Role of ortho in surgery /certified fixed orthodontic courses by Indian dental academy

ROLE OF CONTEMPORARY
ORTHODONTICS IN
ORTHOGNATHIC SURGERY
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com

INTRODUCTION

Severe orthodontic problems:

- growth modification

- camouflage
- surgical realignment of jaws or repositioning of
dentoalveolar segments

Correction of the malocclusion by tooth
movement alone:

-Undesirable
-Teeth tipped into position of neuromuscular

imbalance
-Treatment of choice – correction of skeletal jaw
dishormony

- Surgery not substitute of orthodontics
- Properly coordinated with orthodontics

- Dramatic progress in recent years

CLOSED CONTAINER
- Orthodontics rearranges the content
- growth modification and surgery changes

the shape

ENVELOPE OF DISCREPENCY

-Severity as a indicator for orthognathic surgery
-outlines the limit of hard tissue changes towards the
ideal occlusion

-soft tissue limitations not reflected
-amount of changes produced by orthodontics alone
-Orthodontic tooth movement + growth modification
-Orthodontics + orthognathic surgery

-Not symmetrical with
regard to plane of space
-retraction / proclination
-Extrusion / intrusion
UPPER

-Growth modification same
-Surgery to move lower

jaw back has more
potential than to advance
it
LOWER


INDICATIONS

Severe class II or class III skeletal discrepancy
Deep over bite in non- growing patients
Severe anterior open bite
Extreme vertical excess or deficiency in maxilla or mandible
Severe dentoalveolar problem

Skeletal asymmetry

AIMS
 Optimal facial esthetics
 Optimum dental esthetics
 Functional occlusion

 Future health of orofacial structures
 Rapid treatment
 Stable result
 Minimum morbidity

PRINCIPLES OF TREATMENT
PATIENT MOTIVATION

Chief complaint
Patient – Parent conference
problem list
risk- benefit, treatment alternatives
patient’s expectations and values

Probable outcome

DIAGNOSIS

Accurate diagnosis fundamental to treatment planning


clinical examination and evaluation of history



lateral cephalogram and OPG



study models



photographs (extraoral and intraoral)

JOINT PLANNING
Orthodontist and oral surgeon

Surgical procedure
Presurgical orthodontics
Extraction
Mock model surgery/
prediction
Cephalometric prediction
tracing
Computerized prediction

PRESURGICAL ORTHODONTICS
Prepare patient for surgery
Treatment objective entirely opposite of conventional
orthodontics alone
Extraction pattern reverse of orthodontic case
PRESURGICAL DECOMPENSATION
Teeth inclined to partially offset skeletal discrepencies

Nature’s mechanism to compensate
Ideal axial inclination

PRESURGICAL OBJECTIVES
INTRA ARCH OBJECTIVES


Initial stages – similar objectives
Correction of arch length deficiencies
Rotation correction

Arch alignment


Post surgical interdigitation



Class I canine and molar relationship



Teeth ideal to underlying bases

Malocclusion look worse- underlying skeletal deformity

Extractions- spaces closed / segmental surgical closure

Tooth size discrepencies-best anterior occlusal interdigitations

Interdental enamel reduction
Extraction of mandibular incisor
Distribution of excess space

ANTEROPOSTERIOR (SAGGITAL) OBJECTIVES
Compensation in all three planes
Most apparent in saggital
Skeletal class II- proclined lower
upright upper incisors

Skeletal class III- proclined upper
upright lower incisors
Decompensation- surgery minimum interference from
occlusion

Class II case demonstrating incisor
positions before (— ) and after (----)
dental decompensation.

Class III case demonstrating
incisor positions before (— )
and after (----) dental
decompensation.

REVERSE ORTHODONTICS

Class III elastics in Class II- upright lower incisors
advance maxillary molars

Class II elastics in class III- upright upper incisors
advance mandibular molars

Anchorage considerations-class II mandibular arch

class III maxillary arch

Extraction pattern- class II

upper 5’s
lower 4’s

class III upper 4’s
lower 5’s

Extractions - to align the teeth to their respective jaws
Relapse

- dental opposite direction than skeletal
chance of maintaining optimal occlusal
relation

“DECOMPENSATION COMPLIMENTS SURGERY”

A, Class ll case with upper first and lower
second premolar extraction requiring
maximum anchorage in the maxillary arch
using conventional orthodontic techniques
to retract the incisors. B,Class II case with
upper second and lower first premolar
extraction
requiring
maximum
mandibular arch anchorage to retract the
proclined incisors prior to orthognathic
surgery.
A, Class lll case with extraction of
upper second and lower first
premolars
requiring
maximum
anchorage in the mandibular arch to
retract the incisors by conventional
orthodontic techniques. B, Class III
case with extraction of upper first and
lower second premolars requiring
maximum anchorage in the maxilla to
retract the incisors prior to
orthognathic surgery.

