Introduktion: Det Muskuloskeletala systemet består av skelettmuskulatur, nervsystem och skelett. Systemet bidrar till att kroppen kan röra sig. Muskelskador kan uppkomma genom direktvåld mot muskeln eller kraftig uttöjning och skadan bidrar till smärta och svullnad. Vanliga behandlingsmetoder på muskelskada är NSAID och andra fysioterapeutiska interventioner. Low- level laser therapy (LLLT) har senaste tiden fått ökad acceptans och blivit mer intressant. LLLT används med varierad dosering för att stimulera cellfunktion, minska smärta och påskynda läkningsprocessen. Tidigare studier visar varierat resultat av LLLT på muskelskador, därför vill vi undersöka den beprövade erfarenheten, eftersom det inte undersöks vetenskapligt utan finns bland klinikerna. När LLLT utförs med den mest gynnsamma dosen har behandlingen en pålitlig och biologisk verkan på muskelvävnad. Vi vill se om fysioterapeuters upplevelse av LLLT speglar tidigare forskning. Syftet: med studien är att undersöka fysioterapeuters subjektiva upplevelse och erfarenhet av low-level laser therapy (LLLT) som behandlingsmetod vid muskelskada. Metod: Studien är en kvantitativ tvärsnittsstudie med en online enkät. 30 Leg. Fysioterapeuter med mer än 1 års erfarenhet av LLLT deltog. Fysioterapeuterna rekryterades via 2 portaler och mejlutskick. Resultat: Majoriteten av fysioterapeuterna anser att LLLT är en adekvat behandlingsmetod på muskelskada och patienter upplevs nöjda. Fysioterapeuterna hade varierade upplevelser med en antydan till samband mellan upplevd effekt och dosering (J) på muskelskada som kunde noteras. Konklusion: Enligt de deltagande fysioterapeuterna har LLLT effekt på muskelskada och anses vara en adekvat behandlingsmetod. Det finns en antydan till ett visst samband mellan hänsynstagandet till dos och effekten.

Indiana University-Purdue University Indianapolis (IUPUI) / Introduction: Microbial biofilms have been shown to be a cause of persistent endodontic infections. It is more resistant than planktonic bacteria to host immune defenses and antimicrobials. Studies indicate that photodynamic light therapy (PDT), which involves using light at specific wavelengths, has a potent antibacterial effect on bacterial biofilm. PDT is an antimicrobial strategy that involves the use of a nontoxic photosensitizer (PS) along with a light source. The excited PS reacts with molecular oxygen to produce highly reactive oxygen species, which induce injury or death to microorganisms. PSs have a high degree of selectivity for inhibiting microorganisms without negatively affecting host mammalian cells. PDT has been suggested as an adjuvant to conventional endodontic treatment. Studies at IUSD have shown that blue light at 380 nm to 440 nm has the ability to inactivate Streptococcus mutans biofilm without any exogenous PS. Objective: The objective of this study was to determine the effectiveness of blue light at 380 nm to 440 nm to reduce adherence of Enterococcus faecalis biofilm after NaOCl irrigation at various concentrations. Materials and Methods: E. faecalis biofilm was established for 72 hours in 96- well flat-bottom microtiter plates using Tryptic Soy Broth supplemented with 1.0-percent sucrose (TSBS). Biofilm was irradiated with blue light for 5 minutes before exposure to various concentrations of NaOCl for 30 seconds. A crystal violet biofilm assay was used to determine relative density of the biofilm. Data were analyzed with two-way ANOVA and Sidak-adjusted multiple comparisons using a 5.0-percent significance level. Null Hypothesis: Blue light and NaOCl will not have an effect against E. faecalis biofilm adherence. Results: Overall, there was a significant effect (p < 0.05) for NaOCl and a significant effect for blue light. The effects of the combination of NaOCl and blue light were also significant. Conclusion: We reject the null hypothesis and accept the alternative hypothesis that blue light when used in conjunction with NaOCl will reduce adherence of E. faecalis biofilm.

This thesis explores the topic of light and migration and what actions through light can be done to improve the life quality of the inhabitants of temporary shelters/refugee camps. In this ambiance where there is the feeling of pain, destruction, unsafety, uncertainty and limited access to basic needs, only relying on the support of institutions. A wide range of needs need to be covered, however this thesis proposes to aid the migrants’ when they reach a refugee camp by the creation of Winkilab, a light post that becomes a universal communication tool and function simultaneously as light therapy to have a positive impact on the migrant’s emotions.

