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Expansion in orthodontics

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Expansion in orthodontics

  2. 2. INTRODUCTION Arch expansion is a method of gaining space. An apparently complex yet relatively simple procedure in orthodontics is palatal expansion. The correction of transverse maxillary deficiency can be an important component of an orthodontic treatment plan. Expansion of palate was first achieved by Emerson C.Angell in 1860.Ever since numerous expansion appliance have been described with varying force levels & duration of treatment.
  3. 3. CLASSFICATION Expansion of the dental arches can be classified as: 1. Dento-alveolar expansion 2. Skeletal expansion They can also be classified broadly as: 1. Slow expansion 2. Rapid expansion
  4. 4. Armamentarium 1. Screws 2. Loops 3. Springs 4. Flexible wire,e,g NiTi
  5. 5. Slow Expansion Slow expansion has traditionally been termed as dento-alveolar expansion ,although some skeletal changes can be observed.  The slower expansion have also been associated with a more physiologic adjustment to the maxillary expansion,producing greater stability & less relapse potential than in rapid expansion procedures  The force generated by such procedures are 2-4 pounds.  Expanded slowly at a rate of 0.5-1mm per week.
  6. 6.  Pure dento-alveolar expansion should always be slow  Normal width of PDL is approx 0.25 mm.For orthodontic tooth movement to take place an expansion device should not be activated >0.25mm at a time.  Pitch of a jackscrew is 1mm,i.e. a 360⁰ rotation separates two halves of expansion appliance by 1mm. Rule for slow expansion : Two ¼th turn per week,that means 8 turns a month
  7. 7. Indication & contraindication of slow expansion INDICATIONS : 1. PMBAW (premolar basal arch width)>PMD (premolar diameter)- Ashley Howe’s Analysis 2. Any age 3. PMBAW × 100 ≥ 44% = PMBAW% -Ashley Howe’s Analysis TTM CONTRAINDICATIONS : 1. Buccal or labial inclination of teeth 2. Bone loss on buccal aspect of teeth 3. Mandibular inter-canine width
  8. 8. Appliance used for slow expansion Fixed  W arch  Quad helix  Ni-Ti arch wires Removable  Coffin spring  Expansion screws  Functional appliances  Active  Passive
  9. 9. W arch  0.9mm stainless steel wire soldered to molar bands  Patient cooperation not required  Preferred in deciduous and mixed dentition where mild to moderate expansion is required  Activation : outside mouth,3mm wider than passive width
  10. 10. Quad helix  Four helices:more flexibility  Helices in the anterior component impart bulkiness which can be useful in preventing digit sucking  Activaton :either inside or outside mouth,4mm wider than passive width Retained for 3-4 months,after overcome is achieved
  11. 11. Ni-Ti expanders  It has capacity to rotate,upright,distalize & expand the anterior & posterior arch with gentle biocompatible force.  It is capable of a uniform,slow,continuous force  Depends on shape memory and super elasticity of NiTi  Transition temperature is 84°F  Continuous force levels between 230gms to 300 gms.  Available in 8 intermolar widths; ranging from 26-47 mm  Freeze gel packs can be used to make appliance flexible for insertion
  12. 12. Coffin spring It is a removable appliance capable of slow dento-alveolar expansion The appliance consists of an omega shaped wire of 1.25 mm thickness,placed in mid- palatal region  Activation : the spring is activated by pulling the two sides apart manually.It can also be activated by using three prong pliers
  13. 13. Expansion screws The expansion screw is a very small metallic appliance which may be designed to move a single tooth or a group of teeth or the skeletal bases as required. This screw as a source of force together with the acrylic segment of the plate effect the teeth and the alveolar process. Different type of screws may be used advantageously for certain procedure during treatment with removable appliance .
  14. 14. Functional appliances This expansion is not produced through the application of extrinsic bio-mechanical but rather than by intrinsic forces in the dental arch such as those produced by the tongue.(passive expansion) When the forces of the buccal and labial musculature are shielded from the occlusion, a widening of the dental arches often occurs.
  15. 15. Rapid expansion Rapid maxillary expansion is also known by the terms rapid palatal expansion or split palate.It is skeletal type of expansion that involves the separation of mid-palatal suture & movement of the maxillary shelves away from each other.
  16. 16. Indications of rapid maxillary expansion 1. Posterior crossbite 2. Class II malocclusion 3. Cleft palate patients 4. Face mask therapy 5. Medical indications : nasal stenosis,septal deformities,recurrent ear & nasal infection,allergic rhinitis
  17. 17. Contraindications of R.M.E 1. Single tooth crossbites 2. Un-cooperative patients 3. After ossification of mid-palatal suture unless it is accompanied by adjunctive surgical procedures 4. Skeletal asymmetry of maxilla & mandible & adult cases with severe antero-posterior skeletal discrepancies
  18. 18. Diagnostic aids The routine diagnostic aids such as :  Case history  Clinical examination & study models  Maxillary occlusal view radiograph – to see mid- palatal suture  P.A cephalogram – to estimate the amount of expansion that has taken place Occliusal radiograph
  19. 19. Rapid maxillary expansion appliances Numerous appliances have been used for rapid maxillary expansion.Broadly they can be classified as : a. Tooth borne b. Tooth & tissue borne These are fixed appliance & appliance that are fixed onto the teeth are more reliable & found to produce consistent skeletal effects. Examples of tooth borne appliances include: i. Isaacson type ii. Hyrax type Two of commonly used tooth & tissue borne appliances are : i. Derichsweiler type
  20. 20. Isaacson type  This appliance has a special spring loaded screw called a MINNE expander,consists of a coil spring having a nut that can compress the spring  It is soldered directly to the bands  No acrylic is used  Easy to fabricate  Expander is activated by closing the nut so that the spring gets compressed.
