Functional appliances


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Introduction to Orthodontics
Fifth Year

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Functional appliances

  1. 1. Functional appliances -Undesirable class 2 : upper teeth are too forward -Class 1: Upp. K9 distal to low.K9 , the M-B cusp of upp. 1st molar fits into the B groove of the low. 1st molar How can class 2 change to class1? By any combination of: Moving the upp. Backward = = low. Forward 2 figures low pull and high pull (push the top jaw backward) extract the 2 upp. Pre. And retract the ant. Move the upp. Teeth distally (molar distalizer) Figure of “smart alex appliance” fro (space opening or protraction) -Functional treatment: holding the ow. Jaw forward and waiting for growth and remodeling to make the change permanently. -Functional appliances: are removable or fixed appliance that alter the posture of the man. And transmit the force created by the resulting stretch of the muscles and s.t. and by the change in the neuwomuscuarenvi. To the dental and skeletal tissue to produce movement of theteeth and modification to the growth of the jaw and low. face . -.The most common use of the functional appliance is to encourage the forward growth of a retrusive or “under-developed’ low. Jaw. .-The functional appliance hold the low. Jaw forward over a period until the teeth, jaw amd joint have “adapted” and the desired jaw postion has been obtained . .-Functional appliance align the jaws not the teeth, so they are usually used as a first stage of tx. (in a growing patient with a significant jaw disharmony) prior to the alignment of the teeth with fixed appliances (braces). -Indications for functional appliances: .Well aligned dental arches .Posteriorpositioned man. .Non severe skeletal discrepancy. .Lingual tipping of man. Incisors. .Properpatient selection. -Contraindications: .Class 2 skeletal by max. prognthism. .Vertical directed grower. .Labial tipping of low. Incisors. .Crowding.
  2. 2. The effectiveness of a functional appl. Depends on: -how much the appl. Is worn? -howquickle the patient is growing? Mode of action  Through posturing of the man, forward causing stretching of the facial musculature.  This generate faroces which are delivered primarily to the teeth and there will be: 1. Posteriorly directed force acts upon the upp. Arch. 2. And an anteriorly directed force acting on the low. Arch.  Dento-alveolar changes: 1. Move the upp. Teeth. Post. 2. Anterior movement of the low. Arch.  Changes in the max. growth: 1. Restriction of the max. growth similar to the headgear effect.  Changes in the man. Growth: I. Extra 1-2mm growth of the man..  Changes in the glenoid fossae: o Remodeling of the glenoid fossae more ant. Has been seen in exp. Hence the TMJ and the man. Would become repositioned slightly further forward. Functional appl. Do increase man. Length -Timing of tx.:  These appl. Work only in pt, who are growing and their effect is greatest when growth is most rapid.  The appl. Should be worn until the end of the pubertal growth spurt.  Skeletal age.  Performed during the main growth .  Period around puberty  The most favorable age for therapy  8-11 yr for girls  10-13 yr for boys (pancherz 2000) Categories of functional appl. -Graber & Neumann 1948 categorized functional appl into 2 categories: i. Myodynamic : that displace the man. Only to a moderate extent. ii. Myotomic: that displace the man. To a more extreme displacement and rely on the elastic properties of the muscle and facia for their action. -Vig and Vig 1986 have proposed a classification based on the components that each applincorporates ;these components are : i. ii. iii. Bite planes: which produce differential eruption. Lip/cheek shields: which alter the linguofacial muscle balance. The working bite: which effect the man. Posture.
  3. 3. -Isaacson, reed and stephens 1990RECENT , they divide these functional appl into 2 types: i. Rigid (Anderson, harvold, activator, bionator,etc..) ii. More flexible (function regulator of frankel). -Proffit (1986) proposes the following classification: 1- Tooth-borne passive. 2- Tooth-borne active 3- Tissue borne -History of development of functional appl. I. Robin 1902 monobloc II. Anderson 1908 activator III. Herbst 1934 herbst IV. Balters 1960 bimler V. Frankle 1967 frankel VI. Clark 1977 twin block COMPONENTS OF Fas 1. Functional components  Lingual flanges (effective)  Lingual pad (less effective) Lingua pads contact the tissue behind the low. Incisors, the flanges are against the alveolar mucosa below the man. Molars provide the stimulus to posture the man. To a new position.  Lip pads: these pads are positioned in the vestibule and remove li[ pressure from the teeth. Also force the lip to stretch during function, presumably improving the tonicity of the lips and may promote s.t. remodeling stability of incisors position.  Sliding pin&tube: Normally found only in the herbst appl.Also force the man. To be positioned forward not by pressure against the mucusa, but by holding the teeth.  Bite ramps: Ramps that contact when the pt. closes down where man. Can be posture forward (twin block). 2. Tooth-controlling components: I. Arch expansion: buccal shields, wire shields, expansion screws and spring. II. Vertical control: occlusal stops & bite blocks. III. Stabilizing components: clasps, labial bows & ant. Torqueing springs.
