Effect of Carbonated Beverages on the Surface Roughness of Orthodontic Arch Wires via Profilometry Method

One of the problems of the fixed orthodontic treatments is the changes of surface characteristics of the orthodontic wires. Presence of the surface roughness on orthodontic wires can affect the corrosion, friction, dental movement, biocompatibility, and esthetic, which can prolong the treatment and interfere with tooth movement. The present study was carried out to evaluate and measure the influence of the most popular soft drink, Coca Cola, on the surface roughness of nickel titanium and stainless steel wires.

An experimental research was performed in vitro on 80 wires. Orthodontic wire packages of nickel titanium and stainless steel with round (diameter of 0.016 inches) and rectangular (0.016 × 0.022 inches) cross section of American Orthodontic (AO) Company were randomly prepared in 10 millimeter pieces. The samples were cleaned via alkaline solution and then surface roughness of the wires (Rₐ, Rq, Rz) were tested using profilometr machine. This process was repeated daily for 30 days. Eventually, the same surface roughness parameters were re-evaluated and compared with that before the intervention. We used Cronbach's alpha test to evaluate internal consistency of primary data, and in each group before and after changes were measured running Wilcoxon test. Also, to test the meaningfulness of differences between groups, Mann-u-Whitney statistical analysis was used.

Statistical analysis showed that the changes on Rₐ, Rq, Rz in all four groups were not significant (P<0.9). Also, Rₐ, Rq, Rz before inserting the wires in Coca Cola revealed that variables in stainless steel group were higher compared with those in Ni-Ti groups. For example, the amount of Rₐ, Rq, Rz of stainless steel and Ni-Ti groups were 18.08  ± 3.55, 105.31 ± 8.84, 95.64 ± 4.54 vs. 6.19 ± 0.34, 60.78 ± 3.66, 53.74 ± 1.91 respectively. These findings were the same after placing the samples in the Coca Cola, too (P<0.9).

It can be concluded that the carbonated drinks cannot affect the surface roughness of arch wires neither the treatment duration.