In vitro study: methylene blue-based antibacterial photodynamic inactivation of Pseudomonas aeruginosa.

Pseudomonas aeruginosa is one of the most antibiotic-resistant and opportunistic pathogens in immunocompromised and debilitated patients. It is considered the cause of most severe skin infections and is frequently found in hospital burn units. Due to its high antibiotic resistance, eliminating P. aeruginosa from skin infections is quite challenging. Therefore, this study aims to assess the novel in vitro antibacterial activity of methylene blue using a 635-nm diode laser to determine the effective power and energy densities for inhibition of P. aeruginosa. The strain was treated with various concentrations of methylene blue and 635-nm diode laser at powers of 300 mW/cm2 and 250 mW/cm2. The diode laser's potency in the photo-destruction of methylene blue and its degradation through P. aeruginosa were also evaluated. Colony-forming unit (CFU)/ml, fluorescence spectroscopy, optical density, and confocal microscopy were used to measure the bacterial killing effect. As a result, the significant decrease of P. aeruginosa was 2.15-log10, 2.71-log10, and 3.48-log10 at 60, 75, and 90 J/cm2 after excitation of MB for 240, 300, and 360 s at a power of 250 mW/cm2, respectively. However, a maximum decrease in CFU was observed by 2.54-log10 at 72 J/cm2 and 4.32-log10 at 90 and 108 J/cm2 after 300 mW/cm2 of irradiation. Fluorescence images confirmed the elimination of bacteria and showed a high degree of photo-destruction compared to treatment with methylene blue and light alone. In conclusion, MB-induced aPDT demonstrated high efficacy, which could be a potential approach against drug-resistant pathogenic bacteria. KEY POINTS: • Combination of methylene blue with 635-nm diode laser for antibacterial activity. • Methylene blue photosensitizer is employed as an alternative to antibiotics. • aPDT showed promising antibacterial activity against Pseudomonas aeruginosa.

Biological effect of laser-assisted scar healing (LASH) on standardized human three-dimensional wound healing skin models using fractional non-ablative 1540 nm Er:Glass or 1550 nm diode lasers.

PURPOSE: In postoperative wound healing after surgical operations or ablative laser treatments, recent studies suggest the timely use of non-ablative fractional laser treatments with the aim to improve wound healing and prevent pathological scar formation. However, the underlying molecular mechanisms are poorly understood. The aim of this study was to investigate the effects of laser-assisted scar healing (LASH) at the molecular level and to combine it with already established wound healing-promoting local treatments. METHODS: We irradiated full-thickness 3D skin models with a fractional ablative Er:YAG laser to set standardized lesions to the epidermal and upper dermal layer. Subsequently, LASH was induced by irradiating the models with either a fractional non-ablative 1540 nm Er:Glass or 1550 nm diode laser. In addition, we tested the combination of non-ablative fractional laser treatment and topical aftercare with a dexpanthenol-containing ointment (DCO). RESULTS: Histological analysis revealed that models irradiated with the 1540 nm Er:Glass or 1550 nm diode laser exhibited accelerated but not complete wound closure after 16 h. In contrast, additional topical posttreatment with DCO resulted in complete wound closure. At gene expression level, both non-ablative laser systems showed similar effects on epidermal differentiation and mild anti-inflammatory properties. The additional posttreatment with DCO enhanced the wound-healing effects of LASH, especially the upregulation of epidermal differentiation markers and anti-inflammatory cytokines at the gene expression level. CONCLUSION: This in vitro study deciphers the biological effects of LASH with a fractional non-ablative 1540 nm Er:Glass or a 1550 nm diode laser in 3D skin models. These data help to better understand the biological properties of the LASH technique and is important to optimize its application.

Could Photobiomodulation help lactating women and their newborns?

