Copy of jc presentation 29 oct o9 /certified fixed orthodontic courses by Indian dental academy

Early treatment of vertical skeletal
dysplasia : The hyperdivergent
phenotype
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com

Introduction
• Early treatment is indicated.
( Nanda SK ; Am J Orthod Dentofacial Orthop 1988 ; 93 : 103-16)
• Factors associated with favorable growth in patients
with hyperdivergent phenotypes :
a. Increase in posterior facial / anterior facial ratio.
b. An average or greater amount of „true‟ forward
mandibular rotation.
c. More of anterior direction of condylar growth.
d. Enhanced condylar growth.
(In short , mandible is displaced more anteriorly than
inferiorly)
( Vaden JL ; Am J Orthod Dentofacial Orthop 1994 ; 105 : 438-43 )
( Bjork A ; Eur J Orthod 1983 ; 5 : 1-46 )

• Commonly used orthodontic appliances redirects
condylar growth posteriorly , rotates mandible
backwards and increases anterior facial height.
( Hultgren BW ; Am J Orthod ; 1978 ; 74 : 388-95 )
• Control of vertical dimension is probably the single
most important factor in correction of the
hyperdivergent case. ( Fotis V ; Am J Orthod 1984 ; 86 : 224-32 )
• Orthodontists attempt to limit vertical dimension
increase in growing patients by one or more following
methods:
1. High pull headgear with or without splint.
2. Extraction therapy.
3. Bite blocks ( active or passive ).
4. Vertical pull chin cup.
5. Any of the combination.www.indiandentalacademy.com

• High pull head gear modifies maxillary growth but
compensatory eruption of the mandibular molars
prevents autorotation of the mandible and control of
anterior facial height. ( Baumrind S ; Am J Orthod 1981 ; 80 : 17-30 )
• High pull head gear attached to a splint modifies
maxillary growth effectively to a more postero-superior
direction ; does not correct mandibular dysmorphology.
( Caldwell SF ; Am J Orthod 1984 ; 85 : 376-84 )
• Extraction therapy produces effective dento-alveolar
compensation , molar eruption during space closure
negates potential improvement of facial height.
(Staggers JA ; Am J Orthod Dentofacial Orthop 1994 ; 105 : 19-24)

• Combination of high pull head gear and extraction
therapy appears to have similar effect with even more
eruption of lower molars.
( Dougherty HL ; Am J Orthod 1968 ; 54 : 29-49 )
• Bite blocks have been shown to be effective for
controlling anterior facial height in both animal models
and clinical trails .
( Kuster R ; Eur J Orthod 1992 ; 14 : 489-99 )
• Magnetic bite blocks produce significant treatment
changes but they can also create
a. Asymmetric mandibular posture & subsequent
unilateral crossbite due to shearing forces of repelling
magnets.
b. Increased root resorption due to excessive forces.
( Melson B ; Am J Orthod Dentofacial Orthop 1995 ; 108 : 500-9 )

• Vertical skeletal excess anteriorly is commonly
accompanied with transverse maxillary constriction.
• Active expansion of maxilla may lead to unfavorable
inferior displacement of maxilla and mandible.
(Wertz R ; Am J Orthod 1977 ; 71 : 267-81)
• Bonded palatal expanders have been shown to
minimise inferior displacement in posterior maxilla
whereas bonded and banded palatal expander show
similar inferior displacement for anterior maxilla.
(Asanza S ; Angle Orthod 1997 ; 67 : 15-22 )
• To counteract inferior anterior maxillary displacement
and increase in mandibular plane angle , chin-cup may
be an effective appliance.
(Majourau A ; Am J Orthod Dentofacial Orthop 1994 ; 106 : 322-8)

• Hence , this study examines the effects of a novel
treatment regime consisting of :
a. Lip seal exercises.
b. Bonded palatal expander constructed to function as a
bite block.
c. Banded lower Crozat / lip bumper.
d. High pull chin cup.
• Aim of the study : To whether this treatment regime
a. Change the amount and direction of true mandibular
rotation.
b. Alter the amount and direction of mandibular growth.
c. Control mandibular and maxillary molar eruption .
d. Improve the vertical skeletal relationship.

