Page 67 - C:\Users\uromn\Videos\seyyedi pdf\

Low Level Laser Therapy for Orofacial Pain

In this article we reviewed the English manuscripts Clinical Applications of Laser in
about effect of low level laser therapy on orofacial Orofacial pain
pain published in pubmed from 1988 to 2012.
Management of Myofacial Pain
Mechanisms of Action Myofacial pain dysfunction syndrome (MPDS) is the
most common reason for pain and limited function of
Stimulation of any point of the body creates neural the masticatory system. The effects of low-level lasers
impulses that are transmitted to upper nervous centers (LLLs) for controlling the discomfort of patients are
by neurons that have different features. These impulses investigated frequently. Several studies have shown that
finally reach the CNS. Low-power lasers can leave use of 830-nm wavelength laser in several appointments
their effects in different parts of the body (3). Laser can reduce or eliminate myofacial pain (5, 6).
radiation may alter cell and tissue function and Some authors (Ilbuldu, Irnich) have reported
decrease patients’ pain. significant pain reduction in a number of conditions
Arcive of SID
Currently the following analgesic effects are such as myofascial pain syndrome, chronic neck pain
recognized: - Anti-inflammatory. LLLT reduces after laser application (7, 8).
oxidative stress: Mitochondria in stressed or ischemic In a study by Kulekcioglu, semi-conductive (diodic)
tissues produce nitric oxide (mtNO) that binds to gallium arsenide(GaAs) laser (wavelength: 904
cytochrome oxidase competitively displacing oxygen nanometers, mean output power: 17 mW) was used in
leading to oxidative stress and reduced ATP production. treatment of temporomandibular disorder. The patients
Light of suitable wavelength, sufficient irradiance and were treated with fifteen sessions of low-level laser
time when applied to injuries is absorbed by cytochrome concurrent with daily exercise program. Active and
oxidase displacing mtNO thereby reducing oxidative passive maximum mouth opening, lateral motion and
stress and increasing ATP production. A cascade of number of tender points were significantly improved
downstream metabolic effects lead to a reduction in patients who undertaken laser therapy compared
in inflammatory markers including prostaglandin with placebo group, although pain relief was observed
E2, interleukin 1β and tumor necrosis factor α (3).- in both groups (9).
Analgesia. LLLT creating a nerve block. Higher Altafini et al. reported no pain in their patients
energy can induce an analgesic effect by disrupting up to 3 months after laser therapy. Furthermore,
fast axonal transport in small diameter fibers, in effectiveness of laser acupuncture has been confirmed
particular nociceptors. This temporary (reversible) in decreasing myofacial pain (10).
inhibition of A-delta and C fiber transmission Shirani et al. evaluated the efficacy of a LLLT
reduces tonic peripheral nociceptive afferent input producing 660 nm and 890 nm wavelengths that was
and facilitates reorganisation of the modulation of recommended to reduce the pain in the masticatory
synaptic connections. Repeated treatments lead to a muscles. This was a double-blind and placebo-
reduction in central sensitization (3). controlled trial. Treatment was given twice a week
Bjordal in a systematic review of possible for 3 weeks. In each group the reduction of pain before
mechanisms of action and clinical effects in randomized and after the treatment was meaningful, but, between
placebo-controlled trials, found that there was strong the two groups, low-level laser therapy (LLLT) was
evidence that LLLT can modulate inflammatory pain by more effective (P=0.03). According to their study,
reducing levels of biochemical markers (PGE , mRNA LLLT was an effective treatment for pain reduction
2
Cox 2, IL-1β, TNFα), neutrophil cell influx, oxidative in MPDS patients (11).
stress, and formation of edema and hemorrhage in Oz et al. compared the effects of low-level laser with
2
a dose-dependent manner (median dose 7.5 J/cm , occlusal splints in patients with signs and symptoms
2
range 0.3–19 J/cm ). Compared with non-steroidal of myofacial pain (MP) dysfunction syndrome.
anti-inflammatory drugs (NSAIDs) in animal studies, Vertical movements showed statistically significant
they found optimal doses of LLLT and NSAIDs to improvements after the treatments in both groups,
be equally effective. It was concluded that LLLT can but when the groups were compared with each other,
modulate inflammatory processes in a dose-dependent there were no significant difference between the
manner and can be titrated to significantly reduce acute groups. In both groups, tenderness to palpation of
inflammatory pain in clinical settings (4). the muscles decreased significantly. Pressure pain

98 Journal of Lasers in Medical Sciences Volume 3 Number 3 Summer 2012
www.SID.ir