During the first several weeks following lactation, nipple pain frequently prevents mothers from continuing breastfeeding. To evaluate the efficacy of using Photobiomodulation (PBM) versus anti-inflammatory topical cream, on inflamed nipple, and the effect on milk production. This study was carried-out on 50 breastfeeding women with nipple pain and fissure. Our patients were divided into two groups ; study group (Group I): 25 patients received 12 sessions of PBM using Diode laser for a period of 4 weeks, 3 sessions per week every alternative day, and controlled group (Group II): 25 patients used Anti-inflammatory topical cream. Regarding inflammatory signs in both groups, Group I showed a significant decrease in redness compared to Group II at the 3rd and 4th week, and a significant decrease in nipple fissure and pain at the 3rd week. There was a significant increase in milk amount reflected on the infant's weight. We concluded that PBM was more effective in decreasing nipple pain, inflammation and subsequently milk production and infant weight than topical anti-inflammatory creams.

A mechanistic study on the toluidine blue/ photodynamic therapy inhibition of lipopolysaccharide-induced inflammatory response in rat gingival fibroblasts.

The purpose of this research was to investigate the effect of toluidine blue (TB) mediated photodynamic therapy (PDT) on the inhibition of lipopolysaccharide (LPS)-induced inflammation in rat gingival fibroblasts through in vitro experiments. Rat gingival fibroblasts were divided into five groups: (1) control, (2) LPS treatment, (3) laser treatment, (4) TB treatment (1.0 µg/mL), and (5) PDT treatment (TB plus laser irradiation at 320 mW/cm2 for 240 s). After 24 h, cell growth activity was measured using MTT assay. The levels of receptor activator for nuclear factor-κB ligand (RANKL) and osteoprotegerin (OPG) in the cell culture supernatant were measured using enzyme-linked immunosorbent assay (ELISA). Nuclear proteins were extracted and the phosphorylation levels of phosphorylated nuclear factor-κB/p65 (p-p65) and phosphorylated inhibitor of nuclear factor-κB (p-IκBα) were determined using Western Blot. MTT results showed no significant difference in cell viability between the groups (P > 0.05). After LPS induction, OPG expression decreased, RANKL expression increased, and the OPG/RANKL ratio decreased, which was different from the control group (P < 0.05). After PDT treatment, OPG expression increased, RANKL expression decreased (P < 0.05), and the OPG/RANKL ratio increased (P < 0.05). Compared to the control group, there was no significant difference in OPG and RANKL expression or the OPG/RANKL ratio (P > 0.05). The activation of NF-κB was closely related to the phosphorylation levels of p-p65 and p-IκBα. LPS significantly up-regulated p-p65 and p-IκBα expression (P < 0.05), while PDT treatment decreased their phosphorylation levels (P < 0.05). TB-PDT treatment can inhibit NF-κB signaling pathway activation, decrease RANKL and OPG expression, and reduce the OPG/RANKL ratio, thereby reducing inflammation and playing a role in periodontitis treatment.

Anti-biofilm activity of 445 nm and 970 nm diode laser on mixed species colonies of- aggregatibacter actinomycetemcomitans and porphyromonas gingivalis cultured on titanium discs -an in vitro study.

To assess and compare the anti-microbial efficacy of 445 nm and 970 nm diode laser on mixed species biofilm of Aggregatibacter actinomycetemcomitans [A.a] and Porphyromonas gingivalis [P.g] cultured on machined pure titanium discs. A total of 65 machined pure titanium discs with no surface modifications with a 10-mm diameter and a 2-mm height were sterilized by autoclaving at 121 °C for 15 min and incubated with the commercially available bacterial strains ATCC(American Type Culture Collection- P.g 33277 and A.a 29522)mixture of Aggregatibacter actinomycetemcomitans(A.a) and Porphyromonas gingivalis(P.g).After a 2-week incubation period with the mixture of bacteria to develop a mixed species biofilm, the discs were divided into three groups: (1) no treatment (control), (2) 445 nm laser (test), (3) 970 nm laser (test). For each laser wavelength (445 and 970 nm), the discs were exposed to 1.0 W and 2.0 W in continuous wave mode for the times points of 15, 30, and 60 s. The antimicrobial efficacy was assessed by qPCR. A significant reduction in the levels of both species of bacteria was observed between control and the laser intervention groups. A higher efficacy for the 445 nm diode laser against Porphyromonas gingivalis and a similar efficacy against Aggregatibacter actinomycetemcomitans was observed as compared to the 970 nm group. 445 nm wavelength represents a potential and effective laser wavelength which can be used for the management of peri-implant infection. The present study findings also need to be further validated through clinical interventional trials.

