Corrosion Resistance of Titanium Alloy Orthodontic Mini-implants Immersed in Chlorhexidine, Fluoride, and Chitosan Mouthwashes: an in-vitro Study

Orthodontic mini-implants are widely used as an intraoral skeletal anchorages. Titanium alloy orthodontic mini-implants are known to have high corrosion resistance, but studies have found some corrosion behavior after contact with mouthwashes. The current in-vitro study aimed to examine surface topography and elemental composition as parameters of corrosion resistance for titanium alloy orthodontic mini-implants after being immersed in three different types of mouthwashes. A total of 28 titanium alloy orthodontic mini-implants were divided equally into four groups and immersed for 28 days in chlorhexidine gluconate 0.2% mouthwash, sodium fluoride 0.2% mouthwash, chitosan 1.5% mouthwash, and distilled water. All the orthodontic mini-implants’ heads and necks were then examined for surface topography using a scanning electron microscopy (SEM) and the elemental composition was assessed using energy-dispersive x-ray spectroscopy (EDS). Surface topography of the orthodontic mini-implants immersed in chlorhexidine gluconate, sodium fluoride, chitosan, and distilled water exhibited some manufacturing defects and rough surfaces, but no signs of crevices or pitting corrosion on the heads and necks. The elemental composition of all groups was comparable, but there was a statistically significant difference between titanium and aluminum (at%) between the sodium fluoride group and the chitosan group. Titanium alloy orthodontic mini-implants exhibited good corrosion resistance after immersion for 28 days in chlorhexidine gluconate 0.2%, sodium fluoride 0.2%, and chitosan 1.5%. Orthodontic mini-implants immersed in chitosan showed a smoother surface and higher titanium and aluminum (at%) than other groups.