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Journal: Lasers in medical science


The Achilles tendon has a high incidence of rupture, and the healing process leads to a disorganized extracellular matrix (ECM) with a high rate of injury recurrence. To evaluate the effects of different conditions of low-level laser (LLL) application on partially tenotomized tendons, adult male rats were divided into the following groups: G1, intact; G2, injured; G3, injured + LLL therapy (LLLT; 4 J/cm(2) continuous); G4, injured + LLLT (4 J/cm(2), 20 Hz); G5, injured; G6, injured + LLLT (4 J/cm(2) continuous); and G7, injured + LLLT (4 J/cm(2), 20 Hz until the 7th day and 2 kHz from 8 to 14 days). G2, G3, and G4 were euthanized 8 days after injury, and G5, G6, and G7 were euthanized on the 15th day. The quantification of hydroxyproline (HOPro) and non-collagenous protein (NCP), zymography for matrix metalloproteinase (MMP)-2 and MMP-9, and Western blotting (WB) for collagen types I and III were performed. HOPro levels showed a significant decrease in all groups (except G7) when compared with G1. The NCP level increased in all transected groups. WB for collagen type I showed an increase in G4 and G7. For collagen type III, G4 presented a higher value than G2. Zymography for MMP-2 indicated high values in G4 and G7. MMP-9 increased in both treatment groups euthanized at 8 days, especially in G4. Our results indicate that the pulsed LLLT improved the remodeling of the ECM during the healing process in tendons through activation of MMP-2 and stimulation of collagen synthesis.

Concepts: Collagen, Extracellular matrix, Cartilage, Matrix metalloproteinase, Tendon, Achilles tendon, Tendons, Type-I collagen


More than just a cosmetic concern, onychomycosis is a prevalent and extremely difficult condition to treat. In older and diabetic populations, severe onychomycosis may possibly serve as a nidus for infection, and other more serious complications may ensue. Many treatment modalities for the treatment of onychomycosis have been studied, including topical lacquers and ointments, oral antifungals, surgical and chemical nail avulsion, and lasers. Due to their minimally invasive nature and potential to restore clear nail growth with relatively few sessions, lasers have become a popular option in the treatment of onychomycosis for both physicians and patients. Laser or light systems that have been investigated for this indication include the carbon dioxide, neodymium-doped yttrium aluminum garnet, 870/930-nm combination, and femtosecond infrared 800-nm lasers, in addition to photodynamic and ultraviolet light therapy. This systematic review will discuss each of these modalities as well as their respective currently published, peer-reviewed literature.

Concepts: Oxygen, Ultraviolet, Light, Laser, Sunlight, Fluorescent lamp, Infrared, Light therapy


Dentinal hypersensitivity is one of the oldest recorded complaints of discomfort to mankind and yet there appears to be no permanent treatment for this clinical condition. This study was designed to evaluate the clinical efficacy of potassium binoxalate gel and neodymium:yttrium-aluminum-garnet (Nd:YAG) laser on dentin hypersensitivity for a period of 9 months. Eighty teeth (20 subjects, 25-55 years old, M = F) were evaluated in a split-mouth design to receive potassium binoxalate (group A, 40 teeth) and Nd:YAG (group B, 40 teeth: 1 W, 10 Hz, and 60 s, irradiated twice). The diameter of output beam was about 300 μm with a distance of 2 mm between laser fiber or tip and tooth surface. The clinical efficacy was evaluated by air-blast test and cold-water test using visual analog scale. Electron microscopy photomicrographs were taken to confirm the results. Analysis was done at baseline; immediately post-treatment; and at 3, 6, 9 months post-treatment. Student’s paired and unpaired T tests were used to evaluate the statistical analysis. Both treatment modalities were effective in reducing dentine hypersensitivity. However, Nd:YAG laser was better when intragroup comparison was made at 9 months post-treatment. Nd:YAG lasers is better in long-term treatment (up to 9 months) owing to the melting of dentinal tubules. However, due to depth of penetration of microcrystals, gel was better when ease of the procedure is considered. Nevertheless, both treatment modalities resulted in recurrence. Hence, further studies are needed to discover an agent, which can be considered as a “gold standard”.