Effects of topically administered 0.6% hyaluronic acid on the healing of labial frenectomy in conventional and 940-nm indium gallium arsenide phosphide (InGaAsP) diode laser techniques in pediatric patients: a randomized, placebo-controlled clinical study.

This study aimed to investigate the effects of 0.6% hyaluronic acid (HA) gel on the healing process and postoperative pain levels after diode laser-assisted labial frenectomy in pediatric patients. Ninety-six pediatric patients (females, 50 and males, 46) aged 8-14 years were randomly divided into four groups as follows: (1) conventional frenectomy with 0.6% topically administered HA (CFH, n = 24); (2) conventional frenectomy with placebo gel (CFP, n = 24); (3) frenectomy performed by diode laser with 0.6% topically administered HA (DLH, n = 24); and (4) frenectomy performed by diode laser with placebo gel (DLP, n = 24). HA application was continued for 1 week thrice daily after the frenectomy. Visual analog scale forms were collected from patients 1 week after the operation. In addition, the plaque index, gingival index, periodontal probing depth, and keratinized tissue width and thickness were recorded. This process was repeated 1 and 3 months after the first visit. The DLH group revealed significant differences in the probing depth, bleeding on probing, keratinized gingiva width, and attached gingiva width according to dual comparisons of the initial, first, and third-month values (p = 0.010, p = 0.007, p<0.001, and p = 0.001, respectively). Significant differences were observed between the CFP and CFH groups according to the initial and initial third-month values with regard to the bleeding on probing (p=0.019 and p = 0.019, respectively). The attached gingival thickness revealed significant differences between the CFP and CFH groups for the initial and initial-third-month comparisons (p = 0.005 and p = 0.007, respectively). The mean values of the initial and initial-third-month differences were significantly higher in the CFH group than those in the CFP group. HA- and laser-assisted labial frenectomies revealed better outcomes in terms of the probing depth, attached gingiva width, keratinized gingiva width, healing process, and postoperative comfort.

Fluorescent microscopy evaluation of diode laser effect on the penetration depth of turmeric (Curcuma longa) extract cream on skin tissues of Wistar rats.

The study investigates the effect of diode laser exposure on curcumin's skin penetration, using turmeric extraction as a light-sensitive chemical and various laser light sources. It uses an in vivo skin analysis method on Wistar strain mice. The lasers are utilized at wavelengths of 403 nm, 523 nm, 661 nm, and 979 nm. The energy densities of the lasers are 20.566 J/cm2, 20.572 J/cm2, 21.162 J/cm2, and 21.298 J/cm2, which are comparable to one another. The experimental animals were divided into three groups: base cream (BC), turmeric extract cream (TEC), and the combination laser (L), BC, and TEC treatment group. Combination light source (LS) with cream (C) was performed with 8 combinations namely 523 nm ((L1 + BC) and (L1 + TEC)), 661 nm ((L2 + BC) and (L2 + TEC)), 403 nm ((L3 + BC) and (L3 + TEC)), and 979 nm ((L4 + BC) and (L4 + TEC)). The study involved applying four laser types to cream-covered and turmeric extract-coated rat skin, with samples scored for analysis. The study found that both base cream and curcumin cream had consistent pH values of 7-8, within the skin's range, and curcumin extract cream had lower viscosity. The results of the statistical analysis of Kruskal-Wallis showed a significant value (p < 0.05), which means that there are at least two different laser treatments. The results of the post hoc analysis with Mann-Whitney showed that there was no significant difference in the LS treatment with the addition of BC or TEC when compared to the BC or TEC treatment alone (p > 0.05), while the treatment using BC and TEC showed a significant difference (p < 0.05). Laser treatment affects the penetration of the turmeric extract cream into the rat skin tissue.

