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A new torquing method for anterior tooth inclination control: a clinical report with a 7-year follow-up

Hyung-Kyu Noh
Hyung-Kyu Noh
, 
Ho-Jin Kim
Ho-Jin Kim
 and 
Hyo-Sang Park
Hyo-Sang Park
   | Jun 17, 2023
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Published Online: Jun 17, 2023
Page range: 183 - 194
Received: Mar 01, 2022
Accepted: Apr 01, 2023
DOI: https://doi.org/10.2478/aoj-2023-0016
© 2023 Hyung-Kyu Noh et al., published by Sciendo
This work is licensed under the Creative Commons Attribution 4.0 International License.

Figure 1.

The configuration of mechanics. (A) Frontal view. The red circles represent the tooth surface with which the thread is in contact. (B) Force diagram. The red arrows indicate the force vectors acting on the incisor, and the blue arrow denotes the force vector working on the archwire. The green circular arrow represents the couple force acting on the incisor. (C) Quantitative analysis of wire twisting technique. The red arrows denote orthodontic force generated from twisted wire. Due to the bracket play, the moment arm is less than the wire dimension. Despite high orthodontic force, the obtainable moment is rather limited. (D) Quantitative analysis of Park’s cervical torque tie. The red arrows demonstrate forces from the elastic thread. The moment arm is adjustable between 3 and 5 mm. With small orthodontic force, a large moment is obtainable.
The configuration of mechanics. (A) Frontal view. The red circles represent the tooth surface with which the thread is in contact. (B) Force diagram. The red arrows indicate the force vectors acting on the incisor, and the blue arrow denotes the force vector working on the archwire. The green circular arrow represents the couple force acting on the incisor. (C) Quantitative analysis of wire twisting technique. The red arrows denote orthodontic force generated from twisted wire. Due to the bracket play, the moment arm is less than the wire dimension. Despite high orthodontic force, the obtainable moment is rather limited. (D) Quantitative analysis of Park’s cervical torque tie. The red arrows demonstrate forces from the elastic thread. The moment arm is adjustable between 3 and 5 mm. With small orthodontic force, a large moment is obtainable.

Figure 2.

(A, B) The cervical torque tie’s intraoral view. The composite resins on the cervical area prevent the gingival damage which can be caused by the gingivally displaced thread. (C, D) Diagrams showing the couple force direction. The grey tooth indicates the initial position, and the orange tooth represents the latter position. Depending on whether the thread is on the cervical or incisal area, palatal or labial root moment can be obtained.
(A, B) The cervical torque tie’s intraoral view. The composite resins on the cervical area prevent the gingival damage which can be caused by the gingivally displaced thread. (C, D) Diagrams showing the couple force direction. The grey tooth indicates the initial position, and the orange tooth represents the latter position. Depending on whether the thread is on the cervical or incisal area, palatal or labial root moment can be obtained.

Figure 3.

Pretreatment extra-, intraoral photographs, cephalogram, panoramic radiographs and 3-dimensional virtual model.
Pretreatment extra-, intraoral photographs, cephalogram, panoramic radiographs and 3-dimensional virtual model.

Figure 4.

Treatment progress. (A) Initiation of treatment. (B) Three-month intraoral photograph. (C) 10-month intraoral photograph. (D) 16-month intraoral photograph. (E) 18-month intraoral photograph.
Treatment progress. (A) Initiation of treatment. (B) Three-month intraoral photograph. (C) 10-month intraoral photograph. (D) 16-month intraoral photograph. (E) 18-month intraoral photograph.

Figure 5.

Change in the incisors’ inclination. (A) 18-month intraoral photograph. (B) 29-month intraoral photograph.
Change in the incisors’ inclination. (A) 18-month intraoral photograph. (B) 29-month intraoral photograph.

Figure 6.

Post-treatment extra-, intraoral photographs, cephalogram, panoramic radiographs and three-dimensional virtual model.
Post-treatment extra-, intraoral photographs, cephalogram, panoramic radiographs and three-dimensional virtual model.

Figure 7.

Cephalogram superimposition between pre- (black) and post-treatment (red).
Cephalogram superimposition between pre- (black) and post-treatment (red).

Figure 8.

CBCT superimposition between pre- (white) and post-treatment (blue).
CBCT superimposition between pre- (white) and post-treatment (blue).

Figure 9.

CBCT images’ sections at pretreatment, post-treatment and 7-year follow-up. The dehiscence on the palatal side, discovered after treatment, was recovered to the cortical bone 7 years later.
CBCT images’ sections at pretreatment, post-treatment and 7-year follow-up. The dehiscence on the palatal side, discovered after treatment, was recovered to the cortical bone 7 years later.

Figure 10.

Seven-year follow-up extra- and intraoral photographs.
Seven-year follow-up extra- and intraoral photographs.

Cephalometric measurements

Pretreatment Posttreatment
SNA (degree) 80.4 80.2
SNB (degree) 77.1 75.8
ANB (degree) 3.3 4.4
Wits appraisal (mm) 0.74 1.2
FMA (degree) 20.7 22.1
U1 to FH (degree) 102.6 107.1
IMPA (degree) 87.8 93.2
Interincisal Angle (degree) 148.9 137.6
Upper lip to E-line (mm) –3.6 –3.8
Lower lip to E-line (mm) –1.1 –1.9
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