orthognathic surgery

Orthognathic surgery

Combined Surgical and Orthodontic Treatment

تقويم \ خامس اسنان

د. الاء م(3-4)
9\ 5\ 2017

Orthognathic surgery

• Orthognathic surgery refers to the surgical repositioning of the maxilla, mandible, and the dentoalveolar segments to achieve facial and occlusal balance.
• One or more segments of the jaw(s) can be simultaneously repositioned to treat various types of malocclusions and jaw deformities.

There are only three possible treatment ways to treat a jaw discrepancy problem 1. Modification of growth 2. Camouflage ( dental compensation for a skeletal problem ) 3. Surgical repositioning of the jaws and/or dentoalveolar segments

Limitations Of Orthodontic Treatment:

Both dental and orthopedic approaches to attain ideal occlusion through orthodontic appliances alone may be unsuccessful.

1. Skeletal deformity may be too great.

2. Completion of jaw growth may limit
the amount of orthodontic treatment
possible.

Limitations of Orthodontic Treatment3. Patient may refuse to wear orthodontic appliances.4. Loss of posterior teeth may limit available anchorage.5. Some orthodontic movement are difficult or impossible (significant intrusion).6. Esthetic consideration (gummy smile).

Limitations Of Surgical Treatment:

Surgery alone is not enough and may
be unsuccessful due to:

1. Teeth need to be properly aligned.

2. Arch forms must be compatible.
3. Dental compensations should be
eliminated, so that teeth are well
related with respect to individual jaws.

Indications for Surgery

Severity of the skeletal malrelationship (the envelop of discrepancy).

Esthetic and psychological considerations.

Severity of the skeletal malrelationship
The envelop of Discrepancy
It shows the amount of change that could be produced by orthodontic tooth movement (inner envelop); orthodontic tooth movement + growth modification (the middle envelop); and orthognathic surgery (the outer envelop).

Esthetic and psychological considerations

75 %-80% of individuals referred for orthognathic surgery seek esthetic improvement.

Changes in the position of the nose and chin have a greater impact on facial esthetics than changes limited to the lips.

Surgical Procedures and Treatment Possibilities

Correction of anteroposterior
relationships



Correction of vertical relationships




Correction of transverse
relationships

Correction of Anteroposterior Relationships

I. Maxillary Surgery:


Maxillary advancement


Down fracture technique

Protraction of Maxilla

Correction of Anteroposterior Relationships

Maxillary retraction:


Down fracture technique: limited by
the anatomic structure immediately
distal to the pterygomaxillary fissure.








Retraction of anterior segment by a segmental osteotomy after (extraction of 2 first premolars).

Correction Of Anteroposterior Relationships:

Mandibular Surgery


Mandibular Advancement:
1. Bilateral Sagittal Split Osteotomy (BSSO) of the mandibular ramus

Mandibular Advancement

Correction Of Anteroposterior Relationships

Bilateral sagital split osteotomy
has the following advantages:


Intra oral approach


Broad interface of medullar surface (Rapid healing)


Rigid internal fixation (RIF) with bone screws

Bilateral Sagittal Split Osteotomy ( BSSO ) drawbacks  Altered sensation in the lingual nerve distribution ( transient 2 - 6 months ).  Paresthesia over the distribution of the inferior alveolar nerve.

Correction Of Anteroposterior Relationships

Mandibular Setback:

1. Bilateral Sagittal Split Osteotomy

(BSSO)



Excellent control of the condylar segment.


Osteosynthetic screws can be
employed for fixation.

Mandibular set back: (cont’d.)

2.The Trans Oral Vertical Oblique
ramus osteotomy (TORVO)
(limited to the reduction of
mandibular prognathism.)

Full thickness overlapping segments
Less likely to produce neurosensory changes
Jaws immobilization is necessary
Difficult control of the condyles

Correction Of Vertical Relationships

Maxillary Surgery:
Correction of skeletal open bite
(long face) deformity by:

Le Fort I down fracture of the maxilla with

superior repositioning of the maxilla (maxillary
impaction) after removal of bone from the lateral
wall of the nose, sinus and nasal septum.

Correction Of Skeletal Open Bite (cont’d.)

Long- face problems are best treated by intrusion of the maxilla leading to




Mandibular rotation around the condyle (autorotation)



Reduction of mandibular plane angle





Shortening of the face





Closure of the open bite

Correction of Skeletal Open Bite

Correction Of The Vertical Relationships (cont’d.)

Mandibular Surgery

1. Surgery to reduce mandibular plane angle

and close the open bite by rotating the
mandible down posteriorly and up anteriorly
is highly unstable due to:
a. Lengthening the ramus and stretching
the muscles of the pterygomandibular
sling( masseter, medial ptyregoid)
b. Lack of neuromuscular adaptation in
these powerful muscles.

