Combined Diode Laser Research Articles

Transected sciatic nerve repair by diode laser protein soldering

Background and ObjectiveDespite advances in microsurgical techniques, repair of peripheral nerve injuries (PNI) is still a major challenge in regenerative medicine. The standard treatment for PNI includes suturing and anasthomosis of the transected nerve. The objective of this study was to compare neurorraphy (nerve repair) using standard suturingto diode laser protein soldering on the functional recovery of transected sciatic nerves. Study Design/Materials and MethodsThirty adult male Fischer-344 Wistar rats were randomly assigned to 3 groups: 1. The control group, no repair, 2. the standard of care suture group, and 3. The laser/protein solder group. For all three groups, the sciatic nerve was transected and the repair was done immediately. For the suture repair group, 10.0 prolene suture was used and for the laser/protein solder group a diode laser (500mW output power) in combination with bovine serum albumen and indocyanine green dye was used. Behavioral assessment by sciatic functional index was done on all rats biweekly. At 12weeks post-surgery, EMG recordings were done on all the rats and the rats were euthanized for histological evaluation of the sciatic nerves. The one-way ANOVA test was used for statistical analysis. ResultsThe average time required to perform the surgery was significantly shorter for the laser-assisted nerve repair group compared to the suture group. The EMG evaluation revealed no difference between the two groups. Based on the sciatic function index the laser group was significantly better than the suture group after 12weeks (p<0.05). Histopathologic evaluation indicated that the epineurium recovery was better in the laser group (p<0.05). There was no difference in the inflammation between the suture and laser groups. ConclusionBased on this evidence, laser/protein nerve soldering is a more efficient and efficacious method for repair of nerve injury compared to neurorraphy using standard suturing methods.

COMBINED EFFECT OF FLUORIDE GEL AND DIODE LASER 980 NM ON ROOT CARIES INHIBITION

Aim: To study the evaluation of the combined effect of Diode laser and fluoride gel on root dentin demineralization and compare between the use of laser only & laser with fluoride in root caries. Methods: Tooth preparation & grouping, fluoride treatment, laser treatment, fluoride & laser treatment, tooth-sectioning and artificial caries application & environmental scanning electron microscope analysis. Results: The effect of artificial caries on the fluoride and diode laser specimens showed an augmentation of the caries prevention mechanism. Conclusion: Our results strongly dictate a synergistic rather than an additive effect of the combined diode laser and fluoride gel treatments in root caries inhibition.

Generation of blue light by sum-frequency generation of a spectrally combined broad-area diode laser array.

We present the first demonstration of a spectrally beam combined diode laser array with subsequent sum-frequency generation (SFG). The combined beam of the diode laser array with 19 emitters has the same beam quality as a single emitter, and the wavelength of each emitter is different. The blue light is generated by sum-frequency mixing of pairs of emitters in the diode laser array. About 93 mW of blue light power is produced using a PPLN crystal. Compared with the SFG of two emitters, this approach can increase the number of lasers participating in nonlinear frequency conversion. Thus, it can enhance the available power.

Narrow linewidth operation of a spectral beam combined diode laser bar.

Our experiment is expected to provide an approach for realizing ultranarrow linewidth for a spectral beam combined diode laser bar. The beams of a diode laser bar are combined in a fast axis after a beam transformation system. With the help of relay optics and a transform lens with a long focal length of 1.5m, the whole wavelength of a spectral combined laser bar can be narrowed down to 0.48nm from more than 10nm. We have achieved 56.7W cw from a 19-element single bar with an M2 of 1.4 (in horizontal direction)×11.6 (in vertical direction). These parameters are good evidence that all the beams from the diode laser bar are combined together to increase the brightness.

