MANAGEMENT OF TRANSVERSE MAXILLARY DEFICIENCY

Question 1

• What age is the growth of the midpalatal normally completed by ?

Answer 1

• 17 years of age

Question 2

• What is the mean transverse growth of the maxilla between the ages of 4 yrs and adulthood ?

Answer 2

• 6.9mm
• There is such a small amount of trasnverse growth of the maxilla throughout life . THEREFORE UNLIKELY THAT A XBITE PRESENT IN THE PERMANENET DENTITION WILL SPONTANEOUSLY RESOLVE.

Question 3

• List 6 indications for maxillary expansion

Answer 3

1. XBITE
2. Distal molar movement
3. Functional appliance RX
4. Surgical cases ( arch co-ordination)
5. To aid Maxillary protraction
6. Mild crowding

Question 4

• CROSSBITES

Answer 4

1. Maxillary expansion may help eliminate a Mandibular displacement that is associated with a xbite.
2. Manxillary expansion may also help to create space for the relief of minimal crowding.
3. Sometimes a pt will present with a BILATERAL crossbite involving all the molar teeth WITHOUT A DISPALCEMENT.

If correction is attempted there is the riskof relapse which may lead to the formation of a unilateral XBITE WITH a displacement. AND SO….

Accept Bilateral Xbites with no displacement.

Question 5

• Distal Molar Movement

Answer 5

• HG is often used to distalise the posterior segment to create space for the relief of crowding and to reduce OJ.
• During distal movement its important to expand the upper arch- BECAUSE you’ll have the Umolars occluding with a wider part of the mandible.
• Expansion in these cases is achieved in these ways:

1. Slight expansion of the inner bow -KLOEHN BOW
2. URA with midpalatal expansion screw in conjunction of HG.

Question 6

• FUNCTIONAL APPLIANCE TREATMENT

Answer 6

• Most commonly used in a MODERATE Class II in a GROWING PATIENT.
• OJ is reduced by:
  
  • Retroclination of UINC’s
  • Proclination of LINC’s
  • Restraint of Maxillary growth
  • Accelerated Mandibular growth (??)
• In most cases important to expand upper arch to maintain arch coordination as the MAXILLARY DENTITION IS DISTALISED RELATIVE TO THE MD DENTITION.
  *

Question 7

• Ways to increase IM width during funcitonal appliance RX ?

Answer 7

• Midline expansion screw ( TBK)
• Coffin spring ( The Bass appliance)
• Buccal shield ( removes pressure of cheeks on upper arch and allows the tongue to exert an expansive force).

Question 8

• Surgical Cases

Answer 8

• Arch expansion maybe indicated in orthognathic cases to maintain arch coordination following correction of the sagittal sk discrepancy.
• Good post surgery occlusion is important for stability.

Question 9

• Maxillary protraction

Answer 9

• PHG can be used for the management of a Class III malocclusion IN A GROWING PATIENT.
• This technique works by a combination of;
  
  • Proclination of Maxillary Incisors
  • Retroclination of Mandibular Incisors
  • Forward Maxillary movement
  • Downward & Backward redirection of MD growth.
• RME maybe used to facillitate protraction as it disrupts the circummaxillary sutures.

Question 10

• Mild Crowding

Answer 10

• Maxillary expansion maybe used in carefully selected cases for the relief of mild crowding.
• Maxillary IM width maybe increased by 2-3mm

Question 11

• What does the evidence generally suggest is the amount that the intermolar width can be increased by and still remain stable ?

Answer 11

2-3mm

Question 12

• List the 5 techniques that can be used for maxillary expansion ?

Answer 12

1. Removable appliances
2. QHX
3. RME
4. FA ( AW’s, Auxillary AW’s and Cross Elastics)
5. Surgical methods ( SARPE, Segmental Le Fort 1 osteotomy).

Question 13

• Removable Appliances

Answer 13

URA + Midline expansion Screw:

Expansion produced maily thro tipping of molar teeth buccally

V. small amount of expansion by separation of midpalatal suture ONLY IN PREPUBERTAL children.

Symmetrical expansion= baseplate in half, equal no of anchor molars on either side of midline.

Asymmetric expansion- sectioning baseplate so that more teeth are in contact with it on the non expansion side.

PT INSTRUCTED TO:

Turn screw 1x/week ( QUARTER TURN).

RATE OF EXPANSION MONITORED BY:

Measuring dital bw 2 dimples in acrylic on either sid eof the baseplate.

Intermolar width with callipers

FOLLOWING EXPANSION:

Appliance kept in for 3/12 retention

ADVANTAGE:

Allows good hygiene- can be taken out

DISADVANTAGE:

Rely on pt compliance.

ADDITIONAL NOTE:

The appliance with apply RELATIVELY large forces when the screw is turned . This will disiipitate rapidly and the OB with reduce as the palatal cusps of the MX Incs drop down as the molars are TIPPED BUCCALLY.

Question 14

• Quadhelix Appliance

Answer 14

• Incorporates 4 helices - INCREASES FLEXIBILTY AND RANGE.
• Maybe prefabricated or laboratory constructed.
• Typically made from SS

MODE OF ACTION:

• Combination of:
  
  • Buccal tipping
  • Skeletal expansion
• AT A RATIO OF 6:1 IN PREPUBERTAL CHILDREN.

