orthodontic perspective of distraction osteogenesis

ORTHODONTIC PERSPECTIVE OF
DISTRACTION OSTEOGENESIS
www.indiandentalacademy.com

The symbiotic relationship between the
Orthodontist and the Oro-Maxillofacial
surgeon is a fairly recent phenomenon

While the surgeon can bring about gross
changes (which make dramatic improvement
in facial appearance), the orthodontic
expertise is needed in fine-tuning the results.

Application of Distraction Osteogenesis to the
craniofacial areas is even more recent. Hence,
the role of Orthodontics is now getting
properly defined.

DISTRACTION OSTEOGENESISDISTRACTION OSTEOGENESIS
Our experiences with distractionOur experiences with distraction

Pre-surgical Orthodontic phasePre-surgical Orthodontic phase

SCOPE OF THE TALK
1) How the Orthodontic practice will get
benefited from this surgical procedure
2) How the surgeon can utilise the
Orthodontist’s expertise to improve the
quality of treatment.

Why is Distraction of interest to an
Orthodontist?
1. It enlarges the envelope in which he/she
operates. It is one step ahead of
Orthognathic surgery.

Orthodontist?
Envelope of discrepancy

Orthodontist?
2. It more or less eliminates the restrictions
imposed by the soft tissues. Hence,
chances of relapse reduce drastically

Orthodontist?
3. Early intervention in life helps to restore the
normal growth process.

Orthodontist?
4. Reduced morbidiy, reduced need for bone
grafts,improved airway.

Application from an Orthodontist’s point of view
1. Treating craniofacial deformities.

2. As an alternative to surgery in less gross
deficiencies.

Application from an Orthodontist’s point of
view
3. Widening the transverse dimension of the
mandible

4. Surgically assisted RME

Application from an Orthodontist’s point of
view
5. Distraction for Orthodontic tooth movements

DENTAL DISTRACTIONDENTAL DISTRACTION

How will the surgeon benefit by associating
with the Orthodontist?
1. Treatment Planning Amount
Vector
2. Pre and Post-surgical Orthodontics for
facilitating surgery and for optimum post-
surgical occlusal function

How will the surgeon benefit by associating
with the Orthodontist?
3. During Surgery – for fixing intra-oral
devices, for adjusting the vector of extra-
oral devices.
4. For maintaining or improving the results of
surgery – use of functional appliances or
headgears, elastics - ‘Bone moulding’
5. Post-op followups, records, measurements
etc.

Thank you
THANK YOUTHANK YOU

ROLE OF CEPHALOMETRICS IN PLANNING
DISTRACTION

Treatment Planning- Consideration of size,
placement, orientation.
Cephalometry – not a perfect science but a
great tool if used properly (also could
totally mislead if used without proper
understanding)

How to judge the amount of distraction
needed?
1. Use of normative values ?
Not very appropriate, since they cannot be
accurately applied to different ethnic
groups,males and females, persons with
varying builds etc.

2. Norms based on hard tissues alone?
Not appropriate because variable thickness of
soft tissues can compensate for/or
aggravate the hard tissue relations.

3. Instead of absolute linear measurements,
their projected values are more meaningful
to judge their true contribution to the
skeletal dysplasia in a horizontal or vertical
direction

The best known analysis employing the
co-ordinate reference is the COGS of
Burstone and Legan.

COGS of Burstone and Legan.
The drawbacks, however, are
1. Small sample
2. Unreliable ‘surrogate’ horizontal plane.

4.The best option would be probably the True
horizontal or the True vertical references
as applied to the ‘ Natural Head Position’.
The values for Indian population are currently
being established.

5.Ratios are more reliable than individual
linear measurements, because they
overcome the differences in the individual
size.

Certain useful ratios are
a) For sagittal measurements
i. Antr. Cranial base/ Max./Mand
= 20/ 14 /21
ii.. Mandibular components
Corpus/ Ramus
= 7 / 5

b. For vertical dimension
Post. Face height/Ant.Face height(Jarabak
ratio)
= 62-64%

6. These help to customize the ‘normal’ values
for maxillary and mandibular sizes in
proportion to the cranial base. Thus,
individual specific norms (as against
population specific) can be derived.

7. Placement of the maxilla and mandible with
respect to the cranial base (sella) can
compensate or aggravate the size
abnormality

8. Orientation of the maxillary base or the
mandibular corpus would affect the final
position of the anterior limits of maxilla and
mandible.

9. These are assessed in relation to the
thickness of the soft tissue drape to arrive
at the final estimate of maxillary and
mandibular alterations needed.

10. As of now, there is some uncertainty about
the exact quantum of soft tissue
displacement which follows hard tissue
changes.

THANK YOUTHANK YOU

orthodontic perspective of distraction osteogenesis

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