSIONS: The low intensity laser stimulated neither cell growth nor the production of alkaline phosphatase.