Feasibility of Using Detuned Laser as a Placebo In Manual Therapy Research: An Analysis of Participant Perceptions.

OBJECTIVE: The purpose of this study was to determine the feasibility of using detuned laser as a placebo intervention in manual therapy research. METHODS: We performed a secondary data analysis of a randomized controlled trial. In our analysis, 30 participants with chronic ankle instability (manual therapy group: n = 13, age = 33.1 ± 8.1 years, female participants = 50%; detuned laser group: n = 17, age = 31.9 ± 11.8 years, female participants = 72%) were asked to indicate which intervention (manual therapy [active] or detuned laser [placebo]), they thought they had received and to give a confidence rating on their response regarding the received intervention at the conclusion of the course of intervention. Independent t tests were used to compare the groups. Participants in both groups were asked the following open-ended question: "What did you think of the intervention?". RESULTS: There were 52.9% participants in the detuned laser group and 53.8% participants in the manual therapy group who perceived that they had received the active intervention. The confidence ratings about their perceptions (6.7 ± 2.0, detuned laser group; 6.3 ± 2.4, manual therapy group) (P = .66) and the self-reported recovery ratings (1.9 ± 1.5 and 1.8 ± 1.2, respectively) (P = .77) were similar. CONCLUSIONS: Participants in this study confidently perceived that detuned laser was an active intervention. They positively rated their recovery following the course of the placebo intervention and perceived that detuned laser was effective in treating their condition. Therefore, it is feasible for detuned laser to be used as a placebo for manual therapy trials.

Regulaciones puntero láser: reporte breve de evidencia / Laser pointer regulations: brief report of evidence

ANTECEDENTES Y OBJETIVO Definición de láser y puntero láser "Láser" es un acrónimo que significa "Light Amplification by Stimulated Emission of Radiation". Los productos que usan energía láser vienen en muchos tamaños y formas, lo que tiene en común es la presencia de un láser que almacena energía de una fuente, como una descarga eléctrica, una reacción química o una potente iluminación óptica que libera la energía como luz. Debido a los posibles riesgos que pueden generar esta herramienta, la Dra. Solana Terrazas solicita este reporte breve de evidencia con el objetivo de entrega evidencia científica respecto regulaciones existentes sobre punteros láser. METODOLOGÍA Este resumen fue realizado a través de una búsqueda de evidencia en bases de datos científicas Medline, Cochrane, Social System Evidence, OECD, Google scholar y Google, utilizando palabras claves relacionadas a puntero láser. Por no encontrar revisiones sistemáticas que evaluaran regulaciones de puntero láser en el mundo, es que se hizo una búsqueda de estudios primarios en las bases de datos mencionadas. Como criterios de elegibilidad se consideraron todo tipos de estudios, reportes, normas, regulaciones y leyes sobre puntero láser. RESULTADOS Se incluye un estudio en el desarrollo de esta síntesis -En los países de Australia, Canadá e Inglaterra se encuentra presente un tipo de regulación y descripción sobre el uso de punteros láser en aeronaves. -En Australia poseen el reglamento de seguridad radiológica que regula el láser clase 3B. -En Canadá y Suecia tienen un reglamento sobre el uso y regulación de punteros láser en lugares públicos. -La Unión Europea desarrolló normas de seguridad frente al uso de punteros láser, que establece requisitos de seguridad que deben cumplir las normas europeas para productos láser. -Nueva Zelanda y Suiza presentan Regulación de importación, venta, distribución y regalo de los punteros láser. -En Noruega poseen una ley que regula la posesión y uso de punteros láser de 5 mW o superior. La ONU impone el protocolo respecto a las armas de combate, la cual prohíbe o limita el uso de armas láser específicamente diseñadas para cegar o dañar la visión en contextos de combate.

Methods for bladder cancer diagnosis - The role of autofluorescence and photodynamic diagnosis.

