Search

Background: Rehabilitation with dental implants has been frequent in athletes with extensive activity that involves contact sports. The use of mouthguards can reduce the incidence and severity of sports-related oral injuries.Aim: The purpose of this study was to evaluate mouthguard shock absorption ability, strain, and stress generation during impact on dental implants placed in the anterior maxilla. The mouthguard material was also characterized.Materials and Methods: Sixty experimental models were created and divided into six groups (n = 10): implant type, external hexagon (EH) and Morse taper (MT); without and with two mouthguards (MTG), EVA custom-fitted (Ct-MTG) and standard self-adapted (St-MTG). The Shore A hardness, EVA sheet and mouthguard thickness, and elastic modulus were measured to characterize the mouthguard material. A strain gauge was attached to the palatal surface of the implant abutment, which was subjected to an impact test. Distortion of the abutment and implant was determined after impact from centroid displacements in standardized radiographic images. Two-dimensional finite element models were created to represent the six groups and were submitted to nonlinear dynamic impact analysis. The data were statistically analyzed using analysis of variance (ANOVA) and Tukey test (significance= .05).Results: Ct-MTG resulted in higher Shore A hardness (P < .001). After the heat-forming process, the St-MTG maintained the original thickness, but the Ct-MTG thickness had decreased. The elastic modulus of EVA was 18.1 u00b1 0.5 MPa. The mouthguard presence reduced strain values significantly (P < .001), particularly for Ct-MTG. There was no significant difference between implant connection types EH and MT (P = .547).Conclusions and Clinical Implications: The external hexagon abutment resulted in higher stress and micro-displacement values. The mouthguard was able to absorb 40% to 46% of the energy caused by the impact on the dental implant. This study supported the importance of the use of MTG for shock absorption for patient rehabilitated with dental implant. It was evident that the material Ct-MTG thermoforming suffers thickness reduction, being necessary to use 2 sheets for a better result, especially in anterior teeth.

Backgroud: The presence of metal in irradiation field can create a radiomorbidity of local tissue induced by increasing dose of irradiation, generated from backscatter high energy photons and electrons at the tissue-metal interface, which can compromise bone repair. Ionizing radiation (IR) can also be negatively influenced bone/implant integration resistance and little comprehensive information is available regarding the effects of scattered irradiation on regions with implants.Aim: This study analyzed the effect of ionizing IR on bone microarchitecture and biomechanical properties in osseointegrated dental implants.Materials and Methods: Twenty rabbits received 3 implants and were divided into 2 groups (n = 10): Control group (NoIr) - animals without IR; Irradiation group (Ir) - animals were irradiated with 30 Gy in a single dose, 2 weeks after implant installation. The animals were euthanized 4 weeks after implant installation, implant/bone were removed and submitted to microcomputed tomography (micro-CT) to calculate bone cortical volume (CtV), cortical thickness (CtTh) and porosity (CtPo). Elasticity modulus (E) and Vickers hardness (VHN) were calculated by dynamic indentation test. Failure load, displacement and stiffness were calculated from Pull-out test. Ir group were performed two measurements in micro-CT and dynamic indentation analyses: close 1 mm to the implant surface (Ir-C), and 2.5 mm from the external limit of the first close measurement (Ir-D).Results: The bone of Ir-C group had lower E, VHN, CtTh, and CtV values and higher CtPo than the Ir-D group. Ir-D group had lower E, VHN, CtTh values and higher CtPo than the NoIr group. NoIr group had higher failure load, displacement and stiffness values than the Ir group.Conclusions: IR in osseointegrated implants resulted in negative effects on microarchitecture and biomechanical properties of bone tissue, mainly near the surface of the implant.Clinical Implications: The increase dental implant on rehabilitation and need for some patients submitted to radiotherapy, our results showed that IR decrease bone-to-implant contact in osseointegrated implants.

