Orthopedic appliances

orthopedic appliance used in orthodontics

1. ORTHOPEDIC APPLIANCES

2. INTRODUCTION There are essentially 3 alternatives for treating any skeletal malocclusion – Growth Modification Dental Camouflage Orthognathic Surgery Growth modification should be opted wherever applicable because this precludes the need for both tooth extraction and surgery.

3. There are 3 types of orthodontic appliances that can be used for modifying the growth of maxilla/mandible-

4. ORTHODONTIC FORCE VS ORTHOPEDIC FORCE when applied brings about dental change. They are light forces ( 50- 100 gm) bringing about tooth movement. when applied brings about the skeletal changes. They are heavy forces ( 300-500gm) that bring about changes in the magnitude & direction of bone growth. ORTHODONTIC FORCES ORTHOPEDIC FORCES

5. The appliances that produce skeletal changes by applying orthopedic forces are known as orthopedic appliances. Since they employ heavy forces, adequate anchorage required is gained by extra oral means using occipital, parietal, frontal cranial bones and cervical vertebrae. The most widely used orthopedic appliances are- Headgear Protraction Face Mask (reverse pull headgear) Chin Cup

6. BASIS OF ORTHOPEDIC APPLIANCE THERAPY Orthopedic appliances generally use teeth as “handles” to transmit forces to the underlying skeletal structures. Basis of orthopedic appliance therapy resides in :- Amount of force Duration of force

7. PRINCIPLES OF USING ORTHOPEDIC APPLIANCES Following are the basic principles of using orthopedic appliances effectively :- Magnitude of force Duration of force Direction of force Age of the patient Timing of force application

8. Magnitude of force

9. Duration of force

10. Direction of force

11. Age of the patient

12. Timming of force application

13. Orthopedic Appliances

14. Head gear

15. Introduction Headgears are the most widely used extra oral orthopedic appliances. During growth period to intercept or correct skeletal malocclusion. To distalize the maxillary dentition or maxilla As an anchorage unit

16. Components of headgear

17. Face bow It is a metallic framework made of large gauge wire. It can be attached to teeth either via brackets ( fixed orthodontic appliance ) or removable appliance. Parts of face bow i - junction ii- inner bow iii- outer bow

18. Junction It is the point of attachment of the inner and outer bow, which may be soldered or welded. The junction is situated in the midline of the bows, although it can be shifted either right or left side depending upon asymmetrical force need.

19. Inner bow It is made up of 0.045” or 0.052” round stainless steel wire and is countered to follow the shape of dental arch. Friction stops are placed in the bow mesial to the buccal tube of first permanent molar to prevent the inner bow from sliding too far distally through the buccal tube.

20. Outer bow/ Whisker bow It is made of a round stainless steel wire of 0.051” or 0.062” that is contoured to fit around the face. The length of the outer bow can be adjusted to produce the desired force vector/ line of force. Outer bow on both sides at the distal end is curved to form a hook that gives attachment to the force generating unit. The outer bow can be short, medium or long. Short – outer bow is lesser in length than inner bow. Medium – outer bow length is equal to inner bow. Long – outer bow is longer than inner bow.

21. J’ Hook This type of face bow consists of two 0.072” curved  wires whose ends form hooks that are contoured to fit over a small soldered stop on anterior segment of the maxillary arch wire. Their normal site of attachment on the arch wire is between the lateral incisors and the canine. The J hook type of face bow is therefore used along maxillary fixed appliance having a continuous arch wire. They are used for retraction of maxillary anteriors and have limited orthopedic indications .

22. Force generating unit May be in the form of: - i ) springs ii) elastics iii) other stretchable material Force generating unit Springs are preferred as they provide a constant force whereas elastics tend to undergo force decay.

23. Anchor unit Headgear appliance derives anchorage from extra oral sites using the rigid bones of skull or back of the neck. Two basic types of extra oral attachments that provide anchorage for headgear are : 1. cervical attachment / neck strap 2. occipital attachment / head cap A combination of cervical & occipital attachments may also be used to distribute the external forces over a wide surface area.

24. Principles in the use of headgear The following factors should be considered when planning the use of headgears : 1) Centre of resistance of the dentition :- The inner bow is generally attached to the maxillary first permanent molars through buccal tubes on these teeth. Force acting on the molars tends to displace them. A decision should be made as to whether bodily movement or tipping of the teeth is required.

25. The centre of resistance for a molar is usually at the mid root region.

26. Line of forces passing through the centre of resistance of the molars results in their bodily movement.

27. Line of force passing passing above the centre of resistance of molar causes causes distal root tipping.

28. Line of force passing below the centre of resisitance of molar causes distal Crown tipping.

29. Centre of resistance of maxilla Centre of maxilla is believed to exist at the posterosuperior aspect of zygomaticomaxillary suture.

30. Forces passing through the centre of resistance of the maxilla produce translation of maxilla in a distal direction Forces passing above or below this point cause rotation of the maxilla.

31. Line of force vector to center of resistance when occipital head gears are used The line of force pases below both the center of resistance of maxilla and dentition . Produces clockwise rotation of both the maxilla and the dentition .

32. The line of force passes below the center of resistance of maxilla & above the center of resistance of dentition . Produces clockwise rotation of maxilla & anticlockwise rotation of dentition .

33. Line of force vector to center of resistance when cervical head gears are used The line of force pases below both the center of resistance of maxilla and dentition . Produces clockwise rotation of both the maxilla and the dentition .

34. The line of force passes below the center of resistance of maxilla & above the center of resistance of dentition . Produces clockwise rotation of maxilla & anticlockwise rotation of dentition .

35. Types of head gear

36. Cervical headgear Nape of the neck Extrusion of molars leading to an increase in the lower facial height . Move maxillary dentition and maxilla in distal direction .

37. Occipital head gears Back of the neck Distal and superiorly directed force

38. Combination headgears Upward force is exerted on maxilla and maxillary dentition .

39. Uses of head gears

40. Face Mask Reverse pull head gear

41. Hickman 1972 was the first to use reverse headgear Modality was made popular by Delaire . It basically consist of a rigid frame work , which take anchor from chin or forehead or both for anterior traction of maxilla

42. Indication

43. Site of anchorage Anchorage from chin :- Used in Britain . Chin cup with post are employed . Anchorage is obtained solely from the chin the force is transmitted to condylar cartillage . Disadvantage alters the growth . Anchorage from skull :- Anchorage from forehead only . Disadvantage include pateint discomfort, cost and time . Anchorage from chin and forehead :- Combination of both .

44. Biomechanical consideration

45. Parts of reverse pull head gear Chin cup Forehead cap Elastics Metal frame Intraoral appliance

46. Types of reverse pull head gear

47. Hickham protraction head gear In 60’s Uses chin & head . Force distribution 15% head & 85% chin . Two short arm front of the mouth . Two long arm parallel to the lower border of the mandible .

48. Delaire face mask In 60’s Both chin and head support Square shaped metal frame work

49. Tubinger model Modification of Delaire

50. Petit face mask Modified form of D elaire Chincup and forehead cap with a single rod running in the midline A cross bar at the level of mouth

51. Chin cup

52. Introduction Reffered to extra oral orthopedic device to control the downward and forward growth of the mandible. Consist of chin cup a head cap and an adujustable elastic strap

53. Types of chin cups

54. Force magnitude and duration of wear At the time of appliance delivery a force of 150 – 300 gm / side is used Over the next two months force is gradually increased to 450 – 700 gm /side Pateint is asked to wear the appliance 12 – 14 hrs /day .

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