Bladder cancer is one of the most common Genito-urinary malignant tumors in humans. Improved diagnostic and therapeutic methods that aim to reduce rates of recurrence and progression of bladder cancer are needed. In current publications, one can find information on such methods as Raman spectroscopy, ultraviolet autofluorescence microscopy, confocal laser endoscopy, photoacoustic imaging, molecular imaging, multi-photon microscopy and many other new diagnostic techniques. These methods do not show significant adverse effects and are procedures well tolerated by patients as they use mostly physical phenomena that are neutral towards the human body. This review highlights the techniques of autofluorescence (AF) or laser induced fluorescence (LIF) and photodynamic diagnostics (PDD) which have been widely clinically studied for many years as a complement to cystoscopy. These methods can be performed during standard cystoscopy and they can be used in routine practice. This review shows that Autofluorescent and Photodynamic diagnostics are effective and have great potential in enhancing the diagnosis of bladder cancer. However, more research should be performed to help realize their full potential.

The "in's and outs" of laser hair removal: a mini review.

Conventional treatments for excessive hair are tedious and time consuming. Laser hair removal has become the leading therapy option for long-term results. It works on the principle of selective photothermolysis, whereby photons destroy the hair follicle while sparing the surrounding tissue. As demand increases, there has been an increase in the regulation of these treatments. Laser hair removal is not risk-free and side effects are associated with the treatment. Adequate training is vital to minimise adverse side effects. Certain countries have regulatory boards that laser operators need to register with, as well as the completion of mandatory hours. Others require laser operators to register with a Care Quality Commission (CQC) to ensure that minimum training and safety standards are met. Currently, in South Africa, the lack of regulatory boards and mandatory hours poses a risk to the public as anyone with little or no qualification is allowed to perform laser hair removal treatments, placing patients at risk. This review looks at some of the devices used and basic mechanisms of action of laser hair removal, its associated risks, side effects and current regulation.

Photo-Modification of Melanin by a Mid-infrared Free-electron Laser.

Melanin is rigidly constructed by several nitrogen-containing aromatic rings, and its excess accumulation in skin tissue is closely associated with melanosis. Although visible lasers (wavelength: 600-1000 nm) are conventionally used for the photo-thermolysis of melanocyte, several pigmented nevi are difficult to be treated. Here, we propose an alternate method for targeting the molecular structure of melanin using an infrared free-electron laser (FEL) tuned to 5.8 µm that corresponds to the stretching vibrational mode of carboxylate group. A drastic morphological change on the black-colored surface of melanin powder was observed after the pulse irradiation with power energy of 500 mJ cm-2 , and the minimum irradiation time for damage to the morphology was 1.4 s. Analyses by mass spectroscopy, infrared spectroscopy, and 13 C-nuclear magnetic resonance implied that a pyrrole group was removed by the FEL irradiation. In addition, the FEL irradiation dispersed almost all of the melanoma cells from a culture solution without any influence on other ingredients in the medium, and one-cell analysis by infrared microscopy showed that the structure of melanoma could be substantially damaged by the irradiation. This study proposes the potency of intense mid-infrared laser as novel alternative way to reduce melanin.

Overview of Lasers for Flow Cytometry.

Lasers are critical elements of all flow cytometers. Instrument capabilities are dictated by the wavelengths and characteristics of its laser sources. In this chapter, we review the lasers available for flow cytometry, and provide guidance in choosing laser wavelengths and characteristics to best match the analytical needs of biomedical research laboratories.

[Vein morphology after endovenous laser coagulation at different power and similar linear density of energy]. / Morfologiia ven posle éndovenoznoi lazernoi koaguliatsii pri raznoi moshchnosti i odinakovoi lineinoi plotnosti énergii.

The purpose of the study was to assess the depth of damage to the venous wall after endovenous laser coagulation (EVLC) at different power of the unit - 5, 7 and 10 W and similar linear density of energy (LDE) - approximately 70 J/cm. Our prospective comparative morphological study with blinding included a total of 30 patients subjected to EVLC of the great saphenous vein using the unit with a wavelength of 1,470 nm and radial light guides with automatic traction. The patients were divided into three groups, each comprising 10 patients. The unit's power (W) during EVLC and velocity of light guide traction (mm/s) in group one amounted to 5 and 0.7 (LDE - 71.4 J/cm), in group two to 7 and 1.0 (LDE - 70 J/cm) and in group tree to 10 and 1.5 (LDE - 66.7 J/cm), respectively. The coagulated veins were then procured from mini approaches and subjected to three sections made at a distance of 2 mm from each other. Specimens were stained with haematoxylin-eosin and picrofuxin according to the van Gieson technique. Then, in four places of each section (at 3, 6, 9 and 12 hours) we assessed the depth of the damage to the venous wall and calculated the average percentage of alteration - the ratio of the depth of the lesion to the venous wall thickness. The average depth of damage to the venous wall (µm) amounted in the first group to 122.9 ?m, in the second group to 182.9 µm, and in the third group to 267 µmm. The index of alteration (%) averagely amounted: in group one to 25.7, in group two to 37.9 and in group three (at a power of 10 W) to 55.5 (p=0.0001 when comparing each of the groups (the Kruskal-Wallis test)). Hence, despite an inconsiderable decrease of the LDE from the first to the third group, as power increased, the depth and percentage of damage to venous walls increased statistically significantly. It follows from the above-mentioned that: 1) an increase in power (from 5 to 10 W) of the unit during EVLC at comparable LDE (approximately 70 J/cm) leads to a deeper damage of the venous wall; 2) it is necessary to carry out a clinical study aimed at comparing different modes of coagulation, with the assessment of the frequency of recanalization and the level of pain syndrome.