Concepts: Clinical trial, Statistics, Effectiveness, Gold, Teeth, Dentin, Dentine hypersensitivity, Potassium nitrate


Fox-Fordyce disease is an uncommon inflammatory disease of the apocrine sweat glands. Two recent reports indicated laser hair removal as a novel cause of axillary Fox-Fordyce disease. We report the first case of Fox-Fordyce disease developing in women after completing treatment with a depilatory hair laser appearing in the axillae, umbilicus, and pubis. We describe a case of Fox-Fordyce disease that developed in a 27-year-old woman 3 months after she had completed two LightSheer Diode laser treatments of her axilla, periumbilical region, and bikini area. Clinical and histopathological changes are as well detailed. Laser therapy induces damage to follicular infundibulum, resulting in altered maturation of keratinocytes which led to keratin plugging causing the common pathologic features in Fox-Fordyce disease. Differences in the physiologic features of the anatomic sites, in the susceptibility to laser-induced injury among these areas, or additional factors may contribute to Fox-Fordyce disease.

Concepts: Medicine, Laser, Laser medicine, Sweat gland, Axilla, Hair removal, Laser hair removal, Electrology


Endometriosis is a chronic disease affecting mainly women of the reproductive age. Its most common manifestations include impaired fecundity, pelvic pain, and dyschezia. Laparoscopic removal of endometriotic foci remains to be the gold standard for the treatment of endometriosis. More effective techniques of endoscopic approach-among others, laser application-are continually being developed. The aim of the study was to evaluate the efficacy of laparoscopic treatment with the use of CO2 laser ablation vs. electroablation with regard to pain complaints in the affected patients. The study included 48 women (aged 22-42) with varying degrees of endometriosis of the lesser pelvis. The Numeric Rating Scale (NRS) was used to evaluate pain intensity before the surgery in all patients, followed by either laser ablation or electroablation of the endometriotic foci. The results of the laparoscopic treatment were monitored after 3 and 6 months postoperatively. p value of 0.05 was considered to be statistically significant. Patients from both groups reported less intensive pain before/during menstruation (dysmenorrhea) 6 months postoperatively, with more distinct tendency in the electroablation group (p = 0.004) as compared to the laser ablation group (p = 0.025). Despite the initial improvement reported at the 3-month checkup (p = 0.008), 6 months postoperatively, a statistically significant increase in pain intensity was noted in both groups (p = 0.016 and p = 0.032 for CO2 laser ablation and electroablation, respectively). Both surgical methods seem to be effective only in the treatment of endometriosis-related dysmenorrhea, whereas the intensity of other pain complaints (dyspareunia, dysuria, dyschezia, pelvic pain syndrome (PPS)) has remained on the same level.

Concepts: Statistics, Surgery, Statistical significance, Laser, Pelvis, Efficacy, Endometriosis, Laser ablation


The common regime of eccentric exercise in use for Achilles tendinopathy is somewhat arduous and compliance issues can arise. This is the first study to investigate the effectiveness of a regime of fewer exercise sessions combined with photobiomodulation for the treatment of Achilles tendinopathy.

Concepts: Pharmacology, Clinical trial, Randomized controlled trial, Efficacy


Given that the pigment particles in tattoos have a relaxation time of <10 ns, picosecond lasers would be expected to be more effective than nanosecond lasers in tattoo removal. To systematically review the evidence regarding the effectiveness and safety of picosecond lasers for tattoo removal, Pubmed, Cochrane Central Register of Controlled Trials (CENTRAL),, and reference lists were searched for relevant trials. The primary outcome was >70 % clearance of tattoo pigment. Secondary outcomes were 90-100 % clearance of tattoo pigment, number of laser sessions required, and adverse effects. Eight trials were included, six with human participants (160 participants) and 2 with animal models. Seven of the eight trials explored the usage of either 755, 758, 795, 1064, or 1064/532-nm picosecond lasers for black and blue ink tattoos. In the human trials, 69-100 % of tattoos showed over 70 % clearance of pigment after 1-10 laser treatments. Reported side effects included pain, hyperpigmentation and hypopigmentation, blister formation and transient erythema, edema, and pinpoint bleeding. Included articles varied in type of laser investigated, mostly non-comparative studies and with a medium to high risk of bias. There is sparse evidence that picosecond lasers are more effective than their nanosecond counterparts for mainly black and blue ink tattoo removal, with minor side effects.