O objetivo deste estudo foi avaliar o efeito do laser de baixa intensidade na regeneração de defeitos ósseos críticos preenchidos com diferentes biomateriais. Foram utilizados 80 ratos machos adultos (Rattus norvegicus, albinus, Wistar) e um defeito de tamanho crítico (5 mm) foi criado na calvária de cada animal. Os animais foram divididos em 8 grupos experimentais (n=10): 1) Grupo C (Controle - coágulo sanguíneo), 2) Grupo LB (Laser de baixa intensidade - GaAlAs), 3) Grupo OA (osso autógeno), 4) Grupo OALB (osso autógeno + laser de baixa intensidade), 5) Grupo VB (vidro bioativo - Biogran), 6) Grupo VBLB (Biogran + laser de baixa intensidade), 7) Grupo BO (osso bovino - Bio-Oss®) e 8) Grupo BOLB (Bio-Oss® + laser de baixa intensidade). Os animais foram submetidos à eutanásia aos 30 dias pós-operatórios. Foram avaliadas as áreas de osso neoformado (AON) e de partículas remanescentes (APR). Os dados foram submetidos ao teste paramétrico ANOVA, seguido pelo teste de Tukey (p<0,05). O efeito fotobiomodulador do laser foi demonstrado no presente estudo uma vez que todos os grupos apresentaram maiores quantidades de AON quando comparados com o grupo C (9,96 ± 4,49%). Ao ser associado aos biomateriais, foi estatisticamente significativo somente quando relacionado ao Bio-Oss® (BOLB 48,57± 28,22). A menor área de APR foi encontrada nos grupos irradiados pelo laser, com diferença significativa somente no grupo BOLB (48,57± 28,22, p < 0,05). O laser de baixa intensidade demonstrou melhores resultados na regeneração óssea de defeitos de tamanho críticos, com maior taxa de AON, quando associado ao Bio-Oss®. / The purpose of this study was to evaluate the effect of low intensity laser on the regeneration of bone defects filled with different biomaterials. Eighty male rats (Rattus norvegicus, albinus, Wistar) were used and a critical size defect (5 mm) was created in the calvaria of each animal. The animals were divided into 8 experimental groups (n = 10): 1) Group C (Control - blood clot), 2) Group LB (Low intensity laser - GaAlAs), 3) Group OA (autogenous bone), 4) OALB group (autogenous bone + low intensity laser), 5) Group VB (bioactive glass - Biogran®), 6) VBLB Group (Biogran® + low intensity laser), 7) BO Group (bovine bone - Bio-Oss®) and 8) BOLB Group (Bio-Oss® + low intensity laser). The animals were submitted to euthanasia after 30 days postoperative. The areas of neoformed bone (AON) and of remaining particles (APR) were evaluated. The data were submitted to the ANOVA parametric test, followed by the Tukey test (p <0.05). The photobiomodulatory effect of the laser was demonstrated in the present study since all groups presented higher amounts of AON when compared to group C (9.96 ± 4.49%). When associated with biomaterials, it was statistically significant only when related to Bio Oss® (BOLB 48.57 ± 28.22, p < 0,05). The lowest APR area was found in the groups irradiated by the laser, with significant difference only in the BOLB group (48.57 ± 28.22). The low intensity laser showed better results in bone regeneration of critical size defects, with a higher AON rate, when associated with Bio-Oss®.