[Hybrid (femtosecond laser-assisted) phaco surgery and the state of the macula]. / Gibridnaia (femtolazernaia) fakokhirurgiia i sostoianie makuliarnoi zony setchatki.

The review covers different aspects of the impact of femtosecond laser-assisted cataract surgery on the state of the macular zone of the retina. Literature search has revealed inconsistency of the published data and indicated the need for a more detailed study of this problem.

Efficacy of Multiwave Locked System Laser on Pain and Function in Patients with Chronic Neck Pain: A Randomized Placebo-Controlled Trial.

BACKGROUND: Multiwave locked system (MLS) laser therapy utilizes the synchronized emission of an 808 nm continuous laser and a 905 nm pulsed laser. It is postulated that MLS enables greater penetration and therapeutic benefit than single-wavelength low-level laser therapy (LLLT). OBJECTIVE: The aim of this research was to evaluate the efficacies of MLS laser therapy and the 830 nm laser in the treatment of patients with chronic neck pain (CNP). MATERIALS AND METHODS: Seventy-five patients with CNP (mean age 46.28 ± 5.89, weight 83.78 ± 5.65 kg, height 1.72 ± 4.96 m, and duration of illness of 5.98 ± 1.44 months). They were randomized into three groups. Group I received MLS laser therapy and exercises, Group II received LLLT and exercises, and Group III received placebo laser therapy plus exercises (PL + EX). Neck pain levels and neck function were measured using the visual analogue scale (VAS) and neck disability index (NDI), respectively. RESULTS: Both VAS and NDI were significantly reduced post-treatment for all treatment groups. After 6 weeks of treatment, MLS plus exercise showed a significantly greater decrease in pain and disability scores {Δ VAS (6.68) and Δ NDI (39.84)} compared to both LLLT plus exercise group {Δ VAS (5.72) and Δ NDI (37.88)} and PL + EX {Δ VAS (4.84) and Δ NDI (36.68)}. CONCLUSIONS: MLS laser therapy in conjunction with exercises decreased pain and increased functional activity following 6 months of therapy. MLS laser therapy in combination with exercises is a more effective therapy for CNP compared to exercise plus LLLT or exercise alone.

Estudio comparativo entre láser tulio (Tm: YAG) 150W y láser verde (LBO:ND-YAG) 120W para el tratamiento de la hiperplasia benigna de próstata: eficacia y seguridad a corto plazo / Comparative study between thulium laser (Tm: YAG) 150W and greenlight laser (LBO:ND-YAG) 120W for the treatment of benign prostatic hyperpplasia: short-term efficacy and security

