대한치과교정학회 임상저널

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대한치과교정학회 임상저널

대한치과교정학회

Volume 11 Number 2 June 2021 http://kao.or.kr/cjkao

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편집위원장

채 종 문 (원광대학교)

편집이사

장 인 산 (강릉원주대학교)

편집위원

안 효 원 (경희대학교) 최 동 순 (강릉원주대학교)

임 승 원 (전남대학교) 홍 미 희 (경북대학교)

이 경 민 (전남대학교) 이 상 민 (단국대학교)

김 용 일 (부산대학교) 안 정 섭 (서울대학교)

이 승 엽 (전북대학교) 이 미 영 (관악서울대학교치과병원)

최 윤 정 (연세대학교) 임 성 훈 (조선대학교)

영문교정 편집위원 장 나 영 (원광대학교)

통계 편집위원 서 혜 영 (원광대학교)

Editorial Board

Editor-in-Chief

Jong-Moon Chae(Wonkwang University)

Deputy Editor

Insan Jang (Gangneung-Wonju National University)

Editorial Board

Hyo-Won Ahn (Kyung Hee University) Dong-Soon Choi (Gangneung-Wonju National University) Seung-weon Lim (Chonnam National University) Mihee Hong (Kyungpook National University)

Kyung-Min Lee (Chonnam National University) Sang-Min Lee (Dankook University) Yong-Il Kim (Pusan National University) Jung-Sub An (Seoul National University)

Seung-Youb Lee (Chonbuk National University) Mi-Young Lee (Seoul National University Gwanak Dental Hospital) Yoon-Jeong Choi (Yonsei University) Sung-Hoon Lim (Chosun University)

English Manuscript Editor Na-young Chang (Wonkwang University) Biostatistical Reviewer

Hye Young Seo (Wonkwang University)

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CASE REPORT

상악 골격성 확장장치와 페이스 마스크를 사용한 골격성 III급 성장기 아동의 치험례

김태균, 이영준, 채종문, 장나영 ··· 102

Microimplant Assisted Rapid Palatal Expansion을 이용한 골격성 III급 크라우딩 환자의 비수술적 비발치 교정 치료

박경호 ··· 115

역위된 매복 상악 소구치의 자가이식 치험례

장인산, 송근수, 김민근, 최동순, 최항문, 차봉근 ··· 129

비대칭 구치 관계를 가진 입술돌출 환자에서 편측 구치부 후방 이동을 동반한 발치교정치료

강주만, 오문비 ··· 140

상·하악 제2대구치 발치를 동반한 II급 부정교합의 치료

노민기 ··· 150

SPECIAL ARTICLE - Orofacial Orthopedics-Part 1

하순 깨물기 습관을 가진 골격성 II급 성장기 환자의 액티베이터 치험례

양재희, 최혜림 ··· 160

109 MSE and facemask

144 Unilateral molar distalization

153 Second molar extraction treatment

122 Non-extraction treatment using MARPE

132 Inverted premolar and impacted canine

163 Myofunctional therapy

with lip sealing 투고안내

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ORIGINAL ARTICLE

Biomechanical Analysis for Total Arch Distalization according to Location of Force Application and Types

of Temporary Skeletal Anchorage Devices

Jung Youn Lee, Jae Hyun Park, Nam-Ki Lee, Jaehyun Kim, Jong-Moon Chae,

Yoon-Ah Kook ··· 89

CASE REPORT

Treatment of a Growing Patient with Skeletal Class III

Malocclusion Using Face Mask and Maxillary Skeletal Expander

Tae-Gyun Kim, Young-Jun Lee, Jong-Moon Chae, Na-Young Chang ··· 102

Nonextraction Camouflage Orthodontic Treatment of Skeletal Class III Malocclusion with Severe Crowding Using Microimplant Assisted Rapid Palatal Expansion

Kyung-Ho Park ··· 115

Autotransplantation of an Inverted Maxillary Premolar

Insan Jang, Geun-Su Song, Min-Keun Kim, Dong-Soon Choi, Hang-Moon Choi, Bong-Kuen Cha ··· 129

Extraction Treatment Using Unilateral Molar Distalization for Lip Protrusion Patient with Asymmetric Molar Relationship

Ju-Man Kang, Moon-Bee Oh ··· 140

Treatment of Class II Malocclusion with Extraction of Maxillary and Mandibular Second Molars

Min-ki Noh ··· 150

SPECIAL ARTICLE - Orofacial Orthopedics-Part 1

Activator Treatment in a Girl with Skeletal Class II Malocclusion with Lower Lip Biting Habit

Jae-Hee Yang, Hye-Rim Choi ··· 160

91 Total arch distalization-FEA

109 MSE and facemask

144 Unilateral molar distalization

153 Second molar extraction treatment

122 Non-extraction treatment using MARPE

132 Inverted premolar and impacted canine

163 Myofunctional therapy with lip sealing

Vol 11 No 2 June 2021

Information for Authors

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Dr. 국 윤 아 Dr. 채 종 문

Dr. 김 재 현 Dr. 이 남 기

Dr. 박 재 현 Dr. 이 정 윤

Corresponding author: Yoon-Ah Kook Department of Orthodontics, Seoul St. Mary’s Hospital, College of Medicine, The Catholic University of Korea, 222 Banpo-daero, Seocho-gu, Seoul 06591, Korea

Tel: +82-2-2258-1776 Fax: +82-2-537-2374 E-mail: [email protected] Received: May 3, 2021 / Revised: May 25, 2021 / Accepted: May 25, 2021

