Comparison of Diode Laser and Conventional Method in Treatment of Gingival Melanin Hyperpigmentation

Purpose: The goal of this study is to compare the scalpel and diode laser methods for treating gingival hyperpigmentation in terms of postoperative discomfort and wound healing. Materials & Methods: Sixteen systemically healthy individuals diagnosed with light or moderate gingival hyperpigmentation were enrolled for this study. Patients were randomly assigned to one of two treatment groups: scalpel or laser. Dummett’s oral pigmentation index was recorded at baseline. Early wound healing and post-operative discomfort were evaluated on the 7th day by using the VAS form. Comparisons between the groups were tested using the Mann-Whitney U test and P-value < 0.05 was considered significant. Results: Total epithelization was observed in the laser group, whereas the epithelization was incomplete in the scalpel group at the end of the observation period. The pain perception on the first two days after the surgery was significantly higher in the scalpel group than in the laser group. (p=0,002 and p=0,038, respectively). No significant differences were found between the fourth- and seventh-day when surgical techniques were compared regarding pain perception (p>0,05). Similarly, pain perceptions of female and male individuals showed no significant difference (p>0,05). Conclusion: In the treatment of gingival hyperpigmentation, both surgical techniques were clinically successful. Although the treatment process was long, according to the results of our study, the laser technique is superior to the scalpel method in terms of patient comfort. The choice of the method may vary depending on the available equipment and the clinician’s preference or request of the patient.

Gingival Depigmentation Using Diode 980 nm and Erbium-YAG 2940 nm Lasers: A Split-Mouth Clinical Comparative Study

Aim of the Study. This study aimed to compare the effectiveness of diode laser (980 nm) and erbium-YAG laser (2940 nm) for gum depigmentation. Background. Gingival hyperpigmentation, “black gum,” refers to black discrete single or multiple pigments on the gingiva. Several factors may play a role in gingival hyperpigmentation ranging from physiologic pigmentation to manifestations of systemic diseases. Several techniques have been used for gingival depigmentation to lighten its color. Methods. Fifteen patients exhibiting nonsmoking melanin hyperpigmentation, with the mean age of 28.6 ± 7.8 years, were recruited. The facial gingiva of the anterior teeth and premolars of each jaw was divided into two halves. The right or left side of each jaw quadrant randomly received either diode laser operating at 980 nm wavelength or erbium-YAG laser at 2940 nm. Parameters such as degree of gingival depigmentation, bleeding, pain, patient satisfaction, and wound healing were assessed and compared between the two techniques. The subjects were followed up to six months for melanin pigmentation recurrence. Results. Both techniques were efficient for gingival depigmentation. Nevertheless, bleeding during surgery was statistically higher for Er:YAG laser technique as compared to diode laser. Wound healing showed statistically nonsignificant differences between the two lasers, although Er:YAG seems to give better outcomes than the diode. The patients were satisfied with both laser techniques during and after gingival depigmentation. However, the pain score was higher for Er:YAG laser than for diode laser. Conclusion. This study demonstrated that both lasers’ techniques are efficient for gingival depigmentation. However, diode laser seems to show less painful experience and relatively better bleeding control.

Comparison between laser sheaths, femoral approach and rotating mechanical sheaths for lead extraction

