Development of a cost-effective confocal Raman microscopy with high sensitivity.

Confocal Raman microscopy is a powerful technique for identifying materials and molecular species; however, the signal from Raman scattering is extremely weak. Typically, handheld Raman instruments are cost-effective but less sensitive, while high-end scientific-grade Raman instruments are highly sensitive but extremely expensive. This limits the widespread use of Raman technique in our daily life. To bridge this gap, we explored and developed a cost-effective yet highly sensitive confocal Raman microscopy system. The key components of the system include an excitation laser based on readily available laser diode, a lens-grating-lens type spectrometer with high throughput and image quality, and a sensitive detector based on a linear charge-coupled device (CCD) that can be cooled down to -30 °C. The developed compact Raman instrument can provide high-quality Raman spectra with good spectral resolution. The 3rd order 1450 cm-1 peak of Si (111) wafer shows a signal-to-noise ratio (SNR) better than 10:1, demonstrating high sensitivity comparable to high-end scientific-grade Raman instruments. We also tested a wide range of different samples (organic molecules, minerals and polymers) to demonstrate its universal application capability.

Efficacy of fluoride varnish containing casein phosphopeptide-amorphous calcium phosphate application and diode laser irradiation on white spot lesions remineralization: An in vitro study.

BACKGROUND/OBJECTIVES: The prevention of white spot lesions (WSLs) during orthodontic treatment with fixed appliances is of paramount importance to orthodontists. Numerous non-invasive techniques have been extensively researched to effectively manage WSLs. The objective of this study was to investigate the efficacy of MI varnish application, diode laser irradiation and their combination on remineralization of WSLs. MATERIALS AND METHODS: In this in vitro study, 40 enamel samples were divided randomly into 4 groups based on the applied treatment after demineralization. In Group I, MI varnish was applied to the enamel samples for a period of 7 days. In Group II, samples were irradiated with diode laser. In Group III, MI varnish was applied for 7 days, followed by diode laser irradiation. Whereas Group IV (control group) received no treatment and samples were stored in artificial saliva for 7 days. Microhardness assessments were performed at baseline, after demineralization and following the different treatment protocols. A representative sample from each group was randomly selected for scanning electron microscopy (SEM) analysis. One-way ANOVA, repeated measures ANOVA, and Tukey's Post Hoc tests were used for statistical analysis, with significance set at P≤0.05. RESULTS: All treatment groups demonstrated significantly higher mean microhardness values compared to the control group (P<0.05). Group 1 (MI varnish) had a final microhardness mean value of 193.50 (P<0.001), Group 2 (diode laser) recorded the highest final mean of 214.20 (P=0.018), and Group 3 (MI varnish+diode laser) had a mean of 203.93 (P=0.011). SEM observations supported these findings by showing enhanced surface morphology in the treatment groups. CONCLUSIONS: MI varnish application, laser irradiation, and their combination demonstrated enhanced microhardness of artificially demineralized enamel, highlighting their effectiveness in remineralization of WSLs.

The Comparison of 940nm and 810nm Diode Laser Effects on the Repair of Inferior Alveolar Sensory Nerve Injury: A Clinical Trial.

Statement of the Problem: Healing of the inferior alveolar nerve injury during dental procedures is one of the biggest concerns of dentists. There are still debates on different treatment modalities. Purpose: This study aimed to compare the effect of 940nm and 810nm diode lasers on the repair of the inferior alveolar sensory nerve. Materials and Method: In this single-blinded randomized clinical trial, 39 patients with inferior alveolar nerve injury were divided into three groups: 1. 810nm laser irradiated, 2. 940nm laser irradiated, and 3. No laser irradiation (control group). All patients were treated in 12 sessions (3 days per week) and evaluated using a complete clinical neurosensory test (CNT), including brushstroke, 2-point discrimination, pinprick nociception, and thermal discrimination before and after treatment. Results: The mean dysesthesia of the patient treated with 810nm diode laser was significantly lower than the control group in all sessions (the 1st (p= 0.003), 3rd (p= 0.008), 7th (p= 0.006), and 12th sessions (p= 0.005)). The 810nm laser resulted in more satisfaction in patients than the control group in almost all sessions (1st (p< 0.001), 7th (p= 0.028), and 12th (p= 0.006)). More patient satisfaction was seen in the 1st and 3rd sessions in the 810nm laser than in the 980nm laser (p< 0.001 and p= 0.003, respectively). Conclusion: 810nm diode laser can be better than 940nm in repairing inferior alveolar sensory nerve damage.

