Ion release and surface roughness of silver soldered bands with two different polishing methods: An in-vitro study.

OBJECTIVE: To evaluate the surface roughness and ion release of silver-soldered joints by using two polishing methods. METHODS: 174 orthodontic bands with and without silver-soldered joints were evaluated and divided into three groups: two experimental, with different polishing methods (SP1 and SP2), and one control (SS) composed of bands without silver solder. For ionic release, 50 bands of each group were immersed in saline solution and submitted to atomic absorption spectrophotometry to quantify the amount of Fe, Ni, Cr (in all the three groups), Ag, Cu, Cd, and Zn (in the two experimental groups). A rugosimeter was employed to verify the surface roughness. RESULTS: Ni and Cr were released in higher amounts after soldering. Cd, Ag, Zn, and Cu may be released from silver-soldered bands independently of the polishing method employed. Ag was released in higher amounts from the soldered bands that presented higher surface roughness. CONCLUSIONS: Differences exist in relation to the surface roughness of silver-soldered bands when distinct polishing methods are used. Toxic ions may be released from silver soldered joints and higher surface roughness may cause higher ionic release.

Assessment of frictional resistance and surface roughness in orthodontic wires coated with two different nanoparticles.

Several mechanical and biological factors may change the orthodontic wire frictional resistance (FR). Titanium dioxide (TiO2 ) and silica dioxide (SiO2 ) nanoparticle (NP) coatings may be used to improve the characteristics of materials, reducing FR between archwire and bracket. This in vitro study aimed to evaluate the FR of orthodontic wires with and without coating in both dry and wet environments and measure the surface roughness (SR). One hundred and eighty segments of rectangular Cr-Ni orthodontic wires (Morelli Co, Brazil) were divided into three groups according to the NP coating applied: TiO2 group; SiO2 group; and control group. The SR parameters were measured in an optical profilometer, the surface morphology was analyzed with scanning electron microscopy (SEM), and FR was performed in a universal testing machine in dry and wet environments (n = 30). The statistical analysis was performed using the Generalized Estimated Equations model with a Bonferroni post-test (α = 0.05). It was observed that SiO2 NP coating decreased FR significantly when compared to the TiO2 and control groups, in both environments (p < .001). The SiO2 and TiO2 groups presented statistically lower SR than the control group and were similar to each other (p < .001). The SiO2 group presented the lower depth of Valley parameter than the TiO2 group (p < .001). The SEM showed that the TiO2 coating had the most heterogeneous surface morphology than the SiO2 and control groups. The orthodontic wires with NP coating modified the FR and morphology. The SiO2 coating reduced FR in both dry and wet environments and decreased SR. Titanium dioxide (TiO2 ) and silica dioxide (SiO2 ) nanoparticles coatings may be used to reduce frictional resistance (FR) between archwire and bracket as well as to improve surface morphology. The SiO2 coating reduced FR in both dry and wet environments and decreased the SR of Cr-Ni orthodontic wire. The TiO2 coating promoted the most heterogeneous surface morphology of Cr-Ni orthodontic wire.