What we learned from master class in orthognathic surgery


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What we learned from master class in orthognathic surgery

  1. 1. 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  Cassos,  Opal,  Orthognathic planner  Dolphin. 3. Cast Prediction (Model Surgery) 4. Visual prediction (bull eye) need experience clinician.
  2. 2. Overlay Method Tracing (Reyne) There are two types of VTOs: 1. Pretreatment VTO  It is developed once the primary surgical procedure has been selected.  There are two components that need to be traced and repositioned according to the predicted plan during the pretreatment VTO: 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
  3. 3. 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 starts. 6. It helps analyze the need for tooth extractions or which teeth to extract. 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 audit purposes. 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.
  4. 4. Practical demonstration Maxillary advancement Step 1: The prediction tracing. All facial structures that will not be affected by the surgery are traced in red.
  5. 5. 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).
  6. 6. 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.
  7. 7. The intended surgical repositioning is apparent by comparing the Le Fort I osteotomy lines,
  8. 8. The maxilla has been advanced and slightly inferiorly repositioned. The dental and soft tissue prediction should be done now.
  9. 9. Prediction of incisor and molar positions
  10. 10. By comparing the position of A-point on the prediction tracing and the original tracing (arrow), the amount of bone advancement can be seen (6.5 mm in this case).
  11. 11. Soft tissue prediction
  12. 12. Completed pretreatment prediction
  13. 13. 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) Conclusion: 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 methods 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, .