Influence of diode laser irradiation on microtensile bond strength of etch-and-rinse adhesive to dentin using two different etchants: An in vitro study.

Aim: The aim of this study was to evaluate the influence of 970 nm diode laser (DL) irradiation on the microtensile bond strength (µTBS) of etch-and-rinse adhesive (ERA) to dentin using phosphoric acid (PA) or alpha-hydroxy glycolic acid (GA) as etchants. Materials and Methods: A total of 32 human third molars were selected and assigned randomly among two different groups and four subgroups based on etching protocols and DL irradiation: PA, PA-DL, GA, and GA-DL. After tooth preparation and subsequent incremental composite build-up, the samples were stored in distilled water for 24 h at 37°C. µTBS values were obtained using the universal testing machine. The failure modes observed in dentin were categorized as adhesive, cohesive within dentin/resin, or mixed. Statistical Analysis: The data were analyzed using one-way analysis of variance, followed by Tukey's post hoc test (P ≤ 0.001). Results: GA showed better or similar bond strength values to PA. Furthermore, irradiation of DL increased the µTBS to dentin when both PA or GA are used as etchants. Conclusion: GA can be used as an alternative etchant to PA. DL irradiation stands as a promising approach for elevating the performance of ERA adhesive systems to dentin.

Effect of postoperative 660-nm low-level laser therapy on the radiographic crestal bone loss of fresh-socket dental implants.

Background: Although the benefits of low-level laser therapy (LLLT) in soft tissue healing have been demonstrated, the effects of laser on bone have remained controversial. This study investigated the impact of postoperative 660-nm LLLT on the radiographic crestal bone loss of fresh-socket dental implants. Methods: Thirty patients referred to the Department of Oral and Maxillofacial Surgery for tooth extraction and placement of fresh-socket implants were selected and assigned to two groups: laser (intervention) and no-laser (control) groups. Immediately after tooth extraction, the implant was inserted into the tooth socket. 660-nm LLLT was immediately started after surgery and was repeated three times per week for two weeks. Bone quantification at the implant site was assessed using periapical intraoral radiographs and computerized software immediately after surgery and after six months. Results: This study showed a statistically significant difference in mean bone resorption between the mesial and distal aspects of the two groups, with lower bone resorption in the laser group compared to the no-laser group. Conclusion: The results of this study suggest that LLLT can effectively reduce bone resorption in fresh-socket implant placement. This might indicate the positive effect of LLLT on bone resorption reduction.

Comparative Study of Photobiomodulation Effects on Alveolar Socket Hard Tissue Healing in Rats: Application of 980 nm Versus 810 nm Lasers.

