MANAGEMENT OF TRANSVERSE MAXILLARY DEFICIENCY Flashcards
- What age is the growth of the midpalatal normally completed by ?
- 17 years of age
- What is the mean transverse growth of the maxilla between the ages of 4 yrs and adulthood ?
- 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.
- List 6 indications for maxillary expansion
- XBITE
- Distal molar movement
- Functional appliance RX
- Surgical cases ( arch co-ordination)
- To aid Maxillary protraction
- Mild crowding
- CROSSBITES
- Maxillary expansion may help eliminate a Mandibular displacement that is associated with a xbite.
- Manxillary expansion may also help to create space for the relief of minimal crowding.
- 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.
- Distal Molar Movement
- 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:
- Slight expansion of the inner bow -KLOEHN BOW
- URA with midpalatal expansion screw in conjunction of HG.
- FUNCTIONAL APPLIANCE TREATMENT
- 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.
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- Ways to increase IM width during funcitonal appliance RX ?
- 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).
- Surgical Cases
- 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.
- Maxillary protraction
- 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.
- Mild Crowding
- Maxillary expansion maybe used in carefully selected cases for the relief of mild crowding.
- Maxillary IM width maybe increased by 2-3mm
- What does the evidence generally suggest is the amount that the intermolar width can be increased by and still remain stable ?
2-3mm
- List the 5 techniques that can be used for maxillary expansion ?
- Removable appliances
- QHX
- RME
- FA ( AW’s, Auxillary AW’s and Cross Elastics)
- Surgical methods ( SARPE, Segmental Le Fort 1 osteotomy).
- Removable Appliances
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.
- Quadhelix Appliance
- 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.
ADVANTAGES AND DISADVANTAGES OF QHX:
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
