Iraqi Journal of Laser

Crown lengthening is a surgical procedure that apically positions the gingival edge and/or removes supporting bone in order to increase the amount of supra gingival tooth structure for restorative or cosmetic purposes.
The objective of the study: The purpose of this study was to evaluate the efficacy of the 940nm diode laser in esthetic crown lengthening surgery through clinical observations, patient questionnaires, clinical photographs, and gingival healing following gingival operations. Material and methods: In this randomized clinical trial, 16 patients (11 females and 5 males) had their crowns surgically lengthened using a diode laser (940 nm) in continuous wave (CW) mode with 1 watt energy settings. A visual analogue scale is used on the first, third, seventh, and twenty-first days following surgery to record pain, swelling, bleeding, functional interference, tooth sensitivity, and success from an aesthetic standpoint, as well as overall patient satisfaction based on patient opinion and clinical photographs. Results: In the present study, we noticed that the scale of pain, bleeding, oedema, function interferance, and tooth sensitization significantly decreased gradually during the first two visits. The measured parameters completely disappeared after one week in most cases, as well as increase patient satisfaction and aesthetic achievement. The patients were recalled three weeks later, the wounds had totally healed, and the patient were not complaining of any pain. Conclusion: Crown lengthening requires optimal gingival margin design. This involves precise shaping of delicate tissues, which is difficult with the scalpel. While Lasers give improved gingival sculpting control and can be used for aesthetic crown lengthening. The laser surgery has many advantages, including excellent hemostasis with little or no bleeding, being less invasive and sterile wound cut, causing less pain and suffering during and after surgery, and enhancing patient satisfaction since the operation is short and, in most circumstances, relatively painless. Also, in laser surgery, there is less functional interruption and enhanced patient satisfaction since a periodontal pack is not needed to cover the surgery site. The healing is faster and more aesthetic when using laser surgery procedure.

When it comes to applications in welding, cutting, and surface engineering, the utilization of high-power fiber-delivered beams from solid-state lasers offers several benefits. This paper addresses the issue of cleaning the surface of the samples with different spot sizes (50, 100 and 200) (industrial ytterbium fiber laser) to prepared it to be welded. Angular laser cleaning with incident angles (5, 10, 15, 20, 25, 30) ° with different powers (3, 5, 7, 10) W and hatch distance 0.001 was use for implemented.

Microfluidic devices present unique advantages for the development of efficient drug assay and screening. The microfluidic platforms might offer a more rapid and cost-effective alternative. Fluids are confined in devices that have a significant dimension on the micrometer scale. Due to this extreme confinement, the volumes used for drug assays are tiny (milliliters to femtoliters). In this research, a microfluidic chip consists of micro-channels carved on substrate materials built by using Acrylic (Polymethyl Methacrylate, PMMA) chip was designed using a Carbon Dioxide (CO2) laser machine. The CO2 parameters have influence on the width, depth, roughness of the chip. In order to have regular channel surface, and low roughness the laser power (60 W), with scanning speed (250 m/s) for allows us to obtain microchannels with a minimum diameter of width (450 μm), depth of the channels was 89.4 μm and( Arithmetic Average Roughness Ra = 2.3), (Relative roughness, Ɛ = 5%) surface roughness with high accuracy and good surface quality.
The functionalized multiwalled carbon nanotubes (F-MWCNTs) was used to enhance the drug signal inorder to detect very tiny Ibuprofen concentration. In this work, laser microfluidic sensor have high accuracy in Ibuprofen detection compared to the traditional method(UV-VIS) spectrophotometer with LOD equal to 0.25 nM, 1000μM respectively.