ABSTRACT

Introduction: The purposes of this study were to analyze the displacement pattern of the maxillary dentition accord- ing to the location of the force applied and the vertical position of the hook on the palatal retraction arch (PRA) when the dentition is distalized using the palatal plate, and to compare those done by buccal miniscrew using finite element analysis. Methods: A finite element model was created and consisted of four treatment modalities with fifteen models. Modalities 1, 2, and 3 used modified C-palatal plates (MCPPs) with a short, medium, and long length PRA respectively and each modality included four models that had anterior hooks with vertical position of 0, 4, 7, and 10 mm respectively. In modality 4, miniscrews were placed on the buccal side. For each model, a force of 300 g per side was applied. Results: The long length PRA with a hook at 0 mm was the most effective model for distalization of the maxillary dentition. The short and medium-length PRAs caused uncontrolled distal tipping. Displacement of the molars using a long length PRA with a short hook led to intrusion, but with the long hook, it caused extrusion. Buccal miniscrews with hook lengths at zero caused first molars to distally tip and intrude. The molar crowns showed more distal displacement and extrusion as the hook length increased. Conclusions: Long length PRAs with MCPPs were the most effective for bodily distal movement of the maxillary molars. This information should be useful when applying temporary skeletal anchorage devices (TSADs) during total arch distalization. (Clin J Korean Assoc Orthod 2021;11(2):89-101)

Key words Molar distalization, Modified C-palatal plate, Buccal miniscrews, Finite element analysis

Biomechanical Analysis for Total Arch Distalization according to Location of Force Application and Types

of Temporary Skeletal Anchorage Devices

Jung Youn Lee,¹ Jae Hyun Park,^2,3 Nam-Ki Lee,⁴ Jaehyun Kim,⁵ Jong-Moon Chae,⁶ Yoon-Ah Kook⁵

1Department of Orthodontics, Graduate School of Clinical Dental Science, The Catholic University of Korea, Seoul, Korea

2Postgraduate Orthodontic Program, Arizona School of Dentistry & Oral Health, A.T. Still University, Mesa, Arizona, USA

3International Scholar, Graduate School of Dentistry, Kyung Hee University, Seoul, Korea

4Department of Orthodontics, Section of Dentistry, Seoul National University Bundang Hospital, Seongnam, Korea

5Department of Orthodontics, Seoul St. Mary’s Hospitaal, College of Medicine, The Catholic University of Korea, Seoul, Korea

6Department of Orthodontics, School of Dentistry, Wonkwang Dental Research Institute, University of Wonkwang, Iksan, Korea

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Temporary skeletal anchorage devices (TSADs) have been used in non-extraction cases to overcome these drawbacks.^4,5 Oh et al.⁴ reported that molars were distalized with less distal tipping using miniscrews for arch distalization. Bechtold et al.⁵ installed an additional miniscrew in the premolar area to prevent clockwise rotation of the occlusal plane while inducing the intrusive translation of the whole arch. However, the range of tooth movement using buccal miniscrews is limited due to the narrow interradicular space.

To avoid root damage with the buccal approach, TSADs have been placed on the palatal side.^6-9 Modified C-Palatal Plates (MCPPs) have been proven to be effective for molar distalization with few side effects, especially tipping effects.^10-13 Recently, Shoaib et al.¹⁴ demonstrated long-term stability with minimal changes 3 years posttreatment after total maxillary arch distalization with MCPPs in adults.

In addition, regarding the movement patterns of the anterior teeth, several studies demonstrated that a combination of lever arm height and anchor screw position can produce efficient and effective retraction of maxillary anterior teeth.^15-17 Howev- er, they analyzed only the retraction of maxillary anterior teeth after the extraction of the first premolar.

On the other hand, Yu et al.¹⁸ evaluated tooth displacement relative to different notches on the lever arms of MCPPs. They achieved bodily molar movement and intrusion with the 10 mm notch for

dentition according to the location of the force applied and the vertical position of the hook on the palatal retraction arch (PRA) when the dentition is distalized using the palatal plate, and to compare those done by buccal miniscrew using finite element analysis.

MATERIALS AND METHODS

Commercial tooth models (Model-i21D-400G, Nissin Dental Products, Kyoto, Japan) were scanned three-dimensionally to produce the tooth images. Then, the images were aligned on a broad dental arch form (Ormco^®, Glendora, CA, USA) without curves of Spee and Wilson.

The thickness of the periodontal ligament was modeled as a 0.25 mm uniformly thick layer as the study of Coolidge.¹⁹ The alveolar bone was de- signed to follow gingivally of the cemento-enamel junction, extended 1 mm beyond the apices.²⁰ Mi- cro-arch^® brackets (Tomy Co., Tokyo, Japan) were selected. The brackets and archwire were assumed to have no-play and no-friction relationship, and all materials were considered to be homogenous, isotropic, with non-linear elasticity. The material properties (Young’s modulus and Poisson’s ratio) were reported in previous studies.^21-23

Boundary conditions

The zygomaticomaxillary suture, frontonasal suture, palatomaxillary suture, pterygomaxillary suture was fixed (Figure 1A). The 3D co-ordinates

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were the X plane, sagittal plane; Y plane, transverse plane; and Z plane, vertical plane. Positive values indicate forward, inward, and upward dis- placements on the X, Y, and Z planes, respectively.

Determination of axes

Tooth movement was expressed in three axes [x-axis, anterior (+) to posterior (-) direction; y-axis, median (+) to lateral (-) direction; and z-axis, superior (+) to inferior (-) direction] (Figure 1B).

The landmarks on the crowns were as follows;

mid-center of the incisal edge of the incisors and canine cusp tip; inner center of the premolar and molar cusps. For the roots, the root apexes of the incisors, canines and second premolars, and the palatal root apexes of the first premolars and molars were the landmarks.

