Abstract
Objectives. The purpose of this work was to determine the influence of residual alumina after sand blasting treatment in titanium dental implants. This paper studied the effect of alumina on physico-chemical surface properties, such as: surface wettability, surface energy. Osseointegration and bacteria adhesion were determined in order to determine the effect of the abrasive particles. Materials and Methods. Three surfaces were studied: (1) as-received, (2) rough surface with residual alumina from sand blasting on the surface and (3) with the same roughness but without residual alumina. Roughness was determined by white light interferometer microscopy. Surface wettability was evaluated with a contact angle video-based system and the surface free energy by means of Owens and Wendt equation. Scanning electron microscopy equipped with microanalysis was used to study the morphology and determine the chemical composition of the surfaces. Bacteria (Lactobacillus salivarius and Streptococcus sanguinis) were cultured in each surface. In total, 110 dental implants were placed into the bone of eight minipigs in order to compare the osseointegration. The percentage of bone-to-implant contact was determined after 4 and 6 weeks of implantation with histometric analysis. Results. The surfaces with residual alumina presented a lower surface free energy than clean surfaces. The in vivo studies demonstrated that the residual alumina accelerated bone tissue growth at different implantation times, in relation to clean dental implants. In addition, residual alumina showed a bactericidal effect by decreasing the quantity of bacteria adhering to the titanium. Conclusions. It is possible to verify the benefits that the alumina (percentages around 8% in weight) produces on the surface of titanium dental implants. Clinical relevance. Clinicians should be aware of the benefits of sand-blasted alumina due to the physico-chemical surface changes demonstrated in in vivo tests.
Highlights
Alumina is the most commonly used abrasive by commercial companies and most implants are treated with these particles, as they give excellent osseointegration results and in no case have foreign body reactions or allergic effects
As the Al2 O3 and clean samples presented the same roughness, these results showed the possible trend to bacteria adhesion on surfaces correlated to particles chemical composition because in general the CFUs/mm2 was lower on Al2 O3 shot-blasted compared to control and clean surfaces
It can be stated that roughness is the most important surface parameter for osteoblast adhesion, osseointegration as well as for the colonization of microorganisms
Summary
Sand blasting or grit blasting is a widely used surface treatment method in order to achieve the appropriate roughness of the titanium dental implants in relation to the biological response. Alumina is the most commonly used abrasive by commercial companies and most implants are treated with these particles, as they give excellent osseointegration results and in no case have foreign body reactions or allergic effects. It is the nature of the abrasive that has an effect, and the projection parameters, such as the distance from the projection gun to the titanium surface, the projection pressure, the saturation time, projection diameter, etc. There are other parameters of the alumina that will influence the roughness, such as the size or shape of the particles
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