Esta tese teve como objetivo verificar a resposta celular de fibroblastos pulpares após a variação nos parâmetros de fotobiomodulação. Fibroblastos pulpares de dentes decíduos humanos em 4a passagem foram plaqueados, deixados a aderir, submetidos a privação nutricional, e em seguida irradiados com laser de baixa intensidade a 660 nm. Os grupos em estudo foram baseados na variação da potência e tempo, resultando em dosimetrias diferentes, variando entre 2,5 a 6,2 J/cm2. No artigo 1, o efeito dos diferentes parâmetros da fotobiomodulação foram verificados por meio da expressão gênica do COL1 por RT-PCR, nos períodos de 6, 12 e 24 horas. No artigo 2, avaliou-se a síntese proteica de fatores angiogênicos (VEGF-A, VEGF-C, VEGF-D, VEGFR1, VEGFR2, FGF-2, PDGF, PLGF, PECAM-1, e BMP-9) por ELISA Multiplex, nos períodos de 6, 12 e 24 horas após fotobiomodulação, no sobrenadante e lisado celular. Os dados foram analisados por ANOVA a dois critérios seguido pelo teste de Tukey (p<0.05) nos dois artigos. No artigo 1, a comparação intragrupo da expressão gênica do COL1 mostrou que a variação da fotobiomodulação com mais tempo (50 s) e menor potência (5 mW) em uma densidade de energia de 6,2 J/cm2 mudou o padrão de expressão gênica do COL1 pelos fibroblastos pulpares de 12 h para 6 h. A comparação intergrupo da expressão genica COL1 não mostrou diferenças estatisticamente significativas. No artigo 2, fibroblastos pulpares secretaram e produziram todas as proteínas testadas antes e após a fotobiomodulação, exceto PDGF no lisado. A comparação intragrupo, no artigo 2, mostrou padrões similares da síntese proteica dos fatores angiogênicos para todos os grupos: a secreção de VEGF-A, VEGF-C, VEGFR1 e BMP-9 aumentou significativamente no sobrenadante enquanto que FGF-2 e VEGF-A aumentou significativamente no lisado. A comparação intergrupo da sintese de proteínas revelou que a dosimetria 2,5 J/cm2 aumentou a secreção de VEGF-D (p=0.4779), VEGFR1 (p=0.8570) e BMP-9 (p=0.0042) no sobrenadante e VEGFR1 (p=0.0128) e VEGF-D (p=0.0036) no lisado; e diminuiu VEGF-A (p=0.0176), VEGF-C (p=0.0328), PDGF (p=0.0077), PLGF (p=0.0004) no sobrenadante e PLGF (p=0.0094) e BMP-9 (p= 0.5645) no lisado. A dosimetria de 3.7 J/cm2 aumentou VEGF-A p=0.8410), FGF-2 (p=0.4778), BMP-9 (p=0.0042) e VEGFR1 (p=0.8570) no sobrenadante e VEGF-A (p=0.8412), VEGF-C (p=0.5908) e VEGFR1 (p=0.0128) no lisado; e diminuiu VEGF-A (p=0.0176), PDGF (p=0.0077) e PLGF (p=0.0004) no sobrenadante e PLGF (p=0.0094) e BMP-9 (p=0.0276) no lisado. Concluiu-se que as dosimetrias de 2,5 a 6,2 J/cm2 biomodularam a expressão gênica de COL1, e as dosimetrias de 2,5 J/cm2 e 3.7 J/cm2 biomodularam a síntese proteica de vários fatores angiogênicos. Na dosimetria de 6,2 J/cm2, o maior tempo e a menor potência mudaram o padrão da expressão gênica de COL1 pelos fibroblastos pulpares. A dosimetria de 3.7 J/cm2 foi a mais efetiva na produção e secreção de fatores angiogênicos. / This thesis aimed to verify the cellular response of pulp fibroblasts after the variation in photobiomodulation parameters. Pulp fibroblasts at 4th passage were plated, led to adhere, subjected to serum starvation, and subsequently irradiated with 660 nm lowlevel laser. The study groups were based on the variation of the power and time, resulting in different dosimetries ranging from 2.5 to 6.2 J/cm2. In article #1, the effect of different photobiomodulation parameters were verified through the COL1 gene expression by RT-PCR, at 6, 12, and 24 hours. In article #2, the protein synthesis of angiogenic factors (VEGF-A, VEGF-C, VEGF-D, VEGFR1, VEGFR2, FGF-2, PDGF, PLGF, PECAM-1, and BMP-9) was measured by ELISA Multiplex assay, at 6, 12, and 24 hours, in the supernatant and lysate. Data were analyzed by two-way ANOVA followed by Tukey test (p<0.05) in both articles #1 and #2. In article #1, the intragroup comparison of the COL1 gene expression showed that the variation of PBM application with longer time (50 s) and smaller power (5 mW) at the energy density of 6.2 J/cm2 changed the COL1 mRNA expression pattern by pulp fibroblasts from 12 h to 6 h. The intergroup comparison of COL1 gene expression revealed no statistically significant differences. In article #2, pulp fibroblasts secreted and produced all the tested proteins before and after PBM, except for PDGF in the lysate. The intragroup comparison, in article #2, showed similar patterns of angiogenic factors synthesis for all groups: the secretion of VEGF-A, VEGF-C, VEGFR1, and