  21. 21. Hyrax type This type of appliance makes use of a special type of screw called HYRAX (Hygiene Rapid Expander) The screws have heavy gauge wire extensions that are adapted to follow the palatal contour & are soldered to bands on premolars & molars.
  22. 22. Derichsweiler type  The first premolars & first molars are banded  Wire tags are soldered onto the palatal aspect of the bands  These wire tags get inserted into a split palatal acrylic plate incorporating a screw at its centre.
  23. 23. Hass type The first premolar & molar of either side are banded  A thick stainless steel wire of 1.2mm diameter is soldered on the buccal & lingual aspects connecting the premolar & molar bands  Lingual wire is kept longer so as to extend past the bands both anteriorly & posteriorly  Free ends turned back and embedded in acrylic.  A screw is incorporated.
  24. 24. BONDED R.M.E Most of the RME appliances described earlier are banded appliances .They incorporate bands on the first premolars & molars.  An alternative design of the appliance would be to have a splint covering variable number of teeth on either side to which the jackscrew is attached.  Raymond Howe in 1982 developed this appliance  Clears the palate from acrylic  No banding needed- can be used on malposed teeth where parallel path of insertion is not possible  Less error prone as bands don’t have to be placed in impression  Easy to make on deciduous teeth.
  25. 25. Wire framework Completed appliance On model Acrylic-lined bondable RME appliance
  26. 26. Instruction on how to expand (activation schedule) Schedule by Timms :  Upto age of 15 years : the turn 180⁰ is given as 90⁰ in the morning & 90⁰ in the evening. Zimring & Isaacson in 1965 :  Young growing patients : two turns each day for the first 4-5 days & later one turn each day for remainder of RME treatment.  Non growing adult patients : two turns each day for the first two days & one turn each day for the next 5-7 days & one turn every alternate day till desired expansion is achieved.
  27. 27. Effects of RME Effect on maxilla  Opening of the mid-palatal suture  Downwards & forward maxillary movement Effect on maxillary teeth  Midline spacing between the two maxillary central incisors  Maxillary posterior teeth show buccal tipping & extrusion Effect on mandible  Downward & backward rotation of the mandible  Increase in face height  Reduction in overbite Effect on nasal cavity  Reduced resistance to nasal air flow  Increase in intra-nasal space
  28. 28. Hazards of RME Oral hygiene Length of fixation Dislodgement & breakage Tissue damage Infection Pain or discomfort,dizziness,pressure at the bridge of nose etc
  29. 29. Comparison between slow & rapid expansion Slow expansion Rapid expansion 1. Type of expansion – both skeletal & dental changes seen from beginning 2. Rate of expansion - slow 3. Type of tissue retraction - more physiologic 4. Force used –milder force (2-4 lbs) 5. Frequency of activation- less frequent (0.5- 1mm/week) 6. Duration of treatment- long 7. Type of appliance-either fixed or removable 8. Age-any age 9. Retention-lesser chance of relapse 1. Predominantly skeletal changes initially,later dental changes take place with skeletal relapse 2. Rapid 3. More traumatic 4. Greater force (10-20 lbs ) 5. More frequent (0.5- 1mm/day) 6. Short 7. Mostly fixed appliance 8. Before fusion of mid- palatal suture 9. More chance of relapse
  30. 30. EXPANSION OF CLEFT PALATE CASES  Excessive anterior collapse coupled to little or no posterior collapse  More fan wise expansion needed to restrict posterior expansion.Screws of longer thread of upto 18mm expansion  More difficult to retain due to clinical crowns not developed properly  Unilateral expansion both cap splints & bands can be used  Formation of fistula could be a complication
  31. 31. Expansion of mandibular arch  Stable expansion is difficult to attain in the lower arch  Present studies state that expanding the upper arch allows for spontaneous expansion of the lower arch to some extent.
  32. 32. Other methods of expansion  Surgically assisted RME  Transpalatal arch  Magnets  Ultra rapid expansion Though these methods are not used frequently.
  33. 33. conclusion Expansionofthearcheshasseenitsups&downsinthepast.More& moredocumentationoftheeffects&stabilityofthisprocedurehas throwna newlightonitsclinicalapplication. Whetheritisslowor rapidexpansion,properdiagnosis& case assessmentisveryessentialtoensureconsistentresults.Asmore& more casesare beingtreatedwithoutextractionsduetoprofile considerations,Expansionofthearchesformsa valuableadjuncttotreat a widevarietyofclinicalpresentations.
  34. 34. Reference 1. Contemporary Orthodontics,5th edition by William R.Proffit,Henry W.Fields,David M.Sarver 2. Graber Orthodontics text book,5th edition 3. Kharbanda Orthodontics text book,5th edition 4. Orthodontics text book by S.I. Bhalaji,6th edition
  35. 35. Thank you