Installation of simulated distalization modalities on a finite element model

Four different distalization modalities were installed and fifteen different models were produced on finite element models relative to the vertical position of the anterior hook and length of the palatal retraction arch (Figure 2).

Distalization Modality 1

Models 1-4 (Figure 2A); the MCPPs (Jeil Med- ical, Seoul, Korea) were fixed in the paramedian palatal region at the sagittal level of the center of the first molar with three miniscrews (length, 8 mm; diameter, 2 mm; Jeil Medical). In the model, short stainless steel (SS) palatal retraction arch (PRA), 1.0 mm in diameter, was connected to the bands of the maxillary first premolars, extending anteriorly close to the level of the cervical line of the maxillary teeth. A Roth 0.022-inch bracket system (Tomy, Tokyo, Japan) was attached to the teeth and a 0.019 × 0.025-inch SS archwire was tied through frictionless translational joints and cinched-back on the second molar. Distalization forces of 300 g were applied via coil springs connected to the second notch on the arms of MCPPs (selected for force application and 7.7 mm apical to the archwire vertically and 12.5 mm lateral to the mid-palate horizontally) with the hook attached to the PRA at 0 mm length (Figure 2E, F). Models 2-4 were similar to Model 1, but the hook was attached to the PRA at 4, 7, and 10 mm lengths respectively.

Figure 1. Boundary condition. A, Fixed area, red surface; zygomaticomaxillary suture, frontonasal suture, palatomaxillary suture, pterygomaxillary suture. B, Three axes; x-axis, anterior (+) to posterior (-) direction; y-axis, median (+) to lateral (-) direction; and z-axis, superior (+) to inferior (-) direction.

B A

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Figure 2. Installation of simulated distalization modalities on finite element model 45 × 8 mm (300 × 300 DPI). A, Modality 1, first premolar as the location of force application using MCPP. B, Modality 2, second premolar as the location of force application using MCPP. C, Modality 3, first molar as the location of force application using MCPP. D, Modality 4. E, F, The position of the MCPP and retraction hook 45 × 20 mm (300 × 300 DPI). E, Device (MCPP) position was assumed to be at the level of the first molar centers, antero-posteriorly. The second notch on the lever arms of the MCPP was selected for force application. A hook attached to the PRA between the lateral incisor and canine cingulum. F, Length of the retraction hook was determined at 0 mm (H0), 4 mm (H4), 7 mm (H7), and 10 mm (H10) from the connection point on the PRA.

B

A C

D

Power chain position Hook length

F E

45 × 8 mm (300 × 300 DPI)

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Model 5-8 (Figure 2B); this modality was similar to Modality 1, but a medium length PRA was attached to the banded second premolar. Models 5-8 each included the hook attached to the PRA at 0, 4, 7, and 10 mm length respectively.

Models 9-12 (Figure 2C); this modality was similar to Modalities 1 and 2 but a long length PRA was attached to the banded first molar. Models 9-12 each included the hook attached to the PRA at 0, 4, 7, and 10 mm length respectively.

Models 13-15 (Figure 2D); brackets were placed on all teeth. A 0.019 × 0.025-inch SS archwire was engaged and cinched-back on the second molar.

For distalization, 300 g of force was applied on each side with a coil spring between the miniscrew and a 0.8 mm SS retraction hook attached to the archwire between the lateral incisor and canine. The vertical height of the hook was set at 0, 4, and 7 mm on Models 13, 14, and 15 respectively.

The miniscrew position was set at 8 mm apical to the archwire, at the midpoint between the adjacent brackets.

RESULTS

The effects relative to the location of force applied using MCPP

In all models with MCPPs, mesial-in rotation of the PRA banded teeth was observed (Figure 3).

Distalization with Modality 1

The short length PRA showed an uncontrolled tipping pattern with the greatest distal displacement of the crown and mesial displacement of the root at 0 mm hook. As the hook length increased,

the distal movement of the root apex increased.

The first molar showed uncontrolled distal crown tipping with the hook at 0 mm. However, as the hook length increased, it showed gradually anterior displacement of the crown and posterior displacement of the root apex (Table 1).

The medium length PRA showed severe uncontrolled distal crown tipping with the hook at 0 mm. However, with the hook at 7 mm, it was closer to bodily movement. With the hook at 10 mm, there was a greater distal displacement of the root apex with mesial displacement of the crown. In the first molar area, the movement pattern was near- ly bodily movement with the hook at 0 mm. As the hook length increased, the first molar showed more extrusion with anterior displacement of the crown and posterior displacement of the root apex (Table 2).

The long length PRA showed distal displacement of the crown and root with controlled distal crown tipping with the hook at 0 mm. As the length of the hook increased, the posterior displacement of the crown decreased, and it was closer to bodily movement at 7 mm. In the z-axis, the first molar was intruded with the hook at 0 and 4 mm, but it was more extruded as the length of the hook increased (Table 3).

The effects relative to the vertical

position of the force applied using buccal miniscrews

The incisors showed the greatest backward movement of the crown with anterior root tipping at the 0 mm hook. As the length of the hook increased, the posterior displacement of the crown

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Figure 3. Three treatment modalities included a short length PRA (first premolar), a medium-length PRA (second premolar), and a long length PRA (first molar). And they were divided into 12 models relative to a hook length of 0 mm (H0), 4 mm (H4), 7 mm (H7), and 10 mm (H10). Tooth movement was expressed in three axes [x axis, anterior (+) to posterior (-) direction; y-axis, median (+) to lateral (-) direction; and z-axis, superior (+) to inferior (-) direction]. The arrows mean the line of retraction forces.

