Systemic levels of metallic ions released from orthodontic mini-implants.
BACKGROUND
Orthodontic mini-implants are a potential source of metallic ions to the human body because of the corrosion of titanium (Ti) alloy in body fluids. The purpose of this study was to gauge the concentration of Ti, aluminum (Al), and vanadium (V), as a function of time, in the kidneys, livers, and lungs of rabbits that had Ti-6Al-4V alloy orthodontic mini-implants placed in their tibia.


METHODS
Twenty-three New Zealand rabbits were randomly divided into 4 groups: control, 1 week, 4 weeks, and 12 weeks. Four orthodontic mini-implants were placed in the left proximal tibia of 18 rabbits. Five control rabbits had no orthodontic mini-implants. After 1, 4, and 12 weeks, the rabbits were killed, and the selected tissues were extracted and prepared for analysis by graphite furnace atomic absorption spectrophotometry.


RESULTS
Low amounts of Ti, Al, and V were detectable in the 1-week, 4-weeks, and 12-weeks groups, confirming that release of these metals from the mini-implants occurs, with diffusion and accumulation in remote organs.


CONCLUSIONS
Despite the tendency of ion release when using the Ti alloy as orthodontic mini-implants, the amounts of metals detected were significantly below the average intake of these elements through food and drink and did not reach toxic concentrations.
Mechanical and Aerospace Engineering Department, University of California, San Diego, USA. lilianesmorais@hotmail.com
Liliane Siqueira
LS
de Morais
Glaucio Guimarães
GG
Serra
Elisabete Fernandes
EF
Albuquerque Palermo
Leonardo Rodrigues
LR
Andrade
Carlos Alberto
CA
Müller
Marc André
MA
Meyers
Carlos Nelson
CN
Elias
D000535:Aluminum / Q000737:chemistry / Q000493:pharmacokinetics; D000818:Animals; D003343:Corrosion; D003722:Dental Alloys / Q000737:chemistry / Q000493:pharmacokinetics*; D003758:Dental Implantation, Endosseous / Q000295:instrumentation; D015921:Dental Implants; D007477:Ions / Q000032:analysis / Q000493:pharmacokinetics; D007668:Kidney / Q000378:metabolism*; D008099:Liver / Q000378:metabolism*; D008137:Longitudinal Studies; D008168:Lung / Q000378:metabolism*; D008297:Male; D052280:Orthodontic Anchorage Procedures / Q000295:instrumentation*; D011817:Rabbits; D011897:Random Allocation; D013977:Tibia / Q000601:surgery; D014018:Tissue Distribution; D014025:Titanium / Q000737:chemistry / Q000493:pharmacokinetics; D014639:Vanadium / Q000737:chemistry / Q000493:pharmacokinetics
D003722:Dental Alloys; D015921:Dental Implants; D007477:Ions; D014639:Vanadium; D000535:Aluminum; D014025:Titanium