In vitro and in vivo mechanical stability of orthodontic mini-implants.
OBJECTIVE
To compare in vivo and in vitro mechanical stability of orthodontic mini-implants (OMIs) treated with a sandblasted, large-grit, and anodic-oxidation (SLAO) method vs those treated with a sandblasted, large-grit, and acid-etching (SLA) method.


METHODS
Fifty-four titanium OMIs (cylindrical shape, drill-free type; diameter  =  1.45 mm, length  =  8 mm, Biomaterials Korea Inc, Seoul, Korea) were allocated into control, SLA, and SLAO groups (N  =  12 for in vivo and N  =  6 for in vitro studies per group). In vitro study was carried out on a polyurethane foam bone block (Sawbones, Pacific Research Laboratories Inc, Vashon, Wash). In vivo study was performed in the tibias of Beagles (6 males, age  =  1 year, weight  =  10 to 13 kg; OMIs were removed at 8 weeks after installation). For insertion and removal of OMIs, the speed and maximum torque of the surgical engine were set to 30 rpm and 40 Ncm, respectively. Maximum torque (MT), total energy (TE), and near peak energy (NPE) during the insertion and removal procedures were statistically analyzed.


RESULTS
In the in vitro study, although the control group had a higher insertion MT value than the SLA and SLAO groups (P < .01), no differences in insertion TE and NPE or in any of the removal variables were noted among the three groups. In the in vivo study, the control group exhibited higher values for all insertion variables compared with the SLA and SLAO groups (MT, P < .001; TE, P < .01; NPE, P < .001). Although no difference in removal TE and removal NPE was noted among the three groups, the SLAO group presented with a higher removal MT than the SLA and control groups (P < .001).


CONCLUSIONS
SLAO treatment may be an effective tool in reducing insertion damage to surrounding tissue and improving the mechanical stability of OMIs.
Department of Orthodontics, School of Dentistry, Seoul National University, Seoul, South Korea.
Il-Sik
IS
Cho
Sung-Kyun
SK
Kim
Young-Il
YI
Chang
Seung-Hak
SH
Baek
D000134:Acid Etching, Dental / Q000379:methods*; D000704:Analysis of Variance; D000818:Animals; D001842:Bone and Bones / Q000737:chemistry; D015921:Dental Implants; D004285:Dogs; D005994:Glycerophosphates; D008297:Male; D008855:Microscopy, Electron, Scanning; D052280:Orthodontic Anchorage Procedures / Q000379:methods*; D013499:Surface Properties; D014025:Titanium; D019415:Torque
D015921:Dental Implants; D005994:Glycerophosphates; D014025:Titanium