Bacterial adhesion to biomaterials: What regulates this attachment? A review.

Bacterial attachment to biomaterials is of great interest to the medical and dental field due to its impact on dental implants, dental prostheses, and others, leading to the need to introduce methods for biofilm control and mitigation of infections. Biofilm adhesion is a multifactorial process and involves characteristics relevant to the bacterial cell as well as biological, chemical, and physical properties relative to the surface of biomaterials. Bacteria encountered different environmental conditions during their growth and developed interspecies communication strategies, as well as various mechanisms to detect the environment and facilitate survival, such as chemical sensors or physical detection mechanisms. However, the factors that govern microbial attachment to surfaces are not yet fully understood. In order to understand how bacteria interact with surfaces, as well as to characterize the physical-chemical properties of bacteria adhesins, and to determine their interrelation with the adhesion to the substrate, in recent years new techniques of atomic force microscopy (AFM) have been developed and helped by providing quantitative results. Thus, the purpose of this review is to gather current studies about the factors that regulate microbial adhesion to surfaces in order to offer a guide to studies to obtain technologies that provide an antimicrobial surface.

Influence of AgVO3 incorporation on antimicrobial properties, hardness, roughness and adhesion of a soft denture liner.

The objective of this in vitro study was to investigate the effect of nanostructured silver vanadate decorated with silver nanoparticles (AgVO3) on antimicrobial activity, hardness, roughness, and adhesion of a soft denture liner. The antimicrobial efficacy of the Trusoft (Boswoth) liner incorporated with different concentrations of AgVO3 against Enterococcus faecalis, Pseudomonas aeruginosa, Candida albicans, and Staphyloccocus aureus (n = 5) was evaluated by the agar diffusion method. Roughness, hardness, and adhesion properties were also evaluated. The data were analyzed by analysis of variance (ANOVA) and Tukey's multiple comparison test with significance at the p < 0.05 level. At concentrations of 1 and 2.5%, AgVO3 incorporation was effective only against E. faecalis, and at 5 and 10%, against E. faecalis, P. aeruginosa, and C. albicans. None of the concentrations was effective against S. aureus. A decrease in hardness was found for the 1, 2.5, and 10% AgVO3 concentrations (p < 0.001) and at 5%, hardness was not affected. None of the concentrations affected the roughness of the material. A significant increase in tensile values was observed between the liner and heat-curing acrylic resin for 2.5% (p < 0.001) and 10% (p = 0.042) concentrations. AgVO3 incorporation to a soft denture liner promoted antimicrobial activity against E. faecalis, P. aeruginosa, and C. albicans without affecting roughness, maintaining the hardness properties recommended for soft and extra soft liners, and improving the adhesion between the liner and the acrylic resin used for dentures.

Influence of the ultimate torsion on the geometry of dental implants.

This study evaluated the profile of implants subjected to torsion test. Four types of implants (Conexão®) were analyzed: Master Porous (MP - external hexagon, cylindrical, double-porous surface implants; 11.5 X 3.75 mm), Master Screw (MS - external hexagon, cylindrical, machined implants; 11.5 X 3.75 mm), Conect Conic (CC - external hexagon, cylindrical, machined implants; 11.5 X 3.5 mm) and Master Conect AR (CA - internal hexagon, cylindrical, double-porous surface implants; 11.5 X 3.75 mm). The Nikon® model C profile projector was used for the analysis before and after torsion test with a Mackena® model MK-20XX digital torque meter. The measures analyzed in the profile of implants were: diameter and height of the platform, diameter of the screw/platform connection, angle of the screw/platform connection, external diameter, internal diameter, thread pitch, height and length of the thread. Statistical analysis was performed using ANOVA and Tukey test at 5% significance level. The torsion test caused a visible deformity on the external implant profile. There was a statistical difference among the implants before and after torsion (p<0.05) for the variables: platform diameter, platform height, diameter of the screw/platform connection and length. Changes were observed in platform height of CC and CA, fracture of CA implants, fracture of the MP and MS assembler/connectors, and internal thread stripping of CC. Thus, it was concluded that excessive or some unadvised torque by the manufacturer can lead to changes in different geometric measurements of implants.

Influence of the Ultimate Torsion on the Geometry of Dental Implants

This study evaluated the profile of implants subjected to torsion test. Four types of implants (Conexão®) were analyzed: Master Porous (MP - external hexagon, cylindrical, double-porous surface implants; 11.5 X 3.75 mm), Master Screw (MS - external hexagon, cylindrical, machined implants; 11.5 X 3.75 mm), Conect Conic (CC - external hexagon, cylindrical, machined implants; 11.5 X 3.5 mm) and Master Conect AR (CA - internal hexagon, cylindrical, double-porous surface implants; 11.5 X 3.75 mm). The Nikon® model C profile projector was used for the analysis before and after torsion test with a Mackena® model MK-20XX digital torque meter. The measures analyzed in the profile of implants were: diameter and height of the platform, diameter of the screw/platform connection, angle of the screw/platform connection, external diameter, internal diameter, thread pitch, height and length of the thread. Statistical analysis was performed using ANOVA and Tukey test at 5% significance level. The torsion test caused a visible deformity on the external implant profile. There was a statistical difference among the implants before and after torsion (p<0.05) for the variables: platform diameter, platform height, diameter of the screw/platform connection and length. Changes were observed in platform height of CC and CA, fracture of CA implants, fracture of the MP and MS assembler/connectors, and internal thread stripping of CC. Thus, it was concluded that excessive or some unadvised torque by the manufacturer can lead to changes in different geometric measurements of implants.