Question 15

ADVANTAGES AND DISADVANTAGES OF QHX:

Answer 15

ADVANTAGES:

• Good retetnion
• Non compliance
• LARGE RANGE
• Orthopaedic effect
• Differential expansion
• Habit breaker
• Incorporate FA
• Molar rotation and torque
• Cost effective

DISADVANTAGE:

• Molar tipping
• Bite opening
• Limited skeletal change

Question 16

• Clinical management of QHX ?

Answer 16

• The desirable force= 400g
• Appox 8mm activation ie appo 1 molar width
• RV every 6/52
• Warn patient may leave imprinton tongue
• Expansion should continue until paltal cusps of upper molars are in contact with buccal cusps of lower molars.
• 3/12 Retention period
• If FA used can be removed once in rectangular wire.

Question 17

• Rapid Maxillary Expansion ?

Answer 17

Aim of ths technique is to improve the ratio of

• SK:Dental Movement:
  
  • ​By producing SUTURAL EXPANSION @ MIDPALATAL SUTURE (MPS)
• Achieved by using :
  
  • Rigid wire- limit amount of tipping
  • Expand MPS rapidlyusing High forces- limit the time for dental movement
  • Carry out RX DURING or BEFORE PUBERTAL GROWTH SPURT.
    *

Question 18

• INDICATIONS / CONTRAINDICATIONS FOR RME

Answer 18

GENERAL RULE:

• RME indicated in cases where greater than or equal to 4mm of expansion is needed
• Where maxillary molars are already buccally inclined - to compensate for transverse skeletal discrepancy.

CONTRAINDICATION:

• Pt passed growth spurt
• Recession on buccal aspects of molars
• Poor compliance

Question 19

• Main short tern effects of RME ?

Answer 19

• MAXILLA:
  
  • Expansion MPS
  • DWD & FWD Maxillary movement
• MAXILLARY DENTITION:
  
  • Midline diastema Upper centrals
  • Buccal molar tipped AND Extrusion
• MANDIBLE:
  
  • Downward and backward rotation leading to reduction in OB and Increase Face height.
• NOSE:
  
  • Widneing alar base width reduced resistnace airflow nasal.
  • Nasal deformity of used in very young

Question 20

Wertz: What percentage of expansion with an RME can be attributed to skeletal changes?

Answer 20

Appox 40 %

Question 21

What is the ratio bw anterior and posterior skeletal expansion with an RME ?

Answer 21

ANT: POST

2:1

POSTERIOR EXPANSION IS LESS CF TO ANTERIOR EXPANSION BECAUSE OF THE BUTRESSING EFFECT OF THE ZYGOMA AND THE PTERYGOID PLATES AGAINST THE MAXILLA.

Question 22

• Clinical management of RME

Answer 22

1. Warn re midline diastema- tends to resolve spontaneously in the retention phase.
2. Turn screw 1/4 2x’s/ day
3. Minor discimfort
4. Activation key- floss or handle- avoid inhalatation /swallowing.
5. USO appox 1/52 to assess separation of MPS- if no evidence stop to avoid alveolar fracture or periodontal damage.
6. Activation usually 2-3/52
7. Retention 3/12- to allow for bony infil of MPS.
8. Wire ligature arounf screw during the retention period.

Question 23

• Expansion with AW’s

Answer 23

• Using overexpansed SS AW’s ~ 10mm
• Use large dimension AW eg 0.021 x 0.025 “ ss
• aDV- LESSS BUCCAL TIPPING OF MOLARS AS RECTANGULAR WIRE TORQUES.

Question 24

• AUXILLARY ARCHES

Answer 24

• Expansion arches AKA JOCKEY ARCHES- These are auxillary wires easily/cheaply constructed chairside and incorporated into FA.
• Can be also used to maintain arch width after RME.
• The expansion arch - made from 19 x 25 SS or a large round wire SS with a diamension 1-1.3mm
• Runs over the main AW inserted into the EOT tubes in the molar bands and secured anteriorly with a ligature.
• ADV: Cheap, easily, chairside , dont need change molar bands.
• EXPANSION LLIKELY TO BE PRODUCED BY A DEGREE OF MOLAR TIPPING- MAYBE REDUCED BY INTRODUCING MOLAR BUCCAL ROOT TORQUE INTO THE MAIN RECTANGULAR AW.

Question 25

* CROSS ELASTICS

Answer 25

* Run from palatal aspect of one or more Maxillary teeth to buccal aspect of one or more mandiular teeth. * In addition to lateral forces EXTRUSIVE FORCE alse generated- detrimental in patients WITH A REDUCED OB ( INCREASED LAFH). * To limit degree of molar tipping, cross elastics should only be used in conjunction with rectangular SS AW. * Success - dependent on good compliance.

Question 26

* SURGICAL TECHNIQUES: * Skeletally mature patients * Significant transverse discrepancy 1. SARPE 2. Segmental Maxillary Sx *

Answer 26

* SARPE: * Main resistance to maxillary skeletal expansion comes from zygomatic butress and pterygoid plates * Surgically severed- allows expansion to be achieved using conventional RME. * FA can be used to move apart the roots of the central incisors before surgery so roots arent damaged by midline maxillary cuts. * Expansion typically at rateof 0.5mm/day * High relapse rate * SARPE choice if patient doesnt have vertically maxillary discrepancy wthout saggital discrepancy * SEGMENTAL MAXILLARY SURGERY: * Le Fort 1 and additional cut along the MPS * Maxillary halves separated and retained in new position] * Choice if patient has coexisting saggittal and or vertical maxillary discrepancy.