Laser Tip Research Articles

Morphological Characterization of Tissue Destruction According to the Distance Between Holmium:YAG Laser Tip and Tissue Surface.

Little is known about the soft tissue destruction by holmium laser clinically used for holmium laser enucleation of the prostate (HoLEP), subject to the distance between the laser fiber tip and the tissue surface. We aimed to investigate the impact of the distance between the laser fiber tip and the phantom surface (DLP) on a soft tissue phantom (STP) in relation to the surgical modes of HoLEP. STP responses to the laser pulses produced by a commercial holmium:yttrium aluminum garnet (Holmium:YAG) laser at an output setting 2 J were observed at different values of the DLP (0, 1, 2, 3, and 4 mm) to look at (1) the single laser pulse-induced cavitation bubble and its penetration into the STP, (2) the STP destruction by a single pulse, (3) the STP destruction by 60 pulses repeated at 12 Hz, and (4) the thermal effect by the multiple pulses visualized on a thermosensitive bovine serum albumin (BSA) STP. We observed that the laser pulse produced a heated gas bubble in water centered at the laser fiber tip. The bubble shape depended on the DLP. The bubble completely penetrated into the STP at the DLP of 0 mm and the penetration decreased with the DLP. The size of the destruction of the STP by the laser pulses was shown to decrease as the DLP increased. Test with the BSA STP showed that, at the DLP of 3 mm, the destruction became insignificant while the thermal effects were still effective. We illustrated that soft tissue destruction by the Holmium:YAG laser is associated with cavitation effects. We provide for the first time experimental evidence for various surgical modes in HoLEP such as incision and hemostasis in relation to the DLP.

A Comparative Study on the Safety and Efficacy of Erbium Laser Therapy Versus Traditional Treatments in Managing Dentin Hypersensitivity: An Observational Study.

Background This study aimed to explore the potential efficacy and safety of laser therapy compared with traditional desensitizing treatments in the management of dentin hypersensitivity. Methodology A comprehensive observational study was conducted on 138 adult individuals aged 18-65 diagnosed with dentin hypersensitivity. Participants were allocated to either the laser therapy or traditional treatment group. The laser therapy group received treatment using the Fotona LightWalker® Erbium laser at 2,940 nm. The energy density was set at 20 J/cm² using continuous and contact modes, with the laser tip held perpendicularly to the irradiated site. Each session lasted five minutes, conducted bi-weekly for three months. Traditional treatment included the in-office application of 5% sodium fluoride varnish application once every 15 days for three months and the use of desensitizing toothpaste as part of regular oral hygiene routines. Follow-up assessments were conducted 6 and 12 months post-treatment to evaluate the longevity and stability of the treatment effects. Primary outcomes were assessed by dentin hypersensitivity reduction measured using Visual Analog Scale (VAS) scores and tactile hypersensitivity assessments. Results Laser therapy consistently surpassed traditional treatment in reducing dentin hypersensitivity, as reflected by the significantly lower VAS scores. Notably, at 3, 6, and 12 months, laser therapy demonstrated mean VAS scores of 2.5 (±1.5), 1.2 (±0.9), and 0.6 (±0.5), respectively, while the traditional treatment group exhibited higher scores (3.8 ± 1.2, 4.5 ± 1.0, and 4.0 ± 0.7, respectively). Statistical analysis revealed that these differences were highly significant (p < 0.001). Tactile hypersensitivity assessments echoed these findings, with laser therapy consistently maintaining lower scores (0.8 ± 0.7 at 6 months, 0.4 ± 0.3 at 12 months) compared to traditional treatment (3.5 ± 1.0 at 6 months, 4.0 ± 0.7 at 12 months) with statistical significance at all time points (p < 0.001). Conclusions Although this study lacks a randomized controlled design, the observed substantial reduction in VAS scores and tactile hypersensitivity assessments, along with the favorable safety profile of laser therapy, suggest its potential as an effective alternative for managing dentin hypersensitivity.

Effect of ultrasonic and Er,Cr:YSGG laser-activated irrigation protocol on dual-species root canal biofilm removal: An in vitro study.

