J Korean Assoc Oral Maxillofac Surg.  2013 Dec;39(6):269-273. 10.5125/jkaoms.2013.39.6.269.

Effect of rotation bump on removal torque of orthodontic mini-implants

• Gansukh O
• Jeong JW
• Kim JW
• Kim YK
• Lee JH
• Kim TW

• KMID: 1960976
• DOI: http://doi.org/10.5125/jkaoms.2013.39.6.269

Abstract

OBJECTIVES
This study is designed to evaluate the mechanical stability of orthodontic mini-implants with vertical grooves in rabbits.
MATERIALS AND METHODS
This study was done from March 2011 to February 2012 in Dental Research Institute of Seoul National University. Thirty-two mini-implants in the control group and 32 in the rotation bump (RB) group were inserted in the tibias of 16 rabbits and were removed after two weeks and four weeks, respectively. The maximum insertion torque (MIT), maximum removal torque (MRT), torque ratio (TR) of MRT to MIT and removal angular momentum (RAM) were all measured at the time of removal.
RESULTS
There were no significant differences between the two groups in MIT and MRT at two weeks or four weeks. However, TR and RAM at four weeks in the RB group were significantly higher than in the control group (P<0.05). TR of the RB group was significantly increased at four weeks (P<0.05). In both groups, RAM at four weeks was significantly higher than at two weeks (P<0.05).
CONCLUSION
These results suggest that RB of the mini-implant could provide resistance to the removal rotation, although it did not increase the MRT.

Keyword

Mini-implant; Rotation bump; Torque; Torque ratio; Angular momentum

MeSH Terms

Dental Research
Rabbits
Seoul
Tibia
Torque*

Figure

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  Fig. 1 Tested groups of orthodontic mini-implants. A. Control group. B. Rotation bump group.

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  Fig. 2 Insertion procedure of orthodontic mini-implant and equipment. A. Pre-drilling with saline irrigation. B. Surgical engine which can measure and record the torque.

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  Fig. 3 Schematic graph to explain the mechanical characteristics of mini-implants. (A: maximum insertion torque [MIT], B: time of MIT, C: maximum removal torque [MRT], D: time of MRT, E: 1.5 seconds after MRT, which is a time needed for a half turn, F: removal angular momentum which is the torque integrated from the time of MRT to 1.5 seconds after MRT)

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