“In Vitro” Study About Variables that Influence in Arch Friction with Conventional and Self-Ligating Brackets

Abstract

Many advantages have been described surrounding self-ligating (SL) brackets compared to metallic conventional ligating (CL) brackets, such as: Less total treatment time, alignment efficiency, patient comfort, plaque retention, and low friction. The objective of this in vitro simulation was to know the variables that affect arch displacement in CL and SL brackets—active (ASL) and passive (PSL)—and analyze if static friction values are affected by bracket design, arch wire section, kind of ligature, and use of a friction reducer agent (FRA) in a wet state. Larger values of static friction were found in CL with metallic ligature (ML) (8.01 ± 1.08 N/mm) and elastic ligature (EL) (6.96 ± 0.48 N/mm). Lower values were found in PSL brackets combined with FRA (0.58 ± 0.21 N/mm). The study was carried out using different stereographical models of a maxillary upper right quadrant with canine, first and second premolar, and first molar bonded brackets. A section of 25 mm of 0.019 × 0.025” stainless steel arch with a rectangular section (SS) and hybrid section (HY) was inserted into the different bracket models. Static friction values were collected using a universal test machine in wet conditions and testing the effect of a friction reducer agent (FRA). To assure the reliability of the study, different wire combinations were repeated after two weeks by the same operator and a linear analysis of regression was done. Each bracket model analysis—with the different wires, use of the FRA, and comparison among brackets in similar conditions—was done using an ANOVA test with a confidence interval of 95% and comparative Post-Hoc tests (LSD). In this in vitro simulation we found higher static friction values in CL compared to ASL and PSL. In PSL, lower values were achieved. CL brackets using ML showed the highest static friction values with a great variability. In this setting, the use of HY wires did not reduce static friction values in ASL and PSL, while in CL brackets with EL friction the values were reduced significantly. An FRA combined with ASL reduced significantly static friction values but not with PSL. In the case of CL, the FRA effect was higher with SS and better than with HY wires. ML values were similar to ASL static friction. The direct extrapolation of the results might be inaccurate, since all these findings should be tested clinically to be validated.

Fricción de brackets autoligado y convencionales en el cierre de espacios: revisión de la literatura

“…Los brackets convencionales requieren métodos de ligadura para mantener el arco dentro de la ranura de los brackets, estos son de tipo elástico y metálica, la ligadura elástica se asocia con valores más altos de fricción debido a que tiene un mayor contacto con la superficie de los arcos, mientras que la ligadura metálica podría producir una mayor o menor fricción que depende de la fuerza que utilice el ortodoncista (Moyano et al, 2019).…”

“…La superficie del arco de alambre tales como la rugosidad y la topografía puede influenciar en el coeficiente de fricción durante el deslizamiento. La rugosidad de la superficie de los materiales dentales es muy importante, ya que contribuye al área de contacto de la superficie y, por lo tanto, tiene un impacto en la conducta corrosiva y la biocompatibilidad del material, además la rugosidad puede influir en la acumulación de placa dentobacteriana, lo que contribuye a aumentar la fricción y la salud biológica (Moyano et al, 2019).…”

“…Los brackets de autoligado fueron introducidos en los años 90, y hasta la actualidad presentan ciertas ventajas en relación a los brackets convencionales, en cuanto a un menor tiempo de trabajo para el ortodoncista y generan menor fricción (Dehbi et al, 2017;Moyano et al, 2019).…”

Friction behavior of the wire material Gummetal®

“…Moreover, research showed that materials do not differ in ranking according to the level of their dynamic and static friction component [ 18 ]—the static proved to be higher than the kinetic friction [ 43 ]. There have been a few studies in recent years that focused on static friction [ 27 , 35 ] or include measurements of static friction [ 43 ]. However, we thought that focusing on the measurement of dynamic friction is a more suitable basis for comparison of friction as it is easier to reproduce, even if clinical conditions are insufficiently simulated [ 16 ].…”