The aim of the study was to investigate the disinfecting efficacy of a standardized irrigating solution activated by ultrasonics or laser irradiation on mature dual-species biofilms at different root levels in vitro. Conventional access cavity preparations were done on 160 single-rooted mandibular premolar teeth with single canals. Freshly extracted oral microbial strains of Staphylococcus aureus, Streptococcus mutans, Enterococcus faecalis, and Candida albicans after biochemical confirmation were used to generate two discrete dual-species microbial inoculums. The sterilized tooth samples were randomly segregated into two groups (n = 80) and inoculated with a mixed inoculum of S. aureus + E. faecalis strains (Group 1) and S. mutans + C. albicans strains (Group 2), respectively. Following the 21-day incubation period under aerobic conditions, the infected specimens in each group were divided into four subgroups (n = 20) and subjected to experimental treatment protocols. This included a positive control (no treatment of biofilms), syringe irrigation alone with TruNatomy needle, passive ultrasonically activated irrigation with 20# Irrisafe tip, and laser agitation of irrigant with Er,Cr:YSGG laser using RFT 2 laser tip. Root canals of experimental specimens (except the control samples) are instrumented with TruNatomy rotary file system using 1:1 mixture of 3% NaOCl and 18% etidronic acid as irrigants. The quantitative assessment of reduction in viable biofilm microbes after treatment was done using colony-forming unit counts and confocal laser scanning microscopy image analysis. The obtained data were analyzed statistically with a significant level set at 0.05. Laser-assisted irrigation has shown a considerably higher mean percentage reduction of microbes compared to ultrasonic agitation and the syringe irrigation showed the least microbial reduction (P = 0.001). No significant difference was noted between the three root regions of ultrasonic and laser groups (P > 0.05), whereas in the syringe groups, apical portions showed higher microbial counts compared to cervical and mid-root regions (P = 0.001). Erbium laser-assisted irrigation has performed superior to ultrasonic agitation against both the experimental dual-species biofilms, while the syringe irrigation showed the least microbial reduction specifically at apical root portions.

Root surface roughness evaluation following application of different periodontal instruments and Er:YAG laser: A profilometry and SEM study.

The aim of the present study was to evaluate the efficacy of 30°-angled Er:YAG laser tip and different periodontal instruments on root surface roughness and morphology in vitro. Eighteen bovine teeth root without carious lesion were decoronated from the cementoenamel junction and seperated longitidunally. A total of 36 obtained blocks were mounted in resin blocks and polished with silicon carbide papers under water irrigation. These blocks were randomly assigned into 3 treatment groups. In Group 1,30°-angled Er:YAG laser (2.94μm) tip was applied onto the blocks with a 20Hz, 120mJ energy output under water irrigation for 20s. In Groups 2 and 3, the same treatment was applied to the blocks with new generation ultrasonic tip and conventional curette apico-coronally for 20s with a sweeping motion. Surface roughness and morphology were evaluated before and after instrumentation with a profilometer and SEM, respectively. After instrumentation, profilometric analysis revealed significantly higher roughness values compared to baseline in all treatment groups(p < 0.05). Laser group revealed the roughest surface morphology followed by conventional curette and new generation ultrasonic tip treatment groups (p < 0.05). In SEM analysis, irregular surfaces and crater defects were seen more frequently in the laser group. Results of the study showed that the use of new generation ultrasonic tip was associated with smoother surface morphology compared to 30°-angled Er-YAG laser tip and conventional curette. Further in vitro and in vivo studies with an increased sample size are necessary to support the present study findings.

WATTS happening? Evaluation of thermal dose during holmium laser lithotripsy in a high-fidelity anatomic model.

To evaluate the thermal profiles of the holmium laser at different laser parameters at different locations in an in vitro anatomic pelvicalyceal collecting system (PCS) model. Laser lithotripsy is the cornerstone of treatment for urolithiasis. With the prevalence of high-powered lasers, stone ablation efficiency has become more pronounced. Patient safety remains paramount during surgery. It is well recognized that the heat generated from laser lithotripsy has the potential to cause thermal tissue damage. Utilizing high-fidelity, 3D printed hydrogel models of a PCS with a synthetic BegoStone implanted in the renal pelvis, laser lithotripsy was performed with the Moses 2.0 holmium laser. At a standard power (40W) and irrigation pressure (100cm H2O), we evaluated operator duty cycle (ODC) variations with different time-on intervals at four different laser settings. Temperature was measured at two separate locations-at the stone and away from the stone. Temperatures were highest closest to the laser tip with a decrease away from the laser. Fluid temperatures increased with longer laser-on times and higher ODCs. Thermal doses were greater with increased ODCs and the threshold for thermal injury was reached for ODCs of 75% and 100%. Temperature generation and thermal dose delivered are greatest closer to the tip of the laser fiber and are not dependent on power alone. Significant temperature differences were noted between four laser settings at a standardized power (40W). Temperatures can be influenced by a variety of factors, such as laser-on time, operator duty cycle, and location in the PCS.