Introduction Efficiency and safety are important features in the selection of lead extraction tools. We report our experience with different endovascular techniques to extract individual pacing and defibrillator leads. Methods This is a single-centre study of consecutive lead extraction procedures from 1997 until 2019. A total of 1725 leads were extracted in 775 patients. Direct traction sufficed for 588 leads, and 22 leads were primarily removed by surgery. The endovascular techniques used in the remainder were a laser sheath (190 leads), the femoral approach (717 leads) and rotating mechanical sheaths (208 leads). Results The three approaches were comparably effective in completely removing the leads (p = 0.088). However, there were more major complications with the laser sheath than with the femoral approach or rotating mechanical sheaths (8.4%, 0.5% and 1.2%, respectively). Therefore, the procedural result—extraction without major complications—was significantly better with both the femoral approach and rotating mechanical sheaths than with the laser sheath (p < 0.001). This result was confirmed after propensity score matching to compensate for differences between lead cohorts (p = 0.007). Cross-over to another endovascular tool was necessary in 7.9%, 7.1% and 8.2% of laser, femoral and rotating mechanical attempts, respectively. Conclusion All three endovascular lead extraction techniques showed comparable efficacy. However, there were significantly more major complications using the laser sheath compared to the femoral approach or rotating mechanical sheaths, leading us to abandon the laser technique. Importantly, no single endovascular technique sufficed to successfully extract all leads.

Development of Epoxy Resin-Based Elastomeric Microfluidic Devices Using CO2 Laser Ablation for DNA-Amplification Point-Of-Care (POC) Applications: Assessment of Microchannels' Dimensions and Quality

Microfluidic devices are a rising technology to automatize chemical and biological operations. In this context, laser ablation has significant potential for polymer-based microfluidic platforms' fast and economical manufacturing. Nevertheless, the manufacturing of epoxy-based microfluidic chips is considered highly cost full due to demand for cleanroom facilities that utilize expensive equipment and lengthy processes. Therefore, this study targeted investigating the feasibility of epoxy resins to be fabricated as a lab-on-chip using carbon dioxide laser ablation. The chemical structural properties and thermal stability of the plain epoxy resins were characterized by Fourier transform infrared spectral analysis (FT-IR) and thermogravimetric analysis (TGA). Moreover, a specific migration test was performed to quantify potential migrants by gas chromatography coupled to mass spectrometry (GC-MS) to prove that the cured epoxy resin would not release unreacted monomers to the biological solution test, which caused inhibition of the sensitive biological reactions. By investigating the impact of this process on microchannels' dimensions and quality, a laser technique using CO2 laser was used in vector mode to engrave into a transparent epoxy resin chip. The resulting microchannels were characterized using 3D Laser microscopy. The outcomes of this study showed considerable potential for laser ablation in machining the epoxy-based chips, whereas the microchannels were produced with minor bulges' height (0.027 µm) with no clogging. Moreover, a reasonable depth of 99.31 µm with roughness (Ra) of 14.52 µm was obtained at a laser speed of 5 mm/s and laser power of 1.8 W. This process can produce epoxy resin-based microfluidic chips without the need for cleanroom facilities that require expensive equipment and lengthy process.

Optical Emission Spectroscopic Analysis of Plasma Parameters in Cadmium by Nd: YAG laser Technique

In this work, optical emission spectroscopy (OES) was used to estimate the parameters of plasma electron temperature (Te), electron density (ne), plasma frequency (fp), Debye length (λD), and Debye number (ND). Understanding how an energy pulsed laser affects these variables is also important. Irradiation of pure cadmium using an Nd: YAG laser pulse with a wavelength(1064)nm and energy ranging from (200-600)millijoules, of frequency (6) Hz. The spectrum of laser-induced plasma was detected under atmospheric pressure. It was discovered that when the energy of the laser pulse rises, the intensity of the CdI and CdII lines increases.

Improving the results of treatment of patients with purulent diseases of fingers and hands using laser irradiation and photodynamic therapy

