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. 2021 Nov 15;22(1):42.
doi: 10.1186/s40510-021-00383-3.

Long-term evaluation of factors affecting removal torque of microimplants

Ho-Jin Kim  1 , Hyo-Sang Park  2
Affiliations

Long-term evaluation of factors affecting removal torque of microimplants

Ho-Jin Kim et al. Prog Orthod. .

Abstract

Background: The current study aimed to evaluate factors affecting the long-term stability of microimplants using removal torque and the correlation between removal torque and clinical variables.

Materials and methods: This research evaluated 703 microimplants placed in 354 patients (mean age: 30.4 ± 12.1 years). The removal torque was evaluated according to various clinical variables including sex, age, placement site, microimplant size, and placement method (self-drilling versus pre-drilling). Pearson correlation and stepwise multiple linear regression analyses were performed to investigate different variables and their association with removal torque.

Results: The mean removal torque was significantly higher in the mandible (4.46 N cm) than in the maxilla (3.73 N cm). The values in the posterior teeth/retromolar areas were significantly higher than those in the anterior teeth area. There were no significant difference in terms of sex. Teenagers had a lower removal torque than older adults in the mandible, but not in the maxilla. Microimplants with a greater length and diameter, except for those with a greater diameter in the maxilla, was associated with a higher removal torque. Regardless of placement torque, the removal torque convergently reached approximately 4 N cm in both placement methods. The removal torque was significantly correlated with screw length in the self-drilling group and with diameter in the pre-drilling group.

Conclusions: Removal torque was related with placement site, age, placement method, and length and diameter of microimplants.

Keywords: Long-term stability; Microimplant; Placement method; Removal torque.

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Conflict of interest statement

The authors declare that they have no competing interests.

Figures

Fig. 1
Fig. 1
Flowchart of this study
Fig. 2
Fig. 2
Shape and size of the microimplants used in this study
Fig. 3
Fig. 3
Digital gauge used to measure torque values when placing and removing microimplants
Fig. 4
Fig. 4
Box plot of the distribution of the total placement and removal torques
Fig. 5
Fig. 5
Error bar plot of the mean placement and removal torque values according to placement sites. *p < 0.05, **p < 0.001
Fig. 6
Fig. 6
Error bar plot of the mean placement and removal torque values according to the respective ranges of placement torque. *p < 0.05, **p < 0.001
See this image and copyright information in PMC

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