Background: This study aimed to explore the differential effects of photobiomodulation (PBM) via 980 nm and 810 nm lasers on the hard tissue healing of rat alveolar sockets, with a focus on a comparative analysis of hard tissue regeneration and osteogenic gene expression. Objective: This study aimed to explore the effects of PBM using 980 nm and 810 nm lasers on hard tissue healing of rat alveolar sockets, focusing on hard tissue regeneration and osteogenic gene expression. Materials and Methods: Thirty-six male Wistar rats (5 weeks old) had both right and left maxillary first molars extracted. Post extraction, the right alveolar sockets received PBM treatment with either 980 nm (0.3 W, 18 J/cm2) or 810 nm (0.1 W, 6 J/cm2) lasers for seven days, whereas the left sockets served as controls. Rats were euthanized on days 3, 7, 14, and 28 for histopathological, immunohistochemical, micro computed tomography (micro-CT), and quantitative polymerase chain reactionanalyses. Results: On day 3, early granulation tissue, neovascularization, and inflammatory cell aggregates were observed in all groups. By day 7, active osteoclasts and osteoblasts were noted, with a significant increase in CD31-positive cells in the 980 nm group (p < 0.05). Day 14 showed new bone formation, and by day 28, increased cancellous bone and collagen content were present in all groups, with no significant differences between them (p > 0.05). Gene expression analysis revealed higher BMP-2 and Runx-2 levels in laser-treated groups on day 14 (p < 0.05), with the 980 nm group having higher BMP-2 levels than the 810 nm group (p < 0.05). Bone sialoprotein expression was higher in laser-treated groups on days 14 and 28 (p < 0.05), and osteocalcin expression was highest in the 980 nm group on both days (p < 0.05). Micro-CT analysis showed no significant differences among groups in bone mineral density, bone surface (BS)/bone volume (BV), or bone volume (BV)/TV (total volume) indices. Conclusion: PBM with 980 nm and 810 nm lasers promotes early-stage hard tissue healing in extraction sockets, with the 980 nm laser more effectively enhancing osteogenic gene expression, suggesting its potential as an adjunctive therapy in dental and oral surgery.

Neuroendoscopic Surgery for Intraventricular Cavernous Malformations: a Review on Indications and Surgical Considerations.

BACKGROUND: Intraventricular cavernous malformations (IVCs) are rare vascular lesions of the central nervous system. Surgical resection remains a challenging endeavor, with conventional microsurgical techniques associated with morbidity due to direct brain tissue manipulation. Neuroendoscopic approaches offer a minimally invasive alternative, though their efficacy and safety in treating IVCs remain underexplored. METHODS: A narrative review was conducted to analyze all documented cases of IVCs treated exclusively with endoscopic transventricular approaches (ETVA). Reviews, original research papers, and case reports published from 1990 to May 2024 were included. When available, surgical videos were also reviewed. RESULTS: Seventeen patients with IVCs primarily located in the foramen of Monro were identified. The mean size of the IVCs was 17 mm (range 7-29 mm). Neuroendoscopic procedures achieved gross total resection in all cases, leading to the resolution of clinical symptoms. Except for one patient who experienced memory impairment post-surgery, no persistent neurological dysfunctions were observed. Intraoperative bleeding, a significant challenge in IVC resection, was managed with continuous warm irrigation and dedicated coagulation instruments. Additionally, 6 cases of neuroendoscopic procedures such as endoscopic third ventriculostomy (ETV) and septum pellucidotomy were reported for managing hydrocephalus (HCP). CONCLUSION: Neuroendoscopic surgery offers several advantages in treating IVCs, including minimally invasive access, precise visualization, and reduced brain tissue manipulation. Our findings support the efficacy and safety of ETVA, underscoring its potential as a valuable therapeutic strategy for selected IVCs.

Photothermal Effect of 970 nm Diode Laser Irradiation on Enterococcus faecalis Biofilms in Single-Rooted Teeth Ex Vivo.

Objective: The aim of this study was to evaluate the photothermal effect of a 970 nm diode laser on Enterococcus faecalis biofilms. Methods: 72 extracted human single-rooted teeth were prepared, sterilized, and inoculated with Enterococcus faecalis to establish a two-week-old biofilm. The specimens were divided into six groups (n = 12): Group 1 (G1)-negative control (PBS-no laser), Group 2 (G2)-positive control (1% NaOCl rinse-no laser), Group 3 (G3)-a 970 nm laser in 1.5 W pulse mode, Group 4 (G4)-a 970 nm laser in 2 W pulse mode, Group 5 (G5)-a 970 nm laser in 1.5 W continuous mode, Group 6 (G6)-a 970 nm laser in 2 W continuous mode. Bacterial viability was evaluated using the LIVE/DEAD BacLight kit and analyzed by flow cytometry (FCM). Temperature changes on the root surface during irradiation were analyzed using a K-type thermocouple. Data were statistically analyzed using one-way ANOVA and Tukey's multiple comparison test (α = 0.05). Results: Bacterial viability was significantly reduced after laser irradiation in continuous mode using 1.5 W (21% of live bacteria) and 2 W (14% of live bacteria). When the pulsed mode was applied, the reduction in bacterial viability was less, with a mean survival of 53% (1.5 PF, whereas 29% of bacteria survived after 2 W irradiation). Conclusions: The 970 nm diode laser at 2 W continuous mode effectively reduced the viability of E. faecalis biofilms in root canals without causing unacceptable temperature rises at the root surface.