Principle and antimicrobial efficacy of laser-activated irrigation: A narrative review.

In the last two decades, the activation of root canal irrigants with pulsed lasers as an adjunct in root canal treatment has become increasingly popular. This narrative review explains the physical basics and the working mechanism of laser-activated irrigation (LAI), explores the parameters influencing LAI efficacy, considers historical evolutions in the field and summarizes laboratory and clinical evidence with emphasis on the antimicrobial action of LAI. Cavitation is the driving force behind LAI, with growing and imploding vapour bubbles around the laser tip causing various secondary phenomena in the irrigant, leading to intense liquid dynamics throughout the underlying root canal. High-speed imaging research has shown that laser wavelength, pulse energy, pulse length and fibre tip geometry are parameters that influence this cavitation process. Nevertheless, this has not resulted in standardized settings for LAI. Consequently, there is significant variability in studies assessing LAI efficacy, complicating the synthesis of results. Laboratory studies in extracted teeth suggest that, with regard to canal disinfection, LAI is superior to conventional irrigation and there is a trend of higher antimicrobial efficacy of LAI compared to ultrasonic activation. Clinical evidence is limited to trials demonstrating similar postoperative pain levels after LAI versus no activation or ultrasonic activation. Clinical evidence concerning the effect of LAI on healing of apical periodontitis as yet is scarce.

Effects of self-etch adhesive agitation with diode laser on dentin bond strength.

The present study assessed the effect of active application of self-etch adhesives with diode laser irradiation on the shear dentin bond strength. Sixty bovine incisors, each embedded individually in hard plaster blocks, were divided into two groups based on the adhesive system used: Group 1 Adper Easy One and Group 2 Clearfil SE Protect. Based on the application technique of self-etch adhesives, each main group was further divided into three subgroups: passive application, active application with a micro-brush, and active application with a 976-nm diode laser tip (phototherapy active application). Shear bond strength tests were conducted using a universal testing machine and the data were analyzed by two-way ANOVA. Post hoc multiple comparisons were performed with the Tukey HSD test. Additionally, the statistical analysis of failure mode distribution was carried out using the chi-squared test (p < 0.05). While the adhesive system exhibited significant differences in shear dentin bond strengths, there were no significant differences in application techniques. Regardless of the application technique, Clearfil SE Protect demonstrated significantly higher dentin bond strength than Adper Easy One. In the present study, the utilization of phototherapy through a 976-nm diode laser for the active application of the tested self-etch adhesives demonstrated similar initial dentin bond strengths to conventional application methods.

An in vitro study on the influence of laser-activated irrigation on infiltration and leakage of a dual curing-resin cement as an endodontic sealer.

The study aims to investigate the effects of laser-activated irrigation on infiltration and microleakage of a dual-curing resin cement applied as a root canal sealer. Thirty-eight extracted upper molars were attributed to four experimental groups. Roots were mechanically enlarged and disinfected (NaOCl). Control samples (n = 11) were irrigated with conventional needles and three different lasers were used to activate the irrigant in the other groups (n = 9): 2.94 µm Er:YAG laser, 9,300 µm CO2 laser and 808 nm diode laser with a modified black coated laser tip. Final irrigation was performed in each group with ethylenediaminetetraacetic acid (EDTA), sodium hypochlorite (NaOCl) and sodium chloride (NaCl) activated with lasers and in the control without activation.Dentin tubules were then labeled with a red fluorophore (Rhodamine B) and the root canals were sealed with a dual-curing resin cement (Paracore). The cement fixed the dye on the sealed and infiltrated dentin parts. To remove the Rhodamine not fixed by the cement, roots were then sectioned horizontally and immersed in hydrogen peroxide (H2O2). The empty dentin tubules spaces were then labeled with a green fluorophore (Fluorescein) allowing the visualization of infiltration and microleakage by confocal microscopy. Percentages of infiltration were significantly higher in the middle root third of the control and Er:YAG laser-activated samples compared to CO2 or diode laser groups. Microleakage was present in all experimental groups but significantly less after CO2 laser activation. Laser-activated irrigation impacted resin cement infiltration and microleakage dependent on the applied wavelength. Er:YAG laser activation led to higher values of infiltration and microleakage compared to CO2 and diode lasers.

Topographical Analysis of Human Enamel after Phosphoric Acid Etching and Er,Cr:YSGG Laser Irradiation.

