Functional Appliances Part 1 & 2 PDF

functional appliances definition: functional appliances alter the mandible's posture, by holding it open, forwards and backwards (by Proffit) a loose appliance designed-neuromuscular environment of the pro facial region to improve occlusal development or cranio-facial skeleta...

functional appliances definition: functional appliances alter the mandible's posture, by holding it open, forwards and backwards (by Proffit) a loose appliance designed-neuromuscular environment of the pro facial region to improve occlusal development or cranio-facial skeletal growth (by Moyer) > HISTORY: L > CLASSIFICATION of functional appliances by Proffit (ACCORDING TO MODE OF RETENTION): 1) TOOTH: Tooth-borne passive appliance: desirable change in an antero-posterior (A-P) or transverse direction which is achieved by the soft tissue stretch & muscular activity 2) TOOTH: Tooth-borne active appliance: provides intrinsic forces by screws and springs 3) TISSUE: Tissue-borne appliance: placed on the vestibule, with an altering mechanism that omits forces and pressure generated by soft tissues, to allow jaw growth > CLASSIFICATION of functional appliances by Vig. (Viggo H. S. Malmströ) (ACCORDING TO ACTION): MYOTONIC ACTION: produced by the muscle mass, a passive muscle stretch through large mandibular movement of 8 to 10 mm MYODYNAMIC ACTION: acts by stimulation of muscle activity/movement by medium opening of < 5mm > CLASSIFICATION of functional appliances by Hunt’s (ACCORDING TO CALCIFICATION) 1) FIXED APPLIANCES: Herbst appliance, Jasper Jumper appliance 2) REMOVABLE APPLIANCES: Bionator appliance, Activator appliance 3) SEMI-FIXED APPLIANCES: Lip bumper, Bass appliance PRINCIPLE OF FUNCTIONAL APPLIANCE THERAPY: functional appliances induces changes in form or function, the most important principle is the adaption between form and function this neuromuscular adaption allows the form and function to get adjusted Functional appliances works by 2 principles: (A) force application, (B) force elimination I ↓ A) FORCE APPLICATION: force applied to the dentition and underlying basal bone that induces changes in form and shape secondary adaption of function & form subsequent change in form; the neuromuscular response brings about adaptation in function to the new form B) FORCE ELIMINATION: prevents abnormal & restrictive forces on the dentition, resulting in function rehabilitation/change leading to secondary adaption in form according to the new function > MECHANISM OF ACTION OF FUNCTIONAL APPLIANCES: 1. Re-direction of musculature 2. Lateral pterygoid muscle stimulation 3. Decreased biochemical feedback 4. Unloading of mandibular condyle 5. Differential eruption of teeth 1. Re-direction of musculature: the constant holding of the mandible in forward direction, forces muscle to learn new functional pattern muscular adaption takes place after functional appliance therapy 2. Lateral ptreygoid muscle stimulation: 1) functional appliance 2 stimulation of LPM Z 3) increased activity of retro-discal pad h 4) growth of condylar cartilage 5) posterior superior deposition of bone in condyle 6) sagittal growth of mandible > 3. Decreased biochemical feedback: i) Chondroblasts in the condyle secrete a substance that retards/slows down mitotic activity of stem cells (known as negative feedback) 2 ii) Stimulation of LPM subsequently causes maturation of chondroblasts: leading to reduction in the negative feedback material. ↓ iii) Removal of this biochemical brake causes acceleration of condylar growth. 4. Unloading of condyle: while the func. appliance is used, the condyle is distracted from fossa; facilitating & increasing growth rate adaptation to the new position occurs through condylar growth in a superior-posterior aspect 5. Differential eruption of teeth: the vertical eruption of teeth is modified during usage of func. appliance according to the need; by placing molar stops, or by acrylic guide plane. OVERALL CHANGES IN FUNCTIONAL APPLIANCES Y 1) SKELETAL CHANGES 2) DENTOALVEOLAR CHANGES I 2 4 3 5 3) EFFECT ON OROPHARYNGEAL AIRWAY (OAW) mandibular deficiency might be causative factor in reduced oropharyngeal airway dimensions and an impaired respiratory function cephalometric & CBCT imaging provides sufficient data to analyze airway dimension changes in the nasopharynx, oropharynx & hypopharyngeal areas a significant change was seen in the airway due to repositioning of mandible, especially with removable functional appliances FULL POTENTIAL OF FUNC. APPLIANCES DEPENDS ON THE FOLLOWING FACTORS: patient & family cooperation severity of skeletal problem actively growing patient: > Class II: patient's actively growing growth spurt for boys (12-14) and girls (11-13) age > Class III: patient's actively growing 6 to 10 years of age ADVANTAGES & DISADVANTAGES OF FUNCTIONAL APPLIANCES:  BITE REGISTRATION FOR FUNCTIONAL APPLIANCES; FABRICATION 1. Train patient to move mandible forwards (reaching either edge to edge relation or beyond edge-to-edge relation) 2. Mark the midlines of the U/L arches 3. Evaluate the buccal segments for any crossbites; when moving the mandible forward 4. Form a bulky U-shaped horse wax bite with a vertical opening of 2- 6 mm opening anteriorly 5. Ask patient to move mandible forward and bite on wax sheet til wax hardens TYPES OF FUNCTIONAL APPLIANCES 1) REMOVABLE FUNCTIONAL APPLIANCES > Indications & contraindications of Lip