Concepts: HIV, Pharmacology, Clinical trial, Effect, Effectiveness,, Dermatologic terminology, Tattooing


Muscle regeneration is a complex phenomenon, involving replacement of damaged fibers by new muscle fibers. During this process, there is a tendency to form scar tissue or fibrosis by deposition of collagen that could be detrimental to muscle function. New therapies that could regulate fibrosis and favor muscle regeneration would be important for physical therapy. Low-level laser therapy (LLLT) has been studied for clinical treatment of skeletal muscle injuries and disorders, even though the molecular and cellular mechanisms have not yet been clarified. The aim of this study was to evaluate the effects of LLLT on molecular markers involved in muscle fibrosis and regeneration after cryolesion of the tibialis anterior (TA) muscle in rats. Sixty Wistar rats were randomly divided into three groups: control, injured TA muscle without LLLT, injured TA muscle treated with LLLT. The injured region was irradiated daily for four consecutive days, starting immediately after the lesion using an AlGaAs laser (808 nm, 30 mW, 180 J/cm(2); 3.8 W/cm(2), 1.4 J). The animals were sacrificed on the fourth day after injury. LLLT significantly reduced the lesion percentage area in the injured muscle (p < 0.05), increased mRNA levels of the transcription factors MyoD and myogenin (p < 0.01) and the pro-angiogenic vascular endothelial growth factor (p < 0.01). Moreover, LLLT decreased the expression of the profibrotic transforming growth factor TGF-β mRNA (p < 0.01) and reduced type I collagen deposition (p < 0.01). These results suggest that LLLT could be an effective therapeutic approach for promoting skeletal muscle regeneration while preventing tissue fibrosis after muscle injury.

Concepts: Medicine, Scar, Muscle, Therapy, Classification of Pharmaco-Therapeutic Referrals, Skeletal muscle, Tibialis anterior muscle, Low level laser therapy


Several implant surface debridement methods have been reported for the treatment of peri-implantitis, however, some of them can damage the implant surface or promote bacterial resistance. Photodynamic therapy (PDT) is a new treatment option for peri-implantitis. The aim of this in vitro study was to analyze implant surface decontamination by means of PDT. Sixty implants were equally distributed (n = 10) into four groups and two subgroups. In group G1 there was no decontamination, while in G2 decontamination was performed with chlorhexidine. G3 (PDT - laser + dye) and G4 (laser, without dye) were divided into two subgroups each; with PDT performed for 3 min in G3a and G4a, and for 5 min in G3b and G4b. After 5 min in contact with methylene blue dye (G3), the implants were irradiated (G3 and G4) with a low-level laser (GaAlAs, 660 nm, 30 mW) for 3 or 5 min (7.2 and 12 J). After the dilutions, culture media were kept in an anaerobic atmosphere for 1 week, and then colony forming units were counted. There was a significant difference (p < 0.001) between G1 and the other groups, and between G4 in comparison with G2 and G3. Better decontamination was obtained in G2 and G3, with no statistically significant difference between them. The results of this study suggest that photodynamic therapy can be considered an efficient method for reducing bacteria on implant surfaces, whereas laser irradiation without dye was less efficient than PDT.

Concepts: Bacteria, Surgery, Statistical significance, Implants, In vitro, Dental implant, Methylene blue, Sterilization


The development and use of light and lasers for medical and cosmetic procedures has increased exponentially over the past decade. This review article focuses on the incidence of reported cases of skin cancer post laser or IPL treatment. The existing evidence base of over 25 years of laser and IPL use to date has not raised any concerns regarding its long-term safety with only a few anecdotal cases of melanoma post treatment over two decades of use; therefore, there is no evidence to suggest that there is a credible cancer risk. Although laser and IPL technology has not been known to cause skin cancer, this does not mean that laser and IPL therapies are without long-term risks. Light therapies and lasers to treat existing lesions and CO2 laser resurfacing can be a preventative measure against BCC and SCC tumour formation by removing photo-damaged keratinocytes and encouraged re-epithelisation from stem cells located deeper in the epidermis. A review of the relevant literature has been performed to address the issue of long-term IPL safety, focussing on DNA damage, oxidative stress induction and the impact of adverse events.

Concepts: Cancer, Ultraviolet, The Canon of Medicine, Laser, Avicenna, Squamous cell carcinoma, Skin cancer, Intense pulsed light