Introduction: Dental hard and soft tissues have been successfully removed by using the Er,Cr:YSGG laser, but there is a controversy about using lasers over conventional tooth surface preparation for bonding aesthetic restoration. Surface roughness and wettability in response to Er,Cr:YSGG laser irradiation are essential properties for restoration longevity. Methods: Fifty-one intact human premolars removed in orthodontic treatment were included in this study and divided into three groups (n=17). The first group (G1) was the control without surface treatment, (G2) was treated with 37% phosphoric acid for 15 seconds, and (G3) was treated with the Er,Cr:YSGG laser using the following parameters: 2 W or 3 W at 20 Hz, 10% air and water ratio using the MZ6 laser tip. The standardization of laser irradiation was accomplished by a computerized numerical control unit. The surface of the samples was evaluated by using a light microscope, profilometer, atomic force microscopy (AFM), SEM, and wettability tests. Results: The SEM examination revealed that the lased enamel surface was clean, irregular, and devoid of a smear layer, while the acid etch surface was relatively smooth and covered with a smear layer. The surface roughness of the lased enamel surface was significantly higher than that of other groups, according to the results of the profilometer as well as the AFM tests. The wettability test showed that the lased enamel surface recorded a significant reduction in the contact angle in comparison to the other groups. Conclusion: It can be concluded that the Er,Cr:YSGG laser can be used as an alternative and safe method to the acid-etching technique for surface treatment.

Influence of pulse energy, tip design and insertion depth during Er:YAG‐activated irrigation on cleaning efficacy in simulated severely curved complex root canal systems in vitro

AbstractAimTo investigate the influence of pulse energy, tip geometry and tip position in simulated 3D‐printed root canals with multiple side canals at different levels in all directions on the cleaning performance of laser‐activated irrigation (LAI) compared to sonic activation (EDDY) and conventional needle irrigation (NI).Methodology3D‐printed root canal models (25/.06, length 20 mm, curvature 60°, radius 5 mm) with side canals (diameter 0.2 mm) at 2, 5 and 8 mm from the apex were filled with coloured biofilm‐mimicking hydrogel. LAI (Morita AdvErL Evo, Kyoto, Japan) was performed with six settings (n = 20; pulse‐energy, pulses per second [PPS], tip position): LAI1 (50 mJ, 25 PPS, P400FL, canal entrance [CE]), LAI2 (same as LAI1, but insertion depth 9 mm before the apical endpoint [AE] [corresponding to 1 mm above the first lateral canals]), LAI3 (80 mJ, 25 PPS, P400FL, 9 mm before AE), LAI4 (same as LAI 3, but at CE) for 3 × 20 s each, LAI5 (50 mJ, 25 PPS, P400FL 2 × 20 s, CE &amp; R200T (30 mJ, 25 PPS, 1 × 20 s, 9 mm before AE), LAI6 (30 mJ, 25 PPS, R200T, 9 mm before AE, 3 × 20 s). A continuous irrigation (3 mL/20 s) using distilled water accompanied the irrigation cycles. NI and EDDY (3 × 20 s each; 3 mL/20 s irrigation, insertion AE minus 1 mm, amplitude 4 mm) served as control groups. Biofilm‐mimicking hydrogel removal (ImageJ, NIH) was assessed for the entire system, the central canal and the lateral canals using standardized photographs with a microscope (Expert DN, Müller‐Optronic) and statistically analysed was performed using Kruskal–Wallis and Dunn tests (p = .05). Irrigant extrusion beyond the foramina was also recorded.ResultsLAI2 (99.08%; interquartile range [IQR]: 96.85–100.00) and LAI3 (97.50%; 96.24–100.00) achieved the significantly best and LAI6 (80.08%; 73.41–84.69) the significantly worst removal of hydrogel from the entire root canal system amongst all LAI configurations (p &lt; .05). There were no significant differences between LAI6, EDDY (72.89%; 67.49–76.22) and manual irrigation (54.39%; 51.01–56.94) (p &gt; .05). R200T laser tip caused significantly more often irrigant extrusion than all other techniques (p &lt; .05).ConclusionTip design, energy settings, and the positioning of the laser tip below the canal entrance caused an improvement in cleaning performance of the LAI. However, the small R200T tip created significantly more procedural errors (irrigant extrusion) due to higher concentrated energy.

Suppression of subgingival bacteria by antimicrobial photodynamic therapy using transgingival irradiation: A randomized clinical trial.