bumper removable FAs: The Andresen Activator appliance The Bionator appliances The Twin-block type appliances The Palatal and Labial Medium Opening Activators (MOA) The Frankel appliance The Intrusive Myofunctional Appliances Teuscher appliance 1) Lip bumper > mode of action: change in muscle balance perioosteal stretching > indications: Class II div1 with lip trap interference distalization of lower molars reinforcing lower posterior teeth (anchorage) to avoided loss of space after premature loss of primary teeth (as space maintainers) 2) Bionator Appliance advocated by Balter Bionator 1950, derived from Andresen's activator but is greatly reduced in bulk > philosophy: the equilibrium b/w the tongue and the circumoral muscles is responsible for the shape of dental arches and that the functional space for the tongue is essential for the normal development of the orofacial system (Myodynamic passive appliance) the forward positioning of mandible leads to the dorsum of tongue to be in contact with the soft palate, accomplishing lip closure > mode of action of Bionator: modulates muscle activity enhances normal development of inherent growth pattern eliminates abnormal & potentially-deforming environmental factors I ↓ > indications for Bionater: in mild to moderately severe class II cases with no crowding > design of Bionator: similar to the activator except for; a palatal loop of 1.25mm (encourages forward posture of the tongue & mandible) upper posterior teeth occlusal coverage, while the lower are free to erupt a vestibular bow of 0.9mm contacts the upper incisors, but is clear of the buccal teeth by 2-3 mm to allow for expansion > other Bionator types: a) Open-bite appliance b) Class III or reverse bionator 3) Twin Block Appliance developed by Scottish orthodontist Clark in 1977. twin block is a tooth-borne, two-piece appliance composed of upper and lower bite blocks; a) upper bite block is located posteriorly covering the molars, extending to the 2nd bicuspid · b) lower bite block is located anteriorly covering the bicuspids & c) the inclined planes of the posterior bite blocks are oriented at 40- 70 degrees to the occlusal plane to initiate functional shift of the mandible and to open the closed bite > indication for Twin Block appliances: Angle's class II division 1 overjet of 10-12mm & a deep overbite full-unit distal occlusion in buccal segments > design of Twin Block: -Twinblock Base Plates Bite block wire components: The Delta Clasp and Ball End Clasp > Twin Block Appliance Management Treatment phases: 1) ACTIVE PHASE: 6 - 9 months Pterygoid response (2 to 3 months after appliance insertion). 2) SUPPORTIVE PHASE: 3 - 6 months using upper Anterior Inclined plane Eruption guidance of molars by trimming Upper Occlusal Block *gradual reduction of thickness of acrylic plate* (as mandible 3) RETENTION PHASE: 6 - 9 months advancement occurs) ↑ for using the appliance for retention purpose 4) Frankel Appliance Rolf Frankel believed that active muscle & tissue mass have a major role in development of skeletal & & dentofacial deformities. hence, Rolf developed function regulators as orthopedic exercise devices to aid in the maturation, training & reprogramming of the orofacial neuromuscular system ↓ > mechanism of Frankel appliance: the lip pads eliminate any trapping of the lower lip behind the upper incisors, when the lip is displaced by the lip-pad it will force the appliance back posteriorly, causing some headgear effect. important note!! Class II with overjet that is too large, forward positioning must be done in 2 stages in case of forward positioning of mandible by 7-8 mm, the vertical opening should be slightly moderate; 2-4 mm if forward positioning is not more than 3-5 mm then the vertical opening can be 4-6 mm. 2) FIXED FUNCTIONAL APPLIANCES the concept of fixed func. appliances (FFAs) was introduced by Emil Herbst > main advantages of using FFAs: the appliances are fixed in the intra-oral cavity, so they provide continuous stimulus for mandibular growth occurs. reduce the need for patient cooperation overall treatment time reduced they're fixed on the upper & lower arches, so they transmit forces directly to the teeth i) Herbst appliance Emil Herbst first introduced the fixed appliance in Germany 1905. rigid fixed FA consist of a metallic maxillary and mandibular framework the artificial joint between the maxilla & mandible acts with a telescopic mechanism the Herbst appliance keeps the mandible in a protruded position continuously; both on jaw closure and when teeth are not in occlusion ii) Forsus appliance introduced by 3 M company, USA a flexible fixed FA (flexible open coil springs), so patient can move mandible in all directions comfortably has the action of a Jasper jumper iii) MARA appliance (Mandibular advancing repositioning appliance): introduced by Douglas Toll in 1991 4 stainless steel crowns with double tubing the square tubes are soldered to each of the upper crowns the upper elbows guide the mandible forward the elbows are tied in by ligatures or elastics functional appliances are useful for dysfunction, playing an etiological role in the malocclusion. generally functional appliances are used for correction of Class II, however, the modifications made enable them to be used for Class III and other vertical and transverse malocclusions. usage of type of functional appliances; depends on age, malocclusion, pattern of growth.