Objetivo: Comparar los resultados de eficacia y seguridad del láser tulio 150W frente a láser verde 120W en el tratamiento de la hiperplasia benigna de próstata a corto plazo (12 meses de la cirugía). Material y métodos: Estudio retrospectivo observacional, donde se incluyen varones intervenidos con la técnica de fotovaporización prostática durante un periodo de 4 años en nuestro centro. Se comprobó la homogeneidad de la muestra, y se compararon las complicaciones postoperatorias (retención aguda de orina, reingreso, necesidad de transfusión), los fracasos al año de la cirugía (reintervenciones, flujo máximo < 15ml/seg, ausencia de mejoría en el I-PSS) y disminución de PSA al año de la cirugía. Análisis bivariante mediante Chi-cuadrado y «t» de Student. Resultados: Ciento dieciséis pacientes tratados con tulio y 118 con láser verde. Muestra homogénea para variables preoperatorias (p>0,05). No se objetivaron diferencias en las complicaciones: en retenciones agudas de orina, 4,3% con tulio y 6,8% con láser verde (p = 0,41); en reingresos 2,6% con tulio y 1,7% con láser verde (p = 0,68); en necesidad de transfusión 2,6% con tulio y 0% con láser verde (p = 0,12). Tampoco se observaron diferencias en el porcentaje de pacientes reintervenidos (1,7% en el grupo de tulio, 5,1% en el de láser verde, p = 0,28), ni en el de individuos con Qmáx menor de 15 ml/seg (6,9% con tulio, 6,77% con láser verde, p = 0,75), ni en el de ausencia de mejoría del I-PSS (5,2% con tulio, 3,4% con láser verde, p = 0,65). Tampoco hubo diferencia en los niveles de PSA en ng/ml al año de la cirugía: con tulio 2,78 ± 2,09 y con láser verde 1,83±1,48 (p = 0,75). Conclusiones: La fotovaporización prostática con láser tulio 150W es comparable a la realizada con láser verde de 120 W para el tratamiento de los síntomas obstructivos del tracto urinario inferior por HBP, siendo ambas técnicas eficaces y seguras a los 12 meses de la intervención. Futuros estudios prospectivos aleatorizados son necesarios para confirmar esta conclusión sobre ambas técnicas

Objective: To compare the results of efficacy and safety of Thulium laser 150 W against Greenlight laser 120 W in the treatment of short term benign prostatic hyperplasia (12 months after surgery). Material and methods: This is a retrospective observational study where men who underwent the surgical technique of prostate vaporization over a period of four years in our center are included. The homogeneity of the sample was checked, and postoperative complications (acute urinary retention, reentry, need for transfusion), failures per year of surgery (reoperation, peak flow < 15ml/sec, no improvement in comparing the I-PSS), and decreased PSA were compared a year after surgery. A bivariate analysis using Chi-square and t-Student was carried out. Results: 116 patients were treated with thulium and 118 with green laser. The sample was homogeneous for preoperative variables (P > .05). No differences in complications were observed: in urine acute retention, 4.3% with thulium and 6.8% with green laser (P = .41); in readmissions, 2.6% with thulium and 1.7% with green laser (P = .68); in need for transfusion, 2.6% with thulium and 0% with green laser (P = .12). No differences were observed in the percentage of patients reoperation (1.7% in the group of thulium, 5.1% in the green laser, P = .28); or in individuals with Qmáx less than 15ml/sec (6.9% with thulium, 6.77% with green laser, P = .75), or in the absence of improvement in the IPSS (5, 2% with thulium, 3.4% with green laser, P = .65). There was also no difference in the levels of PSA in ng/mL a year after surgery: with thulium 2.78 ± 2.09 and with green laser 1.83 ± 1.48 (P = .75). Conclusions: Prostate vaporization with thulium laser 150W is comparable to that made with green laser 120W for the treatment of lower urinary tract symptoms caused by BPH, being both effective and safe techniques to 12 months after surgery. Future prospective randomized studies are needed to confirm this conclusion on both techniques

Phototherapy for Improvement of Performance and Exercise Recovery: Comparison of 3 Commercially Available Devices.