Background: The oral cavity is a complex environment, both structurally and functionally, the hard and soft tissues are in close a proximity. Oral tissues subjected to wear throughout the life, that threatened the vitality of the pulp or increase the sensitivity of dentinal tubules. One of the common dental problems is loss of enamel or cementum, which stimulate the nerve ending in or near the pulp and manifested as pain sensation. Aim of the study: This study had done to evaluate the effects of 980nm diode Laser in diameters reduction of exposed dentinal tubules analyze the results and morphological changes of irradiated dentine surface by FE-SEM (field emission scanning electron microscope) analysis. Material and Method: Thirty-nine human extracted impacted 3rd molar teeth were tested in this study and divided into control Group (N=15), pilot study (N=9) and study group (N=15). The study group irradiated with 980nm diode Laser to the occlusal surface of the teeth after the application of 17% EDTA (Ethelyn diamine tetra acetic acid) for smear layer removal. The intra-pulpal temperature recorded for every second and monitored for 120s from the first second of irradiation by a thermometer (prośket MT-1820, 1st Edition, 2016, Taiwan), for detection the recovery time of initial tooth temperature. FE-SEM analysis to all teeth (control, pilot and study groups) for assessment the morphological changes after surface irradiation. Results: FE-SEM analysis to the irradiated surface show significant reduction in diameters of the exposed dentinal tubules irradiated by 980nm diode Laser. Conclusion: The selected parameters (1.5W/10s, 276.3W/cm2) were able to seal exposed dentinal tubules without any sign of cracks or fissures. Suggestion: The parameters used with this study (1.5W, 10s, 276.3W/cm2) can be utilize in the future treatment protocol to the management of dentinal hypersensitivity.

Despite the distinct features of the continuous wave (CW) Terahertz (THz) emitter using photomixing technique, it suffers from the relatively low radiation output power. Therefore, one of effective ways to improve the photomixer emitter performance was using nanodimensions electrodes inside the optical active region of the device. Due to the nanodimension sizes and good electrical conductivity of silver nanowires (Ag-NWs), they have been exploited as THz emitter electrodes. The excited surface plasmon polariton waves (SPPs) on the surface of nanowire enhances the incident excitation signal. Therefore, the photomixer based Ag-NW compared to conventional one significantly exhibits higher THz output signal. In this work, the effect of Ag-NWs dimensions and number on the incident optical field is investigated by utilizing the Computer Simulation Technology (CST) Studio Suite. The simulation results show that increasing Ag-NWs length to SPP propagation length ratio plays a significant role on the incident field increment due to its effect on reducing the SPP propagation losses. The increment of Ag-NWs number and length in the nanoelectrodes based photomixer can contribute to increase the electric field in the active region by 1.5 times at the longer excitation wavelength (850 nm). As a result of this increment, the THz output power and the conversion efficiency are expected to be enhanced by a factor of five.

Polarization beam splitter (PBS) integrated waveguides are the key components in the receiver of quantum key distribution (QKD) systems. Their function is to analyze the polarization of polarized light and separate the transverse-electric (TE) and transverse-magnetic (TM) polarizations into different waveguides. In this paper, a performance study of polarization beam splitters based on horizontal slot waveguide has been investigated for a wavelength of 700nm. PBS based on horizontal slot waveguide structure shows a polarization extinction ratio for quasi-TE and quasi-TM modes larger than 15bd with insertion loss below 1db and a bandwidth of 7nm. Also, the fabrication tolerance of the structure is analyzed.

Background: Optical biosensors offer excellent properties and methods for detecting bacteria when compared to traditional analytical techniques. It allows direct detection of many biological and chemical materials. Bacteria are found in the human body naturally non-pathogenic and pathologically, as they are found in other living organisms. One of these bacteria is Escherichia coli (E. coli) which are found in the human body in its natural and pathogenic form. E.coli bacteria cause many diseases, including Stomach, intestines, urinary system infections, and others. The aim of this study: is sensing and differentiation between normal flora and pathogenic E.coli. Material and method: The optical biosensor constructed of a multi-mode – no core- multi mode optical fibre that differentiates between pathogenic and non-pathogenic bacteria of E.coli by measuring the changing for light intensity using source of light 410nm laser diode. Multi-mode - no core - multi-mode optical fibre (MM-NOC-MM) connected to the OSA analyser (HR2000) by means of an adapter and finally connected to a computer to show the results. Results: The intensity of the transmitted light recorded in the case of pathogenic bacteria is less than the intensity of the transmitted light recorded in the case of non-pathogenic bacteria. Conclusion: these results were obtained because of the ideal and better choice of the wavelength of the laser used with its absorption E.coli bacteria.