Picosecond Time Resolved Studies of Photon Transport Inside Scintillators

The traveling time of scintillation photons from the ionization track to the photodetector varies from photon to photon. For scintillators used in (time-of-flight) positron emission tomography (TOF-)PET systems the resulting optical transit time-spread can have a significant influence on the timing resolution. Using a femtosecond pulsed diode laser in combination with a fast imaging streak camera we measured this time-spread on the picosecond time scale for both polished and etched Ca co-doped and non co-doped LSO:Ce and LYSO:Ce crystals of $3 \times 3 \times 5 ~\hbox{mm}^3$ , $3 \times 3 \times 10 ~\hbox{mm}^3$ , and $3 \times 3 \times 20 ~\hbox{mm}^3$ in size. Measurements were performed with the crystals wrapped on 5 of their sides in 1 to 4 layers of 0.1 mm thick white reflecting Teflon tape (PTFE). Optical photons can migrate through Teflon tape for some time before they re-enter the crystal. This Teflon time-spread was measured as well. The roughness of the crystal surfaces were determined using a surface profiler. In addition to experiments, the optical transit time-spread was obtained by means of ray-tracing software and compared to experimental data. In addition, an analytical model about optical transit time-spreads was derived.

Diode laser and fluoride varnish in the management of dentin hypersensitivity

Aims: The aim of this study is to compare the effectiveness of diode laser in combination with commercially available fluoride varnish to the fluoride varnish alone. Settings and Design: Randomized control trial; split mouth. Subjects and Methods: A total of 50 teeth from 14 patients with visual analog scale (VAS) >2 from both sexes were randomly allocated into two groups: 26 teeth in bifluoride group and 24 in laser + bifluoride group. Dentine hypersensitivity is evaluated with the help of VAS at the start of study, at 15 min; 15, 30, and 60 days. Teeth were subjected to vitality testing to rule out any pulpal pathology. Statistical Analysis Used: SPSS version 17.0. Unpaired t test. Results: After 15 min both the treatment modalities were effective. The effectiveness of fluoride varnish in reducing evaporative stimulus (ES) was maintained until 15 days. However, the laser + fluoride varnish was more effective in reducing thermal stimulus (TS) at 15 days. At any given point of time, the effectiveness of laser + fluoride varnish was more than the varnish group. The effectiveness of laser also reduced after 30 days for both ES and TS. Conclusions: The diode laser and fluoride varnish are effective in the treatment of dentin hypersensitivity. The combined effect is more than fluoride varnish alone, but for a short period.

Microscopic heterodyne interferometry for determination of electron density in high-pressure microplasma

Electron density is paramount for understanding plasma characteristics and for control in plasma applications. To determine the electron density in a plasma by the use of interferometry, the phase shift of a probing electromagnetic (EM) wave induced by interaction with the plasma is measured. In this paper, for the determination of electron density in microplasmas generated under conditions of fluid density higher than that of ambient air, we discuss appropriate wavelength ranges for the probing EM wave (laser beam) in interferometry with consideration of the plasma parameters in the tested plasma source. On the basis of the discussion, we develop an interferometry system using a near-infrared diode laser in combination with a reflection system and a microscope for microplasma diagnostics, and measure the electron density in a 200 ns short-pulse microdischarge generated in a 0.3 MPa helium supercritical fluid.

Systematic Review and Meta‐Analysis of the Effect of Various Laser Wavelengths in the Treatment of Peri‐Implantitis

The primary aim of this systematic review is to address the following focused question: Is laser therapy, as a monotherapy or as an adjunctive therapy, an efficacious treatment modality for patients with peri-implantitis? The PubMed database of the U.S. National Library of Medicine and the Cochrane Central Register of Controlled Trials were electronically searched, complemented by manual searches up to June 2013. The search yielded 137 titles and abstracts. After initial screening, 15 of 137 publications were scrutinized during the second phase of the review. In the second phase, nine articles were excluded from the analysis and six controlled, clinical studies were selected. Narrative synthesis of the results revealed that non-surgical laser treatment with a single application of either an erbium:yttrium-aluminum-garnet (Er:YAG) (2,940-nm) laser or a diode (660-nm) laser in combination with a phenothiazine chloride dye is efficient in controlling inflammation around treated implants for at least 6 months following intervention, whereas it has only a mild effect on reduction in probing depth (PD) and gain in clinical attachment level (CAL). There is limited information regarding the clinical application of the CO2 (10.6-µm) laser in the surgical treatment of peri-implantitis; however, its use may be promising. A meta-analysis could be performed only for the efficacy of Er:YAG laser due to the heterogeneity of the studies and the limited amount of data available. Meta-analysis did not reveal statistically significant evidence for treatment effects in reducing PD and CAL levels in comparison to controls. Based on the limited information currently available, any superiority of laser treatment in comparison to conventional treatment of peri-implantitis could not be identified. Considering the high heterogeneity and the low number of included studies, the authors cautiously conclude that non-surgical laser therapy may be investigated as phase I therapy for the treatment of peri-implantitis. Future research should emphasize detailed description of the specific laser characteristics and power settings in clinical studies.