BMP-9 increased significantly in the supernatant, while FGF-2 and VEGF-A increased significantly in the lysate. The intergroup comparison of the protein synthesis revealed that the dosimetry of 2.5 J/cm2 exhibited upregulation of VEGF-D (p=0.4779), VEGFR1 (p=0.8570), and BMP-9 (p=0.0042) in supernatant and VEGFR1 (p=0.0128) and VEGF-D (p=0.0036) in lysate; and downregulation of VEGF-A (p=0.0176), VEGF-C (p=0.0328), PDGF (p=0.0077), and PLGF (p=0.0004) in supernatant and PLGF (p=0.0094) and BMP-9 (p= 0.5645) in lysate. The dosimetry of 3.7 J/cm2 upregulated VEGF-A (p=0.8410), FGF-2 (p=0.4778), BMP-9 (p=0.0042), and VEGFR1 (p=0.8570) in supernatant and VEGF-A (p=0.8412), VEGF-C (p=0.5908), and VEGFR1 (p=0.0128) in lysate; and downregulated VEGF-A (p=0.0176), PDGF (p=0.0077), PLGF (p=0.0004) in supernatant and PLGF (p=0.0094) and BMP-9 (p=0.0276) in lysate. We concluded that the energy densities from 2.5 to 6.2 J/cm2 biomodulated the COL1 gene expression, but red laser at 2.5 J/cm2 and 3.7 J/cm2 biomodulated the synthesis of several angiogenic proteins. At the energy density of 6.2 J/cm2, longer application time and smaller power changed the pattern of COL1 gene expression by pulp fibroblasts. However, the dosimetry of 3.7 J/cm2 was the most effective for the production and secretion of angiogenic factors.

Orientador: Fabio Luiz Camargo Villela Berbert / Resumo: O melhor tratamento para dentes permanentes avulsionados é o reimplante imediato, porém, quando o dente permanece fora do alvéolo por longo período, o prognóstico pode ser prejudicado. Condutas têm sido buscadas na tentativa de melhorar os problemas decorrentes de reimplantes tardios. A laserterapia, devido à sua propriedade anti-inflamatória, e o plasma rico em plaquetas (PRP), devido à liberação de fatores de crescimento, são boas alternativas visando atenuar o processo inflamatório e auxiliar o processo de reparo. Avaliou-se os efeitos da laserterapia, da aplicação do PRP e da associação de ambos sobre o reimplante tardio de incisivos superiores de ratos. Cinquenta animais foram divididos em dez grupos experimentais (n=5): grupo controle onde o incisivo superior direito não recebeu alguma intervenção, e nove grupos onde houve a extração dentária simulando uma avulsão seguida do reimplante após 40 minutos. Em um desses grupos, a polpa foi mantida no canal radicular, e os demais foram submetidos à um protocolo de tratamento, de acordo com a condição da cavidade pulpar (manutenção da polpa, preenchimento com hidróxido de cálcio ou preenchimento com PRP) e tratamento do alvéolo/periodonto (coágulo ou PRP com ou sem laserterapia). As avaliações foram realizadas por meio de análise histológica e histoquímica após 30 dias e por microtomografia computadorizada (micro-CT) sobrepondo-se as imagens dos períodos imediato e 30 dias após o reimplante. Os dados obtidos a ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The best treatment for avulsed permanent teeth is immediate replantation, but when the tooth remains outside the alveolus for a long period, the prognosis may be impaired. Pipelines have been sought in an attempt to improve the problems arising from late reimplants. Laser therapy, due to its anti-inflammatory property, and platelet-rich plasma (PRP), due to the release of growth factors, are good alternatives aimed at attenuating the inflammatory process and assisting the repair process. The effects of laser therapy, the application of PRP and the association of both on the delayed replantation of upper incisors of rats were evaluated. Fifty animals were divided into ten experimental groups (n = 5): control group where the right upper incisor did not receive any intervention, and nine groups where the dental extraction was performed simulating an avulsion followed by reimplantation after 40 minutes. In one of these groups, the pulp was maintained in the root canal, and the others were submitted to a treatment protocol, according to the condition of the pulp cavity (pulp maintenance, calcium hydroxide filling or filling with PRP) and treatment of the pulp. Alveolus / periodontium (clot or PRP with or without laser therapy).The evaluations were performed through histological and histochemical analysis after 30 days and by computerized microtomography (micro-CT) overlapping the images of the periods immediately and 30 days after the replantation. The data obtained from the histological and histochemical evaluations were analyzed by the ANOVA and Tukey tests and the microtomographic data by the Kruskall Wallis and Dunn tests, with a significance level of 5%. After histological and histochemical analysis, it was verified that there was no statistically significant difference between groups regarding the number of clasts/mm ...(Complete abstract electronic access below) / Doutor

