title: Enhancement of Orthodontic Anchor Screw Stability Under Immediate Loading by Ultraviolet Photofunctionalization Technology.
abstract: OBJECTIVE
  Ultraviolet (UV)-mediated photofunctionalization technology is intended to enhance the osseointegration capability of titanium implants. There are concerns about orthodontic anchor screws loosening under immediate loading protocols in adolescent orthodontic treatment. The purpose of this in vivo study was to evaluate the effects of photofunctionalization on the intrabony stability of orthodontic titanium anchor screws and bone-anchor screw contact under immediate loading in growing rats.
  
  
  METHODS
  Custom-made titanium anchor screws (1.4 mm in diameter and 4.0 mm in length) with or without photofunctionalization pretreatment were placed on the proximal epiphysis of the tibial bone in 6-week-old male Sprague-Dawley rats and were loaded immediately after placement. After 2 weeks of loading, the stability of the anchor screws was evaluated using a Periotest device, and the bone-anchor screw contact ratio (BSC) was assessed by a histomorphometric analysis using field-emission scanning electron microscopy.
  
  
  RESULTS
  In the unloaded group, Periotest values (PTVs) were ~25 for UV-untreated screws and 13 for UVtreated screws (P < .01), while in the immediate-loading group, PTVs were 28 for UV-untreated screws and 16 for UV-treated screws (P < .05). Significantly less screw mobility was observed in both UV-treated groups regardless of the loading protocol. The BSC was increased ~1.8 fold for UV-treated screws, compared with UV-untreated screws, regardless of the loading protocol.
  
  
  CONCLUSIONS
  Photofunctionalization enhanced the intrabony stability of orthodontic anchor screws under immediate loading in growing rats by increasing bone-anchor screw contact.
authors.forename: Maiko
authors.initials: M
authors.lastname: Takahashi
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Motoyoshi
authors.forename: Mizuki
authors.initials: M
authors.lastname: Inaba
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Hagiwara
authors.forename: Noriyoshi
authors.initials: N
authors.lastname: Shimizu
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D001863:Bone Screws; D000069343:Bone-Implant Interface / Q000033:anatomy & histology; D006801:Humans; D020007:Implants, Experimental; D008297:Male; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D023421:Models, Animal; D052280:Orthodontic Anchorage Procedures / Q000295:instrumentation / Q000379:methods*; D016348:Osseointegration; D051381:Rats; D017207:Rats, Sprague-Dawley; D013314:Stress, Mechanical; D013499:Surface Properties; D013977:Tibia / Q000601:surgery; D014025:Titanium; D014466:Ultraviolet Rays
chemical_list: D014025:Titanium