This study evaluated the effect of addition of alumina particles (polycrystalline or monocrystalline), with or without silica coating, on the optical and mechanical properties of a porcelain.Groups tested were: control (C), polycrystalline alumina (PA), polycrystalline alumina-silica (PAS), monocrystalline alumina (MA), monocrystalline alumina-silica (MAS). Polycrystalline alumina powder was synthesized using a polymeric precursor method; a commercially available monocrystalline alumina powder (sapphire) was acquired. Silica coating was obtained by immersing alumina powders in a tetraethylorthosilicate solution, followed by heat-treatment. Electrostatic stable suspension method was used to ensure homogenous dispersion of the alumina particles within the porcelain powder. The ceramic specimens were obtained by heat-pressing. Microstructure, translucency parameter, contrast ratio, opalescence index, porosity, biaxial flexural strength, roughness, and elastic constants were characterized.A better interaction between glass matrix and silica coated crystalline particles is suggested in some analyses, yet further investigation is needed to confirm it. The materials did not present significant differences in biaxial flexural strength, due to the presence of higher porosity in the groups with alumina addition. Elastic modulus was higher for MA and MAS groups. Also, these were the groups with optical qualities and roughness closer to control. The PA and PAS groups were considerably more opaque as well as rougher.Porcelains with addition of monocrystalline particles presented superior esthetic qualities compared to those with polycrystalline particles. In order to eliminate the porosity in the ceramic materials investigated herein, processing parameters need to be optimized as well as different glass frites should be tested.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior The bone is a connective resilient tissue in continuous modification process. This tissue may be adversely affected by action of ionizing radiation, compromising the healing process and osseointegration. The integration between bone and implant is modulated by the surface of dental implants. This study aimed to evaluate overall by mechanical and histomorphometric characterization of bone tissue and its integration to the dental implants in normal conditions and when subjected to ionizing radiation. This study was divided into five specific objectives; specific objective 1: generate, through dynamic indentation test protocol to measure the Vickers hardness and the modulus of elasticity of the periimplantar bone using blocks performed by bone/implant extracted by the rabbit s tibias; specific objective 2: to evaluate the stability and osseointegration of dental implants with different surface treatments by measuring the resonant frequency and histomorphometric analysis quantifying the contact bone/implant and area fraction occupied by bone implants installed in the tibia of rabbits after periods of 2 and 4 weeks; specific objective 3: to assess the effect of ionizing radiation on tibias of rabbits modulated by the time elapsed from the application of ionizing radiation on the force to fracture, work to failure and stiffness of bone tissue measured by 3-bending flexural strength test, on the Vickers hardness and elastic modulus calculated by means of dynamic indentation test, and on the cortical bone thickness, bone volume and bone porosity percentage measured by microCT and quantification of osteocytes lacunarity, measured by histological evaluation; specific objective 4: to evaluate the effects of ionizing radiation on previous installed and osseointegrated implants by association of different methods involving Vickers hardness and modulus of elasticity measured by dynamic indentation; implant/bone stability measured by pull-out test, the thickness of cortical bone, volume of bone tissue, and percentage of bone porosity measured by microCT; specific objective 5: generate manuscript that summarize the main findings of specific objective 1, 2, 3 and 4 designated to Brazilian clinical fulfilling the social function of knowledge generation. After analyzing the results it can be concluded that the dynamic indentation method proved to be highly useful for individualized characterization of the periimplantar bone tissue. The implant surfaces with different wettability are capable of producing adequate integration bone / implant installed using instrumentation normal condition. Radiation therapy negatively affected the mechanical and structural properties of bone tissue. In areas rehabilitated with dental implant, the radiotherapy reduced partially the