TRANSVERSE OBJECTIVES
o Skeletal / dental
o Study casts articulated to anticipated post surgical relation
o Skeletal class II- transverse maxillary deficiency
o Skeletal class III- relative transverse maxillary deficiency
o Correct buccal segment torque

o Isolated maxillary constriction + no maxillary sugery
surgically assisted RME
o Maxillary constriction +other maxillary problems
multiple segment maxillary procedure

A, Clinically normal-appearing transverse relationship in
Class II malocclusion. B, Simulated correction of Class II
malocclusion to Class I canine relationship exhibiting
bilateral palatal crossbite as a result of absolute bilateral
transverse maxillary deficiency.

A, Clinically exhibited bilateral palatal crossbite in
Class III malocclusion. B, Simulated correction of
anteroposterior (sagittal) discrepancy, with no

palatal

crossbite

now

apparent.

This

case

exemplifies relative bilateral transverse maxillary
deficiency


VERTICAL CONSIDERATIONS
Open bitesanterior face height to be reduced surgically
orthodontic tooth movement prior to surgery
minimum post surgical mechanics

minimum to moderate curves
extractions

Continuous arch

excessive anterior spacing


Severely accentuated and reverse curve of spee
surgical correction
segmental arch – segmental surgery

Deep bite- short anterior face height

leveling of mandibular occlusal plane after surgery
maxillary easily prior to surgery
vertical elastics
occlusion primarily on molars and incisors

A, Class II case leveled presurgically (— ).
Surgical changes (----) noted include: A, Closing
mandibular rotation; B, increased posterior face
height; C, no increase in anterior face height. B,
The same Class II case not leveled presurgically
(— ). Surgical changes (----) noted include: A,
Opening mandibular rotation; B, no increase in
posterior face height; C, increased anterior face
height

CONSIDERATIONS FOR SEGMENTAL OSTEOTOMY

Root divergence at osteotomy site
Adequate access- minimize trauma to tooth roots
Second order bends to create adequate space

Anatomic constrains- unable to position
premaxillary segment posteriorly without tipping the
segment
Leave incisors slightly proclined

APPLIANCE SELECTION
Appliance- stabilization of teeth and basal bone
Rectangular archwire for strength and stability
Variations of edgewise- PEA
Begg- edgewise combination

Begg- poor control
ribbon archwire and special retaining pins
Ceramic brackets- fracture during manipulation
restricted to maxillary anterior teeth

STABILIZING ARCHWIRES

4 weeks before surgery- passive at the time of splint making
17 x 25 steel in 18 slot
21 x 25 TMA or steel in 22 slot

Brackets incorporating hooks
Brass lugs soldered to the archwire
Ball end hooks soldered, welded or carefully crimped
Tight intermaxillary fixation till rigid fixation

MODEL SURGERY
Model surgery simulates actual surgery, in the dental arch
models of the patient.

It gives the three dimensional understanding of the post
operative relationship of the jaws.


Major aims of the model surgery:
1.To get the definite idea about the extent of bone / arch
advancement or reduction required in the surgery.

2.To get a post-operative relationship of the jaws,
dentition and occlusion.
3.To decide about the post-surgical orthodontic
treatment.
4.As a vehicle for fabrication of splints for stabilization
after surgery


ARMAMENTARIUM:

1) A fret saw and fine blades (size M2) or a 10cm (4 inch)
fine fiber or metal cutting disc mounted on a lathe.
2) Hand-piece and motor.

3) A steel fissure bur.
4) A plaster bur or an Ash acrylic cutter pear.
5) Surgical scalpel blades, NO.10 or 20.


6) Plaster knife, Spatula, 15 cm(6 inch) rubber bowl.
7) Bunsen burner, spirit lamp,or soldering iron.
8) Wax knife and carver.
9) Soft ribbon wax, hard modeling and sticky wax.
10) 15cm (6inch)flexible ruler.

11) Spring dividers(15cm /6 inch)
12) Plane line hinge articulator, and face bow.


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.

Method:
Individually remove the tooth from the dental cast and
reset the tooth in soft wax so that their alignment and
interdigitation can be observed

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

METHODS OF MODEL SURGERY
 Simple method
 Anatomically oriented model surgery


Sulcus impressions of the upper and lower arches are
obtained.(midline marking can be done before making
the impressions)

The impressions are cast in stone. Models are trimmed
and two duplicate sets prepared.
The master set is dated, labeled and
preoperative reference study models.

stored as

If movements of the whole arch are anticipated,the
upper and lower models are first occluded in the
planned postoperative position and carefully marked
using a pencil.

The amount of movement between the pre-operative and
post-operative position is then measured and noted on the
models. This may be done with the hand held trimmed
study model or,with plaster-less articulator
The marked models may also be mounted with plaster on
a metal hinge articulator in the planned postoperative
position.
This mounted set of models is also used for designing or
making the means of fixation

 If segmental movements are involved, a set of models is

sectioned at the osteotomy sites. Care should be taken when

sawing not to damage teeth other than those which are going
to be extracted at the time of surgery.
The sectioned segments are then sited in the desired position
and fixed with soft red ribbon wax which will allow the
manipulation in to the planned position


• Cuspal interferences can be marked on the cast which
can be later ground intra-orally.
• Establish a proper over-jet and
anterior region.

overbite

in

the

• A degree of over-correction may be necessary to
compensate for
the relapse, especially with mandibular
forward movements
 Once the desired position is achieved the ribbon wax is
replaced with hard modelling or sticky wax to secure the
mobilized segments in their new place.