OBJECTIVE: Low level light therapy (LLLT) is being widely used in wound healing and pain relief, and its use is expected to be expanded rapidly to treatment of other disorders as well in a foreseeable future. However, before its expansion, the fear that LLLT could initiate or promote metastasis must be addressed thoroughly. As an initial effort towards this end, the current study evaluates the safety of LLLT in vitro using two different human cancer cell lines (Michigan Cancer Foundation-7 (MCF-7) and Jurkat E6-1) by determining the viability of cells after low level light (LLL) application while treatment under anti-cancer chemotherapeutic drugs (5-fluorouracil (5-FU) and cisplatin) separately on each cell line. METHODS: Two human cancer cell lines (MCF-7 and Jurkat E6-1) were cultured throughout the experiments. Two different anti-cancer chemotherapeutic drugs (5-FU and cisplatin) were used to treat both cell lines. The half maximal inhibitory concentration (IC50) of each drug on each cell line was determined by treating each cell line with varying concentrations of each drug. A total of 3 or 4 trials were done for each cell line with each drug, and the range of concentration was narrowed closer to the IC50 value at each successive trial. Once the IC50 concentrations were determined, each cell line was treated with 808 nm LLL at varying energy densities in a single dose using a light emitting diode (LED) source both in the absence and the presence of each drug at one IC50. A total of 3 or 5 trials were done for each cell line with each drug, and for each trial, six different energy densities ranging from 0 J/cm2 (control) to 10 J/cm2 were applied. The energy densities were varied for each trial with control always being used. After application of LLL, the viability of cells was determined, and three different 1-way ANOVA (Analysis of Variance) analyses were done to compare the viability of cells at each energy density to that of control. RESULTS: The IC50 of 5-FU in MCF-7 and Jurkat E6-1 cells was determined as 70 µM and 20 µM respectively. The IC50 of cisplatin in MCF-7 and Jurkat E6-1 cells was determined as 17 µM and 7 µM respectively. No significant difference (P > 0.05) in the viability of MCF-7 cells was observed between each group treated with different energy density of LLL and control group (0 J/cm2) both in the absence and the presence of 5-FU at IC50 (70 µM). No significant difference (P > 0.05) in the viability of MCF-7 cells was observed between each group treated with different energy density of LLL and control group (0 J/cm2) both in the absence and the presence of cisplatin at IC50 (17 µM). No significant difference (P > 0.05) in the viability of Jurkat E6-1 cells was observed between each group treated with different energy density of LLL and control group (0 J/cm2) both in the absence and the presence of 5-FU at IC50 (20 µM). However, a significant increase (0.01 < P < 0.05) in the viability of cells was observed when treating Jurkat E6-1 cells with 10 J/cm2 of LLL in the presence of cisplatin at IC50 (7 µM) compared to control group (0 J/cm2). Except for the comparison mentioned previously, no significant difference in the viability of Jurkat E6-1 cells was observed between each group treated with different energy density of LLL and control group (0 J/cm2) both in the absence and the presence of cisplatin at IC50 (7 µM). No definite trend in the viability of cells was observed with increasing energy density of LLL for each cell line either in the absence of the presence of each drug at IC50. CONCLUSIONS: The application of LLL at 808 nm with energy densities ranging from 0.1 J/cm2 to 10 J/cm2 under an LED source did not induce cell proliferation or death compared to control (0 J/cm2) for each cell line in the absence or the presence of each drug, and no definite trend was observed with increasing energy density. The study suggests that LLLT at these parameters may be safe to use on cancer patients, but further studies on different cancer cell lines and animal models with different parameters (wavelength, energy density, dosage) of LLL are warranted.