Comparison of the efficacy of micropulse diode laser transscleral cyclophotocoagulation using different energy protocols.

PURPOSE: This study aimed to explore the safety and efficacy of laser treatment settings of micropulse transscleral cyclophotocoagulation treatment in glaucoma patients and to evaluate the relationship between intraocular pressure (IOP) reduction and different treatment parameters. MATERIALS AND METHODS: A total of 74 eyes in 64 glaucoma patients with IOP over 21 mmHg or under 20 mmHg with visual field progression who underwent micropulse transscleral cyclophotocoagulation treatment were included. Patients were divided into success and failure groups based on criteria of 20% IOP reduction rate. The predictive factors of IOP reduction between success and failure groups and the IOP reduction rates in the different treatment duration groups were evaluated. Predictive factors for IOP reduction were analyzed using univariate and multivariate regression models. RESULTS: Patients in the success group had significantly higher baseline IOP (median: 28.0 vs. 23.0 mmHg; P = 0.016) and longer treatment times (median: 240 vs. 160 s; P = 0.001). Treatment duration range between 200 and 240 s achieved significantly higher intraocular pressure reduction rates (47.8 ± 17.4%) than durations under 140 s (23.1 ± 14.2%). Univariate analysis showed that baseline IOP and treatment duration were significant contributing factors in IOP reduction. Multivariable analysis further demonstrated that treatment duration over 200 s was the significant predictive factor for IOP reduction. CONCLUSION: Treatment duration settings were the most significant factor of IOP reduction rates in micropulse cyclophotocoagulation. Customized therapy according to the target IOP reduction rate can be applied with different treatment duration settings to achieve optimal outcomes.

IMPMH, direct tunable diode laser absorption spectroscopy for detection of water vapour under "Optically thick Condition".

Water vapour plays a crucial role in atmospheric processes. Hence, monitoring the altitude-related variations in water vapour properties is important to decipher atmospheric processes. Direct tunable diode laser absorption spectroscopy (dTDLAS) measures the concentration and temperature of gas molecules by scanning the rotation-vibration absorption lines using a high-spectral-resolution laser. In this study, we devised an integrated measurement and data processing method (integrative measurement and processing method for hygrometry, IMPMH) to enhance the in-situ airborne measurement capability of dTDLAS. We measured a wide range (240-18,000 ppm) of water vapour concentrations, aiming for atmospheric measurements in a highly water-saturated regime, called the "optically thick condition". For recovering the full absorption spectra, the "integrative area" was defined and a difference factor D, which is the distance between two spectral regions with width corresponding to the half width of half maximum of the Voigt profile, was used to calculate the area. From the data, the low-bound concentration was measured to be 244 ppm. At D = 1.8, the transition concentration to the "optically thick condition" was measured to be 5,800 ppm. By increasing D from 1.8 to 2.8, the measurable upper-bound concentration increased to 17,993 ppm. IMPMH was applied to the measured data to estimate the final absorber density or water vapour concentration. The estimation was well-fitted with the measured detector signal with signal-to-noise ratio (SNR) of âˆ¼ 300 of the residual spectrum, promising its applicability to in-situ airborne measurements. To validate IMPMH, the water vapour concentration range was divided into two regimes: (1) optically thick (5,800 < c < 18,000 ppm) and (2) optically thin (c < 5,800 ppm) conditions. Under the optically thick condition, IMPMH was validated by comparing the results between the short and long-path cells. In the optically thin condition, IMPMH was validated through comparison with the general dTDLAS method. Lastly, long-term stability of the dTDLAS system was validated by measuring 10 different concentrations (240-18,000 ppm) for 1000 s by characterising the precision and SNRs of the residual. The results demonstrate that IMPMH significantly enhances the in-situ airborne measurement capability of dTDLAS under both optically thick and thin conditions. Furthermore, requirements for the implementation of IMPMH in airborne measurement were investigated considering four aspects-sampling, low-pressure measurement, accuracy and precision, and multiplex detection. The results were examined with regard to atmospheric implications.