Antimicrobial photodynamic therapy (aPDT) is an effective method for eradicating bacteria in periodontal therapy. Standard aPDT requires the insertion of a laser tip into a periodontal pocket, in which the direction of irradiation is limited. Therefore, we devised an aPDT method that uses a transgingival near-infrared wavelength and indocyanine green-encapsulated and chitosan-coated nanoparticles as a photosensitizer. Forty patients undergoing supportive periodontal therapy, who had a single root tooth with a pocket of 5mm or deeper, were used as subjects. In the test group, aPDT was performed by laser irradiation from outside the gingiva using photosensitizer nanoparticles. In the control group, pseudo aPDT without photosensitizer was performed by transgingival irradiation. Subgingival plaque was sampled from inside the pocket before, immediately after, and 1 week after treatment, and evaluated by colony counting and real-time polymerase chain reaction. There were no significant differences in age, sex, periodontal pocket depth, and bleeding on probing between the test and control groups. Compared with the colony count before treatment, the count in the test group was significantly reduced immediately after treatment. The number of patients with colony reduction to ≤50% and ≤10% was significantly higher in the test group than in the control group. None of the participants reported pain, although one participant reported discomfort. As a bacterial control method for residual pockets in patients undergoing supportive periodontal therapy, transgingival aPDT is a promising treatment strategy that is not generally accompanied by pain or discomfort.

Management of recurrent aphthous ulcers with therapeutic Nd:YAG laser, using two different methods.

Low-level laser therapy (LLLT) has been applied for the management of craniomaxillofacial disorders, including intraoral wounds, as well as recurrent aphthous stomatitis (RAS) lesions. However, the proper combination of laser features and tissue characteristics remains the major challenge in the realm of photobiomodulation (PBM). The aim of the present study was to assess the feasibility of neodymium-doped yttrium aluminum garnet (Nd:YAG) laser therapy in treating RAS lesions, and to compare 2 techniques, different with regard to the distance between the fiber tip and the ulcer. A total of 138 patients (94 males and 44 females) with untreated RAS were divided into 3 groups: focused laser (energy density: 48 J/cm2; power density: 0.797 W/cm2; spot size: 0.1256 cm2); defocused laser (energy density: 21 J/cm2; power density: 0.354 W/cm2; spot size: 0.2826 cm2); and placebo. In the focused group, laser irradiation was performed with the laser tip kept 1 mm away from the lesion. Acrylic cylinders were prepared to precisely fit the handpiece tip and hold it in the proper position. In the defocused group, acrylic cylinders were prepared to set the laser tip 6 mm away from the lesion to obtain defocused irradiation. Finally, in the placebo group, a routine laser therapy procedure was carried out with a helium-neon (He-Ne) red light laser. The lesion size, and pain intensity and duration were recorded. Photobiomodulation showed a significantly more efficient pain relief as compared to the placebo group (p < 0.001) and also significantly better results in decreasing pain duration (p < 0.001). Besides, the diameter of the lesions in the exposed cases decreased during the 3 consecutive days of the study, while an increase in the diameter of the lesions was noticed in the placebo group. The Nd:YAG laser therapy, with the conditions and adjustments of the present study, may be successfully applied to manage RAS lesions, using either focused and defocused scanning techniques.

Success Rate of Transcanalicular Diode LASER –Assisted Dacryocystorhinostomy

Objective:To study the percentage of success rate of transcanalicular diode LASER assited Dacryocystorhinostomy TC-DLA-DCR in case of acquired nasolacrimal duct obstruction(NLDO)Method:A thin fiber of 360 micron diameter with 918 nm diode LASER has a very high energy at LASER tip which help in vaporization of bone and soft tissue at low LASER power .In our technique a thin fibro-optic pass through dilated upper or lower punctum to the lacrimal sac and aiming beam seen through a rigid nasal endoscope attached to a screen and once the proper position is reached the laser is fired to ablate the bone and nasal mucosa and appropriate osteotomy is done.Results:Seventy five patients (26male and 49 female)were followed from Jan. 2017 to Aug 2022 with bicanalicular intubation .follow up show absence of epiphora and a patent nasolacrimal duct on irrigation 73 out of 75 patients. 3out 73 patients had epiphora despite a patent NLD on irrigation.Conclusion:980nm diode laser through 360micrometer fiber is very effective inbone penetration and ablation.It minimally invasive, quick surgery,can be done under local anesthesia and in patient with coagulopathyand have a high success rate

Characterization of susceptibility artifacts in magnetic resonance thermometry images during laser interstitial thermal therapy: dimension analysis and temperature error estimation

