Fixed appliance


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Introduction to Orthodontics
Fifth Year

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Fixed appliance

  1. 1. Fixed appliance -Fixed app. Are those attached to the teeth -The fixed attachments are placed by either banding or bonding technique -Since the fixed app. Is attached to the teeth, it's capable of producing a wide range of action in comparison to the removable app. Indication of fixed app. -correction of mild to moderate skeletal discrepancies -intrusion/extrusion of teeth -correction of rotation -overbite reduction -Closure of an openbite -Multiple tooth movement required in one arch -Active closure of extraction space -Edward Angle developed the E-arch. From early 1900s.Bands were placed only on the molar teeth. ligatures from heavy labial arch were used to bring to the line of occlusion (E-arch) -the E-arch was capable only of tipping teeth to a new position, thus angle began placing bands on other teeth and used vertical tube on each tooth into which a soldered from a smaller arch wire was placed.(pin and tube appliance) -this app. Proved impractical in clinical use. The relatively heavy base arch meant that spring properties were poor, and the problem therefore was compounded because many small adjustments were needed -the angle next appliance modified the tube on each tooth to provide a vertically positioned rectangular slot behind the tube. A ribbon arch of 10x20 gold wire was placed into the slot and held with pins.(ribbon arch)
  2. 2. To overcome the deficiencies of the ribbon arch, Angle reoriented the slot from vertical to horizontal and inserted a rectangular wire rotated 90 degree to orientation it had with ribbon arch (edgewise). the dimensions of the slot were altered to 22x28 precious metal wire was used the rectangle wire was tied into a rectangular slot with ligatures, making excellent control of root position possible development of fixed appliance -standard Edgewise appliance -early 1900s -Begg Appliance: -R.Begg had been taught use of the ribbon arch app. at Angle school. Working indecently in Australia, he set out to adapt ribbon arch for better control of root position -His adaptation took three forms: 1- he replaced the precious metal ribbon arch with 16 mil st.steel 2- he retained the original ribbon arch bracket, but turned it upside down, so that it pointed gingivally rather than occlusaly 3- he added auxiliary springs for better root control - combination of Begg and edgewise app. have been proposed on many occasions -one is to use bracket with Begg slot and an edgewise slot: the other is to use a modified bracket that allows tipping in one direction, so that the rectangular slot is available for both root uprighting and torque
  3. 3. Components of the fixed Appliance - bands -molar tubes -brackets -buccal tube -arch wires - auxiliaries: wlastomeric products. Coil spring. Lingual arches. Extra-oral app. Brackets: Acc to: 1-welded/bonded 2-material: st.steel, Cr-cobalt, gold, plastic, ceramic, or silicon 3-esthetic: metal/esthetic brackets 4-self-ligating/conventional ligated 5-narroow/wide 6-slot size -To produce the required movements. Different bends have to be incorporated in the arch wire -1st order bends: made in the plane of archwire to compensate for differing tooth width -2nd order bend: made in the vertical plane to achieve correct mesiodistal angulation or tilt of teeth
  4. 4. 3-3rd order bend: applicable to rectangular archwires only. They are made by twisting the plane of the wire -To (torque) is the least efficient tooth movement using orthodontic app. Significance of accurate bracket/band positioning -precise tooth positioning -optimal effect of "pre-adustment" -occlusion -esthetic -stability -bands: Posterior attachment -Molar tube -Arch wires: Acc to material - Ni Ti -TMA -Elgioly
  5. 5. Elastic properties Elastic properties-strength analysis 3 points on the stress strain graph can be represented to explain "Strength" 1-proportional limit 2-yield strength 3-ultimate tensile strength -proportional limit Point at which first deformation is seen Proportional limit --- elastic limit -yield strength Experimentally it's difficult to measure the proportional limit 0.1% of plastic deformation -ultimate tensile strength Max. load a wire can substain Evolution o orthodontic wire material Stainless steel(entered dentistry-1920:world war I -1930's-popular—refinement of drawing process -1934-opposition *Emil Herbst Angle-steel as ligature wire …> gold>SS -1950's- type 300 series-most orthodontic app. 17-25% Cr 8-25% Ni
  6. 6. Balance Fe Cabalt chromium -1950s-Elgin watch co -rocky mountain orthodontics-Elgiloy TM Various tempers: Red: hard & resilient Green: semi-resilient Yellow: slightly less formable but ductile Blue: soft & formable -nickel titanium alloys (late 1960s) Buehler-office of navy-alloy-shape memory effect (SME) -Nitinol-nickel titanium naval ordnance laboratory Deformed,clamped,heated&cooled-specified shape 1970s George Andreasen. UNITEK-orthodontics 50:50 Ni and Ti -pseudoelastic Niti Pseuudoelasticity- stress induced >>austenitc martensitic phase transformation Copper NiTi cu…5-6% cr… 0.2- .5%
  7. 7. thermoelastic NiTi-Miura thermoelasticity-thermal induce >>austenitic martensitic phase transformation sentalloy –GAC chiness NiTi-general research institute for Non ferrous metals Japanese NiTi-FURUKAWA electric co Ltd -Bet titanium TMA Early 1980s Composition -Ti—80% -molybdenum- 11.5% -zirconium-6% -Tin- 4.5% Fiber reinforced polymeric composites -next generation of esthetic archwires -aerospace industry -pultrusion- round + rectangular
  8. 8. Classification based on cross section ABCDE Direct bonding: -tooth prep -prophy with pumice -etch 30 second with 37% phosphoric acid -moisture control is a must? -determine bracket position -bracket placement -align and push firmly into place -express excess composite -bracket base should be flat against tooth Indirect bonding -accurate bracket placement -less chair time -more hygienic Cementation: -ZPH CEMENT -ZPC CEMENT -GI CEMENT
  9. 9. Ligation: Elastic module: Single or chain Lingual orthodontics -developed by Dr.Kinjita in Japan in 1976 to satisfy the need of [patients who practical martial arts -craven Kurz patented his lingual bracket in the Us in 1976, and with ORMCO developed pliers and other instruments -early successes were tempered by difficulty of the technique and the poor results which it rendered Advantages: orthodontist -treat pts who refuse labial tx. -better evaluation of esthetics during tx. -protrusive, expansive and intrusive movement are easier -"splint effect" encourages deep bite correction and relaxes muscles Anterior leveling -upper arch (.016 Cu—Niti) -lower arch (.016 Cu-NiTi)