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Table 1. Displacement by modality 1 with a short length PRA using MCPP

Hook 0 Hook 4 Hook 7 Hook 10

X Y Z X Y Z X Y Z X Y Z

Crown (mm)

1 -0.0020 0.0002 -0.0016 -0.0081 0.0008 -0.0039 -0.0114 0.0011 -0.0051 -0.0141 0.0014 -0.0060 2 -0.0005 0.0002 -0.0001 -0.0043 0.0014 -0.0007 -0.0067 0.0022 -0.0009 -0.0090 0.0031 -0.0013 3 0.0003 0.0003 0.0049 0.0040 -0.0046 0.0068 0.0068 -0.0083 0.0077 0.0089 -0.0114 0.0077 4 -0.0480 -0.0254 0.0080 -0.0360 -0.0439 0.0026 -0.0259 -0.0572 -0.0028 -0.0161 -0.0684 -0.0088 5 -0.0091 -0.0074 0.0012 -0.0032 -0.0173 -0.0008 0.0004 -0.0233 -0.0024 0.0033 -0.0277 -0.0039 6 -0.0028 -0.0024 -0.0008 0.0010 -0.0031 -0.0003 0.0022 -0.0031 0.0001 0.0031 -0.0027 0.0005 7 -0.0022 0.0001 -0.0003 -0.0023 0.0013 -0.0001 -0.0011 0.0021 0.0001 0.0000 0.0026 0.0002 Root (mm)

1 0.0008 -0.0001 -0.0002 0.0027 -0.0002 0.0016 0.0037 -0.0002 0.0025 0.0045 -0.0003 0.0034 2 -0.0001 -0.0001 0.0001 0.0007 -0.0003 0.0018 0.0012 -0.0005 0.0030 0.0016 -0.0008 0.0041 3 -0.0026 0.0004 0.0039 -0.0042 0.0020 0.0032 -0.0051 0.0032 0.0022 -0.0055 0.0041 0.0009 4 0.0042 -0.0044 0.0156 -0.0010 0.0024 0.0078 -0.0045 0.0089 0.0004 -0.0062 0.0140 -0.0071 5 0.0030 0.0035 0.0032 0.0007 0.0078 0.0038 -0.0007 0.0105 0.0038 -0.0017 0.0125 0.0035 6 0.0013 0.0007 -0.0004 -0.0003 0.0010 -0.0006 -0.0009 0.0011 -0.0005 -0.0014 0.0010 -0.0002 7 0.0005 -0.0003 0.0002 -0.0009 -0.0014 0.0004 -0.0022 -0.0021 0.0003 -0.0032 -0.0026 0.0001 X: sagittal (+), anterior, (-), posterior, Y: transversal, (+), palatal, (-), buccal, Z: vertical, (+), intrusion, (-), extrusion. *Short length PRA means force applied through first premolar using MCPPs.

Table 2. Displacement by modality 2 with a medium length PRA using MCPP

Hook 0 Hook 4 Hook 7 Hook 10

X Y Z X Y Z X Y Z X Y Z

Crown (mm)

1 -0.0038 0.0005 -0.0018 -0.0066 0.0009 -0.0030 -0.0069 0.0009 -0.0033 -0.0069 0.0010 -0.0034 2 -0.0031 0.0017 -0.0020 -0.0062 0.0034 -0.0032 -0.0073 0.0040 -0.0036 -0.0079 0.0043 -0.0038 3 -0.0006 0.0006 -0.0013 -0.0026 0.0021 -0.0018 -0.0036 0.0029 -0.0018 -0.0045 0.0036 -0.0017 4 0.0030 -0.0059 0.0065 0.0058 -0.0129 0.0056 0.0079 -0.0182 0.0042 0.0092 -0.0215 0.0028 5 -0.0300 -0.0167 0.0241 -0.0187 -0.0411 0.0131 -0.0054 -0.0620 -0.0010 0.0079 -0.0757 -0.0116 6 -0.0006 -0.0120 0.0008 0.0060 -0.0180 -0.0001 0.0086 -0.0221 -0.0011 0.0104 -0.0243 -0.0017 7 -0.0024 0.0014 -0.0011 -0.0054 0.0026 -0.0011 -0.0052 0.0042 -0.0006 -0.0050 0.0052 -0.0001 Root (mm)

1 0.0012 -0.0001 0.0007 0.0022 -0.0002 0.0015 0.0023 -0.0003 0.0014 0.0024 -0.0003 0.0014 2 0.0012 -0.0008 0.0003 0.0022 -0.0014 0.0013 0.0024 -0.0016 0.0016 0.0026 -0.0018 0.0019 3 0.0007 -0.0005 -0.0007 0.0014 -0.0010 0.0000 0.0016 -0.0013 0.0005 0.0017 -0.0015 0.0010 4 -0.0032 0.0027 0.0055 -0.0037 0.0053 0.0042 -0.0039 0.0073 0.0024 -0.0038 0.0086 0.0009 5 0.0088 -0.0042 0.0262 0.0033 0.0108 0.0225 -0.0052 0.0265 0.0150 -0.0136 0.0343 0.0084 6 -0.0005 0.0048 0.0002 -0.0028 0.0065 -0.0021 -0.0038 0.0076 -0.0037 -0.0045 0.0081 -0.0048 7 0.0001 -0.0013 -0.0004 0.0002 -0.0021 0.0004 -0.0003 -0.0027 0.0011 -0.0005 -0.0029 0.0016 X: sagittal (+), anterior, (-), posterior, Y: transversal, (+), palatal, (-), buccal, Z: vertical, (+), intrusion, (-), extrusion. *Medium length PRA means force applied through secondS premolar using MCPPs.