Orientador: Carlos Alberto de Souza Costa / Resumo: A fixação do tecido conjuntivo à superfície dos abutments de implantes dentários impede a migração apical do epitélio juncional e previne a reabsorção da crista óssea normalmente ocasionada pela inflamação peri-implantar, o qual promove comprometimento estético e o sucesso do procedimento reabilitador. O uso de terapias para favorecer a adesão celular, a fim de induzir um selamento biológico efetivo, pode melhorar as condições estéticas e funcionais nas reabilitações protéticas. O objetivo desta pesquisa foi avaliar o efeito da laserterapia de baixa potência (LBP) e do recobrimento de superfícies de titânio (Ti) e zircônia (ZrO2) com fator de crescimento epidérmico (EGF), sobre a adesão e metabolismo de células da mucosa oral humana expostas ao estímulo inflamatório com o fator de necrose tumoral α (TNF-α). Fibroblastos de gengiva e células epiteliais foram isolados e cultivados sobre discos de Ti e ZrO2, simulando o selamento biológico in vitro. Nos grupos com EGF, este fator de crescimento foi aplicado sobre as superfícies de Ti e ZrO2 previamente ao cultivo celular. Após a semeadura das células, estas foram irradiadas 3 vezes com LBP (LaserTABLE, InGaAsP, 780±3nm), em intervalos de 24 h, nas doses de 0,5 J/cm2; 1,5 J/cm2 e 3,0 J/cm2, de acordo os grupos estabelecidos e então, o TNF-α foi aplicado sobre as mesmas por 24 h. Foram realizadas as análises de rugosidade da superfície dos discos por Microscopia Confocal (n=8) e de liberação do EGF dos substratos recobertos, além ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The attachment of the connective tissue to abutment surface of dental implants prevents the apical migration of the junctional epithelium and the bone crest reabsorption, normally caused by the peri-implant inflammation, which compromises the aesthetics and the success of the rehabilitation procedure. The use of therapies to promote cell adhesion in order to induce effective biological sealing can improve aesthetic and functional conditions in prosthetic rehabilitation. The aim of this study was to evaluate the effects of low-level laser therapy (LLLT) and surfaces coating of titanium (Ti) and zirconia (ZrO2) with epidermal growth factor (EGF) on adhesion and metabolism of oral mucosa cells exposed or not to tumor necrosis alpha (TNF-α) inflammatory stimuli. Gingival fibroblasts and epithelial cells were isolated and seeded on surface Ti or ZrO2 surfaces, simulating the in vitro biological sealing. In EGF-coated groups, this growth factor was applied to Ti and ZrO2 surfaces prior to cell culture. After seeding cells, they were irradiated 3 times with LLLT (LaserTABLE, InGaAsP, 780 ± 3 nm) at 24 h intervals at doses of 0.5 J/cm2, 1.5 J/cm2 and 3.0 J/cm2, according to the established groups and then, TNF-α was applied to them for 24 h. Discs surface roughness analyzes were performed by confocal microscopy (n=8), EGF release of the coated substrates and cell adhesion by direct fluorescence. Cell viability (AlamarBlue, n=8), IL-6, IL-8 and VEGF (qPCR, n=5) gene expression, IL-6, ... (Complete abstract click electronic access below) / Doutor

No description available.