Despite the evolution in modern surgery and in pharmaceutical industry, purulent pathology of the hand is occupying a leading position for many years among all diseases with which patients are admitted to hospitals. Over the years, medical care for such patients has been improving. A high social and economic significance of this problem makes surgeons to continue searches of new directions not only in surgical techniques, but also in postoperative wound management to improve outcomes in patients with purulent diseases of the hand.The purpose of this work is to assess results of care of patients with purulent finger and hand diseases treated with laser light necrectomy and photodynamic therapy. A comparative analysis of wound process dynamics and treatment outcomes in 198 patients with hand purulent diseases who had been admitted to Moscow City Hospital No. 4 was made by the authors. All patients were divided into four groups depending on the curative modality. In Group 1 (n = 53), a wound was sutured after surgery, and a drainage-lavage system (DLS) was installed; in Group 2 (n = 50), a wound was not sutured because of contraindications to suturing; in Group 3 (n = 46), patients had laser necrectomy after which a wound was sutured and DLS was installed; in Group 4 (n = 49), a wound was not sutured because of contraindications like in Group 2, but it was treated with antiseptic dressings and photodynamic therapy at an early postoperative period. Various aspects of the effectiveness of laser techniques have been analyzed: dynamics of wound healing, changes in wound defect size, level of pain syndrome assessed by VAS, changes in clinical blood tests, changes in wound exudate cytological picture as well as changes in wound microflora. Acceleration of wound healing was noted in all patients who were treated with laser light what, consequently, shortened their inpatient stay. Laser light also changed cytological and microbiological patterns of wound exudate, as evidenced by the decrease of wound detritus and by the decrease of microbial content in the wound. In patients, who were treated with laser light, less pain syndrome was registered immediately after laser technique application.The obtained findings demonstrate a positive effect of laser necrectomy with DLS at wound process as well. Photodynamic therapy significantly improved results in patients with open wound management on the hand and fingers. Laser techniques have good perspectives in purulent surgery of the hand.

Multiphoton intersubband transitions in an armchair graphene nanoribbon

We present an analytical approach to the problem of the interband transitions in an armchair graphene nanoribbon (AGNR), exposed to the time-periodic electric field of strong light wave, polarized parallel to the ribbon axis. The two-dimensional Dirac equation for the massless electron subject to the ribbon confinement is employed. In the resonant approximation the probability of the transitions between the valence and conduction size-quantized subbands are calculated in an explicit form. We trace the dependencies of the Rabi frequency for these transitions on the ribbon width and electric field strength for both the multiphoton-assisted and tunneling regimes relevant to the fast oscillating and practically constant electric field, respectively. Estimates of the expected experimental values for the typically employed AGNR and laser technique facilities show that the Rabi oscillations can be observed under laboratory conditions. The data, corresponding to the intersubband tunneling, makes the AGNR a 1D condensed matter analog, in which the quantum electrodynamic vacuum decay can be detected by the employment of the attainable electric fields.

Placental Abruption after Fetoscopic Laser Surgery in Twin-Twin Transfusion Syndrome: The Role of the Solomon Technique

<b><i>Introduction:</i></b> Twin-twin transfusion syndrome (TTTS) is a complication in monochorionic twin pregnancies which is preferably treated with fetoscopic laser surgery. A few small studies suggested a possible association between the Solomon laser technique and placental abruption. <b><i>Methods:</i></b> The objective of this study is to compare the rate of and to explore potential risk factors for placental abruption in TTTS treated with fetoscopic laser surgery according to the Selective and Solomon laser technique. We conducted a large retrospective cohort study of consecutive TTTS-cases treated with fetoscopic laser surgery in Shanghai, China, and Leiden, The Netherlands treated with either the Selective laser technique (Selective group) or Solomon laser technique (Solomon group). <b><i>Results:</i></b> The rate of placental abruption in the Selective group versus the Solomon group was 1.7% (5/289) and 3.4% (15/441), respectively (<i>p</i> = 0.184). No risk factors for placental abruption were identified. Placental abruption was associated with lower gestational age at birth (<i>p</i> = 0.003) and severe cerebral injury (<i>p</i> = 0.003). <b><i>Conclusion:</i></b> The prevalence of placental abruption in TTTS after fetoscopic laser surgery is low, although it appears higher than in the overall population. Placental abruption is associated with a lower gestational age at birth, which is associated with severe cerebral injury. The rate of placental abruption was not significantly increased with the use of the Solomon technique. Continued research of placental abruption in TTTS is necessary to determine why the rate is higher than in the overall population.