stability of implant/bone interface, thereby reducing the mechanical properties of the periimplantar bone tissue, mainly that bone tissue located close to implant surface, which can compromise the long-term prognosis. O osso é um tecido conjuntivo resiliente em contínuo processo de modificação. Este tecido pode sofrer efeitos adversos frente ação da radiação ionizante, comprometendo o processo de reparo e a osseointegração. Integração esta que é modulada pela superfície de implantes dentais, Este trabalho tem como objetivo geral avaliar por meio da caracterização mecânica e histomorfométrica o tecido ósseo e a sua integração a implantes dentais em condições de normalidade e quando submetido à radiação ionizante. Este estudo foi dividido em cinco objetivos específicos; objetivo específico 1: gerar, por meio de ensaio dinâmico de indentação, protocolo para mensurar a dureza Vickers e o módulo de elasticidade do osso periimplantar, utilizando blocos composto por implante dental/osso extraídos de tíbias de coelhos; objetivo específico 2: avaliar a estabilidade e osseointegração de implantes com diferentes tratamentos de superfícies por meio da mensuração de frequência de ressonância e da análise histomorfométrica quantificando o contato osso/implante e fração de área ocupada pelo osso em implantes instalados em tíbias de coelhos, nos períodos de 2 e 4 semanas; objetivo específico 3: avaliar o efeito da radiação ionizante em tíbias de coelhos em função do período decorrido da aplicação da radiação ionizante nas propriedades de força, energia e rigidez do tecido ósseo por meio de ensaios mecânicos de resistência flexural, dureza Vickers e módulo de elasticidade por meio de ensaio de indentação dinâmica, espessura de cortical óssea, volume de tecido ósseo e percentual de porosidade por meio de microCT e quantificação das lacunas de osteócitos vazias, por meio de avaliação histológica; objetivo específico 4: avaliar o efeito da radiação ionizante sobre implantes previamente instalados e osseointegrado por meio de associação de metodologias envolvendo dureza Vickers e módulo de elasticidade mensurado por indentação dinâmica, resistência de integração implante/osso por meio de ensaio pull-out, espessura de cortical óssea, volume de tecido ósseo e percentual de porosidade por meio de microCT; objetivo específico 5: gerar síntese dos achados dos objetivos 1, 2, 3 e 4 em um artigo de comunicação aos clínicos brasileiros cumprindo a função social da geração do conhecimento. Após análise dos resultados pode-se concluir que o método de indentação dinâmica mostrou ser altamente útil na caracterização individualizada do tecido ósseo periimplantar. As superfícies de implantes com diferente molhabilidade são capazes de produzir adequada integração osso/implante em condição normal de instrumentação do osso cortical. A radioterapia interfere nas propriedades mecânicas e estruturais do tecido ósseo. Em áreas reabilitadas com implantes a radioterapia resulta em redução parcial da integração osso/implante, reduzindo as propriedades mecânicas do osso periimplantar principalmente daquele localizado próximo à superfície do implante, o que pode comprometer o prognóstico de longo prazo. Doutor em Odontologia

ObjectiveEvaluate the biological performance of titanium alloys grade IV under different surface treatments: sandblasting and double etching (Experimental surface 1; Exp1, NEODENT); surface with wettability increase (Experimental surface 2; Exp2, NEODENT) on response of preliminary differentiation and cell maturation.Material and methodImmortalized osteoblast cells were plated on Exp1 and Exp2 titanium discs. The polystyrene plate surface without disc was used as control group (C). Cell viability was assessed by measuring mitochondrial activity (MTT) at 4 and 24 h (n = 5), cell attachment was performed using trypan blue exclusion within 4 hours (n = 5), serum total protein and alkaline phosphatase normalization was performed at 4, 7 and 14 days (n = 5). Data were analyzed using one-way ANOVA and Tukey test.ResultThe values of cell viability were: 4h: C– 0.32±0.01A; Exp1– 0.34±0.08A; Exp2– 0.29±0.03A. 24h: C– 0.43±0.02A; Exp1– 0.39±0.01A; Exp2– 0.37±0.03A. The cell adhesion counting was: C– 85±10A; Exp1- 35±5B; Exp2– 20±2B. The amounts of serum total protein were 4d: C– 40±2B; Exp1– 120±10A; Exp2– 130±20A. 7d: C– 38±2B; Exp1– 75±4A; Exp2– 70±6A. 14 d: C– 100±3A; Exp1– 130±5A; Exp2– 137±9A. The values of alkaline phosphatase normalization were: 4d: C– 2.0±0.1C; Exp1– 5.1±0.8B; Exp2– 9.8±2.0A. 7d: C– 1.0±0.01C; Exp1– 5.3±0.5A; Exp2– 3.0±0.3B. 14 d: C– 4.1±0.3A; Exp1– 4.4±0.8A; Exp2– 2.2±0.2B. Different letters related to statistical