Photobiomodulation (PBM) also referred to as low-level laser (or light) therapy (LLLT), has been illustrious for nearly fifty years however still has not gained widespread acceptance, for the most part because of uncertainty regarding the molecular, cellular, and tissular mechanisms of action. 

    Photobiomodulation (PBM) are low-level lasers (class III) that are outlined with an output power of five hundred mW, and there also are high-level lasers (class IV) with an influence output of 500 mW or more. 

    Photobiomodulation (PBM) will induce cell proliferation and enhance stem cell differentiation. 

    Photo credit: Skin58 (Wikipedia commons)


    Mitochondria contain chromophores that absorb photons from PBM. 

    The first chromophore to absorb red light is that the catalyst cytochrome c oxidase, which is found at unit IV of the mitochondrial respiratory chain, leading to the activity of assorted molecules like nitric oxide (NO), adenosine triphosphate, calcium ions, reactive oxygen species (ROS), and numerous alternative communication molecules. 

    It's thought that metabolism and ATP production are promoted due to PBM stimulating electrons in chromophores to maneuver from higher energy orbits, so electron carriers (such because the chromophore cytochrome c oxidase) deliver these electrons to their final electron acceptors while a proton gradient is made, additionally to creating a proton gradient that will increase adenosine triphosphate production. 

    PBM conjointly encourages the assembly of ROS during a similar fashion as photodynamic therapy (PDT). 

    Regulation of ROS levels is important, because it affects several signaling pathways answerable for the development and proliferation of stem cells. 

    Cytochrome c enzyme is the main chemical group to absorb red light, however different molecules at higher wavelengths are thought to also absorb the upper wavelengths out of vary for cytochrome c oxidase. 

    Use of blue and green light suggests that, at lower wavelengths, light-gated ion channels may be stimulated. a distinct chromophore may also be activated by blue and green light, like one present in channelrhodopsin. 

    Photo credit: Dompe, Claudia et al. “Photobiomodulation-Underlying Mechanism and Clinical Applications.” Journal of clinical medicine vol. 9,6 1724. 3 Jun. 2020, doi:10.3390/jcm9061724 (figure 1)


    Oral mucositis will have an effect on up to 100 percent of patients undergoing high-dose chemotherapy and hematopoietic stem cell transplantation. 

    Photobiomodulation can improve tissue repair and immune reaction within these patients. Oral mucositis (OM) may be a common consequence of chemotherapeutic drug infusion, moreover as head and neck radiation therapy (HNRT). 

    Burning mouth syndrome (BMS) is a disorder condition that manifests itself primarily with the onset of a burning sensation in the oral mucosa. 

    The administration of PBM, has been one of the foremost used therapeutic approaches for up the standard of life of BMS patients. 

    The improvement in the symptoms ensuing from the reduction of the capillary diameter (and so of the vasodilatation typical of inflammation) might be related to PBM. 

    PBM might scale back phlogosis, so the burning sensation. In addition, the effects of PBM on BMS aren't connected to a placebo effect, however to an objectifiable effect that may be seen through the observation of the oral vascular pattern of those patients.

    Recurrent aphthous stomatitis (RAS), additionally referred to as the perennial oral ulcer, may be a commonest oral lesion that can be classified as a minor, major, or herpetiform ulcer. 

    Though the reason behind oral lesion formation isn't entirely known, it's related to immune system dysfunction, genetic factors, allergic agents, nutrition, secretion changes, stress, and infective viruses. 

    Nd:YAG laser at a hundred mJ, a pair of W, 20 Hertz for 2–3 min involved mode has higher patient acceptance, shorter treatment time, and lower rates of pain. 

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    PBM stimulates protoplasm aggregation and activates coagulation pathways and therefore plays an essential role in stopping and promoting proliferation of mast cells and additionally plays a vigorous role within the degradation of mast cells. 

    Reactive chemical element species (superoxide, O2−) generated throughout the first direct events react with nitric oxide (NO, made by interaction of LLLT with nitrogen) to create ONOO − (peroxynitrite) that causes biological responses. 

    PBM-generated ROS will produce modulation of antioxidants and induce protein modification and aerophilic stress-mediated gene expression and cause transcription of cistron products. 

