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KJO Korean Journal of Orthodontics

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pISSN 2234-7518
eISSN 2005-372X
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Korean J Orthod

Published online December 8, 2021

Copyright © The Korean Association of Orthodontists.

Influence of late removal after treatment on removal torque of microimplants

Ho-Jin Kima; Hyo-Sang Parkb

aDDS, MSD, Assistant Professor, Department of Orthodontics, School of Dentistry, Kyungpook National University, Daegu, Korea
bDDS, MSD, PhD, Professor and chair, Department of Orthodontics, School of Dentistry, Kyungpook National University, Daegu, Korea

Correspondence to:Dr. Hyo-Sang Park, Professor, Department of Orthodontics, School of Dentistry, Kyungpook National University, 2175, Dalgubul-Daero, Jung-Gu, Daegu, Korea 41940
Tel: +82-53-600-7373
e-mail Address: parkhs@knu.ac.kr

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Objective: To compare the removal torque of microimplants upon a post-used removal and post-retention removal and to assess the factors influencing the removal torque.
Methods: The sample group consisted of 241 patients (aged 30.25 ± 12.2 years) with 568 microimplants inserted. The sample was divided into a post-used (microimplants were removed immediately after use or treatment) and post-retention (microimplants were removed during retention period) removal groups. Removal torque of both groups was assessed according to sex, age, placement site and method, and microimplant size. For analyzing variables that influenced removal torque, Pearson correlation and multiple linear regression analysis were performed.
Results: The mean period of total in-bone stay of microimplants in the post-retention removal group (1,237.00 days) was approximately two times longer compared to the post-used removal group (656.28 days). The removal torques in the post-retention removal group (4–5 N cm) were higher than that in the post-used removal group. The mandible and pre-drilling group demonstrated higher placement and removal torques than the maxilla and no-drilling group, respectively. In the no-drilling post-used removal group, placement torque and microimplant length were positively correlated with removal torque. For the post-retention removal group, unloading in-bone stay period and microimplant diameter were positively correlated with removal torque in no-drilling and pre-drilling methods, respectively.
Conclusions: Differences in removal torques were observed according to the orthodontic loading and removal time of microimplants. With prolonged retention of microimplants by no-drilling method, the removal torque was clinically acceptable and showed positive correlation with unloading in-bone stay period.

Keywords: Microimplant, Stability, Retention, Removal torque

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Korean J Orthod

Published online December 8, 2021

Copyright © The Korean Association of Orthodontists.

Influence of late removal after treatment on removal torque of microimplants

Ho-Jin Kima; Hyo-Sang Parkb

aDDS, MSD, Assistant Professor, Department of Orthodontics, School of Dentistry, Kyungpook National University, Daegu, Korea
bDDS, MSD, PhD, Professor and chair, Department of Orthodontics, School of Dentistry, Kyungpook National University, Daegu, Korea

Correspondence to:Dr. Hyo-Sang Park, Professor, Department of Orthodontics, School of Dentistry, Kyungpook National University, 2175, Dalgubul-Daero, Jung-Gu, Daegu, Korea 41940
Tel: +82-53-600-7373
e-mail Address: parkhs@knu.ac.kr

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Objective: To compare the removal torque of microimplants upon a post-used removal and post-retention removal and to assess the factors influencing the removal torque.
Methods: The sample group consisted of 241 patients (aged 30.25 ± 12.2 years) with 568 microimplants inserted. The sample was divided into a post-used (microimplants were removed immediately after use or treatment) and post-retention (microimplants were removed during retention period) removal groups. Removal torque of both groups was assessed according to sex, age, placement site and method, and microimplant size. For analyzing variables that influenced removal torque, Pearson correlation and multiple linear regression analysis were performed.
Results: The mean period of total in-bone stay of microimplants in the post-retention removal group (1,237.00 days) was approximately two times longer compared to the post-used removal group (656.28 days). The removal torques in the post-retention removal group (4–5 N cm) were higher than that in the post-used removal group. The mandible and pre-drilling group demonstrated higher placement and removal torques than the maxilla and no-drilling group, respectively. In the no-drilling post-used removal group, placement torque and microimplant length were positively correlated with removal torque. For the post-retention removal group, unloading in-bone stay period and microimplant diameter were positively correlated with removal torque in no-drilling and pre-drilling methods, respectively.
Conclusions: Differences in removal torques were observed according to the orthodontic loading and removal time of microimplants. With prolonged retention of microimplants by no-drilling method, the removal torque was clinically acceptable and showed positive correlation with unloading in-bone stay period.

Keywords: Microimplant, Stability, Retention, Removal torque