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decreased. In the z-axis, only the crown of the cen- tral incisor was intruded with the hook at 0 mm, but as the length of the hook increased, the incisors showed more extrusion movement. In the first molars, as the length of the hook increased, the posterior movement of the crown increased with increased forward movement of the roots. In the z-axis, the intrusion of the first molar increased as the length of the hook increased. With transverse displacement, the anterior teeth and first premolar showed palatal displacement, but the second premolar and molars had lateral displacement in the hook at 0 mm (Figure 4, Table 4).

DISCUSSION

Buccal miniscrews have been applied as a sta- tionary anchorage for total maxillary arch distalization in non-extraction treatment. However, the risk of root damage due to narrow interradicu-

lar space led us to consider the use of the palatal plate. This study was conducted to biomechanical- ly analyze tooth movement depending on different PRAs using MCPPs during total arch distalization.

In a finite element study, Von-mises stress is expressed by the sum of pressure, elongation, and torsion, so there is a limit to express the effects of orthodontic force over time. Therefore, our study only focused on the pattern of teeth displacement to evaluate tooth movement affected by PRA types during distalization of the maxillary dentition using MCPPs.

Depending on the location of force applied, displacement of the maxillary dentition showed uncontrolled distal crown tipping of the first and second premolars with forward movement of the root in a short and medium-length PRA. This might be because the line of force of short and medium-length PRA passed far from the center of re-

7 -0.0064 -0.0046 -0.0010 -0.0068 -0.0066 -0.0012 -0.0060 -0.0079 -0.0011 -0.0064 -0.0092 -0.0015 Root (mm)

1 0.0015 -0.0001 0.0015 0.0020 -0.0001 0.0019 0.0021 -0.0002 0.0020 0.0025 -0.0002 0.0025 2 0.0014 -0.0008 0.0011 0.0019 -0.0012 0.0015 0.0021 -0.0013 0.0015 0.0025 -0.0015 0.0018 3 0.0013 -0.0009 0.0007 0.0018 -0.0013 0.0010 0.0020 -0.0015 0.0011 0.0024 -0.0018 0.0014 4 0.0002 0.0001 0.0003 0.0000 0.0004 0.0006 0.0000 0.0005 0.0008 0.0000 0.0004 0.0011 5 -0.0006 0.0024 0.0039 -0.0016 0.0061 0.0049 -0.0022 0.0084 0.0053 -0.0027 0.0102 0.0054 6 -0.0134 -0.0032 0.0081 -0.0145 0.0018 0.0019 -0.0152 0.0060 -0.0037 -0.0153 0.0106 -0.0100 7 0.0014 0.0013 -0.0001 0.0010 0.0017 -0.0005 0.0005 0.0020 -0.0008 0.0005 0.0023 -0.0013 X, sagittal (+), anterior, (-), posterior; Y, transversal, (+), palatal, (-), buccal; Z, vertical, (+), intrusion, (-), extrusion. *Long length PRA means force applied through first molar using MCPPs.

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Figure 4. Fourth treatment modality using a buccal miniscrew divided into three models relative to a hook length 0 mm (H0), 4 mm (H4), and 7 mm (H7). The arrows mean the line of retraction forces.

Table 4. Displacement by modality 4 according to hook length using buccal miniscrews

Hook 0 Hook 4 Hook 7

X Y Z X Y Z X Y Z

Crown (mm)

1 -0.0607 0.0194 -0.0069 -0.0545 0.0165 0.0037 -0.0481 0.0133 0.0121

2 -0.0594 0.0270 0.0128 -0.0403 0.0216 0.0365 -0.0173 0.0121 0.0561

3 -0.0184 0.0314 0.0115 -0.0248 0.0369 -0.0257 -0.0260 0.0349 -0.0395

4 -0.0039 0.0009 0.0040 -0.0159 0.0098 -0.0086 -0.0211 0.0122 -0.0114

5 -0.0009 -0.0007 0.0011 -0.0105 0.0024 -0.0056 -0.0144 0.0025 -0.0069

6 -0.0005 -0.0002 0.0006 -0.0059 0.0008 -0.0012 -0.0087 0.0001 -0.0015

7 0.0003 -0.0030 -0.0007 -0.0167 -0.0074 -0.0008 -0.0191 -0.0081 -0.0007

Root (mm)

1 0.0113 -0.0031 0.0245 0.0047 -0.0006 0.0294 -0.0003 0.0013 0.0326

2 0.0009 -0.0052 0.0391 -0.0119 -0.0024 0.0497 -0.0199 0.0002 0.0559

3 -0.0006 -0.0113 0.0211 0.0158 -0.0168 -0.0086 0.0210 -0.0149 -0.0209

4 -0.0002 -0.0004 0.0043 0.0076 -0.0044 -0.0069 0.0100 -0.0052 -0.0092

5 -0.0001 0.0001 0.0012 0.0040 -0.0001 -0.0072 0.0053 -0.0001 -0.0089

6 0.0011 0.0006 0.0007 0.0043 -0.0003 -0.0007 0.0055 -0.0002 -0.0007

7 0.0009 0.0013 -0.0011 0.0085 0.0043 0.0010 0.0096 0.0049 0.0014

X: sagittal (+), anterior, (-), posterior, Y: transversal, (+), palatal, (-), buccal, Z: vertical, (+), intrusion, (-), extrusion.

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second premolar, and first molar, and the acting point of the actual force is on each tooth. There- fore, although the line of force is parallel, the point of force is different depending on the type of tooth. So, the distance between each line of force and the CR of the entire maxillary dentition is also different.

Also, the tooth movement pattern is clinically influenced by the archwire size and the line of force. When the maxillary dentition is connected as one unit by a rigid archwire, the line of force is the same. However, in this study, the wire size was set to 19 × 25 SS, which could allow slight movement of individual teeth; results were shown according to variables in Figure 3A.

