Propriedades físicas e desenvolvimento de formação de biofilme em fios ortodônticos estéticos

Abstract

Humanity is constantly in search of new aesthetic standards. In Orthodontics, this is reflected by the use of orthodontic archwires. Therefore, these materials have limited scientific evidence. Thus, the objective of this study was to evaluate the bacterial biofilm formation, topography surface and roughness before and after brushing cycles in aesthetic archwires. Nitinium® Super Elastic (Ortho Organizers, Inc., USA), Tooth Tone® Coated Archwire (Ortho Technology, BR), NiTi Dental White S (Acme Monaco Co, USA), FLI® Wire (RMO, Inc., USA), NT3 ™ SE (American Orthodontics, USA), Niti Micro Dental White (Acme Monaco Co,USA), Dany Coated Archwire (Dany BMT Co., Ltd., South Korea), Bio-active RC (GC Orthodontics, Japan) and Copper Ni-Ti (Ormco Corporation, USA). Conventional metal wires were control groups (Ormco, American Ortho). Aesthetic archwires were: two wires were coated by epoxy resin (Ortho Technology, Ortho Technology), two Teflon (RMO, Monaco MD), two Rhodium (GC, Monaco DWS) and one silver+polymer (Dany). The evaluation of biofilm formation was verified by means of a violet crystal staining technique and bacterial cell viability by counting of colony forming units (CFU). The bacterium selected for the bacterial count assay was Streptococcus mutans (ATCC® 25175 ™). Regarding the topographic evaluation, the wires were prepared on aluminum stubs, covered with a thin layer of gold-palladium (MED 010, Balzers Union, Liechtenstein) and observed in MEV (JSM 5600LV, Jeol ) operating at 15 kV in increments of 50 to 5,000X. The surface roughness was analyzed using a SurfCorder SE 1700 rugosimeter, Kosaka Laboratory Ltd., Japan, with a 5μm detector and 4mN measuring force, previously calibrated and adjusted for a reading of 0.05 mm, 1.25 mm length and a cut-off of 0.025 mm. The measurements were performed before and after the simulation of brushing cycles. The simulation used soft toothbrushes (Sorriso, Colgate) mounted into the brushing machine (MEV 3Y-XT; Odeme, Luzerna, SC, Brazil). The samples were evaluated after 1200, 2400 and 3600 cycles, using a ratio of 1: 3 wt% water / toothpaste (Oral-B® Pro-Health, Procter & Gamble, São Paulo, SP, Brazil). The biofilm data were tabulated and submitted to analysis of variance and Tukey's test; and the roughness and brushing data were analyzed by One-way ANOVA. According to the Article #1 results, microbiological and bacterial analysis, indicated that the group A8 (Teflon) was statistically different from group A7 (control) regarding the biofilm formation. However, the colony count did not present statistically significant difference. Article #2, SEM and roughness before and after brushing, visually demonstrated that the groups A3 (Teflon) had the highest superficial irregularity. For roughness, there was an increase in roughness in the group A7 (control) and A1 (Epoxy) of 40% and a reduction in groups A8, A3 (Teflon), A5 (Silver + Polymer) and A9 (Rhodium) about 50% after brushing. In conclusion, Teflon wires demonstrated a greater adhesion of biofilm and superficial irregularity; however, 50% of its roughness was reduced after 3 months of brushing.