Objective. Laser interstitial thermal therapy (LITT) is a minimally invasive procedure used to treat a lesion through light irradiation and consequent temperature increase. Magnetic resonance thermometry imaging (MRTI) provides a multidimensional measurement of the temperature inside the target, thus enabling accurate monitoring of the damaged zone during the procedure. In proton resonance frequency shift-based thermometry, artifacts in the images may strongly interfere with the estimated temperature maps. In our work, after noticing the formation of the dipolar-behavior artifact linkable to magnetic susceptibility changes during in vivo LITT, an investigation of susceptibility artifacts in tissue-mimicking phantoms was implemented. Approach. The artifact was characterized: (i) by measuring the area and total volume of error regions and their evolution during the treatment; and (ii) by comparison with temperature reference provided by three temperature sensing needles. Lastly, a strategy to avoid artifacts formation was devised by using the temperature-sensing needles to implement a temperature-controlled LITT. Main results. The artifact appearance was associated with gas bubble formation and with unwanted treatment effects producing magnetic susceptibility changes when 2 W laser power was set. The analysis of the artifact’s dimension demonstrated that in the sagittal plane the dipolar-shape artifact may consistently spread following the temperature trend until reaching a volume 8 times bigger than the ablated one. Also, the artifact shape is quite symmetric with respect to the laser tip. An absolute temperature error showing a negative Gaussian profile in the area of susceptibility artifact with values up to 64.4 °C was estimated. Conversely, a maximum error of 2.8 °C is measured in the area not-affected by artifacts and far from the applicator tip. Finally, by regulating laser power, susceptibility artifacts formation was avoided, and appreciable thermal damage was induced. Significance. These findings may help in improving the MRTI-based guidance of thermal therapies.

Laser-activated irrigation: Cavitation and streaming effects from dental lasers

IntroductionThe aim of the present study was to assess the generation of laser-activated irrigation (LAI) with a 9,300-nm CO2 laser, a 455- and 970-nm diode laser, as well as an 810- and 980-nm diode laser with and without carbon-coated “hot tips” for improved irrigation in endodontics. Therefore, the formation of cavitation bubbles at the laser tip ends in different liquids was evaluated and compared with the traditionally applied Er:YAG laser.MethodsThe CO2 laser was applied at different power settings at a repetition rate of 14 Hz, SIROLASE for each wavelength at 10% Duty Cycle, and WISER with both wavelengths at different power settings and wavelengths. The LAI was videotaped with a high-speed camera. To measure the streaming velocity due to cavitation, all lasers were loosely coated with carbon particles and activated in pure water. Then, due to LAI, moving particles were videotaped with the same high-speed camera setup. To determine the streaming velocities, the movement of one carbon particle was tracked with the help of a measuring tool in ImageJP software and streaming velocities were calculated.ResultsWith both diode laser devices at four wavelengths, it was only possible to introduce clear cavitation bubbles with low-power parameters (180 mW for the SIROLASE and 200 mW average power for the WISER laser), with the black coating of the laser tips. The 9,300-nm CO2 laser produced clear cavitation bubbles with all tested parameters. Consequently, all tested lasers produced streaming of the liquid, with decreasing velocities at increasing distances from the laser tip: Er:YAG laser 6.4 m/s, CO2 laser up to 5 m/s, and diode lasers in the range of 0.01–0.09 m/s. LIA with the Er:YAG and 9,300-nm CO2 lasers generated high and similar streaming velocities. The diode lasers tested generated significantly lower streaming velocities.

Efficacy of Smear Layer Removal at the Apical One-Third of the Root Using Different Protocols of Erbium-Doped Yttrium Aluminium Garnet (Er:YAG) Laser.