    ROS additionally modulates mitochondrial respiration and activates NF-κB signaling pathway. 

    ROS tends to activate Src, a non receptor amino acid kinase, that successively enhances cell proliferation, attachment, migration, and cell survival. 

    PBM-generated ROS interacts with methionine 253 on latent TGF-β1 and results in its activation, this contributes to oral membrane wound healing. 

    PBM aids in neovascularization, ontogenesis and improves the tensile strength of wounded tissues and restores useful structure of repaired tissues. 

    It therefore stimulates reorganization, repair, and wound healing.


    Parkinson’s disease (PD) may be a complex and multisystem disease, characterised by the loss of the monoamine neurotransmitter producing neuronal cells of the substantia nigra pars compacta (SNc) within the brain. 

    The accepted treatment is replacement of the lost Dopastat victimisation Levodopa, that helps the motor symptoms however doesn't modify the course of the disease. 

    Amine oxidase-B inhibitors and dopamine agonists can be used later in the course of the disease. 

    Photobiomodulation (PBM) involves the utilization of powerless  red and near-infrared (NIR) light from a laser or light-emitting diode (LED) to stimulate, heal, and regenerate broken or dying tissues. 

    The mechanism of action primarily involves absorption of the light through the mitochondria, resulting in an enhanced membrane potential, electron transport, oxygen consumption, and adenosine triphosphate synthesis because the brain is heavily dependent on mitochondrial activity. 

    These latter effects are often thought of as “helping the brain to repair itself”, and recommend that PBM can be helpful for several traumatic brain disorders, resembling stroke and traumatic brain injury, Alzheimer's disease and PD. 

    First, stem cells are mobilized from their hypoxic niche and may migrate towards sites of injury wherever they will repair the damage. 

    Second, the mitochondrial alteration can switch the scavenger cell and microglial composition from the pro-inflammatory m1 state, to the anti-inflammatory and phagocytic m2 state. 

    Within the brain, brain-derived neurotrophic factors [BDNF] are up-regulated, adult hippocampal development is stimulated, and synaptogenesis and neuroplasticity is encouraged.

    Photo credit: Hemal (Wikipedia commons)


    Thus by considering all the mechanism of action and its effect on angiogenesis, wound healing and pain relief it is used after cancer treatment complication such as 

    • Oral mucositis
    • Radiation dermatitis 
    • Lymphedema

    PMD also has an effect of nerve cells it also used in parkinsonism, alzimers, stroke and most of the brain related disorders

    By concluding Photobiomodulator is being one of the important treatment procedures in future but more research has to be done to know more about the efficacy of PMD. 


    • Salehpour F, Hamblin MR. Photobiomodulation for Parkinson's Disease in Animal Models: A Systematic Review. Biomolecules. 2020;10(4):610. Published 2020 Apr 15. doi:10.3390/biom10040610
    • Dompe C, Moncrieff L, Matys J, et al. Photobiomodulation-Underlying Mechanism and Clinical Applications. J Clin Med. 2020;9(6):1724. Published 2020 Jun 3. doi:10.3390/jcm9061724. 
    • Karu T. Is it time to consider photobiomodulation as a drug equivalent?. Photomed Laser Surg. 2013;31(5):189-191. doi:10.1089/pho.2013.3510. 
    • de Freitas LF, Hamblin MR. Proposed Mechanisms of Photobiomodulation or Low-Level Light Therapy. IEEE J Sel Top Quantum Electron. 2016;22(3):7000417. doi:10.1109/JSTQE.2016.2561201. 
    • Hamblin MR. Photobiomodulation or low-level laser therapy. J Biophotonics. 2016;9(11-12):1122-1124. doi:10.1002/jbio.201670113. 
    • Scardina GA, Casella S, Bilello G, Messina P. Photobiomodulation Therapy in the Management of Burning Mouth Syndrome: Morphological Variations in the Capillary Bed. Dentistry Journal. 2020; 8(3):99.
    • Vinesh E, Jeyapriya S M, Kumar M S, Arunachalam M. Photobiomodulation and oral wound healing. Indian J Multidiscip Dent 2017;7:129-34

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