Investigation of Changes in the Reflection Spectrum of Human Blood When Exposed to Laser Radiation With Wavelengths of 450 or 980 nm.

OBJECTIVES: This study aimed to determine and explain changes in the reflectance spectrum of human blood in vitro when exposed to laser radiation at wavelengths of 450 or 980 nm. METHODS: Reflectance spectra of venous blood samples were measured before and after exposure to a single pulse of 450 or 980 nm laser radiation. A numerical optical model based on the Monte Carlo method was applied. RESULTS: Laser irradiation at 450 and 980 nm caused the most significant changes in the reflectance spectrum around 600 nm, associated with alterations in blood oxygen saturation. The maximum efficiency of reducing oxygen saturation was 0.20%/W for 980 nm and 0.72%/W for 450 nm, likely due to differences in blood absorption at these wavelengths. CONCLUSIONS: The greatest change in intensity reflectance spectra and oxygen saturation of human venous blood occurs when exposed to laser radiation at 450 nm, not at 980 nm.

Optimizing the Synergistic Role of Diode Laser and Drug Therapies in the Management of Oral Submucous Fibrosis: A Case Report.

Oral submucous fibrosis (OSMF) is one of the most common precancerous conditions of the oral mucosa involving any part of the oral cavity resulting in tissue scarring, dysphagia, and trismus. Habits of chewing areca nut, tobacco, and pan masala and smoking have revealed a strong association with the occurrence of OSMF. Due to its high morbidity and high malignant transformation rate (MTR), continuous efforts have been made to develop effective treatment options. Based on the stage of the disease, various treatment modalities such as medical and surgical therapies are available, each with its own set of advantages and disadvantages. Photobiomodulation (PBM) is an emerging minimally invasive therapy that can be utilized to treat OSMF through its anti-inflammatory and analgesic effects. With the advent of dual-wavelength diode lasers, the current case report focuses on a novel treatment strategy for managing OSMF in combination with pharmacological and oral physiotherapy to achieve optimal results.

Enhanced Therapeutic Efficacy of Gold Nanoparticle-Enhanced Laser Therapy for Oral Cancer: A Promising Photothermal Approach.

Introduction: Laser therapy employs a concentrated and slender light beam to eliminate or eradicate cancerous cells and pre-cancerous abnormalities. The specific wavelength of 808 nm light is preferentially absorbed by tumor cells compared to healthy cells. This study aimed to assess the combined therapeutic impact of laser and gold, given that gold exhibits photothermal properties when exposed to laser radiation. Methods: In this in vitro study, two cell lines, namely healthy HuGu cells (human gingival fibroblast cells) and head and neck cancer cells (HN-5), were obtained from the Pasteur Institute. The effect of the laser diode with a density of 3 J/cm2 and wavelength of 808 nm on the proliferation and the survival rate of oral squamous cell carcinoma (HN-5) and human gingival fibroblast (HUGU) was assessed in 60seconds. MTT assay, DAPI test, and trypan blue staining were used to determine the growth and proliferation of HN-5 and HUGU cell lines. Results: Findings showed that the laser diode along with gold decreased the rate of proliferation and survival cells in HN-5 compared to healthy cells. The changes in the cell population treated with gold and laser diode 808 were insignificant. Conclusion: Findings reveal that using a low-power laser can effectively inhibit the growth of oral cancer cells. It seems that photothermal therapy is a novel approach to oral cancer therapy.

Salivary Macrophage Inflammatory Protein-1α Levels in Periodontitis Subjects Receiving Non-surgical Periodontal Therapy With and Without Photo-Biomodulation: A Prospective Interventional Controlled Trial.