Effect of diode laser in the treatment of patients with nonspecific chronic low back pain: a randomized controlled trial.

Low back pain is a common, highly debilitating condition, whose severity is variable. This study evaluated the efficacy of treatment with Ga-Al-As diode laser (980 nm) with a large diameter spot (32 cm(2)), in association with exercise therapy, in reducing pain. The present study aimed to evaluate the pain reduction efficacy of treatment with the Ga-Al-As diode laser (980 nm) in combination with exercise therapy, in patients with chronic low back pain (CLBP). This study evaluated 100 patients with CLBP (mean age 60 years) who were randomly assigned to two groups. The laser plus exercises group (Laser+EX: 50 patients) received low-level laser therapy (LLLT) with a diode laser, 980 nm, with a specific handpiece [32 cm(2) irradiation spot size, power 20 W in continuous wave (CW), fluence 37.5J/cm(2), total energy per point 1200 J] thrice weekly, and followed a daily exercise schedule for 3 weeks (5 days/week). The exercises group (EX: 50 patients) received placebo laser therapy plus daily exercises. The outcome was evaluated on the visual analogue pain scale (VAS), before and after treatment. At the end of the 3 week period, the Laser+EX group showed a significantly greater decrease in pain than did the EX group. There was a significant difference between the two groups, with average Δ VAS scores of 3.96 (Laser+EX group) and 2.23 (EX group). The Student's t test demonstrated a statistically significant difference between the two groups, at p<0.001. This study demonstrated that the use of diode laser (980 nm) with large diameter spot size, in association with exercise therapy, appears to be effective. Such treatment might be considered a valid therapeutic option within rehabilitation programs for nonspecific CLBP.

The Inhibition Effect of 940 nm Diode Laser on Some Microorganisms Associated With Gingivitis

Background : Poor oral hygiene lead to gingival inflammation due to the accumulation of plaque and microorganisms. Scaling and polishing was considered as an effective treatment of gingivitis. Several systemic and local antimicrobials were found to enhance the mechanical treatment. However, these antimicrobial agents may lead to bacterial resistance and systemic side effects in addi - tion to limitation in the accessibility to the affected areas. The aim of this study is to explore the effect of diode laser (940nm) in combination to the traditional mechanical treatment. Materials and methods: twenty patients with bilateral gingivitis were selected. For each patient, one side of the mouth was treated traditionally. The other side was treated with 2 W diode laser (940nm) after scaling and polishing. Smears were taken from deepest points of the gingival sulci of both sides. The collected bacterial samples were inoculated in brain-heart infusion and inoculated into blood agar plates and MacConkey agar plates for 24 hours aerobically and 24-48 hours anaerobically (using jar and CO2 gas pack) at 37oC. The collected data of bacterial identification were tabulated in excel tables. Means, standard deviations, ANOVA test and p value were calculated. RESULTS there is highly significant decrease in the identification of aerobic bacteria after using diode laser. Anaerobic bacteria were less identified, but they were completely absent after diode laser treatment. Conclusion: Diode laser (940nm) could be successfully used adjunctive to mechanical scaling and polishing to integrate the antimi - crobial action within the gingival sulci.

Low-Level Laser Therapy and Vibration Therapy for the Treatment of Localized Adiposity and Fibrous Cellulite

IntroductionIn recent years, there has been an upsurge in the application of low-level laser therapy in various medical diseases. Additionally, vibration therapy is a new and effective measure to prevent muscular atrophy and osteoporosis, along with some general health-related beneficial effects of exercise on skeletal muscles such as improvement of endothelial function and an increased enzyme capacity of energy metabolism. The aim of this study was to evaluate the application of a 635 nm and 0.040 W exit power per multiple diode laser in combination with vibration therapy for the application of non-invasive reduction of circumference in patients with localized adiposity and cellulite.MethodsThe study enrolled men and women (N = 33) aged 18–64 years with localized adiposity or fibrous cellulite. The evaluation parameters were: photographic evaluation, perimetric evaluation, blood tests, ecographic evaluation, histological evaluation, and subjective and objective tests.ResultsThe results produced were statistically analyzed and resulted in a significant reduction of fat thickness when compared to the measurement prior to the treatment (P < 0.0001). Moreover, subjective and objective tests, as well as ecographic and histological evaluations, confirmed the reduction of fat thickness.ConclusionIn this study we have demonstrated the safety and efficacy of the combination between low-level laser therapy and vibration therapy for the resolution of localized adiposity and fibrous cellulite.

