title: In vivo degradation of orthodontic miniscrew implants: surface analysis of as-received and retrieved specimens.
abstract: This study investigated in vivo degradation of Ti-6Al-4V alloy miniscrew implants. Miniscrew implants were placed in patients, and the surfaces were studied upon retrieval by scanning electron microscopy, microscale X-ray photoelectron spectroscopy, elastic recoil detection analysis and nanoindentation testing. Bone-like structures were formed on the retrieved specimens. The hardness and elastic modulus of the surfaces of the retrieved specimens were significantly lower than the as-received specimens, although no statistically significant differences were observed for the hardness and elastic modulus in the bulk region. Thick organic over-layer containing carbon, oxygen, and nitrogen, with the thickness greater than 50 nm, covered the retrieved specimens, and higher concentrations of hydrogen were detected in the retrieved specimens compared with the as-received specimens. Minimal degradation of the bulk mechanical properties of miniscrew implants was observed after clinical use, although precipitation of bone-like structures, formation of a carbonaceous contamination layer, and hydrogen absorption were observed on the surfaces of miniscrew implants.
authors: Division of Orthodontics and Dentofacial Orthopedics, Department of Oral Growth and Development School of Dentistry, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido, Japan, iijima@hoku-iryo-u.ac.jp.
authors: Masahiro
authors: M
authors: Iijima
authors: Takeshi
authors: T
authors: Muguruma
authors: Masahiro
authors: M
authors: Kawaguchi
authors: Yoshitaka
authors: Y
authors: Yasuda
authors: Itaru
authors: I
authors: Mizoguchi
mesh_terms: D000497:Alloys; D001863:Bone Screws; D003343:Corrosion; D019250:Dental Implants, Single-Tooth; D003764:Dental Materials / Q000737:chemistry*; D017267:Dental Prosthesis Design; D019094:Dental Prosthesis, Implant-Supported; D019232:Dental Restoration Failure; D020878:Device Removal; D055119:Elastic Modulus; D004866:Equipment Contamination; D019544:Equipment Failure Analysis; D006244:Hardness; D008904:Miniaturization; D052280:Orthodontic Anchorage Procedures / Q000295:instrumentation*; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*
chemical_list: D000497:Alloys; D003764:Dental Materials; C031462:titanium alloy (TiAl6V4); D014025:Titanium
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