CONTEXT: Recent studies suggest the prophylactic use of low-powered laser/light has ergogenic effects on athletic performance and postactivity recovery. Manufacturers of high-powered lasers/light devices claim that these can produce the same clinical benefits with increased power and decreased irradiation time; however, research with high-powered lasers is lacking. OBJECTIVE: To evaluate the magnitude of observed phototherapeutic effects with 3 commercially available devices. DESIGN: Randomized double-blind placebo-controlled study. SETTING: Laboratory. PATIENTS OR OTHER PARTICIPANTS: Forty healthy untrained male participants. INTERVENTION(S): Participants were randomized into 4 groups: placebo, high-powered continuous laser/light, low-powered continuous laser/light, or low-powered pulsed laser/light (comprising both lasers and light-emitting diodes). A single dose of 180 J or placebo was applied to the quadriceps. MAIN OUTCOME MEASURE(S): Maximum voluntary contraction, delayed-onset muscle soreness (DOMS), and creatine kinase (CK) activity from baseline to 96 hours after the eccentric exercise protocol. RESULTS: Maximum voluntary contraction was maintained in the low-powered pulsed laser/light group compared with placebo and high-powered continuous laser/light groups in all time points (P < .05). Low-powered pulsed laser/light demonstrated less DOMS than all groups at all time points (P < .05). High-powered continuous laser/light did not demonstrate any positive effects on maximum voluntary contraction, CK activity, or DOMS compared with any group at any time point. Creatine kinase activity was decreased in low-powered pulsed laser/light compared with placebo (P < .05) and high-powered continuous laser/light (P < .05) at all time points. High-powered continuous laser/light resulted in increased CK activity compared with placebo from 1 to 24 hours (P < .05). CONCLUSIONS: Low-powered pulsed laser/light demonstrated better results than either low-powered continuous laser/light or high-powered continuous laser/light in all outcome measures when compared with placebo. The increase in CK activity using the high-powered continuous laser/light compared with placebo warrants further research to investigate its effect on other factors related to muscle damage.

Control measurements for lasers in physiotherapy.

OBJECTIVES: In physical rehabilitation, is diffused the skin irradiation with near infrared laser at a fluence below 140 J/cm2, achieving a bio-stimulating effect that is due to the absorption of radiation in mitochondria rather than the simple heating of tissues. METHODS: In order to deliver radiation without thermal damage of the skin, are used radiation pulses which duration does not allow heat accumulation and propagation far from the irradiated target; this requires laser sources with average power below 10 W implying a safety classification as "potentially dangerous for eye and skin", or "class 4" according to the applicable international standards. In this paper, 6 laser therapy devices, of 5 different manufactures and models have been analyzed from the point of view of actual radiation output and user safety. In each case, one or more of the characteristic declared by the manufacturer in the user manual have been found different from the actual measured value. RESULTS: The actual accessible energy levels have been found to be complying with risk class 3B. The impact of the new version of the Standard IEC 60825-1 (2014), is also discussed, considering in particular the possible classification in the new class 1C, and the maximum permissible levels for pulsed lasers. CONCLUSIONS: An extension of the measurement protocols is proposed in order to assure effective and safe use of laser in physical therapy.

A systematic review of the use of lasers for the treatment of hidradenitis suppurativa.

AIM: To conduct a systematic review of the effectiveness of various types of lasers (and light based therapies) for the treatment of hidradenitis suppurativa (HS) and to establish recommendations based on our findings. DATA SOURCES: MEDLINE, Cochrane and PubMed databases. STUDY SELECTION: English language studies describing the use of laser for the treatment of HS. DATA EXTRACTION: Multiple reviewers performed independent extraction and identified 22 studies that met the inclusion and exclusion criteria. DATA SYNTHESIS: Studies were categorised according to grading recommendations based on evidence quality guidelines for systematic reviews. Only 2 studies met criteria to be assigned the highest grade. CONCLUSION: Nd:YAG laser has been shown to be effective for the treatment of HS, as is intense pulsed light therapy (IPL) using the same principles of laser hair removal. There is weak evidence to recommend the use of carbon dioxide, diode or alexandrite lasers. The need for larger randomized controlled trials is highlighted.

Blood absorption during 970 and 1470 nm laser radiation in vitro.

AIM: Soon after introduction of water lasers in medical practice for EVLA, less power and energy line density have been used. However, there are no experimental grounds for different energy modes and there is no clear evidence for a difference in the effect of the two wavelengths dealt with in this study. The goal of this study was to evaluate the temperature profile of various laser action modes with testing devices. METHODS: Three experimental testing devices consisted of cylinders filled with whole donor blood and a set of temperature sensors installed in different positions. RESULTS: We have determined the range of temperatures around the fiber tip of 970 and 1470 nm lasers. The average temperature of 970 nm laser at 1 mm distance along the axis from the fiber tip substantially differed from that of 1470 nm laser, power being equal. CONCLUSION: Statistically substantial differences were found in endovenous laser ablation simulation in vitro for the 970 nm and 1470 nm laser radiation. Similar temperatures can be reached with 970 nm lasers if power is increased.

