Korean J Orthod.  2007 Jun;37(3):171-181.

Torque and mechanical failure of orthodontic micro-implant influenced by implant design parameters

• Yu W
• Kyung HM

Abstract

OBJECTIVE
The present study was aimed at an analytical formulation of the micro-implant related torque as a function of implant size, i.e. the diameter and length, screw size, and the bony resistance at the implant to bone interface.
METHODS
The resistance at the implant to cancellous bone interface (S(can)) was assumed to be in the range of 1.0-2.5 MPa. Micro-implant model of Absoanchor (Dentos Inc. Daegu, Korea) was used in the course of the analysis.
RESULTS
The results showed that the torque was a strong function of diameter, length, and the screw height. As the diameter increased and as the screw size decreased, the torque index decreased. However the strength index was a different function of the implant and bone factors. The whole Absoanchor implant models were within the safe region when the resistance at the implant/cancellous bone (= S(can)) was 1.0 or less.
CONCLUSION
For bone with S(can) of 1.5 MPa, the cervical diameter should be greater than 1.5 mm if micro-implant models of 12 mm long are to be placed. For S(can) of 2.0 MPa, micro-implant models of larger cervical diameter than 1.5 mm were found to be safe only if the endosseous length was less than 8 mm.

Keyword

Orthodontic micro-implant; Design parameter; Torque; Torsional failure

MeSH Terms

Daegu
Torque*