Este estudo avaliou o perfil de implantes submetidos à torção. Foram analisados quatro tipos de implantes (Conexão®): Master Porous (MP – implantes cilíndricos com encaixe hexagonal externo e superfície duplamente porosa; 11,5 X 3,75 mm), Master Screw (MS - implantes cilíndricos com encaixe hexagonal externo e superfície usinada; 11,5 X 3,75 mm), Conect Conic (CC - implantes cilíndricos com encaixe hexagonal externo e superfície usinada; 11,5 X 3,5 mm) e Master Conect AR (CA - implantes cilíndricos com encaixe hexagonal externo e superfície duplamente porosa). Utilizou-se para a análise o projetor de perfil Nikon® modelo C, antes e após o ensaio de torção, com torquímetro digital Mackena® modelo MK-20XX. As medidas analisadas do perfil dos implantes foram: diâmetro da plataforma, altura da plataforma, diâmetro da conexão plataforma-rosca, ângulo da conexão plataforma-rosca, diâmetro externo, diâmetro interno, passo de rosca, altura da rosca e comprimento. Para obtenção dos resultados foi realizada análise estatística ANOVA e Teste de Tukey com 5% de nível de significância. O ensaio de torção causou deformação visível no perfil externo dos implantes. Houve diferença estatística entre os implantes (p<0,05), antes e após a torção, nas variáveis: diâmetro da plataforma, altura da plataforma, diâmetro da conexão plataforma-rosca e comprimento. Foram observadas alterações na altura da plataforma dos implantes CC e CA, fratura dos implantes CA, fratura do montador de MP e MS, e espanamento das roscas internas de CC. Portanto, os implantes são homogêneos antes da torção, porém esta influenciou no perfil desses quando excessiva, causando deformação do parafuso.

Desenvolvimento de bases ósseas padronizadas para avaliação da estabilidade primária de implantes / Development of standardized bone specimens to evaluate primary stability of dental implants

A qualidade óssea do sítio receptor é considerada um dos fatores relevantes para o sucesso de implantes orais. O objetivo deste estudo piloto foi avaliar comparativamente cilindros ósseos de origem suína, de alta e baixa densidades, em modelo in vitro, por meio de análises bidimensional (radiografia digital) e tridimensional (tomografia computadorizada). Os cilindros ósseos foram preparados a partir de osso suíno, retirados do côndilo mandibular ou da cabeça do fêmur, e separados em dois grupos: grupo A: cilindros removidos da cabeça do fêmur (alta densidade óssea); grupo B: cilindros removidos do côndilo mandibular (baixa densidade óssea). Para a certificação dos cilindros (análise 2D) foram realizadas tomadas radiográficas digitais para determinar a densidade radiográfica. Foram realizadas ainda análises tridimensionais, por meio de tomografias computadorizadas, avaliando os seguintes parâmetros tomográficos: área óssea do cilindro, volume ósseo do cilindro, densidade óssea tridimensional, volume total do espaço de poros, porcentagem da porosidade total. O teste t Student foi utilizado para verificar a significância da diferença entre os grupos A e B; em todas as análises foi considerado nível de significância de 5%. Os resultados da análise 2D dos blocos ósseos mostraram que a diferença entre os grupos A e B foi estatisticamente significante (p < 0,0001). As diferenças entre os grupos A e B também foram estatisticamente significantes para todos os parâmetros tomográficos avaliados (p < 0,05). Concluiu-se que a metodologia apresentada gera cilindros ósseos padronizados de alta e baixa densidades, que poderão ser utilizados em estudos futuros para avaliar comparativamente a estabilidade inicial de implantes.

Bone quality is one of most important factors for the success of dental implants. The purpose of this study was to comparatively evaluate porcine bone cylinders, of high and low bone density, using 2D- (digital radiograph) and three-dimensional (computerized tomography) analysis. Bone cylinders were prepared from porcine bone, removed from mandibular condyle or from the femur head, and separated in two groups: Group A: cylinders removed from femur head (high bone density), and Group B: cylinders removed from mandibular condyle (low bone density). Digital radiographs were taken for the certification of bone cylinders (2D analysis), to determine the radiographic bone density. Using computerized tomograms, tri-dimensional analysis were made, evaluating the following tomographic parameters: cylinder bone area, cylinder bone volume, tridimensional bone density, total volume of porosity, total percentage of porosity. The Student´s t test was used to verify the significance of differences between groups A and B (at 5% level). The results showed that for 2D analysis of bone cylinders, the difference between groups A and B was statistically significant (p < 0.0001). The differences between groups were also statistically significant for all the evaluated tomographic parameters (p < 0.05). It was concluded that the methodology evaluated can produce standardized bone cylinders of high and low bone density that should be used in future studies to comparatively evaluate the initial stability of dental implants