International Journal of Oral Health Sciences

REVIEW ARTICLE
Year
: 2022  |  Volume : 12  |  Issue : 1  |  Page : 15--18

Laser biomodulation in dentistry


N Nagammai 
 Department of Oral Medicine and Radiology, Faculty of Dentistry, Meenakshi Ammal Dental College, Meenakshi Academy of Higher Education and Research, Chennai, Tamil Nadu, India

Correspondence Address:
Dr. N Nagammai
Department of Oral Medicine and Radiology, Faculty of Dentistry, Meenakshi Ammal Dental College, Meenakshi Academy of Higher Education and Research, Chennai, Tamil Nadu
India

Abstract

The laser is an acronym for “light amplification by stimulated emission of radiation.” After the discovery of laser in 1960, it was very well appreciated that laser therapy has the ability to reduce pain, inflammation, swelling, and also improve wound healing. The dentists are now provided with a wide variety of lasers of different wavelengths and so they readily choose according to their needs of treatment. Each of the wavelengths has specific laser-tissue interactions. One such laser-tissue interaction is called “soft-tissue laser therapy or biostimulation or biomodulation.” This laser uses the specific wavelength from visible red to near-visible red in the electromagnetic spectrum ranging from 630 to 980 nm. Numerous researches on low-level laser therapy are documented in the literature over 30 years before. This review article gives an insight into the mechanism of action, its dosage, and emphasizes its application in dentistry.



How to cite this article:
Nagammai N. Laser biomodulation in dentistry.Int J Oral Health Sci 2022;12:15-18


How to cite this URL:
Nagammai N. Laser biomodulation in dentistry. Int J Oral Health Sci [serial online] 2022 [cited 2022 Dec 1 ];12:15-18
Available from: https://www.ijohsjournal.org/text.asp?2022/12/1/15/350991


Full Text



 Introduction



A laser could be defined as a device that produces light energy through a process of optical amplification according to the stimulated emission of electromagnetic radiation.[1] Lasers are widely implicated in the field of medicine, surgery, dentistry, and cosmetics since its development by Maiman in 1960.[2] Lasers are categorized into hard tissue and soft tissue based on laser-tissue interactions. Laser-tissue interaction depends upon the wavelength and tissue type. If the interaction produces an ablative effect such lasers are called hard tissue lasers whereas when the tissue effects are secondary or indirect such lasers are called soft-tissue lasers. These soft-tissue lasers are also called low-level laser therapy (LLLT) or photobiomodulation.[3]

North American Association of Laser Therapy defines LLLT as a “nonthermal laser light application using photons (light energy)” from the visible and infrared spectrum for tissue healing and pain reduction.[4] Lasers operate with a power <250 mW and so it has a photochemical effect rather than a thermal effect. Photochemical effects are the biochemical changes happening within cells such as activation of the electron transport chain within the membranes of mitochondria due to which there is a production of adenosine triphosphate which serves as a main source of energy for the cell to function.[5] Numerous researches on LLLT are documented in the literature over 30 years before.[6]

 Laser Physics



The components of the lasers are active medium, an energy source, and an optical resonator. The active medium is the source of high-energy light of specific wavelength which then passes through the converging lens. This lens focuses the light to a single point which then delivered to the targeted area using delivery system [Figure 1].{Figure 1}

 Classification of Laser



Based on clinical application:[7]

High power lasers

Output power is more than 500 mW. Their interaction with tissue leads to necrosis, carbonization, vaporization, coagulation, and denaturation.

Intermediate-power lasers

Output powers ranging from 250 to 500 mW. Thus helps in accelerating the therapeutic effect in some cases.

Low-power lasers

Output power is <250 mW. It produces a reaction in cells through light called photobiostimulation.

 Specifications for Low-Level Lasers[8]



The therapeutic laser usually operates with the specific wavelength of 630–980 nm. Semi-conductor material is gallium arsenide and the output range is 5–50 mW.[8]

 Mechanism of Action Low-Level Laser Therapy



Lasers work by a process of adsorption, activation of the respiratory chain, and stimulation that eventually results in physiological changes at the cellular level[9],[10] [Figure 2].{Figure 2}

 Dose Calculation for Low-Level Laser Therapy



To calculate the effective dose = Energy (E)/irradiated area cm2.

Whereas, energy (E) = Power mW (milliwatt) ×time in seconds (s).[11]

 Safety Regarding Low-Level Laser Therapy



Principle risk associated with laser is retinal cell destruction this happens when the cell temperature increases by 10°C. Thus, protective eyeglasses for specific wavelengths must be used for the patient and the therapist. Pregnant women are recommended not to undergo this procedure, since its effects on unborn children remain unknown.

