title: The effect of microrough surface treatment on miniscrews used as orthodontic anchors.
abstract: OBJECTIVE
  The aim of this study was to investigate the effects of two different microrough surface treatments on miniscrews with loading over different time periods in vivo.
  
  
  METHODS
  Twenty-four New Zealand white rabbits were selected. One hundred and forty-four miniscrews with a machined (MA), sandblasted and acid-etched (SLA) or sandblasted and alkaline-etched (SL/NaOH) surface were implanted into the tibia of the rabbits. Then, orthodontic forces with Ni-Ti coils were applied immediately to two of the three miniscrews in each tibia, with the center one serving as the control. After 2, 4, 8 and 12 weeks, the rabbits were sacrificed. The removal torque value (RTV) was tested and bone-to-implant contact (BIC) was examined.
  
  
  RESULTS
  In most groups, there were no differences between the RTV in the unloaded and loaded conditions at different time periods. In the loaded condition, the RTV of the SLA groups increased significantly after 4 weeks of healing. The RTV in the SL/NaOH groups increased after 8 weeks, and reached a significant difference with the SLA groups after 12 weeks. After 12 weeks, the BIC in the SLA and SL/NaOH groups was higher than in the MA groups. A regression test revealed a moderate correlation between the BIC and the RTV.
  
  
  CONCLUSIONS
  There were no differences between the loaded and unloaded conditions in most groups. The RTV and BIC increased with time. In the loaded condition, the RTV of the SLA surface increased earlier, at 4 weeks, while the SL/NAOH group showed the highest RTV after 8 weeks.
authors.affiliation: Institute of Oral Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Chin-Shan
authors.initials: CS
authors.lastname: Chang
authors.forename: Tzer-Min
authors.initials: TM
authors.lastname: Lee
authors.forename: Chih-Han
authors.initials: CH
authors.lastname: Chang
authors.forename: Jia-Kuang
authors.initials: JK
authors.lastname: Liu
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001863:Bone Screws; D015921:Dental Implants; D017267:Dental Prosthesis Design; D020878:Device Removal; D020007:Implants, Experimental; D052280:Orthodontic Anchorage Procedures / Q000295:instrumentation*; D016348:Osseointegration / Q000502:physiology*; D011817:Rabbits; D018709:Statistics, Nonparametric; D013499:Surface Properties; D013977:Tibia / Q000601:surgery; D014025:Titanium; D019415:Torque
chemical_list: D015921:Dental Implants; D014025:Titanium