Blue Laser for Polymerization of Bulk Fill Composites: Influence on dentin bond strength and temperature rise during curing and co-curing method.

Blue diode lasers are alternative curing devices for dental composites. The aim of this study was to investigate the influence of blue diode laser polymerization on shear bond strength of bulk fill composites to human dentin and temperature rise during two types of polymerization. Composite cylinders of SDR Plus(SDR) and Ever X Flow(EX) were bonded to dentin slabs using Adhese Universal and curing devices blue diode laser (449 nm, 1.6 W) and Power Cure LED. For each material and curing device there were two polymerization approaches: 1)conventional: separate curing of adhesive; 2)co-curing: simultaneous adhesive and composite curing. Polymerization modes for each material in conventional and co-curing(c) approach were: blue laser 2000 mW/cm2 for 5 s (L5 and L5c); blue laser 1000 mW/cm2 for 10 s (L10 and L10c); Power Cure 2000 mW/cm2 for 5 s (LED5 and LED5c); Power Cure 1000 mW/cm2 for 10 s (LED10 and LED10c). Temeperature was measured using thermal vision camera. For SDR, the highest bond strength was 24.3 MPa in L10c, and the lowest 9.2 MPa in LED5c. EX exhibited the highest bond strength(21.3 MPa) in LED5, and the lowest in L5(7.7 MPa). The highest temperature rise for SDR was in L10 and L5 (7.3 and 7.2 °C), and the lowest in LED5(0.8 °C). For EX, the highest temperature rise was in L5 (13.0 °C), and the lowest in LED5 (0.7 °C). Temperature rise was higher during blue laser polymerization, especially at high intensity and with conventional curing. Preferable blue laser curing mode is co-curing at 1000mW/cm2 for 10 s.

High-frequency low-intensity semiconductor laser irradiation enhances osteogenic differentiation of human cementoblast lineage cells.

PURPOSE: Laser irradiation activates a range of cellular processes in the periodontal components and promotes tissue repair. However, its effect on osteogenic differentiation of human cementoblast lineage cells remains unclear. This study aimed to examine the effects of high-frequency semiconductor laser irradiation on the osteogenic differentiation of human cementoblast lineage (HCEM) cells. METHODS: HCEM cells were cultured to reach 80% confluence and irradiated with a gallium-aluminum-arsenide (Ga-Al-As) semiconductor laser with a pulse width of 200 ns and wavelength of 910 at a dose of 0-2.0 J/cm2. The outcomes were assessed by analyzing the mRNA levels of alkaline phosphatase (ALP), runt-related transcription factor 2 (RUNX2), and type I collagen (COLL1) using real-time polymerase chain reaction (PCR) analysis 24 h after laser irradiation. Cell mineralization was evaluated using ALP activity, calcium deposition, and Alizarin Red staining. RESULTS: The laser-irradiated HCEM cells showed significantly enhanced gene expression levels of ALP, RUNX2, and COLL1 as well as ALP activity and calcium concentration in the culture medium compared with the non-irradiated cells. In addition, enhanced calcification deposits were confirmed in the laser-irradiated group compared with the non-irradiated group at 21 and 28 days after the induction of osteogenic differentiation. CONCLUSION: High-frequency semiconductor laser irradiation enhances the osteogenic differentiation potential of cultured HCEM cells, underscoring its potential utility for periodontal tissue regeneration.

Evaluation of learning curves for contact laser vaporization of the prostate using the 980 nm diode laser for benign prostatic hyperplasia.

