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Forsus appliance

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Fixed functional appliance - Class II corrector

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Forsus appliance

  1. 1. Forsus Appliance Supervisor: Prof. Maher Fouda Prepared by: Nader A. Giacaman Mansoura University Faculty of Dentistry Orthodontics Department
  2. 2. Force system comparison Class II elastics Vs Forsus
  3. 3. Transverse forces associated with Forsus
  4. 4. Case selection for Forsus Use • Class II division I malocclusion, deep and open bites • Maxillary distalization appliance • Maxillary anchorage in extraction cases • Anchorage for Mandibular incisors • Early intervention in severe Class II • Maxillary and mandibular asymmetries
  5. 5. Transverse forces associated with Forsus
  6. 6. Mandibular Wire • NiTi wires are not recommended due to lack of stiffness. • Can result in an open bite in the bicuspid area. • Should be 0.019 × 0.025 SS or TMA in 0.022 Slot. • Bracket MBT prescription (Lower Torque) (Upper Torque) • Ligate with stainless steel ligature or elastomerics.
  7. 7. Rod Size Selection Determines amount of activation
  8. 8. 22 25 29 32 35 Left and Right rods create the activation through compression of the spring by the stop on rod
  9. 9. Rod Design Activation comes from the distance of the stop to the curve in rod (1) Location where additional activation is placed (2) Length of rod after the stop is what keeps spring and rod from disengaging (3)
  10. 10. No stop is present on the rod Spring travels completely to the curve on the rod Stop is present on the rod Spring travels completely to the stop on the rod
  11. 11. Ruler included with Forsus When you are measuring patient is biting in centric occlusion or centric relationship and is not in a protruded or edge to edge position. Measure both right and left sides.
  12. 12. Place the ledge of the ruler against the distal of the headgear tube and measure to the distal of the bracket where rod will be located 22 mm rod to the 1st Bicuspid or 32 mm rod to the cuspid
  13. 13. Rod location • Options exist for rod placement  Cuspid: Initial manufactured design  Omega loop in archwire: Keeps rod from contacting brackets  1st bicuspid: Modified design
  14. 14. Cuspid Omega Loop 1st Bicuspid
  15. 15. Advantage of 1st Bicuspid Installation Decrease in cheek irritation 1st Bicuspid Vs Cuspid
  16. 16. Advantage of 1st Bicuspid Installation Patients like it because it places spring ‘out of sight’, even less visible than elastics
  17. 17. Clinical advantage of bicuspid attachment Control of lower incisor position and reduced tipping (Favorable force vector of bicuspid attachment when considering the entire Mandibular arch as one unit) Center of rotation of mandibular arch
  18. 18. Cuspid Placement Exception • When placement at 1st bicuspid is over active with a 22 mm rod • When placement is more vertical than needed • Severe Class II malocclusions where a large portion of the discrepancy is from a retruded mandible
  19. 19. Clinical Exception for Bicuspid location 22 mm rod is over active and too vertical Initially place rod at cuspid then reactivate once passive by placing at 1st bicuspid
  20. 20. EZ2 Module • Right and Left sides • Laser marked shield inserts next to molar band • Inserts in occlusal tubes only • Fits best with 3M Unitek molar bands
  21. 21. Push rod installation
  22. 22. Rod Secured to Wire Squeeze with Weingart plier until end of loop touches rod
  23. 23. Checking Activation • Check prior to crimping rod • Correctly installed appliance exerts about 200 grams of force • Over activation can cause:  Debonding of brackets  Rotations  Flaring of Mandibular incisors  Rotation and rolling of the maxillary molars
  24. 24. Correct activation Over activation results in rod being pushed beyond the end of the spring
  25. 25. Over activation Correct activation Spring takes on a tube like appearance
  26. 26. EZ2 clip correct activation Rod lies flush with dentition EZ2 clip over activated Mandibular rod rolls out
  27. 27. Additional Activation • Check existing activation • Usually one split crimp per appointment give 2 mm activation • Can be unilateral
  28. 28. Reactivation • 1 crimpable stop at each appointment, 6-8 week intervals Exceptions: non growing patients 10-12 weeks • May be unilateral • Replace rod after two activations, tend to disengage, will need to increase rod size by two
  29. 29. 25 mm reactivation by adding split crimp
  30. 30. Rod contacting elastomeric guard instead of brackets, reducing bracket failure
  31. 31. Important Step Cinching the Archwire as flush as possible to control incisor movement
  32. 32. Cinch technique
  33. 33. Important step Tie tooth that will be contacting rod with steel ligature Twisted end facing mesial
  34. 34. Clinical Tip • Once Forsus springs are in place do not remove. • Broken brackets: - Remove from wire - Crimpable hook placed if bracket supported rod to act as stop for rod
  35. 35. Backing off wire Distally tipped 1st molar
  36. 36. Removal • Duration: Average 6 months for Class II correction, except unilateral, midline correction and used as anchorage. • Disengage to check occlusion. • Leave in passively for 8 weeks. • Slight over correction.
  37. 37. Very slight over correction (1-2 mm) with overjet eliminated (Mandibular incisors will rebound 3-4 degrees after spring removal) Class I molar or slight over correction Class I buccal segment or slight over correction Targeted amount of correction
  38. 38. Amount of correction prior to Forsus removal
  39. 39. Slight over correction in the buccal segments Ideal overjet with ideal torque
  40. 40. What if I over correct???
  41. 41. Spring was not passive and patient overcorrected
  42. 42. Steps for overcorrection  Remove Forsus  Evaluate maxillary incisor position - Increase arch wire size to increase torque - Remove chain if present  Evaluate mandibular incisor angulation - Chain molar to molar to upright  Evaluate if spacing is present in mandibular arch - Chain molar to molar to close spacing - Class III elastics at night: light force
  43. 43. Class III elastics at night for 8 weeks after Forsus removal

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