Disinfection of Contaminated Canals by Different Laser Wavelengths, while Performing Root Canal Therapy.

Removal of smear layer and disinfection of canals are important objectives of teeth root canal cleaning. In order to achieve this purpose, rinsing substances, intra canal drugs as well as ultrasound are used. Today, use of laser to remove smear layer and to disinfect root canals has increasingly attracted the attentions. Till now different lasers such as CO2, Nd:YAG, Er:YAG, Er,Cr:YSGG have been used for debris and smear removal from the canals. Numerous studies have shown that Er:YAG is the most appropriate laser for intra canal debris and smear removal. In addition different laser wavelengths have been used directly or as an adjunctive to disinfect canals. Laser light can penetrate areas of canals where irrigating and disinfecting solutions cannot reach, like secondary canals and deep dentinal tubules and also can eliminate microorganisms. Different studies have confirmed the penetration of Nd:YAG laser in deep dentin and reduction of microorganisms penetration. But studies on comparison of antibacterial effects of Nd:YAG laser with sodium hypochlorite showed effectiveness of both, with a better effect for sodium hypochlorite. Studies performed in relation with anti-microbial effects of Diode laser with various parameters show that this laser can be effective in reducing intra canal bacterial count and penetration in the depth of 500 microns in dentin. In studies performed on Diode laser in combination with canal irrigating solutions such as sodium hypochlorite and oxygenated water better results were obtained. Although studies on disinfection by the Erbium laser family show that use of this laser alone can be effective in disinfecting canals, studies evaluating the disinfecting effects of this laser and different concentrations of sodium hypochlorite show that the latter alone is more effective in disinfecting canals. And better results were obtained when Erbium laser was used in combination with sodium hypochlorite irrigating solution in canals. Results of the aforementioned articles indicate that this laser is effective in combination with a rinsing solution such as sodium hypochlorite. Results from studies including several types of the different Er:YAG, Ho:YAG, Nd:YAG, Er,Cr:YSGG lasers in disinfecting canals showed that all wavelengths used in disinfection for different thicknesses of dentin were efficacious without damaging thermal effect. Considering that use of different lasers in canals can be accompanied with temperature increase which can sometimes lead to damages to teeth and surrounding tissues, thus the use of photochemical phenomenon for elimination of microorganisms have attracted attention of many researchers. Studies in this field imply the efficacy of this method in reducing canal bacterial count and recommend its use as an adjunctive after biomechanical preparation of canals. Results from performed studies show removal of intra canal debris and smear layer by different lasers and particularly the Erbium laser family. Furthermore various laser wavelengths, particularly of Diode and Nd:YAG lasers can be effective in reducing intra canal microbial count. Maximum effect is obtained when laser light is used in canals in combination with sodium hypochlorite irrigating substance in appropriate concentration. Therefore use of laser energy can improve success rate of root canal treatments.

High‐intensity diode laser in combination with bipolar transurethral resection of the prostate: A new strategy for the treatment of large prostates (&gt;80 ml)

The ideal treatment of large prostates with symptomatic benign prostatic hyperplasia (BPH) remains controversial. We compare the efficacy and safety of monopolar transurethral resection of the prostate (TURP) with high-intensity diode laser in combination with bipolar TURP (DL + b-TURP) in the treatment of large prostates. We retrospectively analyzed all patients with lower urinary tract symptoms (LUTS) secondary to BPH with prostates larger than 80 ml, undergoing monopolar TURP (n = 36) or DL + b-TURP (n = 37) between January 2008 and March 2010. The preoperative and follow-up functional parameters including International Prostate Symptom Score (IPSS), post-void residual urine (PVR), maximum flow rate (Q(max) ), quality of life score (QoLs), prostate size, and prostate-specific antigen (PSA) were assessed. The operative data, peri- and post-operative complications were also recorded. The demographic data were comparable between the two groups. Preoperative prostate volume was 110.8 ± 28.9 ml in the DL + b-TURP group and 103.7 ± 31.2 ml in the TURP group. TURP group had significantly shorter operative time; however, the catheterization time and hospital stay were in favor of the DL + b-TURP group (P < 0.001). The decrease in hemoglobin was statistically significantly greater in the TURP group. Late complications were also comparable. Both groups could achieve significant improvements in functional outcomes during the follow-up of 24 months. With regard to the operative safety and functional results, high-intensity diode laser combined with bipolar TURP is feasible for BPH treatment with large prostates.