• Materials and method :
a. 38 patients from private orthodontic practice of Dr.
Albert H. Owen in Austin , Tex.
b. 38% of the patients had open bite , although not a
selection criteria.
c. 24 (65%) females and 14 (35%) males
• Inclusion criteria :
a. Diagnosis of vertical skeletal dysplasia based on
clinical photographs and cephalometric assessment of
the mandibular plane angle greater than 350.
b. Mixed dentition at the start of treatment.
c. Treatment of no less than 6 months with the same
early vertical treatment protocol.
d. High quality cephalometric records.www.indiandentalacademy.com

• Exclusion criteria :
a. History of temperomandibular dysfunction.
b. Maxillofacial trauma
c. Nasopharyngeal obstruction
d. Missing or poor quality cephalograms
e. Poor patient co-operation with any of the treatment
protocols.
• Control group : drawn from longitudinal data collected
by the Human Growth Research Centre , University of
Montreal , Quebec. (non orthodontic sample with a
variety of malocclusion).
• Mean age pretreatment : 8.2 yrs ( +/- 1.2 yrs )
• Mean age post-treatment : 9.5 yrs ( +/- 1.2 yrs )
• Mean treatment duration : 1.3 yrs (+/- 0.3 yrs)www.indiandentalacademy.com

• The control and experimental subjects were matched
based on age , sex , and mandibular plane angle.

• Treatment protocol : Same practitioner performed all
treatment to the same treatment protocol.
• Lip seal exercises :
a. To train the orbicularis oris muscle to become more
active in creating an anterior oral seal.
b. Thereby , diminishing mentalis activity.
c. Use of lip disc for 60 mins per day with placement of
hand on chin to detect and eliminate mentalis activity.
• Banded Crozat / lip bumper in mandibular arch to gain
expansion.
a. - Cemented in place with a 2 to 3 mm activation for 8
weeks.
b. - Reactivation : 1mm every 8 weeks.www.indiandentalacademy.com

• Maxillary arch treated with bonded palatal expander
with slow expansion
• Activation : ¼ turn / week , ( 1mm / month ) for
approximately 6 months.

• Whether a patient wore chin cup was judged clinically
on the basis of appearance of bite marks on the BPE
acrylic. If no marks were seen ; patient was made to
wear a high pull chin cup.
• Force delivered :16 to 20
ounces of force per side
• Duration : at least 14 hours
per day and asked to record
the time worn on a time card.
• The direction of pull :
approximately 450 upward
and backward in relation
to the occlusal plane.

Measurements :
• All lateral cephalogram digitised and traced by same
technician.
• Pre treatment (T1) and post treatment (T2)
cephalograms were corrected for radiographic
magnification.
• 16 landmarks were digitised ( fig 3 )
• Intra-examiner reliability showed no significant
systematic error.
• Random measurement error ranged 0.2 to 1.5 mm avg.
0.7mm ( using method error statistics )

Evaluation of treatment changes :
• 19 traditional measurements : 9 angular and 10 linear
• Horizontal and vertical displacement of 11 landmarks
using cranial base superimposition
• Mandibular superimposition to measure
a. True mandibular rotation
b. Mandibular dental movements
c. Condylar growth
d. Horizontal and vertical drift of mandibular landmarks.

• Lateral cephalogram were superimposed on stable cranial
and cranial base reference structures.
• The tracings were oriented according to the “best fit”
stratergy.
• A cranial reference axis (CRA) oriented along S-N
minus 70 (SN7) and registered on sella was marked on
T1 tracing and transferred to the superimposed T2
tracing.
• Horizontal and vertical positional changes of landmarks
evaluated parallel and perpendicular to CRA.
• Finally, T1 and T2 mandibles were superimposed using
following natural references structures.

• The skewness and kurtosis statistics showed that all
variables were normally distributed.
• Patients were divided into subgroups :
a. Open bite and overbite groups.
16 of 38 patients had an openbite.
a. Patients with chincup therapy and without chincup
therapy.
30 of 38 patients were treated with chincup.
• Mann-Whitney ; a nonparametric test ; used to test
differences between sub-samples ; as sub-sample size is
small.
• Paired t test to detect significant treatment changes.
• Student t test to compare control and treatment group.www.indiandentalacademy.com