Additionally, the small root surface area of the first and second premolars play an important role in tipping movement. Choy et al.²⁶ suggested that the tooth tipping tendency was associated with the amount of root surface area and demonstrated that roots with the greater surface area had greater resistance to tipping.

On the other hand, the long length PRA, Mo- dality 3, with the hook at 0 mm showed distal displacement with controlled crown tipping and intrusion. Also, hook at 7 mm was closer to translation movement. Therefore, Modality 3, which used the first molar as the point of force application, was the most effective way for distalizing the maxillary dentition without uncontrolled tipping.

This result is similar with previous studies that reported distalization with MCPPs showed bodily

the retraction hook on the PRA, the direction of the force vector was determined via two points.

One was on the lever arm of the MCPP while the other was on the hook of the PRA. Previous research found that when 4, 7, and 10 mm notches were vertically apical to the archwire, the 4 mm notch showed controlled distal tipping and extrusion, but the 10 mm notch caused bodily movement and intrusion.¹⁸ In our study, the force was only applied from the 7 mm notch on the MCPP to different vertical positions of the anterior hook on the PRA. The 7 mm notch on the MCPP was selected based on a previous study.¹⁸

The first molar was intruded when the short hook length was 0 and 4 mm. However, there was extrusion with the long hook at 7 and 10 mm. This could be because the direction of the force vector was below the CR in a low-level hook and above the CR in a high-level hook. As the force vector varies according to the length of the hook, the direction of the vector may change, which may cause an intrusive force.

With Modality 4, using a buccal miniscrew, the first molar showed uncontrolled distal crown tipping in different hook lengths. Our results were similar with an earlier study that reported uncontrolled distal tipping of the first molar and extrusion when buccal miniscrews were used.¹⁸ Sung et al.²⁷ concluded that when force was applied to over 10 mm hook level, it led to the distal translation of the posterior segment, but in our study, over 7 mm level caused distal tipping. This might be due to a

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difference in experimental designs and conditions used in the finite element analysis.

Regarding the y-axis, the second premolars and molars showed buccal tipping with the hook at 0 mm due to increased vertical component of the force on the buccal side, possibly just because of the buccal component of force created by the miniscrew positioned on the buccal side.

Clinically, Bechtold et al.⁵ suggested an additional miniscrew in the premolar area to enhance the direction of the force vector and to facilitate intrusion and distalization of the entire arch. How- ever, a recent clinical study reported that MCPPs showed greater distalization and intrusion with less distal tipping of the first molar and less extrusion of the incisor compared to buccal miniscrews.¹⁰

The design of this study had some limitations as follows; only initial tooth displacement was considered, no occlusal force was applied, there were differences in the mechanical properties of the virtual models and biological tissue. The thickness of the periodontal ligament was supposed to be uniform (0.25 mm), while in reality it was shaped with the narrowest zone at the mid-root level.²¹ Lastly, molar distalization with MCPPs is usually started at the same time as leveling and aligning with a 0.016-inch Ni-Ti archwire. How- ever, the archwire used in this study was a 0.019 × 0.025-inch SS archwire with cinch-back to avoid space opening during total arch distalization. In reality, with a properly angled tooth in a posteri- or crowding case, cinch-back is not necessary to relieve the crowding during molar distalization.

Further study about tooth displacement patterns and stress distribution using a 0.016 in Ni-Ti archwire in posterior crowding cases is required for efficient clinical applications with MCPPs.

CONCLUSION

This study evaluated the effects relative to the vertical position of the anterior hook and second- ly analyzed the pattern of the maxillary dentition displacement on distalization force applied by using the palatal plate according to the location of the force applied, and compared those done by buccal miniscrew using finite element analysis.

The locations of force application were first, second premolar and first molar, which were attached to short, medium, and long length PRA respectively. We made the following observations: first, a long-length PRA using an MCPP showed bodily movement of the first molars. However, short and medium-length PRAs caused uncontrolled distal tipping. Second, displacement of the first molars using long length PRA with a short hook led to intrusion. However, the long hook caused the extrusion. Third, displacement of the first molars using short length PRA with a short hook led to extrusion, and the long hook caused intrusion.

Therefore, this information should be useful when applying TSADs during total arch distalization.

Acknowledgments

The authors would like to thank Dr. Jung Mee Kim, Private practice, Los Angeles, California, USA, Dr. Jiyoung Oh, Resident, Department of Orthodontics, Seoul St. Mary’s Hospital, Catholic University of Korea, Seoul, Korea, and Jin Hyeok Kook, College of Dentistry, Yonsei University for their assistance in manuscript preparation.

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Dr. 장 나 영 Dr. 채 종 문

Dr. 이 영 준 Dr. 김 태 균

Corresponding author: Na-Young Chang Department of Orthodontics, Wonkwang University Daejeon Dental Hospital,

77 Dunsan-ro, Seo-gu, Daejeon 35233, Korea Tel: +82-42-366-1192 E-mail: [email protected] Received: February 11, 2021 / Revised: February 22, 2021 / Accepted: February 22, 2021

ABSTRACT

Face mask treatment with a rapid palatal expander is common in children with Class III malocclusion and maxillary deficiency. However, it can cause anchorage loss and dental side effects. To overcome these disadvantages, the use of skeletal anchorage such as miniplates in the infrazygomatic crest area or palate has been reported. This clinical case report presents face mask treatment in skeletal Class III adolescent with maxillary skeletal expander (MSE). MSE has been developed for the maxillary expansion in adults, but it can be used as a skeletal anchorage for face mask treatment in children. The post-treatment profile was significantly improved without any dental side effects. (Clin J Korean Assoc Orthod 2021;11(2):102-114)

