The effects of seismic forces and thermal expansion on bridge performance necessitate an accurate understanding of the relationship between passive force and backwall deflection. In past case studies, skewed bridges exhibited significantly more damage than non-skewed bridges. These findings prompted studies involving numerical modeling, lab-scale tests, and large-scale tests that each showed a dramatic reduction in passive force with increased skew. Using these results, a correlation was developed between peak passive force and backwall skew angle. The majority of these tests had length to height ratios of 2.0; however, for several abutments in the field, the length to height ratio might be considerably higher than 2.0. This change in geometry could potentially affect the validity of the previously found passive force reduction correlation. To explore this issue, laterally loaded, large-scale pile cap tests were performed with densely compacted sand at a length of 11 ft (3.35 m) and a height of 3 ft (0.91 m), resulting in a length to height ratio of 3.7. The backwall interface was adjusted to fit three various skew angles including: 0°, 15° and 30°. The behavior of both the pile cap and adjacent soil backfill were monitored under these conditions. The peak passive force for the 15° and 30° tests were found to be 71% and 45%, respectively, of the peak passive force for the 0° skew test. These findings are relatively consistent with previously performed tests. Passive forces peaked at deflections between 2% and 5% of the backwall height, decreasing with skew angle. All skews exhibited a log spiral failure plane that transitioned into a linear plane. These results also agreed with previously reported values for large-scale passive force-deflection tests. Rotation of the pile cap was detected in the direction opposite to the skew. Higher pressures were found to be on both corners of the pile cap than in the middle portion, as is suggested by the elastic theory.

Skewed bridges have exhibited poorer performance during lateral earthquake loading in comparison to non-skewed bridges (Apirakvorapinit et al. 2012; Elnashai et al. 2010). Results from numerical modeling by Shamsabadi et al. (2006), small-scale laboratory tests by Rollins and Jessee (2012), and several large-scale tests performed by Rollins et al. at Brigham Young University (Franke 2013; Marsh 2013; Palmer 2013; Smith 2014; Frederickson 2015) led to the proposal of a reduction curve used to determine a passive force skew reduction factor depending on abutment skew angle (Shamsabadi and Rollins 2014). In all previous tests, a uniform longitudinal load has been applied to the simulated bridge abutment. During seismic events, however, it is unlikely that bridge abutments would experience pure longitudinal loading. Rather, an inclined loading situation would be expected, causing rotation of the abutment backwall into the backfill. In this study, a large-scale test was performed where inclined loading was applied to a 30° skewed bridge abutment with sand backfill and compared to a baseline test with uniform loading and a non-skewed abutment. The impact of rotational force on the passive resistance of the backfill and the skew adjust factor was then evaluated. It was determined that inclined loading does not have a significant effect on the passive force skew reduction factor. However, the reduction factor was somewhat higher than predicted by the proposed reduction curve from Shamsabadi and Rollins 2014. This can be explained by a reduction in the effective skew angle caused by the friction between the side walls and the back wall. The inclined loading did not change the amount of movement required to mobilize passive resistance with ultimate passive force developing for displacements equal to 3 to 6% of the wall height. The rotation of the pile cap due to inclined loading produced higher earth pressure on the obtuse side of the skew wedge, as was expected.These findings largely resolve the concern that inclined loading situations during an earthquake may render the proposed passive force skew reduction curve invalid. We suggest that the proposed reduction curve remains accurate during inclined loading and should be implemented in current codes and practices to properly account for skew angle in bridge design.

Skewed bridges have exhibited poorer performance during lateral earthquake loading in comparison to non-skewed bridges (Apirakvorapinit et al. 2012; Elnashai et al. 2010). Results from numerical modeling by Shamsabadi et al. (2006), small-scale laboratory tests by Rollins and Jessee (2012), and several large-scale tests performed by Rollins et al. at Brigham Young University (Franke 2013; Marsh 2013; Palmer 2013; Smith 2014; Frederickson 2015) led to the proposal of a reduction curve used to determine a passive force skew reduction factor depending on abutment skew angle (Shamsabadi and Rollins 2014). In all previous tests, a uniform longitudinal load has been applied to the simulated bridge abutment. During seismic events, however, it is unlikely that bridge abutments would experience pure longitudinal loading. Rather, an inclined loading situation would be expected, causing rotation of the abutment backwall into the backfill. In this study, a large-scale test was performed where inclined loading was applied to a 30 skewed bridge abutment with sand backfill and compared to a baseline test with uniform loading and a non-skewed abutment. The impact of rotational force on the passive resistance of the backfill and the skew adjust factor was then evaluated. It was determined that inclined loading does not have a significant effect on the passive force skew reduction factor. However, the reduction factor was somewhat higher than predicted by the proposed reduction curve from Shamsabadi and Rollins 2014. This can be explained by a reduction in the effective skew angle caused by the friction between the side walls and the back wall. The inclined loading did not change the amount of movement required to mobilize passive resistance with ultimate passive force developing for displacements equal to 3 to 6% of the wall height. The rotation of the pile cap due to inclined loading produced higher earth pressure on the obtuse side of the skew wedge, as was expected.These findings largely resolve the concern that inclined loading situations during an earthquake may render the proposed passive force skew reduction curve invalid. We suggest that the proposed reduction curve remains accurate during inclined loading and should be implemented in current codes and practices to properly account for skew angle in bridge design.