Láser subumbral para coriorretinopatía serosa central activa / Subthreshold laser for active central serous chorioretinopathy

No disponible

Guía terapéutica del glaucoma crónico por cierre angular primario / Guidelines for treatment of chronic primary angle-closure glaucoma

OBJETIVO: Realización de una guía de práctica clínica actualizada sobre el tratamiento médico, láser y quirúrgico del glaucoma por cierre angular primario (GCAP) en el adulto. MÉTODOS: Tras la formulación de preguntas clave utilizando el esquema PICO (Paciente/Problema, Intervención, Comparación, Outcome/Resultado), se realiza una revisión de la literatura publicada hasta el momento, incluyendo guías de práctica clínica internacionales, utilizándose las herramientas AMSTAR y «Risk of Bias» para la evaluación de la calidad de la información. El nivel de evidencia y la elaboración del grado de recomendación se establecieron siguiendo el sistema Scottish Intercollegiate Guidelines Network (SIGN). RESULTADOS: Siguiendo la metodología expuesta, se presentan recomendaciones de tratamiento médico, láser y quirúrgico en el GCAP del adulto y los niveles de evidencia. CONCLUSIONES: Aunque el nivel de evidencia científica para muchas de las preguntas planteadas no es muy alto, se presenta una revisión actualizada de las recomendaciones terapéuticas en el GCAP del adulto. Entre las limitaciones para la aplicación de estas recomendaciones se encuentra que la mayoría de los estudios han sido realizados en población de origen asiático, y que la eficacia se mide casi exclusivamente en términos de reducción de tensión ocular y no en parámetros de función visual, calidad de vida o coste-efectividad

OBJECTIVE: To present a clinical practice guideline update on the medical, laser, and surgical treatment of primary angle closure glaucoma (PACG) in adults. METHODS: Following the formulation of key questions using the PICO scheme (Patient/Problem, Intervention, Comparison, Outcome), a systematic review was performed on the literature published to date, including international clinical practice guidelines. The AMSTAR and Risk of Bias tools were used for evaluating the quality of the information. The level of evidence and grade of recommendation was established following the Scottish Intercollegiate Guidelines Network (SIGN) system. RESULTS: Following the above methodology, recommendations of medical, laser and surgical treatment in adult PACG and levels of evidence are presented. CONCLUSIONS: Although the level of scientific evidence for many of the questions raised is not very high, a review is presented on updated treatment recommendations for adult PACG. Among the limitations for the implementation of these recommendations is that most studies have been conducted in Asian populations, and that the effectiveness is measured almost exclusively in terms of reducing intraocular pressure, and does not include visual function, quality of life or cost-effectiveness parameters

Avaliação in situ do potencial da solução de AmF/NaF/SnCl2, associada ou não ao laser de CO2, em prevenir a erosão em esmalte dental bovino / In situ assessment of the potential of AmF/NaF/SnCl2 solution, associated or not to CO2 laser irradiation, on preventing dental enamel erosion

Apesar de vários estudos terem demonstrado resultados promissores do uso da solução de AmF/NaF/SnCl2 no controle da erosão do esmalte dental, não existem relatos da sua associação com a irradiação do substrato com o laser de CO2, de comprimento de onda de 9,6 ?m. Desta forma, o presente estudo teve como objetivo avaliar o potencial da solução de AmF/NaF/SnCl2, associada ou não ao laser de CO2 (4,5 J/cm2, 20 Hz, 20 ?s), em controlar a erosão em esmalte dental bovino. Treze voluntários participaram desse estudo in situ, de delineamento cruzado, em 02 fases (04 dias cada), onde 04 tratamentos foram testados utilizando réplicas (n = 13): GC - nenhum tratamento (controle negativo); GF - solução de AmF/NaF/SnCl2 (controle positivo); GL - irradiação com laser de CO2 (9,6 ?m); GLF - laser de CO2 associado à solução de AmF/NaF/SnCl2. Os voluntários usaram dispositivos intra-bucais removíveis contendo 08 amostras de esmalte bovino. Na primeira fase, 07 voluntários utilizaram dispositivos intra-bucais contendo amostras dos grupos GC e GL, e outros 06 voluntários utilizaram dispositivos contendo amostras dos grupos GF e GLF. Na segunda fase, os voluntários foram cruzados, permitindo que todos os grupos experimentais fossem avaliados no meio bucal dos 13 voluntários da pesquisa. Os dispositivos intra-bucais foram removidos da boca para ciclagem erosiva ex-situ em ácido cítrico 0,65%, pH 3,6, durante 4 minutos, 2x/dia, em horários pré-determinados. As amostras foram avaliadas em perfilômetro óptico de não-contato (n = 13) para análise da perda de tecido mineral após o desafio erosivo, e um ensaio de ultramicrodureza transversal (n = 13) foi realizado com o objetivo de determinar a profundidade da área de desmineralização abaixo da superfície do esmalte erodido. A análise morfológica foi realizada utilizando microscopia eletrônica de varredura (MEV) (n = 3).

