Distraction osteogenesis versus bsso for advancement of the retrognathic mandible /certified fixed orthodontic courses by Indian dental academy

DISTRACTION OSTEOGENESIS VS BSSO

INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com

INTRODUCTION
BSSO and DO are the most common technique

currently applied to correct mandibular retrognathia
But it is the responsibility of the maxillofacial surgeon
to determine the optimal treatment option in each
individual case.


AIM OF THE STUDY
Was to review the literature on BSSO and DO for

correction of non-syndromic deficent mandible with
emphasis on influence of
Age
Post surgical growth
Damage to inf.alv.N
Post surgical stability
Relapse


MATERIALS AND METHODS
Literature from january1995 to august 2006 was
searched on
Mandibular advancement and mandibular surgery
distraction osteogenesis Angle class II child,inferior
alveolar nerve,mandibular
condyle,retrognathism,stability,TMJ,patient
satisfaction.


Unfortunately randomized clinical trials are lacking

and thus could not be used as an inclusion criterion
for the literature search.

The result were classified according to age and post

surgical growth,nerve damage,stability and
relapse,and patient-centred out come.


AGE:
DO is more advantageous than BSSO in actively

growing children
Facial growth completion of approximately 98%
occurs in
girls
boys
15 yrs
17-18 yrs
Above the age of 5 yrs,the basic dentoskeletal
morphology is established(almost >97%)

Difficulties of performing BSSO in
younger patients due to:
1)greater bone elasticity
2)thick cortical bone
3)unerupted molar
4)lingula-more posterior

and superior placement

As per studies BSSO may be used
as safe technique in growing
children with no restrictions on
post surgical vertical
mandibular growth,but should
be applied with caution in
youngsters.

Difficulties of performing DO
1)patient and parent compliance
2)high risk of damaging tooth bud

But DO is easily accomplished in growing
children due to high bone regeneration
potential.


NERVE DAMAGE
Permanent neurosensory disturbance is a common

complication which may be correlated with
age

magnitude of
mandibular advancement
Older patientmechanical tearing
poor regeneration
of axon
ischemia by
compression of
vasa nervosum

The strech injury from DO beyond the adaptive

capacity of the nerve may result in serious
damage(>7mm)
Therefore distraction rate should not exceed
1mm/24hr which may result in either no change in
sensation or there may be a short period of decreased
function following gradual recovery.
After large mandibular advancements in older
patients the risk of permanent sensory nerve
damage is high in BSSO than in DO

STABILITY AND RELAPSE
Different types of rigid fixation methods are used to

decrease soft tissue tension
Causes of relapse:
1)Anatomic locationa)osteotomy site-slippage of fragment
-perimandibular soft
tissue tension.
b)TMJ-due to condylar malpositioning
or resorption

2)high mandibular plane angle
3)amount of advancement
4)non compliance of patient
5)persistant growth
6)progressive condylar resorption(more in BSSO,but in

DO the force of 1mm/day is gradual and resorption is less).

BSSO is considered a stable procedure with minimal
relapse in patients with normal or decreased facial
height,whereas it shows a tendency for relapse in high
mandibular plane angle and when advancements>7mm
was used.
DO showed less relapse after advancement of 10mm or
more

PATIENT CENTERED OUTCOME
Discomfort experienced by patients are1)General anesthesia
2)Post operative diet and weight loss
3)Absence from work/school
4)Regular check ups
5)Numbness
6)Damage to dentition
7)Swelling,pain,hemorrhage
8)Post surgical infections

Discomforts in patients during DO:
Routine activities are disturbed during DO.
Duration of hospitalization is less in DO than in
BSSO,but DO requires a 2nd surgical intervention for
removal of the distraction device.


DISCUSSION
DO

BSSO

AGE

early intervention possible
POST SURGICAL
GROWTH
growth seen
NERVE INJURY
with distraction rate of 0.51mm/day,no long term
damage seen with large
advancement.


only after 12yrs

no much growth seen

High with age>30yrs
&>7mm advancement

DO



BSSO

 MANDIBULAR PLANE

ANGLE (MPA)
Normal/low MPA-less relapse(due
to osteotomy cut distal to
pterygomasseteric sling & less
periosteal stripping.)
High MPA-more relapse
 AMOUNT OF
ADVANCEMENT
10mm or more
 PCR
Advancement with in the
physiological limit-reversible
Injury
 PATIENT FACTOR
More discomfort

Normal/low MPA-less relapse

High MPA-more relapse

7mm in low to normal MPA
High progressive condylar
resorption
Less discomfort.

CONCLUSION
Considering the literature available,there is support for

the assumption that DO might have advantages over
BSSO in mandibular retrognathism ,in low and normal
mandibular plane angle where large advancemnts are
needed, since BSSO is associated with nerve injury and
relapse.
There is need of more randomized clinical trials
comparing DO with BSSO in all types of retrognathia
inorder to select the type of sugery…..


Distraction osteogenesis versus bsso for advancement of the retrognathic mandible /certified fixed orthodontic courses by Indian dental academy

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