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Integrated tissue biology, biomechanics

and digital diagnosis for non-surgical treatment

Kee-Joon Lee, DDS, PhD

Department of Orthodontics,

Yonsei University College of Dentistry

Envelop of discrepancy

Orthognathic surgery is indicated for severe skeletal discrepancy beyond the limit of orthodontic camouflage in a non-growing patient (Proffit, Contemporary orthodontcs)

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Class III Mn prognathism Q) Can we move mandible

‘backward’ without surgery?

We know it is impossible,

but…

Surgery? (22Y F)

Clue 2-1) Upper ant. axis affects posterior occlusion

Ideal

OB/OJ

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Clue 2-2) Lower ant. axis affects posterior occlusion

Ideal

OB/OJ

Clue) incisor axes affect posterior occlusion

Translation Valladares et al. 2014

Lingual tipping

2D VTO: Class II/III compensation

Class II compensation

U1: Translation~root movement

L1: Intrusion+ controlled tipping

(no flaring!!!)

6/6: Anchor loss or distalization

Class III compensation

U1: Minor retraction

L1: Translation~root movement

U6: anchor loss?

L6: Distalization?

Occlusal

Plane

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Clue 1. Soft

tissue

Understanding the soft tissue…

•1. The thicker, the dumber (refractory)

•Lower lip>Upper lip>Buccal cheek

•2. Facial change after camouflage?

•Class III > Class II > Asymmetry

•2. DDX between rest & active

•(1) Midline at rest & action (philtrum deviation)

•(2) Nasolabial fold at rest & action

• Hypothesis – bodily movement may induce more dramatic soft tissue change esp in the lower lip?

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Clue 2. Mechanics

Summary: appliance construction (modified shape-

driven approach) Angle Orthod 2014

Kee’s protocol Bodily retraction

• Miniscrew (low buccal), long hook

• Anterior torque (++)

• Moderate retraction force (150-200g) renewal 4-6wks

Indication

Incisor axis normal

Incisor exposure normal

Incompetency (+-)

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Clue 3. Biology

Young 3D Young 7D Young 14D

force

Adult 7D Adult 14D

Skerry et al. J. Bone Miner. Res 1989;4:783-788. Klein-Nulend et al. FASEB J;1995:441-445. Cowin et al. J of Biomech Eng ;1991:191-197

Summary)

1. Bone formation on the lateral surface may precede bone resorption

on the ‘pressure’ side PDL

2. Coronal/middle 1/3 bone response may differ from apical 1/3 region

3. Bone formation via ‘light force technology’ may be realistic in young

patients, but not in adults.

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Clue 4. Airway & function

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Class II Mn retrognathism Q) Can we move mandible

‘forward’ without surgery?

We know it is impossible,

but…

Comparison 2017-10-16

Incompetency exaggerates protrusive profile / Mn retrusion

Ob Oris: Lip pursing

Mentalis: Chin flattening

Zmi LLS

LLSAN

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Q) Vertical control of maxilla via total

arch intrusion?

Vertical closure Restriction

of suture growth

Dentoalveolar intrusion

Predictability Poor Good

(WITH MINISCREW)

Stability Questioned Relatively stable?

Dermaut et al. Eur J Orthod 1992 “Orthopedic effect on the maxilla could not be established.”

Orton et al. Eur J Orthod 1992 “Maxiallry restraint -No significant change in the anterior facial

height.”

Sugawara et al.Int J Adult Orthod Orthognat Surg 2002 “SAS would be a valid modality to

intrude mandibular molars”

Cr

Cr

Single miniscrew

Dual miniscrews

Cres of

Mx. dentition

Distalization and rotation

Vertical reduction (-)

Distalization and intrusion

Vertical reduction (+) (p<0.05)

2.41mm

1.56mm

1.29mm 0.49 mm

2.91mm

1.40mm

1.83mm

0.84mm

Q) Effect of

dual miniscrews

on vertical

dimension (in

non-ext model)?

• Vertical angle up to 45dgr: minimal buccal tipping of molars (no palatal miniscrew)

• Vertical angle > 45dgr: significant buccal tipping of molars (+ palatal miniscrew)

• Rotation is related to the relative position of force vector

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Cres of total arch??

Figure 7. Positions of the centers of resistance. A, The center of resistance of the 4 mandibular anterior

teeth; B, the center of resistance of the 6 mandibular anterior teeth; C, the center of resistance of the

complete mandibular dentition.