differences.ConclusionThe surfaces tested exhibit different behavior at dosage of alkaline phosphatase normalization showing that the Exp2 is more associated with induction of cell differentiation process and that Exp1 is more related to the mineralization process. ResumoObjetivoAvaliar o desempenho biológico de ligas de titânio grau IV submetidos a diferentes tratamentos de superfície – jateamento e duplo ataque ácido (Superfície experimental 1; Exp1, NEODENT) e superfície com aumento na molhabilidade (Superfície experimental 2; Exp2, NEODENT) em resposta preliminar de diferenciação e maturação celular.Material e métodoForam plaqueados osteoblastos imortalizados sobre discos de titânio de Exp1 e Exp2 e como controle o poço da placa de cultura sem disco (C). Empregou-se ensaios de viabilidade celular (MTT) em 4 e 24 horas (n = 5), adesão celular em 4 horas (n = 5), dosagem de proteínas totais e fosfatase alcalina normalizada em 4, 7 e 14 dias (n = 5). Os dados foram analisados por ANOVA em fator único seguido de teste de Tukey.ResultadoOs valores de viabilidade celular foram: 4h: C– 0,32±0,01A; Exp1 – 0,34±0,08A; Exp2– 0,29±0,03A. 24h: C– 0,43±0,02A; Exp1– 0,39±0,01A; Exp2– 0,37±0,03A. A contagem de adesão celular foi: C– 85±10A; Exp1– 35±5B; Exp2– 20±2B. Os valores de proteínas totais foram: 4d: C– 40±2B; Exp1– 120±10A; Exp2– 130±20A. 7d: C– 38±2B; Exp1– 75±4A; Exp2– 70±6A. 14 d: C– 100±3A; Exp1– 130±5A; Exp2– 137±9A. Os valores de fosfatase alcalina normalizada foram: 4d: C– 2,0±0,1C; Exp1– 5,1±0,8B; Exp2– 9,8±2,0A, 7d: C– 1,0±0,01C; Exp1– 5,3±0,5A; Exp2– 3,0±0,3B, 14 d: C– 4,1±0,3A; Exp1– 4,4±0,8A; Exp2– 2,2±0,2B. Letras diferentes representam diferenças estatísticas.ConclusãoAs superfícies testadas apresentaram comportamento diferenciado na dosagem de fosfatase alcalina normalizada traduzindo que Exp2 está relacionado com processo de indução de diferenciação celular e Exp1 relacionado com processo de mineralização.

Com base em revisão bibliográfica discute-se a literatura produzida nos anos de 1999 a 2011, no campo da saúde coletiva, sobre uma importante estratégia de prevenção da transmissão do HIV: o aconselhamento e testagem anti-HIV. O artigo realiza um balanço da literatura internacional, analisando criticamente os aspectos mais assinalados pela comunidade científica, apontando divergências e convergências entre os estudos e identificando lacunas que possam estimular o desenvolvimento de novas pesquisas neste campo temático. Como resultado, evidenciou-se que os processos de decisão de realizar um teste e a experiência da testagem são discutidos na literatura com abordagens fragmentadas, sejam de ordem individual ou institucional. Para compreender diversas dimensões implicadas na adoção de uma prática preventiva como o teste HIV, é preciso contemplar indicadores sociais tais como gênero, religião, identidade sexual, raça/cor, e relacioná-los às políticas públicas e à operacionalização dos serviços de saúde. O uso expressivo do conceito de risco (aliado às categorias de grupo, comportamento, percepção) e de escalas quantitativas para aferir a percepção individual do risco como uma barreira para a realização do teste ilustra o foco excessivo sobre uma dimensão individual e parcial do problema. Based in a bibliographical review, this paper discusses the literature produced between 1999 and 2011 in the field of Public Health over an important strategy of prevention of the transmission of HIV virus: the counseling and testing for HIV. The article critically analyzes the aspects highlighted by the literature, indicating divergences and convergences among the studies and identifying possible gaps that can stimulate new researches in this thematic field. The results of this work indicate a tendency of the literature in treating the processes of decision and the experience of taking a test under fragmented approaches at an individual or institutional level. To understand the many dimensions implied in the adoption of a preventive practice such as the HIV test, it's imperative contemplate social determinants such as gender, religion, sexual identity, race/ethnicity, and the intersection of these with individual factors or with those related to the public politics and operation of health services. The expressive use of the risk concept (group, behavior, perception) and of quantitative scales to measure the individual risk perception as a barrier for the test illustrates the focus on an individual and partial dimension of the problem.