OBJECTIVES: We investigated the background of patients who underwent contact laser vaporization of the prostate (CVP) surgery and the learning curve of the operators. METHODS: A total of 207 patients who underwent CVP surgery for benign prostatic hyperplasia between August 2018 and March 2023 were included in this study. Patient background, perioperative results, pre- and postoperative urinary flow tests, and complications were collected retrospectively. RESULTS: We enrolled 12 doctors who were divided into expert (five doctors) and novice (seven doctors) groups based on the number of TURP experiences before CVP. The median patient age was 73 years (51-92 years) and prostate volume was 56 cc (15-190 cc) with no difference between the expert and novice groups. Complications included urinary retention (eight cases), hematuria (four), urinary tract infection (four), intraoperative perforation (two), and postoperative stricture (one). Both cases of intraoperative perforation occurred in the novice group. The expert group had a significantly shorter operative time (38 vs. 66 min) and a higher operative efficacy of prostate volume divided by operative time (1.43 vs. 0.88 cc/min). Postoperatively, IPSS, quality of life scores, and postvoid residual urine volume decreased, and maximal flow rate increased; however, there was no significant difference between the groups. The expert group showed stable operative time and operative efficacy after about five to eight cases, while the novice group showed stable after about 15 cases. CONCLUSIONS: Our findings suggest that CVP was safely performed at our hospital, and operators with limited experience in TURP can achieve stable perioperative results.

Evaluation of the effect of adjunctive diode laser application on peri-implant crevicular fluid biomarker levels: a randomized controlled trial.

OBJECTIVES: To assess both the clinical and immunological effectiveness of diode laser therapy when used as an adjunct to non-surgical mechanical therapy in managing peri-implantitis. MATERIALS AND METHODS: A cohort of 27 participants, comprising 21 females and 6 males, agreed to take part in this investigation. 37 dental implants with peri-implantitis diagnosis were randomly allocated to either the laser group (n = 19) or the control group (n = 18). Evaluation of peri-implant clinical parameters and collection peri-implant crevicular fluid (PICF) samples occurred at baseline, as well as at 3 and 6-month follow-up intervals. The level of various biomarkers (TWEAK, IL-1ß, sclerostin, IL-17, RANKL, OPG and IL-10) within the PICF were quantified using enzyme-linked immunosorbent assay. RESULTS: Significant time-dependent decreases in clinical and biochemical parameters were detected in both groups compared to the baseline. There were marked differences between the groups in terms of periodontal parameters, except probing depth, and IL-1ß, IL-17, sclerostin levels in PICF at 3rd month follow-up. However, no statistically significant difference was detected at 6th month. CONCLUSIONS: Diode laser seems to be a reliable tool as an adjunct for supporting the nonsurgical mechanical treatment during the early stages of peri-implantitis. Furthermore, the findings suggest that IL-17, sclerostin and IL-1ß may serve as promising biomarkers for assessing efficacy of peri-implantitis treatment. CLINICAL RELEVANCE: Based on these outcomes, clinicians may consider the application of adjunctive use of diode laser to non-surgical peri-implantitis treatment to achieve better clinical and immunological improvements than nonsurgical peri-implantitis therapy alone in just early healing period. However, it should be noted that there was no difference between the two methods in the long term.

Efficacy of photobiomodulation therapy in recurrent herpes labialis management: a randomized controlled trial.

OBJECTIVES: This study is aimed at assessing the therapeutic efficacy of photobiomodulation therapy (PBMT) for the management of recurrent herpes labialis (RHL) by evaluating both pain and clinical recovery. MATERIAL AND METHODS: A randomized, double-blind, controlled trial was conducted on 40 patients with RHL, and they were randomly divided into two groups, where 20 patients received treatment with PBMT (650 nm, 100 mW, 4.7 J/cm2), continuous mode, for 120 s, and placebo cream, while another 20 patients (control group) were treated with acyclovir cream 5% (5 times/5 days) and passive laser. Pain was assessed at five different times. The day when the complete disappearance of the pain was observed and the day when the crust fell off spontaneously were also recorded. RESULTS: The pain level in the control group was significantly higher than that in the PBMT group after the second application of the laser, while the differences were not significant between the two groups at other times. The pain in the PBMT group disappeared faster than that in the control group, but the difference was not significant in terms of clinical recovery. CONCLUSIONS: Photobiomodulation therapy of herpes labialis reduced pain significantly faster than acyclovir, but there was no difference in healing time between the groups in light of the parameters used in this study. CLINICAL RELEVANCE: PBMT is a promising treatment that may be an effective alternative to acyclovir in the management of recurrent herpes labialis. TRIAL REGISTRATION ISRCTN: com ID: ISRCTN87606522.