Korean J Orthod. 2017 Jan;47(1):21-30

Finite-element analysis of the center of resistance of the mandibular dentition

A-Ra Jo, Sung-Seo Mo, Kee-Joon Lee, Sang-Jin Sung, and Youn-Sic Chun

Gwang-Mo Jeong, Sang-Jin Sung, Kee-Joon Lee, Youn-Sic Chun, Sung-Seo Mo. Kor J Orthod 2009:39;83-94

Cres of total arch??

Force system for total arch intrusion

1. Vertical vector should be set close to the Cres of total arch.

2. Bimaxillary force vectors and/or dual miniscrews may be reliable.

3. Torque-on-the-wire for incisor control (10dgr)

?

?

?

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Hypothesis: for ‘pure vertical’ discrepancy!!!!!!!!!!

• 3D total intrusion reduction AFH reduction

incompetency

• 2-3mm TAI (Max) + 1-2mm TAI (Man) (+ lip ‘draping’)

= 3-5 mm correction only?

• What if normal soft tissue growth is combined???

• TAI in grower (fast and effective TAI)???????????

Superimposition(Initial / Deb / fu) 12-14Y M

Autorotation during growth peak???

ANB 1.3 -0.7 -1.0

MP angle 34.030.3 25.8

AFH 130.1 127.7 128

Superimposition

Mn ‘advancement growth’ 8mm

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AFH 2mm increased

MP angle 1dgr reduced

Suggestion: 4D Semi-early treatment

• Gray area between growth spurt and growth cessation!!!

• Middle school active orthodontics for vertical issue

Advantage of early correction? KJ’s suggestion

• … Based on soft tissue paradigm…

Category Author Conclusion KJ’s suggestion

Biological rationale D Carlson Suggestion of gene-based approach

Alveolar movement for skeletal change

Tx timing and outcome H Pancherz Negative Positive via 4D concepts (Less non-invasive tx)

Class II WR Proffit JFC Tulloch

Negative Positive via 4D total arch intrusion

Skeletal open bite (high angle)

JD English Inconclusive Positive via 4D total arch intrusion

Open bite PA Shapiro Yes but not stable Positive via 4D intrusion

Impacted incisors A Becker Active orthodontics>waiting

4D Yonsei guided eruption

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Transverse correction for asymmetry

Transverse problem

Camouflage

CR CR

CR CR

U-L CRe difference = -8.7 Req Exp. = +7.5

X +1.0 55.5

Surgery

46.8

54.5

Δ IMW @Cres= -7.5 Req Exp. = +6.5mm

T/S 21 T/S 40 Initial

2M

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what to extract?

#44 Extraction #47 or #48 Extraction

Initial

Debond

Shift from surgery non-surgery

Initial Debond

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2018-04-11 2018-02-22

CBCT comparison

CBCT comparison;

frontonasal disjunction!!!

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*What leads to surgery :

- TVL to Pog’+++ (average to low angle, ‘no rotation’)

- Insufficient ‘U zone’

*For successful camouflage

- Elimination of incompetency

- U1 translation>>tipping

- Total intrusion

- ‘More than’ A type anchorage

*For successful surgery

- Elimination of perinasal depression

- adequate jaw(esp Mx) rotation

- maximum decompensation

In Class II…

*What leads to surgery

- TVL to Pog’ +++

-L1 linguoversion

*What leads to camouflage

- IMPA relatively high

- chin+lower lip protrusion

*For successful surgery

- IMPA << L1 to Facial plane/TVL

- Variation in U1 consideration: MARPE

In Class III…

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Summary : KJ protocol for Class III / asymmetry

•1. Early transverse correction to secure perm teeth eruption - MARPE>> RPE

•2. Minimum/moderate protraction (avoid creation of incompetency!!!)

•- Low angle: RPE, High angle: MARPE

•3. Growth observation / maintenance of transverse

-re-RPE if indicated

-Please, do not ext L4!!!

•4. Phase II: Early phase II in case of high angle / incompetency

-OGS if not camouflageable (pt’s perception)

-Non surgery via Total arch intrusion (in case of incompetency)

-Non surgery via ext L4 & L1 translation (in case of A-P problem+minor protrusion)

Thanks for your

attention!!!

Acknowledgement

Pf. YJ Choi

Dr. CB Park

Dr. JH Chun

Dr. HK Hong

Dr. Amanda Cunha