Vertical maxillary excess

2- “Skeletal deep bite” or patients with a

“short face” problem (seen in Cl. II div.2
cases) are characterized by a long
mandibular ramus, square gonial angle,
and short nose-chin distance.


Short - face problems are best treated by mandibular ramus surgery that allows the mandible to move downward only at the chin.
This will lead to:




increase in the mandibular plane angle
by shortening of the ramus





opening of the gonial angle

Short Face Problems Treated by Maxillary Surgery

Le Fort I down fracture of the maxilla to increase face height is not stable,
therefore not used.

Correction Of Transverse Relationships

Expansion & narrowing of the dental arches

It is possible to move the maxillary segments both away from and toward the midline with relative ease and stability.


Correction Of Transverse Relationships ( cont’d. )


Rapid palatal expansion



Not feasible in adults, because
of the increasing resistance of
the midpalatal & lateral maxillary
sutures.

Correction Of Transverse Relationships

• Surgically-assisted palatal expansion

• to reduce the resistance of the
• segments include:
• lateral antral wall. Mid
• palatal corticotomy.
• Corticotomies in the midline or
• Two para-midline vertical cuts


4. The jackscrew ( RPE ) is cemented before the surgery.

5. Activated after the bone cuts are made to continue for 10 -14 days followed by a period of stabilization.

Corticotomy to hasten the orthodontic movements.

Asymmetry

Mandibular asymmetry often leads
to a secondary maxillary deformity
ex: More vertical mandibular growth
produces:



compensatory changes in maxillary
growth



tilt of the occlusal plane

Asymmetry

Mandibular deviation also leads to
compensatory changes in the mandibular alveolar process and the chin deviates more than the dental midline.



Surgical correction of asymmetry often requires a Le Fort I osteotomy + BSSO for Mandibular ramus correction.





Repositioning the chin may also be needed.

GENIOPLASTY

Is an osteotomy to free a wedge-shaped portion of the symphysis and inferior border that remains pedicled on the genioglossus and geniohyoid muscles.

GENIOPLASTY

Advanced (advancement genioplasty).
Moved backward (reduction genioplasty).
Shifted sideways to correct asymmetry.
Down-grafted to increase lower face height.
By splitting the segment vertically, the wedge can be flared or compressed.

This segment can be:

Timing and Sequencing of Surgical Treatment

General rules:

Orthognathic surgery should be

delayed until growth is completed.
Orthognathic surgery can be considered
earlier in growth deficiencies

TIMING OF TREATMENT

• Actively growing patients with mandibular prognathism can be expected to outgrow their correction. “Relapse`’
• 2. Psychosocial problems may justify early surgery to correct prognathism, however retreatment may be needed
• 3. The Hand-wrist films to determine bone age are not accurate for planning the exact Timing of Surgery.

TIMING OF TREATMENT

• The best method is serial cephalometric tracings, until good documentations that the adult deceleration of growth has occurred.

Diagnostic set-up

A diagnostic set up is employed to be sure that it will be possible to get the teeth to fit together if a given orthodontic treatment plan is employed.

Diagnostic pre-orthodontic set-up showing the proposed extractions and tooth movements.

Sequence of an Orthodontic/Surgical Plan
I. Sequence:
1. Orthodontics to correct alignment
and inclinations of teeth (no attempt
for skeletal correction.)
Note: Malocclusion may temporarily
look worse.

2. Surgery to reposition the jaws.

3. Finishing Orthodontics.

Objectives Of Pre-Surgical Orthodontics

1.Place teeth in their proper
relationships to mandible or maxilla.
i.e. decompensation of teeth
2. Level both arches independently:
It is sometimes necessary to level
teeth in segments, independently.


Pre-Treatment Evaluation:
Records Needed:

1. Dental casts

2. Dental radiographs
3. Facial photographs (frontal and
profile)
4. Cephalometric radiographs

Check List for Treatment Planning

A-P relationships maxillary deficiency/protrusion
mand prognathism/deficiency
amount of deficiency
Vertical relationships open bite
deep bite
Transverse relationships crossbites
before surgery expansion
surgically assisted expansion
during surgery


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Mounting of the maxillary model

Models with completed skeletal and dental reference lines

Model (Mock) surgery

Interrupted line is the proposed osteotomy site.

osteotomy lines







Anterior view: models showing the upper midline split to widen the intercanine width and the lower anterior set-down.

The splint:A acrylic splint is made in the laboratory to transfer the model relationship to the patient during surgery