MicroPulse™ transscleral cyclophotocoagulation in the equine patient: A case series of four horses.

OBJECTIVE: To describe the clinical application and outcome of MicroPulse™ transscleral cyclophotocoagulation (MP-TSCPC) treatment in horses with glaucoma. ANIMALS STUDIED: Four client-owned horses with primary (n = 2) or secondary (n = 2) glaucoma. METHODS: Horses were treated with MP-TSCPC under standing sedation with a minimum of 30 days of follow-up (range 30-1241 days). Affected eyes were treated with a 31.3% duty cycle and 3000 mW laser power for a total of 180 s. Data collected included signalment, pre- and post-procedure intraocular pressures (IOPs), laser settings, medications, complications, and repeat therapy. RESULTS: Four horses (5 eyes) received at least one treatment with MP-TSCPC. Mean preoperative IOP was 44 mmHg (range 33-49 mmHg). The immediate mean postoperative IOP was 34 mmHg (4 eyes; range 19-55 mmHg). At 1 week, IOP was 38 mmHg (5 eyes; range 21-80 mmHg), at 2 weeks was 40 mmHg (3 eyes, range 17-80 mmHg), at 1 month was 35 mmHg (5 eyes; range 20-50 mmHg), at 3 months was 18 mmHg (2 eyes; range 14-21 mmHg), at 6 months was 35 mmHg (2 eyes; range 30-39 mmHg), and at >300 days was 24 mmHg (3 eyes; range 18-29 mmHg). Complications included corneal ulceration (n = 1 eye), uncontrolled IOP (n = 3 eyes), and need for repeat treatment (n = 2 eyes). CONCLUSIONS: MP-TSCPC used with the above-described settings was unsuccessful in treating the majority of cases. Future studies should be targeted at primary glaucoma cases and with use of alternative laser settings.

Micropulse transscleral cyclophotocoagulation in canine glaucoma: A retrospective study evaluating sweep velocity.

OBJECTIVE: To report preliminary results of MP-TSCP in canine patients with glaucoma while evaluating sweep velocity, treatment efficacy, and safety utilizing standardized surgical parameters. ANIMAL STUDIED: Client-owned dogs that underwent MP-TSCP at a veterinary referral hospital. PROCEDURE: Medical records of 19 eyes (14 dogs) treated with MP-TSCP were reviewed. Eleven eyes were treated with a 10 s/sweep (s) velocity and 8 eyes with a 20 s/s. Laser duty cycle was set at 31.3%, mean laser energy was 2766 mW, and mean duration was 120 s per hemisphere. Minimum post-operative follow-up was 6 months. Outcomes of intraocular pressure (IOP), vision status, degree of antiglaucoma medications, and complications were evaluated. RESULTS: There was a significantly lower median (IQR) IOP (<25 mmHg) at each timepoint postoperatively compared to IOP pre-operatively (p < 0.05). The overall success rate for IOP control at 6 months was 84%, 100% for the 10 s/s and 62.5% for the 20 s/s. Vision was preserved in 10/11 (90%) eyes from the 10 s/s group and 4/8 (50%) eyes from the 20 s/s group at 6 months. Average number of glaucoma medications in the 10 s/s group decreased from 4.4 to 1.5 and from 3.3 to 2.5 in the 20 s/s group. Post-operative complications were mild and resolved within 1 week. CONCLUSIONS: MP-TSCP is a non-invasive treatment alternative for canine glaucoma. Employing higher energy levels rendered long-term IOP control while retaining a high safety profile with minimal postoperative complications. There was no statistical difference between a 10 s/s and 20 s/s surgical velocity, both leading to successful surgical outcomes up to 6 months post-operatively.

Longitudinal Mode Number Estimation of External Cavity Diode Laser Using Dual Periodic Grating for Optical Profiler System.

