ФОРМИРОВАНИЕ ГЕОТЕХНИЧЕСКИХ СВОЙСТВ ПРИКОНТУРНЫХ ГРУНТОВЫХ СЛОЁВ ПОДЗЕМНОГО ТУННЕЛЯ ЭЛЕКТРОХИМИЧЕСКИМ МЕТОДОМ

Строительство подземных сооружений и туннелей является приоритетным направлением развития для крупных городов, поверхность которых плотно застроена постройками и объектами городской инфраструктуры. При анализе процессов возведения тоннелей закрытым способом строительства можно отметить, что технологии строительства тоннелей имеют ряд недостатков (повышенные расходы на материалы, высокую энергоёмкость и трудоёмкость, низкое качество уплотнения отделки и т.д.), которые существенно снижают технико-экономические показатели и эксплуатационные свойства сооружений

Randomized in vivo evaluation of photodynamic antimicrobial chemotherapy on deciduous carious dentin

The aim of this randomized in vivo study was to compare antimicrobial chemotherapies in primary carious dentin. Thirty-two participants ages 5 to 7 years underwent partial caries removal from deep carious dentin lesions in primary molars and were subsequently divided into three groups: control [chlorhexidine and resin-modified glass ionomer cement (RMGIC)], LEDTB [photodynamic antimicrobial chemotherapy (PACT) with light-emitting diode associated with toluidine blue solution and RMGIC], and LMB [PACT with laser associated with methylene blue solution and RMGIC]. The participants were submitted to initial clinical and radiographic examinations. Demographic features and biofilm, gingival, and DMFT/DMFS indexes were evaluated, in addition to clinical and radiographic followups at 6 and 12 months after treatments. Carious dentin was collected before and after each treatment, and the number of Streptococcus mutans, Streptococcus sobrinus, Lactobacillus casei, Fusobacterium nucleatum, Atopobium rimae, and total bacteria was established by quantitative polymerase chain reaction. No signs of pain or restoration failure were observed. All therapies were effective in reducing the number of microorganisms, except for S. sobrinus. No statistical differences were observed among the protocols used. All therapies may be considered as effective modern approaches to minimal intervention for the management of deep primary caries treatment2010FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP#2010/07212-5; #2011/08392-