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior Controversy exists concerning the influence of bone loss and of the dental splinting over strain of dental support tissue. The aim of this study was to analyze the effect of support bone loss and the dental splinting type on strain of the anterior mandibular bone in different regions, in simulation of the polystyrene resin mandibular model. Eighty intact human mandibular teeth (20 central incisors, 20 lateral incisors, 20 canines and 20 first premolars; being half of right side and half of left side) were selected and randomly divided in 10 groups. For strain gauge test, 10 mandibular replicas were made in polystyrene resin. Four strain gauges were fixed on 2 mandibular surfaces: buccal surface and lingual surface; and 2 regions: central incisor region and lateral incisor region. On all specimens (n=10) were tested 7 experimental situations: Cont, control group, without bone support alterations and no splinting; Po, simulating 5mm of bone loss between canines teeth; PoRc, Po condition associated with splinting made between canines teeth with composite resin only; PoFa, Po condition and splinting with 0.25mm wire ligature only; PoFaRc, Po condition with splinting made with association between wire ligature and composite resin; PoFvRcExt, Po condition with extra-coronal splinting made with association between fiber glass and composite resin; PoFvRcExt, Po condition with intracoronal splinting made with association between fiber glass and composite resin. The strain values were assessed under compressive oblique load until 150N applied over anterior teeth in a universal testing machine. The data obtained for 50N, 100N and 150N were individually analyzed with 3-way ANOVA followed by the Scheffe test (=.05). Statistical analysis showed that the strain on buccal surface was always higher than on lingual surface, and the strain measured on incisor central region was always higher than on incisor lateral region. The simulation of bone loss resulted in significant increase on strain for 100N and 150N loads. The dental splinting types that use adhesive system and composite resin resulted in significant decrease on strain measured in all sites, with values similar to Cont levels. Within the limitations of this study, it was observed that the loss of dental support increase the strain values mainly in buccal region. The dental splinting made with composite resin produced significantly decrease on strain measured on dental support irrespective of load intensity tested. Existem controvérsias em relação à influência da perda óssea e da contenção na deformação do tecido de suporte dental. O objetivo deste estudo foi analisar a influência da perda óssea e da contenção dental na deformação do tecido de suporte na região anterior da mandíbula em suas diferentes áreas. Oitenta dentes humanos (20 incisivos centrais, 20 incisivos laterais, 20 caninos, 20 primeiros pré-molares) hígidos foram selecionados e distribuídos aleatoriamente em 10 grupos. Para o ensaio de extensometria, em 10 réplicas de mandíbula em resina de poliestireno, 4 extensômetros foram fixados na região do incisivo central e lateral direito, sendo 2 na face vestibular e 2 na face lingual. Nos espécimes (n=10) foram, de forma seqüencial, aplicado as 7 condições experimentais de suporte dental: Cont, controle, sem alteração de normalidade; Po, simulando perda óssea de 5mm; PoRc, Po com contenção feita em resina composta de canino do lado direito a canino do lado esquerdo; PoFa, Po com contenção feita com fio de aço de 0,25mm; PoFaRc, Po com contenção feita com fio de aço de 0,25mm associado a resina composta; PoFvRcExt, Po com contenção realizada com fibra de vidro associado a resina composta extra-coronária e PoFvRcInt, Po com contenção empregando fibra de vidro associado a resina composta intra-coronária. Os espécimes foram submetidos à carga de compressão oblíqua a velocidade de 0,5mm/min até o limite de 150N em máquina de ensaio mecânico. As deformações obtidas para as intensidades de 50, 100 e 150N de carregamento foram submetidas a 3-way ANOVA e o teste de Scheffe ( =.05). Os resultados mostraram que em todos os grupos a deformação na superfície vestibular foi significantemente maior que na lingual. A deformação na região do incisivo central vestibular foi significantemente maior que na região do incisivo lateral. A perda de estrutura de suporte resulta em significante aumento na deformação para as cargas de 100 e 150N. As contenções dentais que empregam resina composta resultaram em redução significativa da deformação aos níveis do grupo Cont. A redução do suporte dental aumenta a deformação principalmente na região vestibular. As contenções dentais que empregam resina composta conseguem reduzir significativamente a deformação independente da intensidade de carregamento. Mestre em Odontologia