Key words Active plate, Maxillary skeletal expander, Face mask, Class III malocclusion

Treatment of a Growing Patient with Skeletal Class III Malocclusion Using Face Mask and Maxillary Skeletal Expander

Tae-Gyun Kim,¹ Young-Jun Lee,¹ Jong-Moon Chae,^1,2,3 Na-Young Chang^1,2

1Department of Orthodontics, School of Dentistry, University of Wonkwang, Iksan, Korea

2Wonkwang Dental Research Institute, Iksan, Korea

3Postgraduate Orthodontic Program, Arizona School of Dentistry & Oral Health, A.T. Still University, Mesa, Arizona, USA

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서론

상악골 열성장을 동반한 골격성 III급 반대교합을 보 이는 성장기 아동에서 상악골의 전방 견인을 위해 페이 스 마스크가 사용되어 왔다.¹ 페이스 마스크 장치와 함 께 구강 내 장치로 접착형 혹은 밴드형의 상악 급속 확 장장치(rapid maxillary expander; RME)가 주로 사 용되는데, 이는 상악궁 확장과 동시에 전방 견인을 효 과적으로 하기 위함이다.² Baik³은 60명의 한국 아동 을 대상으로 상악궁 확장 시 전방 견인이 더 잘 일어남 을 확인했고 J¨ager 등⁴은 메타 분석으로 RME를 사용 하고 상악 전방 견인을 하면 더 큰 효과가 있음을 입증 했다. 하지만 이러한 전통적인 페이스 마스크 치료는 전 치부를 순측 경사 시키고 상악 구치부를 정출 및 협측 경사 시킨다.⁵

골성 고정원과 함께 페이스 마스크를 사용하기 시작 하면서 이러한 치성 부작용을 최소화할 수 있게 되었 다. Cha 등⁶은 관골하능(infrazygomatic crest)에 미 니 플레이트를 식립하여 페이스 마스크의 고정원으로 사용하는 방법을 제시하였는데, 이는 부가적인 외과적 술식이 필요하다는 단점이 있다. 또한 Kook 등⁷은 구개 에 미니 임플랜트를 식립하여 고정원으로 이용하였으나 상악의 횡적 부조화가 있는 경우 이를 개선하기 어렵다 는 단점이 있다.

상악 골격성 확장장치[maxillary skeletal exp

ander (MSE); BioMaterials Korea Inc., Seoul, Korea]는 원래 성인에서 구개 확장을 위한 장치로 개발 되었으나, 성장기 아동에서 전방 견인 치료 시 골성 고 정원 장치로 활용할 수 있다.^8,9 이번 증례보고에서는 상 교정장치(active plate) 및 MSE와 페이스 마스크를 이 용하여 골격성 III급 성장기 아동을 성공적으로 치료하 였음을 보고하는 바이다.

진단

9세 1개월의 남자 환자가 전치부 반대교합을 주소로 의뢰되었다. 전신 및 치과적 병력상 특이사항은 없었다.

보호자의 진술에 의하면 외가 쪽으로 하악 발달 경향의 가족력이 있다고 하였다.

초진 시 정모에서 이부의 우측 변위가 관찰되며, 미소 시 상악 전치의 노출은 부족하였다. 상악 치열의 정중 선은 안모 정중선과 일치하였다. 측모에서는 오목형 안 모를 보이고 있었고 하순 및 턱끝 돌출감이 있었다. 구 내 사진 및 진단 모형에서 전치부 및 우측 구치부 반대 교합을 보였고 그로 인한 하악 치열 정중선의 변위 및 상악 전치부의 크라우딩이 관찰되었다(Figures 1, 2).

측면 두부계측방사선사진에서 전후방적으로는 골격 성 III급 부정교합(ANB: 1.4°, A pointN perpend:

0.8 mm, PogN perpend: 1.5 mm)을, 수직적으로 는 저발산형의 경향(FMA: 18.2°, ODI: 68.7°)을 보였 다. 상악 전치의 경사도(U1 to FH: 117.9°)와 하악 전치 의 경사도(IMPA: 93.3°)는 정상 범주였다(Table 1). 정 면 두부계측방사선사진에서는 이부(Me)가 우측으로 변 위되어 있었다. 파노라마방사선사진상에서 견치 및 소 구치는 치근 형성 단계였고 수완부 방사선사진상 SMI 1단계로 판단되었다. 콘빔 전산화단층촬영 영상은 삼차 원 소프트웨어(ON3D; 3DONS, Seoul, Korea)로 분 석하였다. 상악은 전후방적으로 열성장[A(y): 1.71; 정 상 범위, 0~2]을 보였으며, 하악은 전후방적으로 정 상[Pog(y): 1.14; 정상 범위, +40]이었다(Figure 3, Table 2).

이에 본 환자는 저발산형의 골격 패턴과 전치부, 구치 부 반대교합을 동반한 골격성 III급 부정교합으로 진단 하였다.

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Figure 2. Pretreatment dental casts.

Figure 1. Pretreatment facial and intraoral photographs.

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치료계획

초진 시 상악의 좁은 폭경으로 인한 반대교합을 나 타내고 있었으므로 상악의 폭경 확장을 우선적으로 고 려하였다. 상악 확장을 위한 계획으로는 (1) 상교정장치 (active plate)를 이용한 확장, (2) 상악 급속 확장장치 (RME)를 이용한 확장, (3) MSE를 이용한 확장 등을 고려할 수 있다. 보호자가 안모의 변화를 원치 않았고 구외 장치의 사용을 거부하여 상교정장치(active plate) 를 통한 완속 확장 후 하악의 위치를 재평가한 후 필요 시 상악의 전후방적인 성장 결핍을 개선하기 위한 페이 스 마스크를 고려하기로 하였다.

