Effects of corrosion on orthodontic mini-implants related to removal torque fracture resistance.

Authors

Júlia Dal Paz, Felipe Gomes Dallepiane, Alef da Silva, Lílian Vanessa Rossa Beltrami, William Haupt, Micheline Sandini Trentin

Published in

Journal of clinical and experimental dentistry. Volume 17. Issue 3. Pages e273-e279. Epub Mar 01, 2025.

Abstract

This study evaluated the effect of metallic corrosion on the torsional fracture resistance of mini-implants of different alloys in two solutions: artificial saliva and artificial saliva+fluoride.
The research included 60 mini-implants: 30 of Ti6Al4V and 30 of stainless steel from the brand Morelli. The groups were divided into G1: stainless steel control, G2: Ti6Al4V control, G3: stainless steel in saliva, G4: stainless steel in saliva+fluoride, G5: Ti6Al4V in saliva, and G6: Ti6Al4V in saliva+fluoride, all with n=10. A potentiostat conducted electrochemical corrosion tests. Subsequently, one mini-implant from each group underwent SEM analysis for corrosion examination (80 and 5.000x). Then, the mini-implants were removed from the rods and subjected to a mechanical torsion fracture test (500N) using a mandrel coupled to a universal mechanical testing machine. After fracture or deformation, one mini-implant from each group underwent SEM analysis again (80 and 5.000x).
The statistical analysis showed no significant differences between the groups (stainless steel: 0.076 and Ti6Al4V: 0.199; pp>0.05). The Shapiro-Wilk test indicated that the data did not follow a normal distribution (p<0.05). The pitting potential analysis revealed no significant differences between G3 and G4, G5 and G6, or G4 and G6. Fracture resistance tests showed that most stainless steel mini-implants deformed rather than fractured completely (G1: 33.95N; G3: 40.60N; G4: 28.26N), requiring higher force for fracture. All Ti6Al4V mini-implants fractured at lower forces due to the material's brittleness (G2: 26.35N; G5: 27.50N; G6: 24.01N).
All analyzed groups experienced corrosion and pitting potentials, but none exerted sufficient influence to fracture or deform the devices under torsion. Key words:Mini-implants, corrosion, artificial saliva, fluoride, fracture resistance.

PMID:
40231132
Bibliographic data and abstract were imported from PubMed on 15 Apr 2025.

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