O presente estudo teve o objetivo de avaliar o efeito da Terapia Laser de Baixa Potência (TLBP) na estabilidade e no deslocamento de mini-implantes (MIs) submetidos a carga. A hipótese nula testada foi que a irradiação laser e o tipo de carga aplicada (imediata ou mediata) não influenciam na estabilidade e no deslocamento de MIs. Foram avaliados 48 dispositivos para a estabilidade e 35 para o deslocamento, os quais foram implantados em pacientes da clínica de pós graduação em Ortodontia da Faculdade de Odontologia de Ribeirão Preto da Universidade de São Paulo. Os MIs foram divididos em 4 grupos segundo a intervenção recebida: 1- TLBP + CI (carga imediata), 2- TLBP + CM (carga mediata / após 4 semanas da implantação), 3- CI (sem TLBP) e 4- CM (após 4 semanas da implantação / sem TLBP). Carga de 150 gF foi aplicada por período de 3 meses para todos os dispositivos. A TLBP foi aplicada usando emissão laser vermelha com comprimento de onda de 660 nm e potência de 100 mW, imediatamente após implantação (densidade de energia: 4 J/cm&sup2; ). Nos dias posteriores foram aplicadas emissões laser infravermelhas com comprimento de onda de 808 nm a cada 48 horas durante duas semanas após colocação dos dispositivos (densidade de energia: 8 J/cm&sup2; para cada aplicação). A estabilidade dos dispositivos foi avaliada pela Análise de Freqüência de Ressonância (AFR) em três momentos: T0 no dia da implantação; T1 antes da aplicação da carga, somente nos grupos 2 e 4; e T2 após três meses de aplicação de carga. Para a avaliação do deslocamento dos dispositivos foram utilizadas imagens de Tomografias Computadorizadas de Feixe Cônico (TCFC). Planos tridimensionais foram criados a partir de pontos de referência identificados na maxila e mandibula para medir e comparar as diferenças entre as distâncias inicial (TC0) e final (TC1) da cabeça do MI ao plano tridimensional. Os resultados demonstraram que o grupo 2 apresentou a menor perda de estabilidade de todos os grupos (p= 0.0161). Os dispositivos que receberam TLBP (Grupos 1 e 2) apresentaram menor perda de estabilidade quando comparados aos grupos que não receberam irradiação laser (p= 0.0372). Os MIs que receberam CI (Grupos 1 e 3) apresentaram maior perda de estabilidade quando foi avaliado o tempo efetivo de aplicação da carga (p< 0.0001). Todos os dispositivos apresentaram deslocamento sem diferenças estatisticamente significantes entre os grupos. A hipótese nula foi parcialmente rejeitada. Os MIs que receberam TLBP e CM tiveram menor perda de estabilidade. O deslocamento não foi influenciado pela irradiação laser e pelo protocolo de aplicação da carga / The present study aimed to evaluate the effect of Low-level Laser Therapy (LLLT) on stability and displacement of mini-implants (MIs) submitted to loading. The null hypothesis tested was that laser irradiation and the applied loading protocol (immediate or mediate) do not influence the stability and displacement of MIs. Forty-eight devices were assessed for stability and 35 for displacement. They were implanted in patients from the graduate clinic of Orthodontics of the School of Dentistry of Ribeirão Preto, University of São Paulo. MIs were divided in four groups according to received intervention: 1- LLLT + IL (immediate loading), 2- LLLT + ML (mediate loading / 4 weeks after implantation), 3- IL (without LLLT) and 4- ML (4 weeks after implantation / without LLLT). Loading of 150 gF was applied during 3 months for all devices. LLLT was implemented using red laser emission with wavelength of 660 nm and potency of 100 mW, immediately after implantation (energy density: 4 J/cm2). In the later days they were applied infrared laser emissions with wavelength of 808 nm every 48 hours during two weeks after placement of devices (energy density: 8 J/cm2 for each application). MIs stability assessment was performed by Resonance Frequency Analysis (RFA) at three moments: T0 on the day of implantation; T1 before loading, for groups 2 and 4; and, T2 after three months of loading application. For displacement analysis, images from Cone-beam Computed Tomography (CBCT) scans were used. Threedimensional planes were created based on landmarks identified on maxilla and mandible to measure and compare differences of initial (TC0) and final (TC1) distances from the MIs head to the plane. Results demonstrated that group 2 presented the lowest loss of stability of all groups (p= 0.0161). Devices that received LLLT (Groups 1 and 2) showed lower loss of stability when they were compared with the groups that did not receive LLLT (p= 0.0372). MIs that received IL (Groups 1 and 3) presented greater loss of stability when the effective time of loading application was assessed (p< 0.0001). All groups showed displacement of the devices without significant differences between them. The null hypothesis was partially rejected. MIs that received LLLT and ML had lower loss of stability. Displacement was not influenced by laser irradiation or loading protocol