치료경과 및 결과

치료과정

치료 시작으로 구치부 교합 블록(bite block)을 포함 한 상악 상교정장치를 통한 완속 확장을 시행하였다.

환자 스스로 스크루를 돌릴 수 있도록 교육하였고 환자 는 일주일에 1/4바퀴(0.25 mm)씩 스크루를 활성화하 였다(Figure 4A). 상악의 확장을 시작한 지 1달 만에 구치부 반대교합이 해소되면서 전치부 반대교합도 동시 에 개선됨을 확인하였다. 이때, 상악 좌측 측절치의 구 개측 변위로 인해 교합 간섭이 나타났고 이를 해소하기 위해 상악 전치부에 0.022inch 슬롯 브라켓(Master Series^Ⓡ, MBT prescription)을 부착하여 배열하였다 (Figure 4B).

고정식 장치 부착 한 달 후 상악 좌측 측절치의 반대 교합이 해소되었으나, 하악 유견치 부분의 교합 간섭이 Table 1. Cephalometric measurements

Mesurements Mean Pretreatment Posttreatment

SNA (°) 81.0 80.2 81.2

SNB (°) 78.0 81.6 78.6

ANB (°) 4.0 -1.4 2.7

Wits (mm) -2.0 -8.2 -2.7

Mandibular body length (mm) 71.0 71.5 75.8

APDI (°) 82.0 92.7 85.5

Gonial angle (°) 126.0 113.9 113.3

Sum (°) 396.0 387.3 389.8

FMA (°) 26.0 18.2 21.6

Ramus height (mm) 43.0 47.0 47.0

Post/Ant (%) 61.0 71.9 69.5

SN-MP (°) 36.0 27.3 29.8

ODI (°) 72.0 68.7 78.8

U1 to SN (°) 105.0 108.8 110.0

U1 to FH (°) 116.0 117.9 118.2

IMPA (°) 95.0 93.3 93.0

Interincisal angle (°) 124.0 130.6 127.2

Upper lip EL (mm) 2.4 -0.4 1.9

Lower lip EL (mm) 3.3 2.0 1.9

Stmi-Me’/Sn-Stms (ratio) 2.0 2.2 2.0

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Table 2. 3-dimensional coordinate values of the selected landmarks at the pretreatment, progress, and posttreatment Pretreatment After active plate treatment or

Pre-MSE + face mask Posttreatment

A (1.29, 1.71, -52.75) (1.17, 0.77, -54.37) (1.36, 0.52, -54.11)

Pog (0.96, 1.14, -96.26) (2.44, 1.36, -97.93) (4.17, 6.07, -99.61)

U1MP (4.03, 0.04, -70.18) (1.65, -2.57, -71.37) (2.25, -2.01, -73.12)

L1MP (0.65, -2.41, -70.29) (0.80, -0.10, -73.38) (2.57, 1.30, -70.52)

Pronasale (1.14, -18.56, -42.95) (0.30, -19.95, -43.00) (2.34, -20.73, -43.13)

MSE: maxillary skeletal expander, U1MP: upper dental midline point, L1MP: lower dental midline point.

Figure 3. Pretreatment radiographs.

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관찰되어 전방부의 확장을 계획하였다. 이에 fan형 확 장 스크루(fantype expansion screw)를 갖는 상교 정장치로 변경하여 확장을 더 진행하였다(Figure 4C).

상악궁의 확장 및 상악 전치부의 순측 경사를 동반하 여 치료한 지 5개월 후 더 이상의 치성 간섭이 존재하 지 않았고 안정된 교합관계를 이루고 있음이 확인되었 다. 그러나 상악 전치부의 순측 경사 및 전치부에서 부 족한 수평피개를 보였고, 보호자가 이에 대한 개선을 원했다(Figure 4D). 완속 확장 후 보호자가 순측 경사 된 상악 전치의 수정을 원하였고 하악의 위치를 재평가 한 결과 오목형 안모를 보이고 전치부의 부족한 수평피 개를 보여 MSE를 이용한 페이스 마스크 치료를 시행하 였다.

전통적인 페이스 마스크를 사용할 경우 원치 않는 상 악 전치부 전방 경사나 크라우딩 등의 부작용이 예상 되었다. 따라서 골격성 고정원을 이용한 페이스 마스크

를 시행하기로 하였다. 골격성 고정원으로 MSE를 사 용하였다. 구개부에 4개의 스크루(직경 1.5 mm, 길이 11 mm; BioMaterials Korea Inc., Seoul, Korea)를 부분 마취하에 식립하였고, 기공 과정을 거쳐 레버암 을 견치 부위까지 연장하였다. 환아에게 3/16inch 5 oz 고무줄을 전하방 방향으로 걸도록 교육하여 편측당 300400 g의 힘으로 전방 견인을 시행하였다. MSE로 추가적인 확장은 필요하지 않아 진행하지 않았으며 페 이스 마스크를 사용하였다(Figure 5). MSE를 이용한 페이스 마스크를 8개월간 사용한 후 상악 전치부의 브 라켓을 제거하였고, 설측에 고정식 보정장치를 부착하 였다. 치료 16개월째에 MSE를 제거하였다.

치료결과

상교정장치로 확장 후 하악 위치의 재평가를 위해 콘 빔 전산화단층촬영 영상을 삼차원 소프트웨어(ON3D) Figure 4. Progress intraoral photographs: initial (A), 1 month (B), 4 months (C), 5 months (D).

A

B

C

D