J Periodontal Implant Sci.  2010 Jun;40(3):105-110. 10.5051/jpis.2010.40.3.105.

Biological effects of a semiconductor diode laser on human periodontal ligament fibroblasts

• Choi EJ
• Yim JY
• Koo KT
• Seol YJ
• Lee YM
• Ku Y
• Rhyu IC
• Chung CP
• Kim TI

• KMID: 2212136
• DOI: http://doi.org/10.5051/jpis.2010.40.3.105

Abstract

PURPOSE
It has been reported that low-level semiconductor diode lasers could enhance the wound healing process. The periodontal ligament is crucial for maintaining the tooth and surrounding tissues in periodontal wound healing. While low-level semiconductor diode lasers have been used in low-level laser therapy, there have been few reports on their effects on periodontal ligament fibroblasts (PDLFs). We performed this study to investigate the biological effects of semiconductor diode lasers on human PDLFs.
METHODS
Human PDLFs were cultured and irradiated with a gallium-aluminum-arsenate (GaAlAs) semiconductor diode laser of which the wavelength was 810 nm. The power output was fixed at 500 mW in the continuous wave mode with various energy fluencies, which were 1.97, 3.94, and 5.91 J/cm2. A culture of PDLFs without laser irradiation was regarded as a control. Then, cells were additionally incubated in 72 hours for MTS assay and an alkaline phosphatase (ALPase) activity test. At 48 hours post-laser irradiation, western blot analysis was performed to determine extracellular signal-regulated kinase (ERK) activity. ANOVA was used to assess the significance level of the differences among groups (P<0.05).
RESULTS
At all energy fluencies of laser irradiation, PDLFs proliferation gradually increased for 72 hours without any significant differences compared with the control over the entire period taken together. However, an increment of cell proliferation significantly greater than in the control occurred between 24 and 48 hours at laser irradiation settings of 1.97 and 3.94 J/cm2 (P<0.05). The highest ALPase activity was found at 48 and 72 hours post-laser irradiation with 3.94 J/cm2 energy fluency (P<0.05). The phosphorylated ERK level was more prominent at 3.94 J/cm2 energy fluency than in the control.
CONCLUSIONS
The present study demonstrated that the GaAlAs semiconductor diode laser promoted proliferation and differentiation of human PDLFs.

Keyword

Alkaline phosphatase; Extracellular signal-regulated kinases; Fibroblasts; Periodontal ligament; Semiconductor diode lasers

MeSH Terms

Alkaline Phosphatase
Blotting, Western
Cell Proliferation
Extracellular Signal-Regulated MAP Kinases
Fibroblasts
Humans
Low-Level Light Therapy
Lasers, Semiconductor
Periodontal Ligament
Phosphotransferases
Semiconductors
Tooth
Wound Healing
Alkaline Phosphatase
Extracellular Signal-Regulated MAP Kinases
Phosphotransferases

Figure

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  Figure 1 A gallium-aluminum-arsenate semiconductor diode laser with an 810-nm wavelength was prepared and the fiber tip was perpendicularly positioned at a 10-cm distance from the cell monolayer.

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  Figure 2 Human periodontal ligament fibroblast proliferation after 810-nm semiconductor diode laser irradiation at the energy fluencies of 1.97 (B), 3.94 (C) and 5.91 (D) J/cm2. Periodontal ligament fibroblast proliferation was gradually increased up to 72 hours without any significant difference compared with the control (A) at all levels of irradiation.

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  Figure 3 Incremental difference in absorbance at 490 nm in human periodontal ligament fibroblasts (PDLFs). PDLFs proliferation between 24 and 48 hours was significant at the energy fluencies of 1.97 (B) and 3.94 (C) J/cm2, but was not in the 5.91 (D) J/cm2 and control group (A) (*P<0.05).

• 

  Figure 4 Effect of semiconductor diode laser irradiation on alkaline phosphatase (ALPase) activity in human periodontal ligament fibroblasts (PDLFs). All the laser-irradiated groups showed a significant increase compared to the control. Among the laser-irradiated groups, ALPase activity of PDLFs was significantly greater at 3.94 J/cm2 of laser energy fluency. *Statistically significantly greater than the control (P<0.05). †Statistically significantly greater than other laser-irradiated groups (P<0.05).

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  Figure 5 Result of western blot analysis of phosphorylated extracellular signal-regulated kinase (ERK) at the laser energy fluencies of 1.97 (B), 3.94 (C) and 5.91 (D) J/cm2 compared to the control (A). 3.94 J/cm2 of laser energy-fluency promoted significantly greater ERK activation.

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