Fixed functional appliances in Orthodontics

Fixed functional appliances in Orthodontics

1. Fixed functional appliances

2. Introduction The first fixed functional appliance was used as early as 1905 by Emil Herbst . It was reintroduced by Hans Pancherz in 1979,who popularized its use. These appliances are now used in both compliant and non compliant patients for their enhanced effectiveness in saggital correction of malocclusion in a relatively short duration.

3. Classification Rigid fixed functional - Herbst appliance - Mandibular anterior repositioning appliance. (MARA) Mandibular Protraction Appliance (MPA) Magnetic telescopic appliance,Ritto appliance.

4. Flexible fixed functional appliances -Jasper jumper -Adjustable bite corrector - Klasper super king

5. Hybrid fixed functional -Eureka spring -Twin force bite corrector - Forsus

6. Advantages Generate continuous stimuli for mandibular growth without any break. They are relatively smaller in size therefore permit better adaptation to functions like mastication,swallowing,speech and respiration.

7. Fixed functional appliances treat class II malocclusion successfully in a shorter time span. Less patient cooperation is needed as it is a fixed appliance It can be used successfully in patients who are at the end of their growth.

8. Design( Herbst ) The appliance can be compared to an artificial joint working between the maxilla and the mandible. A bilateral telescopic mechanism keeps the mandible mechanically in continuous anterior position. The device consists of a tube into which the plunger fits.

9. The tube is fixed to the distal end of the maxillary molars while the rod is fixed to the lower first premolars.

10. Types Banded Herbst ; Upper and lower first premolars and first molars are banded. The tubes are fixed to pivots soldered to the disto-buccal aspect of the first molar bands. The shafts or rods are fixed to pivots soldered to the lower first premolar bands.

11. Bonded Herbst;The bonded type of Herbst appliance is a wire reinforced acrylic splint that covers the occlusal and part of the buccal and lingual surfaces of all teeth except the anteriors .

12. Disadvantages Like any other functional appliances it requires patient co-operation as initial discomfort is usually present. It can cause minor functional disturbances in the masticatory system which are temporary and gradually disappear.

13. Risk for the development of dual bite. Repeated breakage. Plaque accumulation and enamel decalcification occur, especially in splint type appliance.

14. Clinical manipulation First few days signs of muscle pain in and around jaw muscles and TMJ do appear. Rapid changes in occlusion within in 6-9 months, seen, showing correction of Class II malocclusion to Class I occlusion. The appliance is removed and second phase of treatment is started with fixed appliance therapy.

15. Jasper jumper Rigidity of the Herbst appliance restricts lateral movement of the mandible. In an attempt to overcome these problems, Jasper(1987) developed a new, flexible pushing device. This appliance produces both sagittal and intrusive forces, as does the Herbst bite jumping mechanism, and also affords the patient more freedom of mandibular movement.

16. Parts of the appliance Force module. The force module, analogous to the tube and plunger of the Herbst bite jumping mechanism, is flexible. The force module is constructed of a stainless steel coil or spring attached at both ends to stainless steel end caps in which holes have been drilled in the flanges to accommodate the anchor unit.

17. The module is surrounded by an opaque polyurethane covering for hygiene and comfort. The modules are available in seven lengths ranging from 26 to 38mm. Force delivered is about 8 ounce or 250 gms of force.

18. Attachment: The force module is attached posterior to the maxillary arch by a ball pin attached through the distal attachment of the force module.The ball pin passes anteriorly through the face bow tube on the first molar tube and cinched forward to activate the module.

19. Transpalatal arch is combined with fixed appliance to enhance maxillary anchorage. Lower lingual arch is combined with fixed appliance to enhance the mandibular anchorage.

20. Differences from Herbst The amount of force applied by the modules is more easily controlled by the clinician. The flexibility of the force module has been shown to increase patient comfort because of greater lateral and sagittal movements possible.

21. The force module curves away from the dental dental arches in its activated position, making mastication and oral hygiene procedures easier to perform. It can be added to existing fixed appliance at virtually any point after arch preparation.

22. Disadvantages Breakage Unwanted tooth movement.

23. Instructions Not to chew on the appliance or perform movements requiring wide opening of the mouth. Strict dietary controls are mandatory.

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