ANATOMICALY ORIENTED MODEL
SURGERY
In complex cases, especially where multiple bimaxillary
movements are required, it is essential to use a more
refined technique
In this technique, in addition to the impressions and sqash
bite, a face-bow recording is taken.
The working models are anatomically trimmed and
articulated on the semi adjustable articulator using the
face-bow recording and then the standard squash bite

Horizontal and vertical reference lines are drawn on the
mounting plaster to register the post-operative position of
each maxillary and mandibular segments before surgery.

Two sets of parallel horizontal lines A/A and B/B are
drawn on the upper and lower models. These are easily
done by rotating the detached model with the felt pen.
The B lines should be just clear of the apices of the teeth,
and not less than 15mm from the A lines. The actual
distance between the A and B lines is then recorded on the
plaster. These lines will be used to plan the vertical
movements

Three vertical lines VC, VB, VM are drawn from upper
base line (A) to the lower baseline (A) on each buccal
segment. These lines pass through the buccal surfaces of
the upper cuspid, bicuspid and the distal cusp of the last
upper molar tooth., and they are extended to their
occluding partners.
These will help to indicate the anteroposterior movements
achieved by the model surgery.

Upper and lower midlines are also drawn.

Marked models with the
recorded distances

The vertical distances from the buccal cusp tips of the
three reference teeth to their A base lines are recorded to
help calculate any vertical movements.

Transverse changes are recorded by the inter-canine and
inter-molar distances measured across the palate and
recorded by taking reference points on the canine tips and
the mesiobuccal cusp of the first molars.


Cuspal reference points are used for
transverse changes.

When all the reference lines have been drawn and the
measurements completed, the osteotomy lines are drawn
between A and B lines to correspond with the bone cuts.
The plaster mounting assembly is then sectioned at the
osteotomy sites with a saw or large abrasive disc and the
whole arch or segments are repositioned in the planned

post-operative position

Interrupted line is the proposed
osteotomy site

Maxilla is reassembled with the wax after the osteotomy
cuts. Mandible closes in to the intermediate occusal
relationship. Intermediate wafer is made at this stage

Lower segmental set-down of 3mm is carried out with the
forward slide of 5mm to correct the interarch occlusal
relationship.

SURGICAL SPLINT


Interocclusal wafer splint



Autopolymerizing acrylic resin



Model surgery



Trimmed on buccal surface- visual
verification



Teeth in desired position



Thin- not more than 2mm in thinnest portion



Wire at edges of splint



Holes for fixation

PATIENT MANAGEMENT AT SURGERY

FINAL SURGICAL PLANNING
presurgical records
impressions without stabilizing archwires

prediction
duplicated in model sugery


POST SURGICAL ORTHODONTICS
Removal of splint
working archwires
Light vertical elastics- to override propioception impulse
from teeth
undesirable convenience bite- new intercuspation
Minor corrections- light round wire 0.016’’
Flexible rectangular archwire in upper 17 x 25 TMA

21 x 25 M- NiTi or braided steel

 Posterior box elastic

light elastics full time wear for 4 weeks (including eating)
then 4 weeks except for eating
followed by night wear for 4 weeks
 Triangular, saw tooth ( M,N or W )
 Class II or class III elastics

 to support surgical correction
 Guide jaw function
 Settling of occlusion

Triangular vertical elastics

Box elastics with a Class
III vector


POST SURGICAL COMLICATIONS
ANTERIOR OPEN BITE
condylar distraction( sag)
(isolated mandibular surgery)
difficult-orthodontic compensation

reoperation
Inadequate posterior impaction(Lefort I)
headgear or heavy elastic traction

LATERAL OPEN BITE
planned- decreased facial height
extrusion of lower buccal segment

ASYMMETRY

mismatch in dental midline
source of problem- submentovertex
one of arch shifted laterally or rotated

Asymmetrical headgear
Oblique elastics or combination of class II, class III
elastics
Asymmetric archwires
Leaving 1 to 2 mm of space distal to canines
Reproximation or interproximal enamel reduction
Reoperation


RETENTION

No difference
Retentive plates-6 months full time wear

followed by 6 months wear at night


STABILITY OF RESULTS
MORE

Maxilla up
Mandible forward

VERY STABLE

Chin, any direction
Maxilla forward

STABLE
PREDICTION

STABLE

Maxilla, asymmetry
Mx up + Mn forward
Mx forward + Mn back

STABLE(Rigid fix)

Mandible, asymmetry
Mandible back

Maxilla down

LESS

Maxilla wider

PROBLAMATIC

PRINCIPLES INFLUENCING POST SURGICAL
STABILITY

Relaxed soft tissue / stretched
Neuromuscular adaptation
Change in orientation of muscle

CONCLUSION

THANK YOU


Role of ortho in surgery /certified fixed orthodontic courses by Indian dental academy

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