Effect of accumulation of coverage nonstick biofilm on orthodontic brackets

O uso de dispositivos ortod??nticos tem sido associado ao aumento da reten????o de biofilme dent??rio. Neste estudo, foi testado o efeito de coberturas hidr??fobas,baseadas em organo-silanos (flourados ou n??o), no aumento do ??ngulo de contato e redu????o de ac??mulo de biofilme inicial em dispositivos ortod??nticos. Dois tipos diferentes de solu????es hidr??fobas foram testadas: solu????o hidr??foba 1 (SH1), obtida pela dilui????o de 2,5% de hexadecil-triet??xi-silano em etanol, e solu????o hidr??foba 2 (SH2), composta por 2,5% de perfluorodecil-triet??xi-silano dilu??do em dimetilsulf??xido. As solu????es foram aplicadas em substratos cer??mico e de a??o inox e, via processo sol-gel e reticula????o, foram formadas redes siloxanas na superf??cie dos dispositivos. O efeito das coberturas foi avaliado em duas etapas. Na primeira etapa, buscando a caracteriza????o da superf??cie, foi analisado o ??ngulo de contato com ??gua. Placas de a??o inox e alumina policristalina foram preparadas, aplicando ou n??o jateamento pr??vio das superf??cies com part??culas de alumina. Foi observado aumento significativo do ??ngulo de contato com a aplica????o das duas solu????es hidr??fobas em ambos substratos, sendo que o jateamento do substrato propiciou a forma????o de superf??cie superhidr??foba no substrato cer??mico (??ngulo de contato de at?? 155o), enquanto superf??cies hidr??fobas foram obtidas no substrato a??o (??ngulo de contato at?? 123o). Na segunda fase do trabalho, avaliou-se o efeito da cobertura no ac??mulo de biofilme em braquetes ortod??nticos, atrav??s de modelo de microcosmos. Braquetes ortod??nticos foram previamente preparados conforme os tratamentos de superf??cie que apresentaram melhores resultados na primeira fase (SH1 para a??o, SH2 para cer??mica). Foi avaliado o efeito da cobertura na forma????o de biofilme em per??odos de 12h e 24h (controles: substratos n??o-recobertos e substratos jateados). Os resultados mostraram que as coberturas hidr??fobas n??o resultaram em efeito significativo no ac??mulo de biofilme no tempo 12h, entretanto todos os tratamentos de cobertura reduziram de forma significativa o ac??mulo de biofilme sobre os braquetes met??licos e cer??micos comparados aos grupos controle no per??odo 24h. Foi observada rela????o de redu????o exponencial significativa entre ??ngulo de contato e ac??mulo de biofilme para o tempo 24h. Dessa forma, conclui-se que a aplica????o de coberturas (super)-hidr??fobas reticuladas via processo sol-gel na superf??cie de dispositivos ortod??nticos met??licos e cer??micos reduziu o molhamento das superf??cies em contato com a ??gua e teve efeito significativo na reten????o de biofilme bucal sobre esses dispositivos ap??s 24hThe use of orthodontic devices has been associated with an increase in dental biofilm retention. In this study, the effect of hydrophobic coatings, based on (fluorinated or not) organo-silanes, on the reduction of the contact angle and early biofilm retention in orthodontic devices was tested. Two different types of hydrophobic were tested: hydrophobic solution 1 (SH1), obtained by dilution of 2.5% of hexadecyl-triethoxy-silane in ethanol, and hydrophobic solution 2 (SH2), composed of 2.5% of perfluorodecyl-triethoxy-silane diluted in dimethyl sulfoxide. The solutions were applied in ceramic and stainless steel substrates and, via sol-gel process and crosslinking, siloxane networks were formed on the surface of the devices. The effect of the coatings was evaluated in two stages. In the first stage, aiming the characterization of the surface, the water contact angle was analyzed. Stainless steel and polycrystalline alumina plates were prepared, previously applying or not alumina sandblasting as surface treatment. A significant increase in contact angle was observed with the application of both hydrophobic solutions in both substrates, with the sandblasting allowing formation of super-hydrophobic surface in the ceramic substrate (contact angle up to 155o), while hydrophobic surfaces were obtained in the steel substrate (contact angle up to 123o). In the second phase, the effect of the hydrophobic coating on the biofilm retention in orthodontic brackets was evaluated using a microscosm model. Orthodontic brackets were previously prepared according to the surface treatments that showed the best results in the phase 1 (SH1 for steel, SH2 for ceramic). The effect of the coatings on the biofilm formation was evaluated in periods of 12h and 24h (controls: uncoated substrates and sandblasted substrates). The results showed that the hydrophobic coatings did not result in significant effect in biofilm retention for the time 12h, whereas all coating treatments significantly reduced the biofilm retention in the metal and ceramic brackets compared with the control groups. A significant exponential reduction in biofilm retention at 24h was associated with the increase in contact angle. It can be concluded that application of (super)-hydrophobic crosslinked coatings via sol-gel process on the surface of orthodontic metal and ceramic brackets reduced the surface wetting of the surfaces in contact with water and had a significant effect on the retention of dental biofilm after 24