CATEGORY AUSTRALASIAN DENTIST 69 CLINICAL injury29, enhancing bone formation and implant stability30,31, reducing severity of oral mucositis and aphthous ulcers23,32, preventing acute flare-ups of cold sores (herpes simplex infections)33, trigeminal neuralgia34, facial palsy24,35 (Fig. 3), managing TMJ disorders36 and deactivating myofascial trigger points amongst many more37 u Oral mucositis, a common complication of chemotherapy, radiotherapy, or hematopoietic stem cell transplants that results in large and painful mouth ulcers, is recommended for treatment with specific PBM protocols worldwide, following ESMO, NICE, and MASCC/ ISOO guidelines38–40 (Fig. 4) u World Association for photobiomoduLation Therapy (WALT) guidelines recommend PBM for a range of cancer care complications, including xerostomia, radiodermatitis, dysphagia, dysgeusia, lymphedema, peripheral neuropathy, fibrosis and other conditions41 • PBM has been used to treat pulmonary disease such as pneumonia, asthma and COPD42,43, the loss of taste and smell associated with COVID44,45, reducing brain fog and other long COVID complications46, Parkinson’s disease47, fibromyalgia48, athlete recovery from elite-level sport49–54, skin, pressure and venous ulcers55, diabetic wounds55,56, dry age-related macular degeneration57,58, postherpetic neuralgia such as from shingles59, pain intensity and postsurgery inflammation following total hip arthroplasty60 PBM must be done by lasers because the light is coherent – FALSE u A distinctive characteristic of lasers is their coherent light, meaning the light waves share the same frequency and are in phase. This property is utilised for photothermal ablation u All non-ionizing light sources, including lasers, LEDs, and broadband light, in the visible and near-infrared spectrum, can be used for PBM8 u Red and near infra-red (NIR) LEDs for PBM can be found in the form of torches, bulbs, panels, flexible wraps and even full-body lightbeds (Fig. 5) u The wavelength, light source, power, pulse frequency, beam area, irradiance, exposure time and application technique will all affect the reproducibility of treatment u The terms ‘low level’ and ‘high level’ are inaccurate and should be avoided61 Stronger light leads to better results – TRUE & FALSE u Light needs to be of sufficient strength to penetrate the target tissues. Deeper tissues will need stronger light or longer treatments to receive the fluence required to have an effect29 u Penetration depths will vary by wavelength. Lasers and LEDs can penetrate up to 5cm into tissues with sufficient beam power and irradiance18,62 u Due to the ‘Biphasic Response’, there is a ‘Goldilocks’ zone with an optimal biological response. Too little or too much light results in minimal or inhibition of healing respectively63–65 (Fig. 6) u All dental diode lasers covering the red to NIR spectrum are suitable for PBM Larger spot size (diameter of the focused laser beam) is better – TRUE u Small fibre lasers have a divergent output and a gaussian beam profile Fig 3. Ramsay Hunt Syndrome – facial palsy – Before treatment (A), 5 months after PBM therapy (B) Fig. 4 Photobiomodulation treatment for oral mucositis with 650 nm Pioon laser Fig. 5 NovoTHOR full-body LED lightbed rendering only the inner 1/3 usable for PBM. Moreover, the beam must continually be moving to create a uniform fluence over a large area. Many manufacturers now make handpieces for PBM treatment to improve their reproducibility66 u Photobiomodulation handpieces now exist that have a homogenous (flat-top), collimated beam profile (Fig. 7) such as the Genova and MarcCo handpieces that attach to the Nd:YAG 1064 nm laser output of the Fotona LightWalker (Fig. 8). u Large LED handpieces and large homogenous profile laser beams mean that affected areas can be treated more quickly but also more uniformly due to less relative scattering of the light67,68 u Improved reporting of the parameters used for PBM will enable better comparisons of wavelength, energy and energy density as well as application technique amongst other parameters69 u These flat-top beam profiles have been shown to improve PBM outcomes by anywhere from 1.5 to 2 times in both cellular and clinical trials in animal and humans compared with gaussian beam profiles67,70,71. u PBM has been found to be equal to pharmacotherapy for the treatment of oral neuropathic pain conditions such as burning mouth syndrome and trigeminal neuralgia20,34,72 Only the tissues are exposed to the light will be modulated – FALSE u Cell-free mitochondria have been found to circulate in the blood which means that mitochondria upregulated by PBM can travel to distant organs like the brain and internal organs and improve their function and reduce inflammation73 u Using ultra-sensitive light equipment it has been found that small amounts of UV, red and NIR light known as biophotons are released from nerve tissue. Biophoton emission can also be induced in stressed/ Fig. 6 The Arndt-Schulz curve showing the “Biphasic” biological response curve of cells to light therapy
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