A proposta deste estudo foi avaliar o comportamento mecânico de dois designs de conexão implante/abutment; hexágono externo e triângulo interno, utilizando parafusos convencionais e parafusos experimentais cone morse. O estudo foi dividido em duas fases: na primeira, foi avaliado o efeito do carregamento mecânico na perda de torque dos parafusos. 40 implantes foram utilizados. Os implantes e abutments foram divididos em 4 grupos: Grupo 1: hexágono externo/parafuso convencional (HE); Grupo 2: triângulo interno/parafuso convencional (TI); Grupo 3: hexágono externo/parafuso cone morse (HECM); Grupo 4: triângulo interno/parafuso cone morse (TICM). Os abutments foram instalados em seus respectivos implantes com torque de aperto de 32Ncm; após intervalo de 10 minutos, foram medidos os valores dos torques de desaperto. Os abutments foram instalados novamente com torque de 32Ncm, e após 10 minutos foram carregados mecanicamente, simulando 1 ano de função oral normal; após o carregamento, os torques de desaperto dos parafusos foram medidos novamente. Os dados foram analisados com o teste one-way ANOVA, com nível de significância de p≤0,05%. Análises por microscopia óptica foram realizadas antes e após os ensaios. Na segunda fase, foi avaliada a resistência à flexão dos conjuntos implante/abutment. Os mesmos 40 conjuntos foram utilizados. Os testes foram realizados em máquina universal de ensaios, com célula de carga de 500 kgf, deslocamento de 1mm/min, e inclinação de 45°. A força máxima de flexão (FMF) e a força de ruptura (FR) foram determinadas. As informações coletadas foram analisadas com o teste one-way ANOVA, para p≤0,05. Análises por microscopia óptica foram realizadas para estudo dos componentes após os ensaios de resistência flexural. Os resultados sugeriram que houve diferença significante (p=0,000) na pré-carga residual antes e após carregamento mecânico entre os dois tipos de parafuso: os parafusos cone morse apresentaram torques de desaperto significativamente superiores aos apresentados pelos parafusos planos convencionais. Houve diferença significante nos resultados da FMF obtidos pelos parafusos planos convencionais e pelos parafusos cone morse (p=0,011), sendo que os conjuntos implante/abutment com parafusos cone morse apresentaram maior resistência à flexão. Para os resultados da FR houve influência significante do tipo de conexão (p=0,019), com melhores resultados para a conexão triângulo interno. Considerando as limitações deste estudo, concluiu-se que os parafusos cone morse apresentaram maiores torques de desaperto em comparação aos parafusos planos convencionais; que o design da conexão protética não teve influência significante sobre o torque de desaperto dos parafusos; que os parafusos cone morse obtiveram maiores valores de resistência à flexão, e que a conexão em triângulo interno obteve maiores valores para a força de ruptura. / The purpose of this study was to evaluate the mechanical behavior of two implant/abutment connection designs; external hex and internal tri-channel, using conventional screws and experimental conical screws. The study was divided in two parts; the first evaluated the effect of mechanical loading in the torque loss of the screws. 40 implants were used. The implants and abutments were divided in 4 groups: Group 1: external hex/conventional screw (HE); Group 2: tri-channel/conventional screw (TI); Group 3: external hex/conical screw (HECM); Group 4: tri-channel/conical screw (TICM). The abutments were installed in their respective implants with a tightening torque of 32Ncm, after a 10 minute interval, loosening torque were measured. The abutments were installed again with a 32Ncm torque, and after 10 minutes, they were mechanically loaded, simulating 1 year of normal oral function; after loading, loosening torques of the screws were measured again. Data were analyzed with one-way ANOVA test, with significance level of p≤0,05. Optical microscopy analysis were performed before and after the tests. The second part evaluated the flexural resistance of the implant/abutment assemblies. The same 40 assemblies were used. The tests were performed in an universal testing machine, with a 500kgf load cell, 1mm/min displacement, and 45° angulation. Maximum bending moment (FMF) and rupture force (FR) were determined. Collected information were analyzed with one-way ANOVA test, for p≤0,05. Optical microscopy analysis were performed for study of the components after the flexural resistance tests. The results suggested that there were significant differences (p=0,000) in the residual preload before and after mechanical loading between the two types of screws: conical screws showed significantly higher loosening torques than conventional flat screws. There were significant differences in the FMF obtained by the conventional flat screws and by the conical screws (p=0,000); the implant/abutment assemblies with conical screws presented higher flexural resistance. For the FR results, there was significant influence of the type of connection (p=0,019); the tri-channel connection presented better results. Considering the limitations of this study, it was concluded that the conical screws presented higher loosening torques compared to conventional flat screws; the design of the implant/abutment connection presented no significant influence on the loosening torques of the screws; conical screws showed higher bending moment values; and the tri-channel connection obtained higher rupture force values.