Prevention of enamel erosion through CO2 laser irradiation. An in situ study

A incidência de lesões dentais não cariosas vem aumentando nos últimos anos, entre outros fatores devido a mudanças de hábitos alimentares da população, assim como ao aumento na freqüência de indivíduos que apresentam distúrbios gastro-esofágicos ou doenças como bulimia. Esse estudo teve como objetivo avaliar se o laser de CO2 associado ou não ao flúor poderia prevenir a erosão ácida causada por ácido cítrico em esmalte. 10 voluntários participaram desse estudo in situ e cruzado, onde 4 tratamentos foram testados: G1 controle, sem tratamento; G2 irradiação com laser de CO2 através dos parâmetros: 0.3J/cm2-5s-226Hz; G3 aplicação tópica de flúor (1.25% - 3 minutos); G4 aplicação tópica de flúor + laser de CO2). Durante cada tratamento os voluntários utilizaram durante o dia e noite, exceto durante as refeições e higiene bucal, dispositivo palatino removível contando amostras de esmalte bovino esterilizadas. A desmineralização das amostras foi realizada através da imersão do dispositivo palatino contendo as amostras em 80 ml de ácido cítrico (0.05M pH 2.3) durante 20 minutos 2 vezes ao dia (entre 6:00 e 9:00 horas a primeira imersão e entre 18:00 e 21:00 horas na segunda imersão). Durante toda a pesquisa a higiene bucal foi realizada pelos voluntários com pasta dentifrícia sem flúor e sem o dispositivo palatino in situ. Antes e durante os tratamentos o intervalo de 7 dias foi mantido. Duas amostras foram coletadas do dispositivo palatino de cada voluntário nos dias 1, 3 e 5 (n=20/dia/tratamento). A perda de estrutura foi medida utilizando-se um perfilômetro digital. Mensurações da quantidade de flúor através da técnica de biópsia e espectroscopia de fluorescência de Raios-X por energia dispersiva (EDX) e análises morfológicas foram realizadas nos grupos nos dias 1, 3 e 5. Nos testes realizados in vitro, os mesmos tratamentos foram realizados durante os mesmos tempos, no entanto, ao invés das amostras estarem presas ao dispositivo palatino na cavidade bucal dos voluntários, as mesmas foram armazenadas em água deionizada em temperatura ambiente (n=12/dia/tratamento). Os resultados mostraram que os grupos laser e flúor + laser apresentaram uma redução significante (p<0.05) na perda de estrutura de esmalte em todos os tempos tanto no modelo in situ quanto in vitro. O grupo flúor apresentou uma redução significativa apenas no modelo in vitro (p<0.05). A análise por EDX mostrou que o grupo flúor + laser apresentou um aumento significativo quantidade de flúor comparado aos outros grupos, assim como as mensurações de flúor através da técnica de biópsia revelaram que apenas no dia 1 os grupos flúor + laser e flúor apresentaram uma quantidade significativa de flúor (p<0.05). A irradiação com laser de CO2 com os parâmetros de baixa fluência (0.3J/cm2, 5s e 226Hz), associada ou não ao flúor, deixou a superfície de esmalte mais resistente a erosão do causada por ácido cítrico tanto in situ quanto in vitro.Dental erosion is increasing as consequence of changing habits from the population, as well as increase of prevalence gastric reflux or vomiting. The possibility of making dental enamel more resistance to erosion is the objective of this study. 10 volunteers participated in the in situ study, in a crossover design with 4 treatments (G1 control, no treatment; G2 CO2 laser irradiation; 0.3J/cm2-5s-226Hz; G3 topical fluoride treatment 1.25% - 3 min; G4 - CO2 laser + fluoride treatment). For each treatment the volunteers used palatal appliances containing fixed sterilized bovine enamel samples during day and night except for meals. For erosive demineralization the mouth appliances were immersed extra-orally in 80ml of 0.05M citric acid (pH 2.3) for 20 minutes twice daily. Individual oral hygiene was performed with fluoride-free products and without the appliance in situ. Before and between the treatment periods, a 1 week wash out period was included. Two samples were collected from the appliances for analysis on days 1, 3 and 5 (n=20/day/treatment). Surface loss was measured by digital profilometer. Additional fluoride measures, morphological analyses and EDX analyses were performed. For the in vitro model all the procedures were repeated, but instead of maintaining the samples in oral cavity, they were maintained for the same time in deionized water (n=12/day/treatment) and the surface loss was analyzed by digital profilometer. The results showed that the groups laser and fluoride + laser presented significant lower surface loss in all times both in situ and in vitro models. Fluoride presented significant surface loss only in the in vitro model. The EDX analysis, showed that fluoride + laser group presented significant more fluoride than the others groups, and the fluoride measurements of the samples showed that only in the first day the groups fluoride and fluoride + laser presented significant more fluoride that the other groups. CO2 laser irradiation at 0.3J/cm2 (5s, 226Hz) associated or not with fluoride decreases enamel erosive surface loss caused by citric acid, in situ and in vitro

Prevention of high glucose concentration effects in fibroblasts proliferation and migration by low intensity laser therapy.

Muitas complicações do Diabetes Mellitus, dentre elas a deficiência na cicatrização de feridas, estão associadas à hiperglicemia crônica, que promove estresse oxidativo e glicação protéica aleatória. O objetivo desse estudo foi avaliar os efeitos de elevada contração de glicose (ECG) sobre a migração, proliferação e morte de fibroblastos cultivados, e o potencial da terapia com laser em baixa intensidade (LILT) (660 e 780 nm; 40mW; 2, 5, 10 e 30J/cm2) na prevenção desses efeitos. A ECG reduziu a proliferação em cerca de 40%, reduziu a migração em 50% e aumentou a morte celular em 30%. A irradiação diária com LILT em 660nm e 10J/cm2 mostrou-se eficaz na prevenção desses efeitos sobre a proliferação e migração celular. A ECG tambem aumentou a produção de especies reativas de oxigênio pelas células, um efeito nao observado em células irradiadas com LILT. Dessa forma, pode-se sugerir que a terapia com LILT favorece a proliferação e migração de células cultivadas sob ECG, processos essenciais para a cicatrização, possivelmente através de um efeito antioxidante.Diabetic complications, including wound healing deficiency, are usually associated to chronic hyperglycemia, which leads to oxidative stress and aleatory protein glycation. The aim of this study was to evaluate the effects of high glucose concentrations (HGC) on proliferation, migration and death of cultured fibroblasts, as well as the potential effect of low intensity laser therapy (LILT) (660 and 780 nm; 40mW; 2, 5, 10 and 30J/cm2) preventing these effects. HGC reduced cell proliferation in about 40%, cell migration in about 50% and increased cell death in 30%. Daily irradiation at 660nm and 10J/cm2 was efficient preventing the effects on cell proliferation and migration. HGC also increased the production of reactive oxygen species, an effect totally prevented by LILT. The results suggest that LILT favors cell proliferation and migration, processes very important for healing, possibly through an anti-oxidant effect