  4. 4. Passive tooth-brone appl.: These appl have no intrinsic force generating capacity from springs or screw. Depends only on s.t. stretch and muscular activity to produce tx. Effect. Activator fits loosely. advances the man forward. usesmoderat opening of vertical dimension. incorporate a labial bow for control of max. anterior teeth. An acrylic cap lower incisors. Facets cut in the acrylic help direct eruption of posterior teeth. Opens the bite 3-4mm. The lingual flanges is the primary mechanism to position the man. The design incorporate a labial bow for control of max. anterior teeth and an acrylic cap over the lower incisors to control both eruption and mesial movement. Activator facts  Original design worn at night.  Large one piece of acrylic.  Teeth could be redirected during eruption.  Largevertical opening construction bite.  Could not speak or eat when worn.  Advanced man. Jaw. The Woodside &Harvold Activator:  Increase vertical opening to help maintain the appl. In the mouth during sleep by stretching the s.t.  The man is advanced so that the incisors are in edge-to-edge relationship  Max. teeth are prevented fro eruption  Man teeth are free to erupt upward and forward Bionator:  Best described as cutdown activator  Palatal coverage is eliminated  This appl. Uses a lingual flange to regulate the posture of the man.  It usually incorporate a buccinators wraparound as an extension of the labial bow  This design which remove much of the bulk of the activator, can include post. Facets or acrylic occlusa; stops to control the amount and direction of eruption Bionator facts: Prototype of less bulky activator Worn day &night Allows more tongue action Man. Advancement Speaking possible yet difficult
  5. 5. Tooth-Born active appl.: these are largely modifications of activators and bionators it include expansion screws, springs to provide intrinsic forces for transverse and anterioposterior changes such as expansion activator. The Stockli-type Activator: Tooth-born appl that attempts to reduce undesirable dental changes with the addition of high pill headgear and torqueing aprings Vertical anterior torqueing springs to reduce lingual tipping of max. incisors. Hebst Appl.: -It can be either fixed or removable. -The max. and man splints usually are cemented or bonded to the teeth. -It can be removable and clasps retained. -The upp. And the low. The pin and tube apparatus that dictate the man position joints splints. -Occlusally a modification of this appl is superiposed on traditional fixed appl. -Pressure against teeth can produce significant dental movement in addition to any skeletal effect. Twin Block: -Lake the Herbst, although it can be used as either a removable or cemented device, it most effective when fixed in place. -It is consisted of individual max. and man. Plates with ramps that guide the man. Orward when the patient closes his man. -The twin block work by two vertical surfaces abutting each other, holding the lower jaw forward. Tissue borne appl (FR): -Frankel is the only tissue-borne functional appl. -A small lingual pad against the lingual mucosa beneath the lower incisors stimulates man. Repositioning. -Much of the appl is located in the vestibule. -It serve as an arch expansion appl in addition to its effects on jaw growth because the arches tend to expand when lips and check pressure is removed . -FR I is used for class II div.1 and it incorporate lip pads ;abial to the lower incisors to allow forward development of the man. Alveolar process. -FR II han in addition a palatal wire to procline the upp. Incisors in class II div.2 cases. Clinical management of functional appl.: Impression: Impression for functional appl differ somewhat from those for orthodontic records in: 1. Areas where appl components will contact s.t. must be clearly delineated.
  6. 6. 2. The impression must not stretch and excessively displace s.t. in an area of contact with the appl. Bite registration:  The construction bite for a functional appl for classII advance the man. So that the condyle are out of the fossae and separate the jaws by a predetermined amount.  In theory, small increments of man. Advancement should produce a greater skeletal effect relative to dental effect by minimizing pressure against the teeth.  It is recommended for most pt, an initial advanced of 4-6mm. Appl. Adjustments: -Clinical adjustments of a fumctionalappl depends on its components and purpose. -Typical adjustments include: 1. Trimming of interocclusal elements to allow teeth to erupt where desired. 2. Adjustment of the labial bow, almost to reduce its contact not to increase it. 3. Outward binfing of buccal shields and lip badstp facilitate expansion. -Clinical adjustment of the amount of man. Advancement may or may not be practical, depending on the metjod for advancement that was chosen. -With lingual flanges a new construction bite and new appl is the best way to produce further advancement. -Frankel appl can be sectioned so that its lingual pads slips further forward and cold cure acrylic is added in the gap. -Increments of advanced can be produced readily by adding spacers to the sliding pin in case with Herbst appl. Potential advantage of functional appl.:  Enlarge transverse width of arch to relieve crowding.  Diminish adverse fixed appl problems (gingival proliferation, TMD, decalcification, extraction-Ismail AJO 2002).  Reduce time with braces?  Reduce eliminate dysfunctional habits.  Tx. Of TMD? DONE BY: The one and only “Yousef AlHomaid”