O sistema de osseointegração desenvolvido por Branemark revolucionou o campo das reabilitações protéticas, incentivando os profissionais a indicar e realizar próteses do tipo overdentures. Estes dispositivos representam uma ótima alternativa para solucionar os problemas dos pacientes desdentados, insatisfeitos por diversos fatores. Várias são as associações entre os implantes e os sistemas de conexões empregados em overdentures. A literatura e a prática clínica fazem observar que na dependência do sistema de conexão empregado, há uma diferença no comportamento biomecânico, realizado por este conjunto: prótese/implante/conexão. Desta forma, é importante analisar como as tensões se distribuem sobre as estruturas que suportam estas cargas, uma vez que não existe o ligamento periodontal ao redor dos implantes que promove o mecanismo fisiológico, natural nos dentes. Assim, o objetivo desta investigação foi de avaliar, com o auxílio do método fotoelástico, o comportamento da distribuição das tensões em sobredentaduras (overdentures), suportadas por quatro implantes Ankylos®/ Dentsply®, utilizando-se o sistema protético de conexão de coroas cônicas Syncone®/ Dentsply®, onde se comparou duas formas de distribuição dos implantes, na primeira (CPM1) os implantes foram posicionados nas regiões de incisivos centrais e pré-molares e o segundo (CPM2) os implantes estavam posicionados nas regiões de caninos e pré-molares. Os modelos receberam cargas de forma crescente de 0,0 a 9,0 kg e, as tensões resultantes nas estruturas de suporte, foram analisadas fotoelasticamente. De acordo com a metodologia empregada nesta pesquisa, somos levados a concluir que: 1) Quando se associa o sistema Syncone® com overdenture ou sobredentadura, apoiada e retida sobre quatro implantes, sendo 2 localizados na região de incisivos centrais e 2 situados, diametralmente opostos, na região de segundos pré-molares na mandíbula - CPM1 - o rebordo residual é quem recebe a maior quantidade de tensões em relação aos implantes; 2) Quando se associa o sistema Syncone® com overdenture ou sobredentadura, apoiada e retida sobre 4 implantes, dispostos 2 a 2, bilateralmente e diametralmente opostos, nas regiões de caninos e pré-molares, na mandíbula (CPM2), as maiores tensões são transmitidas ao rebordo residual, sendo que os implantes suportes resultam mais preservados; 3) Comparativamente, o CPM2, aparenta ter transmitido menores tensões aos implantes que o CPM1; 4) Os implantes são preservados quanto à ocorrência de uma sobrecarga, durante a máxima intercuspidação dos arcos dentários, quando se emprega o sistema Syncone® associado à overdenture ou sobredentadura. / The osseo-integrated system develop by Branemark has revolutionized the prosthetic rehabilitation field, encourage the professionals to indicate and perform prostheses like overdentures. These devices represent an optimal alternative to solve the full dentures patient?s problems, dissatisfied for diverse factors. There are several associations between implants and prosthetic connectors employees for overdentures. The literature and the clinic practice may observe that according of the connection system employed, there is a difference into the biomechanical behavior, realized for this set: prostheses/implant/connection. From this forms, it is important to analyze how the tensions are distributing on the structures subject that support these loads, since it doesn\'t exist the periodontal ligament around the implants, what promotes the physiological mechanism of the natural teeth. Such, the purpose from this investigation was appraising, with the aid of the photoelastic method, the distribution way from the tensions at the overdentures, supported by four implants Ankylos®/ Dentsply, by using the prosthetic system of connection of conic crowns ? Syncone®/ Dentsply, were applied loads from 0,0 to 9,0kg, in crescent forms and, the tensions resulting on the support structures, have been analyzed by the photoelasthic method. Where two forms of distribution of the implantations were compared, first (CPM1) the implants were located at the regions of the central incisors and pre-molar, and as (CPM2) the implants were located at the regions of canines and pre-molar. The models had received loads of increasing form, from 0,0 to 9,0 kg and, the resultant tensions in the support structures, had been analyzed by the photoelastic method. In agreement with the methodology used in this research, we are led to conclude that: 1) When the overdenture is associated with Syncone® system, supported and retained by 4 implants, being 2 located in the region of central incisors and 2, diametrical opposing ones, in the region of the second pre-molar (CPM1) the residual alveolar ridge is who receives the biggest amount of tensions in relation to the implants; 2) When the overdenture is associated with Syncone® system, supported and retained by 4 implants, bilaterally and diametrical opposing ones, in the regions of canine and pre molar (CPM2), the biggest tensions were transmitted to the residual alveolar ridge, being the implants supports resulted more preserved; 3) Comparatively, the CPM2, seems to have transmitted less tensions to the implants than the CPM1; 4) The implants were preserved as the occurrence of an overload, during the maximum intercuspidação of the dental arcs, when the overdenture associated with Syncone® system has been used.

