What we learned from master class in orthognathic surgery
What we learned?
Excellence in orthognathic surgery course/ London 2012
Importance of prediction planning?
The presurgical position of the teeth dictates the surgical movement
of the jaws and, ultimately, the soft tissue facial balance. Correct
planning of the orthodontic tooth positioning before surgery and
accurate presurgical orthodontic plan will enhance the surgical
potential and the esthetic result. These depend on the prediction
planning methods or Visualized Treatment Objective (VTO).
There are many types of VTO including:
1. Manual Cephalometric Prediction
A. Overlay Method Tracing (Reyne)
B. Template Method
2. Computer Prediction
3. Cast Prediction (Model Surgery)
4. Visual prediction (bull eye) need experience clinician.
Overlay Method Tracing (Reyne)
There are two types of VTOs:
1. Pretreatment VTO
It is developed once the primary surgical procedure has been
There are two components that need to be traced and
repositioned according to the predicted plan during the
a. the desired presurgical orthodontic tooth movement and the
resulting soft tissue changes and then
b. a surgical prediction tracing predicting the surgical repositioning
of the jaws and subsequent soft tissue changes
2. Immediate presurgical VTO.
It is created a few days before surgery, plans the definitive
surgical movements and predicts the soft tissue changes.
Accordingly the instruction to the lab technician to duplicate
it in the model surgery and check for its feasibility and
suggest modification as well as construct surgical wafer splint.
While in the immediate presurgical prediction tracing, the
second component is the only part of prediction
Pros and cons:
1. It can accurately predict the soft tissue profile
2. The soft tissue changes can be easily adjusted according to
the clinican experience
3. inexpensive method
4. less radiation exposure compared to other techniques
5. It helps to investigate treatment options and evaluate the
advantages and disadvantages of each option before treatment
6. It helps analyze the need for tooth extractions or which teeth
7. The need for adjunctive surgical procedures, such as
genioplasty, can be assessed.
8. The progress of orthodontic treatment can be monitored using
the orthodontic prediction.
9. The postsurgical skeletal movements can be assessed for
10. It acts as a communication medium between the
orthodontist and the surgeon, as well as between the
clinicians and the patient.
11. A study by Cangialosi et al (1995) on the reliability of
computer generated prediction tracings over manual tracings
was the speed of the process.
Step 1: The prediction tracing. All facial structures that will not be
affected by the surgery are traced in red.
Step 2: The prediction tracing is moved to the left and
slightly upward until A-point is just anterior to the facial depth line
(a)and the maxillary incisor at the chosen vertical height (b).
The treatment possibilities can be studied at this stage.
Note the increased incisor overjet, amount of maxillary advancement
(6.5 mm), amount of inferior repositioning of the maxilla (2
mm), and Class II molar relationship.
The intended surgical repositioning is apparent by comparing the Le
Fort I osteotomy lines,
The maxilla has been advanced and slightly inferiorly repositioned.
The dental and soft tissue prediction should be done now.
Comparison between manual and computerized
Eckhardt and Cunningham (2004) assessed prediction accuracy for
hand-modified tracings and for OPAL.
70 patients (30 single jaw and 40 bimax)
1. The results show that there was marked individual variation
when planning by hand and using the OPAL program
2. Angular measurements were much less predictable with hand
3. ‘artistic prediction’ with hand modification was a credit which
allowing better predictions
4. In the mandibular surgery group, hand planning and OPAL were
of similar accuracy
5. for the bimaxillary group, the hand planning technique appeared
to be more accurate than the OPAL program, .