Background and Objectives: Smear layer forms during cleaning and shaping can obstruct the entry of both irrigant and sealant into the dentinal tubules, resulting in the accumulation of the bacteria and their byproducts. To ensure effective adhesion and better periapical healing, it is strongly advised to remove the smear layer before proceeding with root canal obturation. This study was designed to compare the efficiency of laser-activated irrigation (LAI) in removing the smear layer and debriding the most apical third of the root canal. Materials and Methods: Sixty-five extracted human teeth with straight single roots were randomly and equally divided into four laser and one control groups. Root canals in all samples were shaped using prime size TruNatomy rotary files. During preparation, each canal was irrigated with 3 mL of 3% NaOCl and 3 mL of 17% EDTA alternately, followed by the irrigation with 10 mL of distilled water to avoid the prolonged effect of EDTA and NaOCl solutions. Final irrigation of 5 mL of 17% EDTA of the root canal was done to eliminate the smear layer and was subsequently activated by an endodontic ultrasonic tip for 20 s three times (control group), a flat-end laser tip (test groups 1 and 3) or a taper-end laser tip (test groups 2 and 4) for two cycles. The time of each cycle activation was 10 s (groups 1 and 2) or 20 s (groups 3 and 4) in which the Er:YAG laser of 2940 nm was used. The laser operating parameters were 15 Hz and 50 μs pulse duration. The samples were then split longitudinally and subjected to scanning electron microscopy (SEM). Results: The remaining smear layer at the apical part of the root canals was statistically significant between the control group and the laser groups 1 (p = 0.040) and 2 (p = 0.000). Within the laser groups, the exposed tubules count was greater in the laser with the flat tip as compared with the tapered tip (Laser 1 > Laser 2 and Laser 3 > Laser 4). Finally, no significant differences in the count of debris between the laser groups and control group were observed, except for laser 4 (p < 0.05), which had the highest count of debris. Conclusion: LAI to remove debris and smear layer at the apical third of the root canal is inferior to the current ultrasonic technique. However, when using the Er:YAG LAI, it is recommended to use a flat tip design for 10 s for two cycles to ensure maximum debridement of the apical dentin surface.

Comparing the Effects of Radial and Jacketed Laser Tip Fibers on Outcome of Endovenous Laser Ablation of Lower Limb Truncal Venous Reflux

Saphenous vein reflux is one of the leading causes of cosmetic and functional disabilities.The recent ESVS guidelines recommend endovenous thermal ablation over surgery or sclerotherapy for the treatment of great saphenous vein (GSV) reflux in patients with chronic venous disease.The aim of this study is to compare different laser fiber tip configurations to outcome regarding technical success and incidence of complications. A retrospective analysis conducted on patients with documented GSV reflux from 2020 to 2022, comparing baseline parameters and outcome between 2 groups of laser tip fibers used; radial tip and jacketed tip. Primary end point was technical success. Secondary endpoints included incidence of complications in each group, and VCSS score difference in both groups. Inclusion criteria entailed patients with primary varicose veins over the age of 18 years, free from malignancy, hematological disorders, and having documented GSV reflux of more than 0.5 seconds. All patients had endovenous laser ablation (EVLA) of the, with complementary foam sclerotherapy or ambulatory phlebectomies as required. A total of 74 patients underwent EVLA (85 limbs). 54 were done using the radial laser fibers, and 32 using jacketed fibers. Technical success was achieved in 78 limbs (92.9%), 6 limbs (7.1%) had recanalization of the proximal 3cm GSV at 1 month, 2 patients experienced hematomas, and 5 patients had superficial vein thrombosis.There was no significant association between postoperative pain, bruising, recanalization, hematoma, and superficial vein thrombosis, with different laser fiber tip configurations (p-value .95, .6, .18, 1, & 1 respectively), nor was there any significant difference in VCSS between them (p-value .14).Technical success was 90% in the jacketed fibers and 94.1% in the radial fibers group (p-value 0.18). Neither does laser fiber tip configuration nor its make have a significance on outcome of EVLA of GSV reflux. Both radial and jacketed laser fiber tips exhibit similar safety and efficacy in EVLA.

Factors Affecting Residual Stump Length Following Endovenous Laser Ablation.

Current instruction for endovenous laser ablation (EVLA) recommends that the laser fibre tip should be at least 2cm caudal to the saphenofemoral or saphenopopliteal junction. This is to reduce risk of deep vein thrombosis (DVT) whilst ensuring that the Great Saphenous Vein (GSV)/Short saphenous vein (SSV) occlusion (residual stump) is close to the SFJ/SPJ to reduce recurrence rates. Our aim was to primarily assess the effects of pre-operative junction distance of the laser fibre on stump length but also look at other factors affecting this. This was a retrospective analysis of an electronic collected database performing EVLA of the GSV and SSV under local anaesthesia. Patients with previous venous thromboembolic events and incomplete data were excluded. Patients were reviewed at 6weeks with venous Duplex scan to assess for the residual stump distance and DVT. Multivariable logistic regression was used to account for confounders. Between 2012 and 2018, 2341 patients underwent EVLA and complete data were available on 825 (35.2%) patients. All patients were scanned 6weeks after procedure. Sixty-nine patients (8.4%) had flush occlusion, 3 patients (.4%) had extension into femoral or popliteal vein but not considered to be a DVT and 1 patient had a DVT. High BMI and increasing length of the pre-operative junction was associated with lower incidence of flush occlusion; higher rates of flush occlusions were noted in patients undergoing short saphenous vein (SSV) EVLT (OR 4.11, 95% CI 2.34-7.20; P < .001). Consideration should be given to increase the intra-procedure laser tip junction to more than 2cm particularly in patients undergoing SSV treatment to ensure that residual stump is sufficiently distal to SPJ and SFJ reducing risks of thrombus into the femoral or popliteal veins. Lower BMI may be associated with higher risk of this though the reasons for this are unclear.