A proposta deste estudo foi avaliar o comportamento mecânico de dois designs de conexão implante/abutment; hexágono externo e triângulo interno, utilizando parafusos convencionais e parafusos experimentais cone morse. O estudo foi dividido em duas fases: na primeira, foi avaliado o efeito do carregamento mecânico na perda de torque dos parafusos. 40 implantes foram utilizados. Os implantes e abutments foram divididos em 4 grupos: Grupo 1: hexágono externo/parafuso convencional (HE); Grupo 2: triângulo interno/parafuso convencional (TI); Grupo 3: hexágono externo/parafuso cone morse (HECM); Grupo 4: triângulo interno/parafuso cone morse (TICM). Os abutments foram instalados em seus respectivos implantes com torque de aperto de 32Ncm; após intervalo de 10 minutos, foram medidos os valores dos torques de desaperto. Os abutments foram instalados novamente com torque de 32Ncm, e após 10 minutos foram carregados mecanicamente, simulando 1 ano de função oral normal; após o carregamento, os torques de desaperto dos parafusos foram medidos novamente. Os dados foram analisados com o teste one-way ANOVA, com nível de significância de p≤0,05%. Análises por microscopia óptica foram realizadas antes e após os ensaios. Na segunda fase, foi avaliada a resistência à flexão dos conjuntos implante/abutment. Os mesmos 40 conjuntos foram utilizados. Os testes foram realizados em máquina universal de ensaios, com célula de carga de 500 kgf, deslocamento de 1mm/min, e inclinação de 45°. A força máxima de flexão (FMF) e a força de ruptura (FR) foram determinadas. As informações coletadas foram analisadas com o teste one-way ANOVA, para p≤0,05. Análises por microscopia óptica foram realizadas para estudo dos componentes após os ensaios de resistência flexural. Os resultados sugeriram que houve diferença significante (p=0,000) na pré-carga residual antes e após carregamento mecânico entre os dois tipos de parafuso: os parafusos cone morse apresentaram torques de desaperto significativamente superiores aos apresentados pelos parafusos planos convencionais. Houve diferença significante nos resultados da FMF obtidos pelos parafusos planos convencionais e pelos parafusos cone morse (p=0,011), sendo que os conjuntos implante/abutment com parafusos cone morse apresentaram maior resistência à flexão. Para os resultados da FR houve influência significante do tipo de conexão (p=0,019), com melhores resultados para a conexão triângulo interno. Considerando as limitações deste estudo, concluiu-se que os parafusos cone morse apresentaram maiores torques de desaperto em comparação aos parafusos planos convencionais; que o design da conexão protética não teve influência significante sobre o torque de desaperto dos parafusos; que os parafusos cone morse obtiveram maiores valores de resistência à flexão, e que a conexão em triângulo interno obteve maiores valores para a força de ruptura. / The purpose of this study was to evaluate the mechanical behavior of two implant/abutment connection designs; external hex and internal tri-channel, using conventional screws and experimental conical screws. The study was divided in two parts; the first evaluated the effect of mechanical loading in the torque loss of the screws. 40 implants were used. The implants and abutments were divided in 4 groups: Group 1: external hex/conventional screw (HE); Group 2: tri-channel/conventional screw (TI); Group 3: external hex/conical screw (HECM); Group 4: tri-channel/conical screw (TICM). The abutments were installed in their respective implants with a tightening torque of 32Ncm, after a 10 minute interval, loosening torque were measured. The abutments were installed again with a 32Ncm torque, and after 10 minutes, they were mechanically loaded, simulating 1 year of normal oral function; after loading, loosening torques of the screws were measured again. Data were analyzed with one-way ANOVA test, with significance level of p≤0,05. Optical microscopy analysis were performed before and after the tests. The second part evaluated the flexural resistance of the implant/abutment assemblies. The same 40 assemblies were used. The tests were performed in an universal testing machine, with a 500kgf load cell, 1mm/min displacement, and 45° angulation. Maximum bending moment (FMF) and rupture force (FR) were determined. Collected information were analyzed with one-way ANOVA test, for p≤0,05. Optical microscopy analysis were performed for study of the components after the flexural resistance tests. The results suggested that there were significant differences (p=0,000) in the residual preload before and after mechanical loading between the two types of screws: conical screws showed significantly higher loosening torques than conventional flat screws. There were significant differences in the FMF obtained by the conventional flat screws and by the conical screws (p=0,000); the implant/abutment assemblies with conical screws presented higher flexural resistance. For the FR results, there was significant influence of the type of connection (p=0,019); the tri-channel connection presented better results. Considering the limitations of this study, it was concluded that the conical screws presented higher loosening torques compared to conventional flat screws; the design of the implant/abutment connection presented no significant influence on the loosening torques of the screws; conical screws showed higher bending moment values; and the tri-channel connection obtained higher rupture force values.