Introduction Periodontitis is a complex interplay of bacterial infection and host response. Non-surgical periodontal therapy (NSPT) is effective but limited in thoroughly debriding challenging areas, often leading to recurrent bacterial colonization. Photobiomodulation (PBM), involving precise doses of laser photonic energy, has shown potential in modulating inflammation and promoting healing. This study investigates the impact of NSPT alone and NSPT combined with PBM on clinical parameters and salivary macrophage inflammatory protein-1α (MIP-1α) levels in periodontitis patients. Methods Ethical approval was obtained, and informed consent was secured from all participants. Sixty periodontitis patients aged 30-60 were selected and divided into two groups: Group 1 (NSPT alone) and Group 2 (NSPT with PBM). Clinical parameters including the plaque index (PI), gingival index (GI), probing pocket depth (PPD), and clinical attachment level (CAL) were assessed at baseline and 21 days post-treatment. Salivary MIP-1α levels were measured using an enzyme-linked immunosorbent assay (ELISA). Results Both groups showed significant improvements in the PI, GI, PPD, and CAL from baseline to 21 days post-treatment. Group 2 exhibited greater reductions in the GI, PPD, and CAL compared to Group 1. Salivary MIP-1α levels post-intervention showed reduction in both groups but were not statistically significant between the groups. Conclusion NSPT combined with PBM demonstrates greater clinical improvements than NSPT alone, highlighting PBM as an effective adjunctive therapy. Both groups showed a reduction in MIP-1α levels post-intervention, suggesting the potential of MIP-1α as a biomarker for periodontal disease activity.

Real-World Experience Using a Multi-Modality System using Intense Pulsed Light, Radiofrequency Microneedling, High-Intensity Focused Ultrasound, or Thermal Radiofrequency, 808, HIFU for Skin Rejuvenation Treatment.

BACKGROUND: Medical aesthetic procedures for facial rejuvenation with laser and energy-based devices (EBDs) are rapidly increasing. The following cases highlight real-life experience using a multi-modality system with various handpieces that combine intense pulsed light (IPL), laser hair removal (808 diode), high-intensity focused ultrasound (HIFU), radiofrequency microneedling (RFM), and thermal radiofrequency (RF) for antiaging and rejuvenation treatment. Laser and RFM treatments may improve skin conditions by inducing cutaneous changes that remodel the skin matrix. METHODS: Six physicians who treat patients for skin rejuvenation reported on clinical cases from their practice using a multi-modality system with various handpieces. RESULTS: During the meeting, the advisors discussed 15 cases and agreed to select seven patients with different ages and skin phototypes receiving various treatments for photodamage of the face, neck, and décolleté. The advisors discussed why they selected the case, previous treatment, type of treatment, results, and clinical pearls. CONCLUSION: Sharing best practices in medical aesthetics using combination treatments on a single multi-modality energy-based device such as laser and MRF for facial, neck, and chest skin may support healthcare providers treating patients for skin rejuvenation to improve clinical outcomes.

Cyclodestruction and cyclophotocoagulation: Where are we?

Cyclodestruction is a technique reserved for glaucomas not controlled with medical and surgical treatment and poor visual potential. During the last century, new cyclodestructive techniques were developed, including cyclophotocoagulation, and the use of continuous-wave diode laser transescleral cyclophotocoagulation (CW-TS-CPC) has become widespread. In recent decades, micropulse diode laser transescleral cyclophotocoagulation (MP-TS-CPC) was introduced. We review the cyclodestruction techniques since their origins and these two techniques of cyclophotocoagulation, which are currently the most widely used: how they are performed, their mechanisms of action and their effectiveness and efficacy. We also review the comparison between them and with other techniques.

Efficacy of 1060 nm Diode Laser for Non-Invasive Subcutaneous Fat Reduction in Mini-Pigs.