1,450-nm Diode Laser in Combination with the 1550-nm Fractionated Erbium-Doped Fiber Laser for the Treatment of Steatocystoma Multiplex: A Case Report

Steatocystoma multiplex (SM) is a rare condition characterized by multiple, small, asymptomatic dermal cysts. Treatment options are limited, with varying degrees of success; these include oral isotretinoin, surgical excision or drainage, and liquid nitrogen cryotherapy. The most effective method is excision, but cosmetic considerations, time, overall cost, and pain must be considered, because patients tend to have multiple cysts. Lasers, especially nonablative devices, have not frequently been used to treat SM. Herein, we present the case of a patient with isolated steatocystoma multiplex on the abdomen and lower chest with substantial clearance after two laser treatment sessions using two complementary lasers: a 1,450-nm diode laser to target the abnormal sebaceous glands and a 1,550-nm fractionated erbium-doped fiber laser to target the dermal cysts.

The safety and efficacy of a combined diode laser and bipolar radiofrequency compared with combined infrared light and bipolar radiofrequency for skin rejuvenation

As the demand for noninvasive procedures for skin rejuvenation is increasing, combined diode laser and radiofrequency and combined infrared and radiofrequency devices have recently emerged. To compare Polaris WRA(TM), a combination device of diode light and RF, and ReFirme ST(TM), a combination device of infrared and bipolar RF, in terms of safety and efficacy on skin rejuvenation. Fourteen Korean volunteers of skin type II-IV, with facial laxity and periorbital rhytids, received three treatments at 3-week intervals with combined diode laser and bipolar radiofrequency (laser fluence 30 J/cm2, RF fluence 90 J/cm3) on the right half of their faces and combined infrared light and bipolar radiofrequency (RF fluence 120 J/cm3) on the left half of their faces. Clinical photos of front and bilateral sides of the subjects' faces were taken at baseline and at 6, 9, 12 weeks after the treatment initiation. The investigators' and the subjects' global assessments were performed. There is no statistically significant difference in the overall outcome between Polaris WRA(TM) and Refirme ST(TM) based on pre- and post-treatment objective measurements. Polaris WRA(TM) was more effective than Refirme ST(TM) at reducing wrinkles when therapeutic results of the two appliances were compared based on the patient satisfaction measurements. After the treatment with both instruments, histological increase in the production and rearrangement of collagen fibers at the dermal layer was observed. The density of the collagen fibers was more increased with the Polaris WRA(TM)-treated facial area than that of Refirme ST(TM). Treatment was generally well tolerated, and there was no serious complication. In this study, both the lasers appeared to be safe, and effective methods for treating skin laxity and facial wrinkles. Combined diode laser and radiofrequency was more effective than combined infrared and radiofrequency at reducing wrinkles and pores when the therapeutic results of both the appliances were compared.

Bactericidal Effects of Diode Laser Irradiation on Enterococcus faecalis Using Periapical Lesion Defect Model

Objective. Photodynamic therapy has been expanded for use in endodontic treatment. The aim of this study was to investigate the antimicrobial effects of diode laser irradiation on endodontic pathogens in periapical lesions using an in vitro apical lesion model. Study Design. Enterococcus faecalis in 0.5% semisolid agar with a photosensitizer was injected into apical lesion area of in vitro apical lesion model. The direct effects of irradiation with a diode laser as well as heat produced by irradiation on the viability of microorganisms in the lesions were analyzed. Results. The viability of E. faecalis was significantly reduced by the combination of a photosensitizer and laser irradiation. The temperature caused by irradiation rose, however, there were no cytotoxic effects of heat on the viability of E. faecalis. Conclusion. Our results suggest that utilization of a diode laser in combination with a photosensitizer may be useful for clinical treatment of periapical lesions.