Os implantes cone morse apresentam um travamento e vedamento por meio de atrito entre as paredes do implante e do pilar protético. Nos sistemas convencionais do tipo Hexágono externo e interno, para reduzir o afrouxamento dos parafusos protéticos, são utilizados materiais de cobertura de superfície, como carbono e ouro. Não foram encontradas referências na literatura da utilização desse tipo de deposição em componentes do sistema cone morse. O propósito desse estudo é mensurar, registrar e avaliar os valores do torque de desaperto em pilares protéticos dos tipos sólido e parafuso passante do sistema cone morse com a deposição de carbono na zona de atrito do pilar protético. Foram utilizados 40 implantes cone morse com seus respectivos pilares divididos em 4 grupos (n=10): G1- pilar sólido; G2- pilar sólido com deposição de carbono na zona de atrito do sistema morse; G3- estudo somente do parafuso do pilar passante; G4- estudo somente do parafuso do pilar passante com deposição de carbono na ponta ativa; G5- estudo somente do pilar passante sem ação do parafuso; G6- estudo somente do pilar passante revestido em carbono na zona de atrito do sistema morse sem ação do parafuso. Cada pilar recebeu uma seqüência de 5 apertos e desapertos (20Ncm para o pilar sólido e 10Ncm para o parafuso passante). Os resultados mostraram no teste estatístico ANOVA para dois fatores de variação (desaperto e carbono), haver diferença estatística significante entre os grupos: G1 maior que G2 (p < 0,01); G4 maior que G3 (p < 0,01); G6 maior que G5 (p < 0,01). Esse estudo concluiu que o grupo controle G1 mostrou maior valor através da media aritmética (23,706 Ncm) em relação ao grupo experimental G2 (22,114 Ncm); o grupo experimental G4 mostrou maior valor através da media aritmética (8,218 Ncm) em relação ao grupo controle G3 (7,354 Ncm) e o grupo experimental G6 mostrou maior valor através da media aritmética (10,268 Ncm) em relação ao grupo controle G5 (6,906 Ncm), mostrou também que não houve diferença significativa (p > 0,01) para o fator desaperto em todos os grupos estudados, ou seja, não houve interferência da deformação do material com a repetição dos ciclos de aperto e desaperto. / The morse taper implants present a locking and sealing by means of the attrition between implants internal walls and the abutment. In the external and internal conventional hexagon system, to reduce the prosthetic screw loosing, its used covering surface materials, as carbon and gold. Literature reference using these kind of surface deposition were not found in morse taper abutment implants. The aim of this study is to measure, register and evaluate the removal torque values in morse taper solid abutment and passing screw abutment with carbon deposition in attrition zone. They were used 40 morse taper implants with their respective abutments divided in 4 groups (n = 10): G1 solid abutment; G2 - solid abutment with carbon deposition in attrition zone; G3 evaluation only in the screw of the passing abutment; G4 - evaluation only in the screw of the passing abutment with carbon deposition in the screw thread; G5 - evaluation only in the passing abutment without the screw action; G6 - evaluation only in the passing abutment with carbon deposition in attrition zone without the screw action. Each abutment received a sequence of 5 tightening and removal torque (20Ncm in solid abutment and 10Ncm in passant screw abutment). The results of ANOVA statistic test for two factors of variation (removal torque and carbon), showed that there is significant statistic difference between the groups: G1 higher than G2 (p < 0.01); G4 higher than G3 (p < 0.01); G6 higher than G5 (p < 0.01). This study concluded that control group G1 showed a higher value through the arithmetical media (23.706Ncm) in relation of the experimental group G2 (22.114Ncm); the experimental group G4 showed higher value through the arithmetical media (8.218Ncm) in relation of the control group G3 (7.354Ncm) and the experimental group G6 showed higher values through the arithmetical media (10.268Ncm) in relation of the control group G5 (6.906Ncm), and also showed that there was not significant difference (p < 0.01) to the removal torque factor in all the groups studied, that is, there was not a material deformation interference with the tightening and removal torque cycles repetition.

