سال:1391 | دوره: | شماره: |تعداد مقالات:8

The laser technology offers a wide range of uses in dentistry with certain advantages to the general dental practitioner like bloodless surgery, minimal post-operative pain, reduction of operative time and high patient acceptance. Patient acceptance has also been demonstrated in various studies. Apart of these major advantages, safety regarding the use of lasers cannot be neglected and has become an important concern in this modern era of dentistry, as application of this technology is growing day by day. Potential hazards can be encountered while using lasers like ocular hazards, tissue injury, inhaling the vapor emitted by the laser procedure, fire and explosion hazards etc. The safe use of lasers includes all the individuals who might be exposed either deliberately or accidently while using lasers and effective measures that can be undertaken by clinicians and health professionals to minimize the injuries caused due to laser accidents. The present article serves to explore the risks involved in the use of lasers in dentistry and suggest some of the laser safety protocols/measures that can be established in the dental office for prevention of laser injuries.

Low-power lasers are a group of lasers with a power less than 500 mW and unlike high-power lasers they have no effect on tissue temperature; they produce light-dependent chemical reactions in tissues. The purpose of this study was to review the clinical applications of these lasers and their success rate in different studies in orofacial pains. The articles with the key word “low level laser therapy” were extracted from pubmed. Clinical trials, meta-analysis, randomized clinical trials, and review articles were selected. Related articles to orofacial region were gathered and selected from the search results and carefully reviewed. Laser therapy may affect many cellular and sub-cellular processes, although exact mechanism has not been well-defined yet. Articles had different points of views as mentioned in the context of this article. Low level laser therapy was effective in orofacial pain relief in most studies, but the use of laser remains controversial. These lasers have analgesic features, and it is according to these features they have been used in the treatment of orofacial pain, including myofacial pain, mucositis, facial myalgia, temporomandibular joint disorders and neuralgia. It seems that laser therapy can be considered as an alternative physical modality in treatment of orofacial pain.

Introduction: In this study, arrangement of a low-cost optical tomography device compared to other methods such as frequency domain diffuse tomography or time domain diffuse tomography is reported. This low-cost diffuse optical imaging technique is based on the detection of light after propagation in tissue. These detected signals are applied to predict the location of in-homogeneities inside phantoms. The device is assessed for phantoms representing homogenous healthy breast tissues as well as those representing healthy breast tissues with a lesion inside.Methods: A diode laser at 780nm and 50 mW is used as the light source. The scattered light is then collected from the outer surface of the phantom by a detector. Both laser and detector are fiber coupled. The detector fiber may turn around the phantom to collect light scattered at different angles. Phantoms made of intralipid as the scattering medium and ink as the absorbing medium are used as samples. Light is collected after propagation in the phantoms and the capability of the device in collecting data and detecting lesions inside the phantoms is assessed. The fact that the detection fiber orbits around the sample and detects light from various angles has eliminated the need to use several detectors and optical fibers. The results obtained from experiments are compared with the results obtaine from a finite element method (FEM) solution of diffusion equation in cylindrical geometry written in FORTRAN.Results: The graphs obtained experimentally and numerically are in good accordance with each other. The device has been able to detect lesions up to 13 mm inside the biological phantom.Conclusion: The data achieved by the optical tomography device is compared with the data achieved via a FEM code written in FORTRAN. The results indicate that the presented device is capable of providing the correct pattern of diffusely backscattered and transmitted light. The data achieved from the device is in excellent correlation with the numerical solution of the diffusion equation. Therefore, results indicate the applicability of the reported device. This device may be used as a base for an optical imaging. It is also capable of detecting lesions inside the phantoms.

Introduction: Dentin hypersensitivity is one of the most common complications that patients suffer from after periodontal therapies. So far many investigators have used different types of fluoride and laser for treatment of this complication. The aim of this study was to evaluate the effects of 5% sodium fluoride varnish and (Neodymium-Doped Yttrium Aluminium Garnet) Nd:YAG laser and their combined application on dentin hypersensitivity treatment.Methods: The study is a prospective interventional clinical trial. We selected a group of 9 patients with a total of 60 hypersensitive teeth. Each patient had at least 4 hypersensitive teeth. These 4 teeth were randomly placed in 4 different groups. Group1 didn’t receive any treatment. Group2 was treated with 5% sodium fluoride varnish (A Durashield Company product). Group3 was irradiated with Nd: YAG laser (1w, 20Hz, 120s). Group4 was treated by 5% sodium fluoride varnish and Nd: YAG laser combined (same parameters as group3). The assessment of the patients’ pain was done with cold air blast test (CAB) and visual analyzing scale (VAS) after stimulation using a probe and cold air. Patients’ pain was assessed before and just after treatment, and also 2 hours, 1 week and 2 weeks after treatment. For the assessment of pulp vitality we used the electric pulp test (EPT) at each session. SPSS 11.5 was used to process the results obtained. For the CAB and VAS changes in different groups, two-way repeated-measures ANOVA as well as Post-Hoc-Tukey tests were used. For the comparison of the different treatment groups at each session, one-way ANOVA, Post-Hoc-Tukey and or Mann-Whitney and Kruskal-Wallis tests were used.Results: VAS and CAB scores didn’t show any significant difference between different groups before treatment. Analysis of results obtained with two-way ANOVA test for repeated measures showed significant statistical differences for CAB and VAS scores in all groups between before and after treatment except for CAB score in control group. In the comparison of the fluoride varnish group and laser group alone with fluoride varnish-laser combined group using VAS and CAB scores, we found a significant difference. But we didn’t find any significant difference for the comparison between the varnish fluoride group and the laser group using the same score.Conclusion: The use of 5% sodium fluoride varnish and laser for treatment of dentin hypersensitivity is accompanied by a placebo effect. Although it appears that, if we omit the placebo effect, we had an improvement in all 3 treatment groups. But this improvement was more obvious for the treatment group4 (fluoride–laser) compared to other groups.