Purpose: To evaluate the efficacy and safety of abdominal fat reduction in mini-pigs, utilizing at 1060 nm diode laser with a wavelength of 1060 nm. Patients and Methods: The laser system non-invasively disrupts adipose tissue; its effectiveness and safety were evaluated by ultrasound imaging and histological analysis. Laser irradiation was performed with various powers, and the cooling function was activated to prevent skin surface damage. Results: The dermal tissue temperature increased to at least 43°C during laser exposure, leading to a decrease in abdominal fat thickness after 30 days. Blood tests revealed no significant changes in kidney and liver function but showed increased blood levels of nonessential free acids (NEFAs), likely due to the release of fatty tissue-derived free fatty acids. Histological evaluation demonstrated rapid transformation of adipose tissue into collagen, muscle fibers, and intracellular fibrous tissue. Conclusion: The 1060 nm laser showed promise as a non-invasive and safe tool for reducing abdominal fat.

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.

Bacterial reduction and temperature increase of titanium dental implant models treated with a 445 nm diode laser: an in vitro study.

In this in vitro study, the use of a 445 nm diode laser was investigated for the decontamination of titanium dental implants. Different irradiation protocols and the effect of repetitive laser irradiation on temperature increase and decontamination efficacy were evaluated on titanium implant models. An automated setup was developed to realize a scanning procedure for a full surface irradiation to recapitulate a clinical treatment. Three irradiation parameter sets A (continuous wave, power 0.8 W, duty cycle (DC) 100%, and 5 s), B (pulsed mode, DC 50%, power 1.0 W, and 10 s), and C (pulsed mode, DC 10%, power 3.0 W, and 20 s) were used to treat the rods for up to ten consecutive scans. The resulting temperature increase was measured by a thermal imaging camera and the decontamination efficacy of the procedures was evaluated against Escherichia coli and Staphylococcus aureus, and correlated with the applied laser fluence. An implant's temperature increase of 10 °C was set as the limit accepted in literature to avoid thermal damage to the surrounding tissue in vivo. Repeated irradiation of the specimens resulted in a steady increase in temperature. Parameter sets A and B caused a temperature increase of 11.27 ± 0.81 °C and 9.90 ± 0.37 °C after five consecutive laser scans, respectively, while parameter set C resulted in a temperature increase of only 8.20 ± 0.53 °C after ten surface scans. The microbiological study showed that all irradiation parameter sets achieved a complete bacterial reduction (99.9999% or 6-log10) after ten consecutive scans, however only parameter set C did not exceed the temperature threshold. A 445 nm diode laser can be used to decontaminate dental titanium rods, and repeated laser irradiation of the contaminated areas increases the antimicrobial effect of the treatment; however, the correct choice of parameters is needed to provide adequate laser fluence while preventing an implant's temperature increase that could cause damage to the surrounding tissue.

Comparison of the Enterococcus faecalis Colony Reduction Effect of Two Wavelengths of Diode Lasers With Three Methods of Root Canal Irrigation: An In Vitro Study.

Introduction: The basis of successful root canal therapy is the reduction of microorganisms. The aim of this in vitro study was to compare the antibacterial effect of three different irrigation methods with two laser wavelengths on Enterococcus faecalis biofilm. Methods: Ninety-five single-canal teeth were prepared, sterilized, and divided randomly into a negative control, a positive control, and five test groups. They were inoculated with the standard strain of E. faecalis. The test groups were conventional irrigation (group 1), Passive ultrasonic irrigation (group 2), Gentle file finisher brush (group 3), 810 nm diode laser (group 4), and 980 nm diode laser (group 5). Microbial sampling, cultivation, and colony counting were done. Data were analyzed with the Kruskal-Wallis test and a negative binomial regression model. Results: There was a significant difference in the colony count between the groups (P<0.001). the 810 nm diode had the highest and the conventional irrigation group had the lowest reduction in the microbial load. Passive ultrasonic, 980 nm diode laser, and Gentle file finisher brush groups were also ranked respectively from the highest to the lowest in terms of decreasing effect on the number of colonies. Conclusion: The 810 nm diode laser and conventional irrigation were respectively the most and the least effective methods for reducing the number of E. faecalis colonies.