Download Herbst Appliance Treatment What We Have Learned

4/20/16 Does Class II malocclusion deserve “Early treatment” ??
Herbst appliance treatment: what we have learned
Bernardo Souki DDS, MsD, PhD Class II vs. Early treatment
Dentoskeletal effects
Special indications for Class II Early treatment
Psychosocial effects
“Early treatment should not
be thought of as an effective
and efficient way to treat most
Class II children.”
“The decision for Class II early
treatment should be based on
Pre-treatment
special indications for each child.”
Post-treatment
with Headgear
Special indications for Class II Early treatment
Psychosocial effects
Special indications for Class II Early treatment
Risk of traumatic injury
“Early orthodontic treatment for Class II/1
malocclusion results in higher self-concept
scores and fewer negative social
experiences.” O`Brien et al., 2003
1 4/20/16 Class II vs. Early treatment
Class II vs. Early treatment
Risk of traumatic injury
Risk of traumatic injury
•  Overjet ≥5mm
“Providing early orthodontic treatment
PEDIR FOTO MARIA ILMA for children with prominent upper front
teeth is more effective in reducing the
incidence of incisal trauma than
providing one course of orthodontic
treatment when the child is in the early
adolescence.”
Thiruvenkatachari et al., 2014
Class II vs. Early treatment
Risk of traumatic injury
•  Overjet ≥5mm
•  Lip incompetence
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2 4/20/16 Class II dentofacial orthopedics
Class II vs. Early treatment
Ideal timing
Peak in Mandibular Growth
Summary
Primary
CS 1
CS 2
CS 3
CS 4
CS 5
Early mixed
Intertransitory
CS 6
Class II vs. Early treatment
Summary
Late mixed dentition
One-phase Class II treatment associated
with fixed appliance
One-phase Class II treatment associated
with fixed appliance
Advantages 1.  Effectiveness: >2 mm mandibular growth
2. Efficiency: Shorter total duration
3. Stability: Ideal intercuspation
3 4/20/16 How to treat
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Class II mal
Skeletal Class II malocclusion
How to treat?
ü  Facial convexity is not bad
ü  Risk of trauma is not too big
ü  No psychosocial problems
ü  Extensive growth potential forecast
ial convexity is
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4 4/20/16 Class II malocclusion
Herbst appliance
The Herbst appliance is the most frequently used mandibular advancement device in the USA. Emil Herbst’s original appliance (1910)
von Bremen, Pancherz, Ruf, 2007
Pancherz, 1979 Silva et al., 2015
Skeletal Class II malocclusion
Mandibular deficiency
Retrusion of the mandible is the most commonly occurring
factor contributing to skeletal Class II malocclusion
Renfroe, 1948
McNamara Jr., 1981
Buschang & Martins, 1998
Pancherz & Ruf, 2008
5 4/20/16 Herbst appliance
Benefits of Herbst appliance
Immediate benefits
• 
• 
• 
• 
Expedite improvement of the self-esteem
Reduce the risk of incisor trauma
Less reliance on patient compliance
Shorter treatment duration
Patients & Methods
Skeletal Class II patients (n=50)
Pubertal stage (CS3 – CS4)
Ethics approval from IRB
Herbst appliance treatment effects 3D assessment study Patients & Methods
Patients & Methods
Herbst group
Sampling design
50 skeletal Class II growing patients
One-step full activation
Herbst Group n = 25 Comparison Group n = 25 Age: Age: 12y – 16y 12y – 16y CS3 – CS4 CS3 – CS4 Permanent den??on Permanent den??on 6 4/20/16 Patients & Methods
Patients & Methods
Comparison group
Comparison group
Marsupialization of cysts
Previous alignment and leveling
Patients & Methods
Comparison group
Patients & Methods
Herbst appliance design
Maxillary impacted canines
Image analysis
3D virtual models
What we have learned
7 4/20/16 What we have learned about
Mandibular displacement
a) Mandibular displacement
b) Condylar growth
c) Condylar displacement
d) Glenoid fossa remodeling
e) Dentoalveolar changes
f) Maxillary adaptations
Mandibular displacement
Pre-treatment
Herbst insertion
2 months
6 months
Herbst removal
8 months of tx.
Pre-treatment
Facial balance improvement
Herbst insertion
Herbst removal
T0 (Pre-treatment)
T1 T2 (Herbst insertion) (Herbst removal)
8 4/20/16 Mandibular forward displacement vs. Facial improvement
Diego – 16 y
8 mos. Herbst appliance T2 T0 Diego’s CBCT scans superimposition
Relative to the cranial base
T0
T1
10mm initial
advancement after
Herbst insertion
T1
T2
Mandible moved
back 6mm during
Herbst treatment
T2
T0
4mm effective
mandibular
advancement
T0 – Pre-treatment
T1 – Immediately after Herbst insertion
T2 – After 8 mos. Herbst treatment
Mandibular displacement
(Superimposition at the cranial base)
Herbst group
Mandibular displacement
Take home message
ü  Mean 65% of rebound during Herbst treatment
(range 47% - 75%).
ü  1.7 mm of effective mandibular forward displacement
(5 mm of Herbst advancement ).
ü  Herbst appliance treatment improved the patient’s profile
(short-term evaluation).
Comparison group
9 4/20/16 3D superimposition at the body of the mandible
Condylar growth
Condylar growth
Condylar growth
(Regional Mandibular Superimposition)
(Regional Mandibular Superimposition)
Herbst group
Herbst group
Comparison group
1.9 mm - backward
0.7 mm - backward
2.5 mm - upward
1.6 mm - upward
Herbst vs. Comparison
Comparison group
+ 1.2mm (2x more) - backward
+ 0.9 mm (0.5x more) - upward
-4.0
-2.0
0.0
2.0
3.0
4.0
Condylar growth
Take home message
Condylar displacement
ü  Effective backward condilar growth (1.2 mm).
ü  Change in the direction of condilar growth.
10 4/20/16 ?
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Condylar displacement
Condyle-Glenoid fossa relationship after Herbst removal
3D superimposition at the glenoid fossa
Difference
Herbst vs. Comparison groups
X (RL) = 0.01 mm
Y (AP) = 0.06 mm
Z (IS) = 0.11 mm
3D = 0.07 mm
Condylar displacement
Take home message
Glenoid fossa remodeling
ü  Regardless how much the condyle is moved
forward and downward, it returned to its
original relationship with the glenoid fossa.
Herbst group
Comparison group
Superimposition at the anterior cranial fossa
Pre-treatment
Immediately after Herbst insertion
Superimposition at the anterior cranial fossa
8 months after Herbst insertion
Baseline
10 months after
11 4/20/16 Glenoid fossa remodeling
Take home message
ü 
ü 
Bone remodeling developed at the
articulating surface of the glenoid fossa of
Herbst patients.
At this point it is not possible to determine
that 8 months of Herbst treatment is
sufficient to produce a stable new bone in
the glenoid fossa.
Dentoalveolar changes
Molars
Incisors
Dentoalveolar changes
Take home message
ü  Significant lower incisor proclination
Mean 7.3 degrees (up to 21 degrees)
ü  Variable, but mostly small, upper incisor uprighting
ü  Maxillary molar
1.4 mm backward
0.4 mm upward (but maxilla moved 0.9 downward)
ü  Mandibular molar
1.1 mm forward
0.6 mm upward
Maxillary changes
Maxillary changes
Take home message
ü  No significant skeletal SAGITAL and VERTICAL
changes were observed.
ü  Essentially dentoalveolar movements
(Headgear effect).
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