A odontologia reabilitadora moderna preconiza cada vez mais o uso de implantes dentais para a substituição de dentes ausentes. É sabido que micro-organismos presentes na cavidade oral, em especial os relacionados à doença periodontal, são responsáveis pelos maiores índices de insucesso dos implantes. Este trabalho estudou a ocorrência de infiltração bacteriana através da interface implante-conector protético de implantes Cone Morse (CM) e Hexágono Interno (HI) após a associação com uma pasta antimicrobiana ou a adição de sais de prata nos pilares. Foram utilizados 72 implantes odontológicos de titânio (PROSS® - Sistema de Implantes, Dabi-Atlante, Ribeirão Preto, Brasil), 36 com conexão do tipo hexágono interno e 36 com conexão do tipo cone-morse, divididos em grupos, da seguinte forma: Grupo Pasta Antimicrobiana- 12 conjuntos implantes HI/conectores protéticos e 12 conjuntos implantes CM/conectores protéticos, Grupo Íons de Prata- 12 conjuntos implantes HI/conectores protéticos e 12 conjuntos implantes CM/conectores protéticos e Grupo Controle- 12 conjuntos implantes HI/conectores protéticos e 12 conjuntos implantes CM/conectores protéticos. Os implantes e os conectores protéticos foram retirados de suas embalagens para aplicação do torque final (20N/cm). Antes disso, em um dos grupos experimentais, uma camada da pasta antimicrobiana foi aplicada sobre a superfície interna dos implantes e conectores protéticos e seus respectivos parafusos. Os conjuntos implantes-conectores foram parcialmente imersos na solução de saliva humana em tubos de ensaio e incubados em estufa bacteriológica a 37°C durante 7 dias. Após esse período, amostras do conteúdo interno dos conjuntos implantes-conectores protéticos dos 3 grupos foram colhidas com o objetivo de detectar e quantificar os micro-organismos presentes, utilizando para isto, a técnica de hibridização com sondas de DNA genômico DNA Checkerboard. Os implantes de conexão do tipo cone morse apresentaram menores valores de contagem de bactérias quando comparados aos implantes hexágono interno no grupo Controle (p<0,001), já para o grupo Íons de prata e Pasta antimicrobiana, foi observado comportamento inverso, maiores valores de contagem de bactérias para os implantes Cone Morse. Comparando-se os implantes de mesma conexão, entre os 03 grupos examinados, as amostras dos implantes Cone Morse dos grupos Controle, Íons de prata e Pasta antimicrobiana apresentaram valor de contagens de micro-organismos em ordem crescente. Os implantes de conexão hexágonal interna dos grupos Controle apresentaram maiores valores de contagens de micro-organismos seguidos pelos implantes do grupo Pasta antimicrobiana e Íons de prata, respectivamente. A partir dos resultados obtidos pode-se concluir que houve a passagem dos 43 micro-organismos analisados in vitro através da interface implante/componente protético em ambos os sistemas avaliados. Para ambos os tratamentos (adição de sais de prata às paredes dos pilares protéticos e aplicação da pasta antimicrobiana no interior dos implantes) houve diminução da infiltração microbiana no interior daqueles sistemas de conexão do tipo Hexágono Interno. / The contemporary and modern dentistry has been preconized the use of dental implants for replacement of missing teeth. The micro-organisms presents in oral environment, particularly those related to periodontal disease, are responsible for the highest failure rates of dental implants. This study evaluated the occurrence of bacterial leakage through the abutmentimplant interface in Morse Taped (CM) and Hexagon Internal (HI) dental implants after the association with antimicrobial paste or addition of silver salts on the abutments. 72 titanium dental implants (Pross ® - Implant System, Dabi-Atlante, Ribeirão Preto, Brazil), 36 with internal hexagon connection type and 36 with cone-morse connection type, divided into groups as follows: group Antimicrobial Paste -12 implants HI / prosthetic connectors and 12 implants CM / prosthetic connectors, group Ion Silver-12 implants HI / prosthetic connectors and 12 implants CM / prosthetic connectors and Control Group-12 implants HI / prosthetic connectors and 12 implants CM / prosthetic connectors. The implants and prosthetic connectors have been removed from their packaging for applying of final torque (20N/cm). Previously, in one experimental group, a layer of antimicrobial paste was applied on the inner surface of implants and prosthetic connectors. The sets connector/implants were partially immersed in human saliva solution in test tubes and incubated in bacteriological oven at 37°C for 7 days. Subsequently, samples of the contents of internal prosthetic sets implantconnectors of the 3 groups were collected to detect and quantify micro-organisms, through the