 Biological Effect of Low-Level Laser Therapy



LLLT can penetrate in order of 5–10 mm, and thus, both the superficial structures and deeper structures are irradiated. Several studies suggest that elements in the mitochondrial system or endogenous pigmentations are energy observing chromophores and so the physiological effects are more distinct.[12]

Effects of low-level laser therapy on fibroblasts

Stimulate the production of basic fibroblast growth factors and also help in the transformation of fibroblasts into myofibroblasts which plays a crucial role in wound contraction.

Effects of low-level laser therapy on epithelial cells

Stimulation with LLT increases the motility of human epidermal keratinocytes and also the expression of nuclear mRNA levels of interleukin 1 (IL) and IL-8 due to which keratinocytes differentiate to synthesis keratins. This synthesized keratin migrates over the wounded area.

Effects of low-level laser therapy on immune cells

Increases mitogen phytohemagglutinin which will recruit more immune cells and helps in improved debridement by phagocytosis and chemotaxis.

Effects of low-level laser therapy on bone cells

Stimulate bone morphogenetic protein which helps in proliferation, differentiation, and calcification of osteoblast and thus helps in healing of tooth extracted site.

Effect of low-level laser therapy on neural tissue

Promote axonal growth in damaged nerve and also increase the mechanoreceptive perception in the damaged alveolar nerve.

Effects of low-level laser therapy on the blood vascular system

LLLT increases the release of nitric oxide from the cell which leads to vasodilatation due to which there is increased blood supply to the wounded area.

 Applications in the Field of Dentistry



Soft-tissue application

Herpetic lesions

Herpes labialis is the most common infection of the lips which causes mild-to-moderate discomfort and pain. LLLT can be used in the prodromal phase as well as in acute stages for 2–3 days with the dose 4 J which shows healing or complete fading of the lesion. Many studies reported that the viral load of the lesion is greatly reduced because of which it may prevent the recurrence.[13]

Recurrent aphthous ulceration

It is also called canker sores or aphthous ulcerations and these lesions are thought to be autoimmune-mediated. LLLT with the dose of 2J/cm2 can be recommended for its pain management and also for shortened healing time.[14]

Oral mucositis

LLLT helps in decreasing pain when irradiated with a specific dose of 1–6J/cm2 for a period of 2–3 weeks.[14]

Oral lichen planus

Many studies have concluded that LLLT with a dose of 4J/cm2 for 2 weeks can significantly reduce the size of the lesion and the pain associated with it.[15]

Xerostomia

After head-and-neck radiotherapy or chemotherapy, LLLT can be used as an auxiliary therapy for salivary gland stimulation and improving patient quality of life. LLLT with a dose of 5J/cm2 irradiated for 10s for 2 weeks can stimulate the acinar cells in both the parotid and submandibular gland which shows a significant increase in salivary flow.[16]

Analgesia

Laser light penetrates the dental pulp and decreases the conduction of C fibers by the release of endorphins and serotonin. It is not widely used in permanent dentition because due to large dental pulp chambers.[17]

Nausea and gagging

Laser when applied in the P6 acupuncture point of the wrist will decrease the gag reflex sensations felt during any treatment.[18]

Postoperative therapy and care

LLLT could be used after many dental procedures, such as surgical and nonsurgical periodontal procedures, endodontic procedures, and after implant placement. The dose of 2 J is applied with the wand-like probe to the patient's operative sites or apical end of the tooth either buccally or lingually or around the cementoenamel junction as it decreases pain and also shortened the healing period.[19]

 Hard Tissue Application



Dentinal hypersensitivity

LLLT with a dose of 2 J/cm2 induces changes in neural transmission which occurs within the dental pulp.

Bone regeneration[18]

LLLT irradiation with a dose of 2 J/cm2 for 2–3 times/week for at least 2 weeks stimulates the osteocytes and bone marrow cells in the surgical site.

Temporomandibular disorders

LLLT with a dose of 4 J/cm2 for a period of at least 2–4 weeks shows significant improvement in patients with myofascial pain dysfunction syndrome.[19]

Pain during orthodontic tooth movement

The dose of 2 J/cm2 reduces the secretion of pro-inflammatory molecules because of which pain transmission is blocked.

Sterilization of hard tissue

Dyes are coupled into the bacterial cell wall and thereby irradiated with the low power energy this is required for the destruction of bacteria. This process is called lethal laser photosensitization.

 Conclusion



LLLT is an evolving technology in the field of dentistry. The broad range of applications of LLLT includes pain relief, wound healing, regeneration, and immune enhancement. It is noninvasive, nonpharmaceutical, and economical and thus this may initiate the interest among clinicians and researchers to gain more knowledge on this working phenomenon. Proper development of treatment protocol, standardized techniques, and validated outcomes are needed for improved health services and treatment outcomes.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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