The concept of an optical profiler based on optical resonance was proposed, highlighting the initial requirements for mode number estimation. We proposed a method for estimating the longitudinal mode number of a laser propagating in an external cavity diode laser with high accuracy, utilizing dual-periodic diffraction gratings. These gratings were fabricated using interference lithography. To estimate the mode number, the wavelengths of two different modes are compared. Therefore, the greater the difference between the wavelengths, the higher the accuracy of the mode number determination. While the mode number difference was approximately 35 when using a conventional diffraction grating, this could be increased by a factor of 20 to around 700 using the dual-periodic grating. The relative accuracy achieved was 1.4 × 10-5.

Study on Linewidth and Phase Noise Characteristics of a Narrow Linewidth External Cavity Diode Laser.

In the field of inter-satellite laser communication, achieving high-quality communication and compensating for the Doppler frequency shift caused by relative motion necessitate lasers with narrow linewidths, low phase noise, and the ability to achieve mode-hop-free tuning within a specific range. To this end, this paper investigates a novel external cavity diode laser (ECDL) with a frequency-selective F-P etalon structure, leveraging the external cavity F-P etalon structure in conjunction with an auxiliary filter to achieve single longitudinal mode selection. The laser undergoes linewidth testing using a delayed self-heterodyne beating method, followed by the testing of its phase noise and frequency noise characteristics using a noise analyzer, yielding beat spectra and noise power spectral density profiles. Furthermore, the paper introduces an innovative bidirectional temperature-scanning laser method to achieve optimal laser-operating point selection and mode-hop-free tuning. The experimental results showcase that the single longitudinal mode spectral side-mode suppression ratio (SMSR) is around 70 dB, and the output power exceeds 10 mW. Enhancing the precision of the F-P etalon leads to a more pronounced suppression of low-frequency phase noise, reducing the Lorentzian linewidth from the initial 10 kHz level to a remarkable 5 kHz level. The bidirectional temperature-scanning laser method not only allows for the selection of the optimal operating point but also enables mode-hop-free tuning within 160 pm.

Evaluation of tooth color change after a bleaching process with different lasers.

The aim of this in vitro study was to evaluate the efficiency of diode laser-activated bleaching systems for color change of teeth. 75 extracted teeth were studied in five different bleaching protocols. Group 1: diode laser 445 nm, 320 µm fiber, 0.5W, continuous wave mode, dose 53 J/cm2. Group 2: diode laser 970 nm, 320 µm fiber, 1W, continuous wave mode, dose 106.10 J/cm2. Group 3: diode laser 940 nm, bleaching handpiece, 7W, continuous wave mode, dose 105 J/cm2. Group 4: diode laser 940 nm, 300 µm fiber, 2W, continuous wave mode, dose 47.16 J/cm2. Group 5: bleaching process without laser activation. In groups 1, 2 and 5, teeth were bleached with Perfect Bleach Office + and in groups 3 and 4, LaserWhite20 bleaching gel was used. Tooth color was determined immediately after the bleaching process using a spectrophotometer. Color change data on the CIE L * a * b* system was analyzed statistically by the one-way ANOVA and Tukey's HSD test. All bleaching procedures resulted in a change of color. All laser groups (∆E * ab > 3) have statistically larger ∆E * ab values than the control group (∆E * ab = 0.73) (p < 0.05). The diode laser 445 nm has the largest ∆E * ab value (∆E * ab = 4.65) and results in a significantly higher color difference than all other groups. In terms of color score difference in VITA Shades, all laser-activated groups lead to a lightening effect while the control group leads to only a slight lightening effect. The diode laser 445 nm produced the greatest color difference. Laser-activated bleaching is more effective than conventional bleaching without light activation. The diode laser 445 nm performs best in this in vitro study.

The Endo-lift Laser (Intralesional 1470 nm Diode Laser) for Dermatological Aesthetic Conditions: A Systematic Review.