DNA Checkerboard Hybridization Technique. The morse taper implants had significantly lower bacterial count compared to internal hexagon implants in the control group (p <0.001), while for the group of Silver Ion and antimicrobial Paste, we observed an inverse behavior, higher counts of micro-organisms for Morse taper implants. Comparing the same connection implants, among the 03 groups examined, samples of implants Morse Taper Control groups, Antimicrobial Paste and Silver ions exhibited values of counts of micro-organisms in ascending order. The internal hexagon implants of the Control group showed higher counts of microorganisms followed by Antimicrobial Paste and Silver Ions groups, respectively. The 43 species analyzed in vitro infiltrated through the interface implant / abutment in both systems evaluated; For both the treatments (adding silver salts in the abutments walls and applying of the antimicrobial paste within the implants) there was decreased microbial leakage through the interface connection for the internal hexagon dental implants

Extreme rainfall events associated with global warming are likely to produce an increasing number of flooding scenarios. A large magnitude of hydrologic events can often result in submerged orifice flow (also called pressure flow) or embankment and bridge overtopping flow, in which the foundation of a bridge is subjected to severe scour at the sediment bed. This phenomenon can cause bridge failure during large floods. However, current laboratory studies have focused on only cases of free-surface flow conditions, and they do not take bridge submergence into account. In this study, abutment scour experiments were carried out in a compound channel to investigate the characteristics of abutment scour in free-surface flow, submerged orifice flow, and overtopping flow cases. Detailed bed contours and three components of velocities and turbulent intensities were measured by acoustic Doppler velocimeters. The results show that the contracted flow around an abutment because of lateral and/or vertical contraction and local turbulent structures at the downstream region of the bridge are the main features of the flow responsible for the maximum scour depth around an abutment. The effects of local turbulent structures on abutment scour are discussed in terms of turbulent kinetic energy (TKE) profiles measured in a wide range of flow contraction ratios. The experimental results showed that maximum abutment scour can be predicted by a suggested single relationship even in different flow types (i.e., free, submerged orifice, and overtopping flow) if the turbulent kinetic energy and discharge under the bridge can be accurately measured.

Introdução: Várias hipóteses, tais como a formação de espaço biológico, as reações inflamatórias devido à contaminação do microgap entre implante-pilar, e a concentração de tensões peri-implantares causando microdanos ao tecido ósseo, têm sido sugeridos para explicar a perda óssea peri-implantar no primeiro ano em função. No entanto, ainda não é bem compreendido em qual extensão o tipo de conexão pilar/implante pode influenciar o processo de remodelação óssea ao redor de implantes. Objetivo: avaliar parâmetros clínicos, bacteriológicos, e biomecânicos relacionados à perda óssea peri-implantar na região da crista óssea, comparando as conexões hexagonal externa (HE) e cone morse (CM). Materiais e Métodos: Doze pacientes com mandíbulas totalmente desdentados receberam quatro implantes Ø 3,8 x 13 mm implantes na região interforaminal da mandíbula, com o mesmo design, mas diferentes conexões protéticas (dois deles HE ou CM, colocadas aleatoriamente com base em um desenho de boca dividida) e uma prótese implanto-suportada com carregamento imediato. Os parâmetros clínicos (profundidade de sondagem, índice gengival modificado e espessura da mucosa peri-implantar,) foram avaliados em 4 sítios ao redor dos implantes, após um ano de acompanhamento. A distância a partir do topo do implante para o primeiro contato entre o osso-implante - IT-FBIC foi avaliada em radiografias periapicais digitais padronizadas realizadas a 1, 3, 6 e 12 meses de acompanhamento. Amostras da microbiota subgengival foram coletadas 1, 3 e 6 meses após o carregamento do implante. DNA foi extraído e usado para a quantificação de Tanerella Forsythia, Porphyromonas gingivalis, Actinobacillus Aggragatibacter, Prevotella intermedia e Fusobacterium nucleatum. Comparação entre vários períodos de observação foram realizadas utilizando medidas repetidas Análise de Variância (ANOVA, α =0,5), seguido de um teste post-hoc de Tukey, enquanto que as comparações com base em dois períodos foram feitas utilizando o teste t pareado. Além disso, os modelos de computador tomográficos base de elementos finitos (EF) foram realizadas, simulando cada um dos doze paciente em três condições de carga. Os resultados para o pico de tensão EQV no osso peri-implantar foram interpretados por meio de um modelo linear geral (ANOVA-three- Way, α=0,5). Resultados: A variação na perda óssea peri-implantar avaliada por meio de radiografias foi significativamente diferente entre os tipos de conexão (P <0,001). A média de IT-FBIC foi de 1,17 ± 0,44 mm para HE, e 0,17 ± 0,54 milímetros para CM, considerando-se todos os períodos avaliados. Todos os parâmetros clínicos não apresentaram diferenças estatisticamente significantes. Diferenças significativas microbiológicas não foram observadas entre os dois tipos de conexões. A maioria das amostras recolhidas tinham muito poucos agentes patogénicos, o que significa que estas regiões eram saudáveis do ponto de vista microbiológico. Na análise EF, um pico significativamente maior de tensão EQV (P = 0,005) foi encontrado para HE (média 3.438,65μ∑) em comparação com CM (média de 840,98 μ∑□. Conclusões: Variar o tipo de conexão protética irá resultar em diferentes padrões de remodelação óssea peri-implantar, independentemente das condições clínicas e microbiológicas. É mais provável que este fato seja atribuído à transmissão de carga através de diferentes conexões implante-pilar para o osso peri-implantar. Os resultados atuais sugerem que uma conexão cone morse seja mais eficiente para prevenir a perda óssea peri-implantar, em comparação com uma conexão de hexágono externo. / Background: Several theories, such as the biological width formation, the inflammatory reactions due to the implant-abutment microgap contamination, and the periimplant stress/strain concentration causing bone microdamage accumulation, have been suggested to explain early periimplant bone loss. However, it is yet not well understood to which extent the implant-abutment connection type may influence the remodeling process around dental implants. Aim: to evaluate clinical, bacteriological, and biomechanical parameters related to periimplant bone loss at the crestal region, comparing external hexagon (EH) and Morse-taper (MT) connections. Materials and methods: Twelve patients with totally edentulous mandibles received four custom made Ø 3.8 x 13 mm implants in the interforaminal region of the mandible, with the same design, but different prosthetic connections (two of them EH or MT, randomly placed based on a split-mouth design), and a immediate implant- supported prosthesis. Clinical parameters (periimplant probing pocket depth, modified gingival index and mucosal thickness) were evaluated at 6 sites around the implants, at a 12 month follow-up. The distance from the top of the implant to the first bone-to-implant contact – IT-FBIC was evaluated on standardized digital peri-apical radiographs acquired at 1, 3, 6 and 12 months follow-up. Samples of the subgingival microbiota were collected 1, 3 and 6 months after implant loading. DNA were extracted and used for the quantification of Tanerella forsythia, Porphyromonas gingivalis, Aggragatibacter actinomycetemcomitans, Prevotella intermedia and Fusobacterium nucleatum. Comparison among multiple periods of observation were performed using repeated-measures Analysis of Variance (ANOVA), followed by a Tukey post-hoc test, while two-period based comparisons were made using paired t- test. Further, 36 computer-tomographic based finite element (FE) models were accomplished, simulating each patient in 3 loading conditions. The results for the peak EQV strain in periimplant bone were interpreted by means of a general linear model (ANOVA). Results: The variation in periimplant bone loss assessed by means of radiographs was significantly different between the connection types (P<0.001). Mean IT-FBIC was 1.17±0.44 mm for EH, and 0.17±0.54 mm for MT, considering all evaluated time periods. All clinical parameters presented not significant differences. No significant microbiological differences could be observed between both connection types. Most of the collected samples had very few pathogens, meaning that these regions were healthy from a microbiological point of view. In FE analysis, a significantly higher peak of EQV strain (P=0.005) was found for EH (mean 3438.65 µ∑) compared to MT (mean 840.98 µ∑) connection. Conclusions: Varying implant-abutment connection type will result in diverse periimplant bone remodeling, regardless of clinical and microbiological conditions. This fact is more likely attributed to the singular loading transmission through different implant-abutment connections to the periimplant bone. The present findings suggest that Morse-taper connection is more efficient to prevent periimplant bone loss, compared to an external hexagon connection. / Dissertação (Mestrado)