Background: Laser irradiation has been introduced in endodontic treatment due to its bactericidal effect. The aim of this study is to evaluate the bactericidal efficacy of a 940 nm diode laser alone or in combination with 5% sodium hypochlorite (NaOCl) against mature biofilms of E. Faecalis.Methods: Sixty-eight (60 for the three groups, 4 for SEM and 4 as negative controls) single-rooted human central incisors were prepared and contaminated with E. Faecalis. After two weeks of incubation, specimens were randomly divided in three groups; group 1 (n =20), the teeth were irradiated with a 940 nm diode laser; group 2 (n=20), specimens were rinsed with 5% NaOCl; group 3 (n=20), the teeth were rinsed with 5% NaOCl and then were irradiated with 940 nm diode laser. Four teeth were used to observe the biofilms by SEM. Intracanal bacteria sampling was done, and the samples were plated to determinate the CFU count.Results: At 24 hours and 7 days, group 3 showed a significant difference (P=0.02; P=0.00) in disinfection if compared to group 1 but did not show this difference if compared to group 2 (P=1, P=0.66), although group 3 obtaining a more extensive disinfection. Groups 1 and 2 did not show difference after 24 hours (P=0.09) but showed a significant difference 7 days afterwards (P=0.04).Conclusion: The combination of sodium hypochlorite and diode laser light (940 nm) has a synergistic effect, intensifying the bactericidal action.

Introduction: The main purpose of the present study was to describe the ultra-structural changes which happened after treatment of the root surfaces with ultrasonic and hand devices followed by Erbium-Doped Yttrium Aluminum Garnet (Er:YAG) laser irradiation.Methods: Sixty single-rooted maxillary and mandibular teeth which had been extracted due to periodontal problems were collected. Crown and apical parts of the root were cut off using a diamond bur. The specimens were mounted on an acrylic resin in order to make a plain surface of the root accessible. The samples were assigned as following: group1: samples were root planed using conventional hand curette, group2: were prepared by ultrasonic device, group3: roots after scaling by hand instrumentation were treated by Er:YAG laser with 50 mJ/pulse and frequency of 10 Hz, group4: roots were prepared by ultrasonic scaler and consequently were treated by laser. Furthermore, the teeth were dried, sputter-coated with gold, and monitored with scanning electron microscope (SEM).Results: Photomicrographs from ten samples of root surfaces which were taken at magnifications up to 500X revealed that there were not any severe morphologic changes, such as melting and charring, in any group. However, the samples treated by laser irradiation showed more irregularities and distortions.Conclusion: Er:YAG laser setting at 50mj/pulse, as an adjunctive to traditional scaling and root planning, did not induce severe damages to root surfaces, although root surface irregularities were more pronounced in laser treated groups compare to hand instruments.

Introduction: A modern technique for elemental analysis of biological samples is laser induced breakdown spectroscopy (LIBS). This technique is based on emission of excited atoms, ions, and molecules in plasma produced by focusing a high power laser pulses on sample surface. Because of several advantages of LIBS including little or no sample preparation; minimally invasive; fast analysis time and very easy to use, in this study, this method was used for investigating the mineral content of fingernails. As the trace element of nail can be changed by several pathological, physiological, and environmental factors, we analyze the human fingernails to evaluate the possibility of thyroidism diagnosis.Method: A Q-switched Neodymium-Doped Yttrium Aluminium Garnet (Nd:YAG) laser operating at wavelength of 1064 nm, pulse energy of 50 mJ/pulse, repetition rate of 10 Hz and pulse duration of 6 ns was used in this analysis. Measurements were done on 28 fingernails belonging to 5 hypothyroid, 2 hyperthyroid and 21 normal subjects. For classification of samples into different groups based on thyroid status, a discriminant function analysis (DFA) was used to discriminate among normal and thyroidism groups.Results: The elements detected in fingernails with the present system were: Al, C, Ca, Fe, H, K, Mg, N, Na, O, Si, Sr, Ti as well as CN molecule. Classification in two groups of normal and patient subjects and also in three groups of normal, hyperthyroid and hypothyroid subjects shows that 100% of original grouped cases were correctly classified. So, efficient discrimination among these groups is demonstrated.Conclusion: It is shown that laser-induced breakdown spectroscopy (LIBS) could be a possible technique for the analysis of nail and therefore identification of health problems.

A 47 year-old woman presented with eight-month history of tattoo allergic reaction of eyebrows after botulinum toxin A injection that was resistant to oral, topical and intralesional injection of corticosteroids. Multiple sessions of treatment with CO2 fractional laser resulted in significant flattening of allergic papules and plaques as well as reduction of tattoo pigmentation.