Functional appliance Dr. Hoori Mir Mohammad Sadeghi
Functional appliance side effects The most desirable and variable effect is for the mandible to increase in length as shown by the open possibly repositioning the TM fossa by apposition. The "headgear effect" restrains the maxilla and the maxillary teeth. Mandibular repositioning often creates forces against the lower teeth that cause anterior movement of the mandibular dentition. The direction in which mandibular growth is expressed, forward and/or inferiorly, is most related to the eruption of the molars. If the molars erupt more than the ramus grows in height the forward mandibular change will be negated and the Class ll malocclusion will not improve.
To facilitate Class ll correction • Mesial and vertical eruption of the mandibular molars. Upward and forward movement of the mandibular posterior teeth will improve the molar relationship. • Establish the posterior occlusal plane at the higher level.
Cervical headgear which uses a cervical neck-strap and a face-bow to produce distal force on the maxillary teeth and maxilla, is aimed at controlling maxillary size and position but is only effective if spontaneous mandibular growth also occurs.
1.Pretreatment Alignment • The incisor position and relationships should be carefully examined. • patient's ability to posture forward at least 4 to 6mm • Most mandibular deficient children have a large overjet and can do this readily but in some cases incisor interferences prevent the mandible from being advanced to the correct position for the bite registration
The problem can be either: • Lingual displacement of the upper incisors (a Class II, division 2 incisor pattern) • Irregular and crowded incisors in either arch. • Either fixed or removable appliances can be used for this purpose, depending on the type and magnitude of tooth movement required.
2.Impression Impression technique depends on the appliance components : • Good reproduction of the teeth • An accurate representation of the area lingual pads or flanges & If buccal shields or lip pads, It is important not to overextend the impressions so that tissue is displaced, location of the components leads tit long-term soft tissue irritation, discomfort, difficulty in appliance adjustment, and poor patient compliance
3.working bite • Multiple layers of a wax hard enough • Patient's preliminary record casts • Not covering the anterior teeth or contacting the retro-molar areas (avoid any soft tissue interference with the wax).
Advanced symmetrically(pretreatment midline) • We recommend a 4 to 6 mm advancement, but always one that is comfortable. Quite large? Modest? relatively small? • Does not move the incisors past an edge-to edge.
Opening • The minimal posterior opening to achieve the vertical space is about 3 to 4 mm (Frankel appliance) There must be enough space for the laboratory technician to place wire and plastic between the teeth to connect major components of the appliance and construct occlusal & incisor stops. • Interocclusal stops or facets to guide eruption, usually require 4 to 5 mm of posterior separation (Activators and Bionators) • If eruption of upper and lower posterior teeth is to be limited, 5 to 6 mm total opening in the molar region ( a child with excessive vertical face height )
Components for Functional Appliances • Components to Advance the Mandible. • Arch Expansion Components. • Vertical Control Components. • Stabilizing Components. • Active Components.
Functional Components Lingual flanges Contact with mucosa ;most effective Lingual pad Contact with mucosa; less effective Sliding pin and tube contact with teeth ;variable tooth displacement Tooth-supported ramps Contact with teeth; tooth displacement likely Lip pad Secondary effect only on mandibular position
Arch Expansion Buccal shields Passive effective Buccinator bow, wire shield Passive less effective Expansions crews Must activates lowly; questionable stability spring
Vertical Control Occlusal or incisal stops Prevent eruption in discrete area Bite blocks Prevent eruption fall posterior teeth Lingual shield Facilitate eruption
Stabilizing Components Clasps No effect on growh modification Labial bow Keep away from incisors lingual tipping undesirable Anterior torquing Needed to control lingual tipping, especially with headgear-activator
1.Activator The activator is also used to advance the mandible • Incorporate anterior and posterior bite block • A labial bow • The lingual shields usually extend deeper along the mandibular alveolus than other functional appliances, • Displacing spring that engages the maxillary first molar s o that the appliance requires a Closed and advanced mandibular posture to retain the appliance in place.
2.Bionator The bionator is borne on the teeth and advances mandible. • A buccal wire to maintain the lips off the teeth • Bite blocks between the posterior teeth • A tongue shield • Major palatal connector to stabilize the posterior segments • Limited in bulk and relatively easy for the patient to accommodate
Frankel The Frankel II appliance advances the mandible and fosters expansion of the arches with the buccal shields .The lower lip pad also moves the lower lip facially. The appliance is largely tissue borne This appliance is more bulky than the activator and bionator and potentially uses more soft tissue irritation. The appliance incorporate more wire and is more susceptible to distortion.lt has wire as a major palatal connector and as stops for the maxillary molars and incisors.
A buccal shield holds the cheek a way from the dentition and (B) facilitates posterior dental expansion b y disrupting the tongue-cheek equilibrium. • The shield is placed away from the teeth in areas where arch expansion is desired). • The lip pad holds the lower lip (or upper lip with a Frankel ll appliance)a way from the teeth and forces he lip to stretch to form a lip seal • The pad must be carefully positioned a t the base o f the vestibule to avoid soft tissue irritation.