Does the Novel Thulium Fiber Laser Have a Higher Risk of Urothelial Thermal Injury than the Conventional Holmium Laser in an In Vitro Study?

Introduction and Objective: The novel thulium fiber laser (TFL) has been shown to break stones more rapidly than the holmium:YAG laser (HL). However, some evidence suggests that the TFL generates more heat. The purpose of this study is to compare ureteral temperatures generated by these lasers during ureteroscopic laser lithotripsy in a benchtop model. Methods: A 1-cm BegoStone was manually impacted in the proximal ureter of a three-dimensional printed kidney-ureter model and submerged in 35.5°C saline. Lithotripsy was performed using a 7.6F flexible ureteroscope and a 200 μm laser fiber without a ureteral access sheath. The Dornier 30 W HL, Olympus 100 W HL, and Olympus 60 W TFL were compared. A needle thermocouple to measure temperature was inserted 2 mm from the laser tip. Irrigation was maintained at 35 cc/minute at room temperature using the Thermedx FluidSmart System. Intraluminal temperature was continuously recorded for 60 seconds of laser activation. Five trials were performed for each of four different power settings: 3.6, 10, 20, and 30 W. Analysis of variance and Mann-Whitney U tests were performed with p < 0.05 considered significant. Results: Intraureteral fluid temperature increased as laser power settings increased for all lasers (p < 0.05). The TFL generated higher average ureteral fluid temperatures than the Dornier and Empower HL at all power settings tested (p < 0.001). The maximum temperature for the TFL was higher than the Dornier and Empower HL at all power settings tested (p < 0.001), except at 20 W with the Empower HL. At 30 W, the TFL exceeded 43°C, the threshold for tissue damage. Conclusions: The TFL generated more heat at all settings tested. Supraphysiologic ureteral temperatures may be generated with extended use at high energy settings and low irrigation rates. Understanding the heat generation properties of both lasers could help improve the safety of ureteroscopic laser lithotripsy.

Thermal Effects of Diode Laser-Irradiation on Titanium Implants in Different Room Temperatures In Vitro.

Objective: The aim of this study was to determine the thermal effects of diode laser irradiation on titanium implants. Methods: An implant (3.5 × 11 mm) was placed into a bovine bone block. A three-wall intrabony defect was created to simulate peri-implant defect. Two thermocouples were secured to the apical and coronal surfaces to measure temperature changes (ΔT) during irradiation. The block was placed in a 37°C water bath and at room temperature (21°C). The defect was irradiated with different diode lasers (fiber 300 μm), while the coronal part of the implant was slightly emerging from the water. While the laser tip was positioned parallel to the implant, the defect was irradiated for 30 sec at 2 W in continuous and pulsed mode. Twenty laser irradiations were performed for each laser wavelength for assessment of ΔT. The linear mixed model was used for comparative statistics. Results: The 980 nm pulsed laser resulted in the highest ΔT (°C) at the coronal (22.45 ± 2.1/14.15 ± 0.13) and apical level (5.4 ± 0.56/3.56 ± 0.35) when this laser was used in both room temperature and water bath conditions, respectively. Similarly, highest ΔT (p < 0.0001) for the 810 nm was 14.3 ± 1.6/12.51 ± 0.63 and apical 3.42 ± 0.52/2.58 ± 0.25, for the 970 nm was 13 ± 1.4/9.93 ± 0.47 and apical 2.89 ± 0.19/2.01 ± 0.19 compared to the 940 nm laser coronally 10.1 ± 0.6/9.19 ± 0.35 and apically 1.67 ± 0.34/1.80 ± 0.17. The coronal part of the implant surpassed the critical threshold of 10°C when irradiated with each of the lasers in the room temperature conditions. Conclusions: Within the limitations of the study, the 940 nm laser seems to control better the risks of overheating during implant irradiation.