BACKGROUND: The prominence of minimally invasive aesthetic approaches has become increasingly pivotal. The endo-lift laser method is an intralesional 1470 nm diode laser connected to a fiber that serves both therapeutic and aesthetic properties. We sought to evaluate the efficacy and safety of the endo-lift laser method for dermatological aesthetic applications. METHODS: PubMed, Ovid-Embase, and Web of Science were systematically searched up to November 5th, 2023. A citation search was also performed. The National Institute of Health (NIH) Quality Assessment Tool was used to evaluate the quality of the studies. RESULTS: Out of 339 articles, twenty-three relevant studies were included in the current review. Applying the endo-lift laser method for rejuvenation, including face and neck lifting, enhancing skin laxity, and disappearing wrinkles, folds, and lines, demonstrated favorable efficacy and safety profile. Moreover, most studies have shown that the endo-lift laser method is promising in eliminating the adipose tissue in the jowl, abdomen, thighs, and arms. The endo-lift laser technique was also efficacious in nose remodeling and blepharoplastic procedures, including treating eyelid and eyebrow ptosis, eye bag, eyebrow position, and eyelid laxity. Patients who suffer from several diseases, such as hidradenitis suppurativa, progressive lipodystrophy, acne vulgaris, scars, and keloids, benefit from procedural treatment with the endo-lift laser technique. Across all studies, the adverse events were mild and self-limiting. Investigating the endo-lift laser method in all aesthetic and therapeutic indications resulted in high patient satisfaction rates. CONCLUSION: The endo-lift laser technique has therapeutic effects and is recommended for various dermatological aesthetic indications. Further clinical studies with control groups and larger sample sizes are needed to acquire more reliable evidence. LEVELS OF EVIDENCE III AND IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Use of both the diode and Er: YAG lasers in esthetic crown lengthening with the aid of digitally guided dual technique: 3 years follow-up.

OBJECTIVE: To explore the feasibility of the usage of digital guides in combination with low- and high-power lasers for the treatment of excessive gingival display, also known as "gummy smile". CLINICAL CONSIDERATIONS: Excessive gingival display due to altered passive eruption can affect patient's perception of their own esthetics and consequently have an impact on self-confidence. Therefore, the management of this condition should offer a predictable and stable long-lasting solution. To attain these objectives, digital planning emerges as a tool in optimizing the outcomes of crown lengthening surgery for this condition by enhancing precision through the use of surgical guides. Additionally, the usage of high- and low-powered lasers can provide a safe approach because of their tissue selective removal properties. CONCLUSIONS: The technique described showed satisfactory clinical results in the short- and long-term follow-up, leading to an improvement in patients' self-esteem. This approach integrates digital and laser technologies to deliver a surgical treatment characterized by precision, efficiency, and safety. CLINICAL SIGNIFICANCE: Digital dentistry has contributed to innovative dental procedures, as personalizing surgical guides for patients, assisting and guiding incisions of the gingival margins, as well as the extension of the osteotomy, during the procedures for increasing the clinical crown. Furthermore, smile esthetics are directly related to an individual's improved emotional and social quality of life.

Assessment of photobiomodulation by a 660-nm diode laser on the reversal of soft tissue anesthesia in children: A randomized controlled clinical trial.

BACKGROUND: Soft tissue anesthesia (STA) following inferior alveolar nerve block (IANB) anesthesia lasts 3-5 h. It is important to reverse STA after treatment to prevent soft tissue injury (STI). AIM: This study evaluated photobiomodulation using a 660 nm diode laser on STA reversal and its impact on STI following IANB anesthesia. DESIGN: A randomized controlled clinical trial was conducted on 32 children, aged 5-8 years, allocated into the test and control groups. Anesthesia was administered; the operative procedure was performed followed by exposure to laser. STA reversal was monitored through lip tapping, current perception threshold (CPT) tests, and paediatric Functional Assessment Battery. RESULTS: The test group showed significantly faster recovery to normal sensation following exposure to laser than the control group which did not undergo any reversal (p < .0001), with a median time of 115 and 60 min according to lip tapping and CPT tests, respectively. The test group also showed significantly faster recovery to normal function (p = .016). The incidence of STI in the form of redness was significantly higher in the control group (p = .022). CONCLUSION: Photobiomodulation using a 660 nm diode laser can be considered as an efficient approach to minimize STA and STI after dental interventions.