Application of a super-luminescent diode coupled with an interference filter for mixed gas sensing

Laser-based spectroscopic techniques are very attractive methods for trace gas, environmental and industrial monitoring. By employing narrow spectral-width tunable coherent light sources, a single absorption line of the substance to be analyzed can be probed with a laser, avoiding interference signals from other species. Here we report a difference frequency generation (DFG) source in mid-infrared region using a tunable laser (825 – 870nm) and a fixed wavelength diode laser (1060nm) in combination with a PPLN having single period. Application of the approach for carbon dioxide (CO2) monitoring in air was studied. Many gas sensing applications do not require extreme sensitivities up to ppb order and in this case, super-luminescent diodes (SLD) are also of great interest. They are commonly produced in the spectral range of optical fibers telecommunications (1.3 – 1.7 m), where overtone vibration bands of many gas molecules of interest. As a typical example, measurements of ammonia (NH3) trace gas were studied for combustion measurement applications. A novel approach of using fiber-coupled SLD along with an interference filter can also be considered for such application to avoid influence of water vapor (H2O). The interest of this system consists in the possibility to detect several species with a single instrument.

1450-nm high-brightness wavelength-beam combined diode laser array

We have demonstrated wavelength beam combining of a 1450-nm diode laser array with a novel smile compensation method. We have achieved 20-W cw from a 25-element single bar with an M(2) of 1.9 (fast axis) x 10 (wavelength-beam-combined dimension).

Bleaching effect of a 405-nm diode laser irradiation used with titanium dioxide and 3.5% hydrogen peroxide

A 405-nm diode laser has recently been developed for soft tissue problems in dentistry. A new in-office bleaching agent consisting of a titanium dioxide photocatalyst and 3.5% hydrogen peroxide has proven to react well with light irradiated at a wavelength of around 400 nm. In this study, we evaluated the bleaching efficacy of a newly developed 405-nm diode laser on bovine teeth treated with a bleaching agent composed of titanium dioxide and 3.5% hydrogen peroxide. Sixteen bovine incisors were randomly divided into two groups: Group A, irradiated by the 405-nm diode laser at 200 mW; Group B, irradiated by the 405-nm diode laser at 400 mW. The bleaching agent with titanium dioxide and 3.5% hydrogen peroxide was applied to bovine enamel and irradiated for 1 min. The specimens were then washed and dried, and the same procedure was repeated nine more times. After irradiation, we assessed the effects of bleaching on the enamel by measuring the color of the specimens with a spectrophotometer and examining the enamel surfaces with a scanning electron microscope. L* rose to a high score, reaching a significantly higher post-treatment level in comparison to pretreatment. In a comparison of the color difference (ΔE) between Group A and Group B, the specimens in Group B showed significantly higher values after 10 min of irradiation for the post-treatment. No remarkable differences in the enamel surface morphology were found between the unbleached and bleached enamel. The use of a 405-nm diode laser in combination with a bleaching agent of titanium dioxide and 3.5% hydrogen peroxide may be an effective method for bleaching teeth without the risk of tooth damage.

Nonablative Wrinkle Treatment of the Face and Neck Using a Combined Diode Laser and Radiofrequency Technology

Nonablative laser systems that integrate optical and conducted radiofrequency (RF) energies are a novel technology for the treatment of wrinkles. This two-center study investigated the safety and effectiveness of combination diode laser (900 nm) and RF for the treatment of wrinkles and skin texture. Patients with grade II to IV wrinkling on the face, according to the Glogau classification system, were treated with a combination diode laser and RF using a fluence of 30 to 50 J/cm2 and RF energy of 80 to 100 J/cm3. Patients received up to three treatment sessions at 2- to 3-week time intervals. Wrinkle assessments using the Glogau scale were conducted at baseline and at 3 months following the last treatment. In addition, patients and physicians graded the level of improvement using pre- and post-treatment photographs. Twenty-three subjects completed all three treatment sessions. Of these participants, more than 50% had a greater than 50% improvement in the appearance of wrinkles. All subjects reported a noticeable improvement in skin smoothness and texture. This preliminary study demonstrates that the combination of diode laser and RF energies decreases the appearance of wrinkles and improves skin texture.