Discussion:
Efficacy ratings* of various modes of treatment on the maxilla, mandible, and dentition
HPHG + HPHG + Passive Active Treatment
Effect site HPHG splint Extraction extraction PBB VCC PBB under study
Condylar growth/amount – – 0 0 0 ? 0 +
Condylar growth/direction 0 0 0 0 – ? 0 +
Mandibular rotation 0 0 0 0 + + + +
Maxillary position + ++ 0 0 + ? + +
Posterior face height – – 0 0 + ? 0 +
Anterior face height 0 0 0 0 + ? + 0
Skeletal AP relations + + 0 0 + ? + +
U6 position ++ ++ – ++ + + + +
L6 position –– 0 – –– + + + +
Overbite 0 0 + ++ ++++ + + +
Overjet + + + ++ + ? + +
*+, Improvement; –, worsening; ?, insufficient data.
HPGH, High-pull headgear.
PBB, Posterior bite-block.
VCC, Vertical chincup.

Discussion:
• Although early orthopedic approaches have been
established in the anteroposterior and transverse
dimensions, the treatment approach for vertical skeletal
dysplasia remains controversial.
• Early treatment regime led to
• Increased condylar growth ; altered direction of
condylar growth ; increased true mandibular rotation ;
increased posterior facial height ; and decreased
anterior facial height for openbite patients, which
subsequently led to
• Anterior chin displacement ; controlled maxillary and
mandibular molar eruption ; increased overbite; and
decreased overjet.

• Based on the assumption that treatment should be
evaluated based on success or failure of all treatment
objectives, this novel treatment must be considered one
of the better approaches currently available.
• Autorotation of mandible:
a. In overbite subsample, autorotation centered around
the incisors and hence did not decrease the AFH.
b. In openbite subsample, pronounced effect was seen on
AFH resulting in no significant increase during
treatment period.
c. It has previously been suggested that the lack of
anterior contact may allow autorotation if the freeway
space can be increased through intrusion of posterior
teeth. ( Kalva V ; Am J Orthod Dentofacial Orthop 1989; 95 : 467-78)

• Studies have shown that banded maxillary expansion
predictably displaces the maxilla inferiorly 1 to 2 mm.
(Asanza S ; Angle Orthod 1997 ; 67 : 15-22 )
• The results of this study showed no vertical displacement
of PNS or ANS.
• Augmentation of PFH is of equally important as
inhibition of AFH.
• Early treatment had significant effect on condylar growth
leading to posterior facial height development.
• Amount of true mandibular rotation was 2.7times in
treatment group as compared to control group.
• In treatment group, chin landmarks were anteriorly
displaced twice that of control group.

• The observed changes in AP chin position may be
attributed to:
a. the BPE appliance that was designed to infringe on the
freeway space and, when combined with the high-pull
chincup, acted as a functional appliance/bite-block
b. the lip seal exercises, and
c. normal muscle forces/mandibular posture or the high-
pull chincup.
• Treatment comparison of patients with chincup did not
differ with those who were not.
• As chin cup therapy was given on the basis of absence
teeth marks on the acrylic ; assuming that these patients
had inadequate masticatory muscle force ; chin cup may
provide suitable alternative for normal muscular forces .

Therapeutic changes in the dentition:
• 1mm of relative upper molar intrusion
• Except posterior bite blocks, all other vertical treatments
have shown to increase molar eruption.
• Lower molar eruption (0.8mm) was controlled and did
not differ significantly from the control values.
• Overbite and overjet improved significantly.
• The overbite increase may have been due to the
separation of the dentition with acrylic and subsequent
increases in soft tissue and facial muscular force.
• The lip seal exercises may also have acted similarly to
augment incisor uprighting and extrusion.

Limitations of the study :
• Long term effects of the treatment regime have not been
established.
• Kuster and Ingervall found a 50% relapse of the
overbite, complete relapse of the gonial angle
change, and a 33% relapse of the true forward rotation
after 1 year of magnetic bite-block therapy.
(Eur J Orthod 1992 ; 14 ; 489-499 )
• Further studies with our novel treatment approach are
needed to corroborate the findings of this study and
evaluate the long-term stability of these treatment effects.

Conclusion:
• This protocol can be used in patients with discrepancies
in all 3 planes of space.
• The result supports the axiom “The whole is greater
than sum of its parts”
• If greater changes are desired than it might be
necessary to extend the treatment.
• In large vertical skeletal discrepancies, surgery might
be the only alternative.
• This treatment protocol can be a non-surgical approach
in borderline cases of vertical skeletal dysplasia.
• Early treatment approach is a promising direction for
such patients.

Thank you
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