Prevention of enamel erosion through CO2 laser irradiation : an in situ study

Dental erosion is increasing as consequence of changing habits from the population, as well as increase of prevalence gastric reflux or vomiting. The possibility of making dental enamel more resistance to erosion is the objective of this study. 10 volunteers participated in the in situ study, in a crossover design with 4 treatments (G1 – control, no treatment; G2 – CO2 laser irradiation; 0.3 J/cm2 – 5 µs - 226Hz; G3 – topical fluoride treatment – 1.25% - 3 min; G4 - CO2 laser + fluoride treatment). For each treatment the volunteers used palatal appliances containing fixed sterilized bovine enamel samples during day and night except for meals. For erosive demineralization the mouth appliances were immersed extra-orally in 80 mL of 0.05 M citric acid (pH 2.3) for 20 minutes twice daily. Individual oral hygiene was performed with fluoride-free products and without the appliance in situ. Before and between the treatment periods, a 1 week wash out period was included. Two samples were collected from the appliances for analysis on days 1, 3 and 5 (n=20/day/treatment). Surface loss was measured by digital profilometer. Additional fluoride measures, morphological analyses and EDX analyses were performed. For the in vitro model all the procedures were repeated, but instead of maintaining the samples in oral cavity, they were maintained for the same time in deionized water (n=12/day/treatment) and the surface loss was analyzed by digital profilometer. The results showed that he groups laser and fluoride + laser presented significant lower surface loss in all times both in situ and in vitro models. Fluoride presented significant surface loss only in the in vitro model. The EDX analysis, showed that fluoride + laser group presented significant more fluoride than the others groups, and the fluoride measurements of the samples showed that only in the first day the groups fluoride and fluoride + laser presented significant more fluoride that the other groups. CO2 laser irradiation at 0.3 J/cm2 (5 µs, 226 Hz) associated or not with fluoride decreases enamel erosive surface loss caused by citric acid, in situ and in vitro. This effect is still observed after 5 days of repeated acid attacks

Immediate laser-induced hemostasis in anticoagulated rats subjected to oral soft tissue surgery: a double-blind study

<div><p>Abstract Given the growing trend towards medical indications for continuous use of anticoagulants, the number of patients on these medications continues to rise. The management of patients on oral anticoagulants requiring oral surgical procedures has aroused much controversy. Changes in an anticoagulation regimen are associated with an increased risk of thromboembolism. However, it seems logical and advantageous for the patients’ health if surgery could be performed without any change to the anticoagulation therapy. In dentistry, high-power lasers have been poorly explored in this field. The hemostatic properties of high-power lasers could be helpful during oral soft tissue surgeries in anticoagulated patients. The aim of this study was to compare bleeding time in anticoagulated rats after lingual frenectomy performed with a scalpel or diode laser with bleeding time in healthy animals. Twenty-four male Wistar rats were assigned to four groups (n = 6): (CS) Control-Scalpel Surgery; (AS) Anticoagulated-Scalpel Surgery; (CL) Control-Laser (diode laser 810 nm/1.5 W) Surgery; and (AL) Anticoagulated-Laser Surgery (diode laser 810 nm/1.5 W). Warfarin administration was used to induce anticoagulation. Blood was blotted every 30 seconds with filter paper until bleeding stopped to verify bleeding time. Two blinded researchers performed the surgeries and collected the bleeding time data. Diode laser surgery led to complete hemostasis in rats during and after lingual frenectomy. Zero bleeding was assessed during surgeries and after diode laser surgeries in anticoagulated rats. Laser-induced hemostasis offered an alternative solution to the controversial issue of intraoperative and postoperative bleeding control in patients on anticoagulation therapy.</p></div