The effect of different mouth washes on metallic ions release from silver‑soldered and laser‑welded orthodontic attachments. A comparative in vitro study

Abstract

Background: To compare the effect of different mouth washes on metallic ions release from
silver‑soldered and laser‑welded orthodontic attachments.
Materials and Methods: In this comparative in vitro study, 32 samples of molar bands without
attachments were used. Sixteen samples were silver soldered to stainless steel (SS) wire and
16 samples were laser welded using laser welding device to SS wire. Each group samples were
divided into four test groups and submerged in solution containing sodium fluoride (NaF),
NaF + alcohol (NaF + alcohol), Chlorhexidine (CHX), and artificial saliva (AS). Samples were shaken
for 24 h with an agitation rate of 60 rpm. One sample from each group was selected to study the
morphologic changes on their surfaces through scanning electron microscopy (SEM), and remaining
samples were studied for metal ions released and dissolved in the solutions using spectrometry. The
metal ions release values of two different attachment methods in three different mouth washes
and AS group were compared using the unpaired t‑test. A two‑way analysis of variance was used to
identify the significant differences between the two types of orthodontic attachments immersed in
four different types of solutions. P < 0.05 was defined to be set significant for all tests.
Results: Level of metal ions released from the samples of silver soldering was higher than from laser
welding. The lowest amounts of metal ions were released in CHX while highest in NaF + alcohol.
The SEM images were in accordance with these findings.
Conclusion: Laser welding should be preferred over silver soldering for the construction of
orthodontic appliances. CHX containing mouthwashes such as Hexidine can be prescribed for the
patients undergoing orthodontic treatment. More in vivo experiments will determine whether the
levels of dissolved nickel ions can reach the toxic or sub‑toxic concentrations or not.
Key Words: Corrosion, Ion release, Laser welding, Orthodontic attachments, Silver soldering