The healing effect of low energy lasers is generally attributed to enhanced cell proliferation due to the irradiation. As it was not clear whether coherent irradiation is essential, we examined the effect of various wavelengths from non-coherent light sources, on fibroblast proliferation. We found that light at 540 and 600-900 nm significantly accelerates the mitosis of these cells, Moreover, we have found that the effect is not only energy-dose dependent, but depends non-lineraly on the intensity of the light source.
It is suggested that S. mutans can be stimulated by LLLT in vivo, and similar modulation could potentially occur in the other bacteria exposed to LLLT. In addition the acceleration of healing in the infected lesion following GaAs LLLT indicates that the cellular activity due to the biostimulation effect of LLLT in the surrounding normal tissue predominates over the tissue irritation due to the bacterial growth in the infected lesion. This study was undertaken to investigate the influence of LLL irradiation on the healing process of skin wounds infected with bacteria. Open wounds of about 6 mm in diameter were formed on both gluteal regions of seven rats and then S. aureus was inoculated on all wounds. One wound of each rat was irradiated by LLL on the 1st, 2nd, 3rd, and 4th day. but the other was not irradiated to be used as control, All wound areas were measured by photographing the wounds from a constant distance on the lst, 3rd, 5th, and 7th postoperative days, and then the control and experimental groups were compared according to the time interval. The results of this study were as follows: (1) The rate of wound closure was significantly increased in LLL irradiation group. (2) The incidence of swelling indicating the spread of inflammation was significantly decreased in the experimental group.
Low-level laser therapy (LLLT) is used clinically to stimulate healing, including re-epithelialization of wounds. The aim of this study was to investigate the effects of laser therapy on the proliferation of keratinocytes. The effects of laser emissions at 632.8 nm (continuous wave) and at 904 nm (200 ns pulses at frequencies of 1205 pps and 3125 pps) at energy densities of 0.25-4 J/cm2 were investigated. Phenotypic alterations have been noted in keratinocytes from cultures kept at confluence for several days. Cells from confluent and sub-confluent keratinocyte cultures were used in order to investigate whether these changes could be reversed more quickly, on subculture, following exposure to laser emission. Keratinocytes were grown in either 5% or 1% fetal calf serum (FCS), proliferation being slower in the latter, and the effects of LLLT on them compared. The results obtained indicate that: (1) LLLT stimulates keratinoycte proliferation; (2) the delay in proliferation observed in keratinocytes taken from confluent cultures may be reduced by laser irradiation; (3) LLLT has a greater effect on cultures grown in the poor conditions of 1% FCS than in the better conditions provided by 5% FCS; and (4) LLLT has biostimulatory properties at energy densities as low as 0.25 J/cm2.
Patients with atopic dermatitis (AD) were treated with diode low reactive level laser therapy (LLLT), and the following results were obtained. (1) Itchy sensation decreased in 63 of 81 cases (79%) after this therapy. (2) Skin eruption improved in 57 of 81 cases (71%). (3) There were no side-effects during and after LLLT. (4) Major histocompatibility complex (MHC) class II antigen and inter-cellular adhesion molecule (ICAM)-1 expression on epidermal cells decreased after the therapy. (5) The number of CDI positive epidermal dendritic cells did not significantly change before and after LLLT.
This study presents our six-year experience in laser therapy for rehabilitation of facial paralysis. Mixed laser irradiation using a 904 nm diode GaAs and 632.8 (HeNe) was utilized. Laser irradiation was performed on the range of facial nerve ramifications in eight different places, 5 min on each place, four times a week. No other medicine was used if the patient arrived 48 h after having the lesion. When the patient arrived after the first week, meticorten was utilized as a supplement, a dosage of 40 mg per day, for seven days. Based on our experience, the patients who are more inclined to attend treatment sessions are those who have been suffering from paralysis for more that a month and who have submitted to other kinds of treatments with negative results. They were even offered surgery. For these patients, we have required up to a maximum of 30 sessions and we have achieved 100% recovery, even with patients who have had the lesion for three or six months. Patients who attended therapy within two weeks after suffering the paralysis recovered 100% with no additional medication-only laser therapy. With these patients we needed a maximum of 15 sessions. LLLT is presented as a safe, noninvasive, easy to apply and comparatively side-effect-free modality offering a complementary and effective tool in the treatment of facial paralysis.
The therapeutic effect of LLLT on the inferior alveolar, mental and lingual nerves was observed in a group of 15 patients with short and long-term neurosensory impairment, In six subjects with clinical symptoms of less than 1 year’s duration, improvement of sensitivity increased from ‘0’ to between 40 and 100% (average 78.3%) as estimated on the visual analogue scale (VAS). In eight patients with clinical symptoms of more than 1 year improvement increased to between 40 and 90% (average 66.9%). Only one patient had no improvement, but remained at 20% level on the VAS. LLLT was applied using an infrared diode laser (GaAlAs 830 nm, 70 mW continuous wave), with a dose of 4.9 J/cm2 at each point three times per week and varied between 2 and 8 weeks, Considerable improvement of sensation was observed after the final treatment session. No side-effects were reported and patients have maintained the effective results for 2 years follow-up. In future studies, methods should be developed to investigate the possible effect of LLLT on peripheral nerve injuries.