Os dados foram analisados estatisticamente por meio do modelo ANOVA 2 fatores para medidas repetidas, com subsequente comparação entre os diferentes tratamentos (? = 0,05). A ciclagem ácida realizada no presente estudo provocou perda de esmalte significativamente maior (p < 0,001) nos grupos GC (4,8 ± 1,4A ?m) e GL (4,4 ± 2,0A ?m). Não houve diferença estatística entre a perda de superfície nos grupos GF (1,9 ± 0,9B ?m) e GLF (1,7 ± 0,9B ?m). Os resultados de ultramicrodureza transversal mostraram que as amostras tratadas com a solução fluoretada (grupo GF) apresentaram uma zona parcialmente desmineralizada com média de dureza semelhante às amostras do grupo que não recebeu qualquer tipo de tratamento (grupo GC), com ambos os grupos apresentando média de dureza significativamente maior que os grupos que foram irradiados com o laser de CO2 (GL e GLF) (p < 0,001). As micrografias mostraram que as características morfológicas superficiais do esmalte nos grupos irradiados com laser de CO2 apresentaram-se semelhantes nos grupos GL e GLF, verificando-se a presença de áreas sugestivas de derretimento, resolidificação, microporos e microtrincas, sem evidências de precipitados fluoretados no grupo GFL. Uma camada amorfa pôde ser observada nas superfícies de esmalte tratadas apenas com a solução fluoretada contendo estanho. Pode-se concluir que o uso do enxaguatório bucal fluoretado contendo estanho (500 ppm F-, 800 ppm Sn2+, pH = 4,5) mostrou potencial de prevenção da erosão de esmalte dental. A irradiação do esmalte dental com o laser associado à solução fluoretada mostrou-se eficaz, mas seu efeito não foi sinérgico. O laser de CO2 (9,6 ?m), nos parâmetros utilizados, não foi capaz de prevenir a erosão em esmalte causada por ácido cítrico.

Although several studies have shown promising results using the AmF/NaF/SnCl2 solution in preventing the erosion of dental enamel, there are no reports of their association with the irradiation of the substrate with the CO2 laser, working at 9.6 ?m. Thus, this study aimed to evaluate the potential of AmF/NaF/SnCl2 solution, associated or not to CO2 laser irradiation (4.5 J/cm2, 20 Hz, 20 ?s), to prevent erosion on dental enamel. Thirteen volunteers participated in this 2-phase (4 days each), crossover study, where 04 treatments were tested using replicas (n = 13): GC - no treatment (negative control); GF - AmF/NaF/SnCl2 solution (positive control); GL - CO2 laser irradiation (9.6 ?m); GLF - CO2 laser irradiation associated with AmF/NaF/SnCl2 solution. The volunteers wore removable intra-buccal appliances containing eight bovine enamel samples. In the first phase, seven volunteers used intra-oral appliances containing samples of groups GC and GL and 6 volunteers, appliances containing samples of groups GF and GLF. In the second phase volunteers were crossed over, allowing all experimental groups were evaluated in the buccal environment of the 13 volunteers. Intra-buccal appliances were removed from the mouth and were exposed to a daily ex-situ erosive cycling (0.65% citric acid, pH 3.6, for 4 minutes, 2x/day) at pre-determined times. Samples were evaluated for surface loss using an optical non-contact profilometer (n = 13) for analysis of loss of mineral after the erosive challenge and a cross-sectional nanohardness test (n = 13) was carried out in order to determine the depth of demineralized area below the erosive lesion. Morphological analysis was carried out using scanning electron microscopy (SEM) (n = 3).