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Orthodontics > Functional Appliance > Flashcards

Functional Appliance Flashcards

1
Q

What is Functional appliance? Myofunctional appliance

A
  • A functional appliance achieves its effect through forces arising from the masticatory and facial muscles
  • This is different to other appliances which achieve their effect through forces within appliance e.g wires, elastics, or screw
  • They are constructed to posture the mandible forward and away from rest position. As a resultant soft tissue stretch generate forces that causes tooth movement.
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2
Q

Which soft tissue generate forces?

A
  • Muscle of mastication
  • facial muscles
  • Oro facial
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3
Q

Classification of functional appliances.

A
  • Myodynamic e.g Andresen - medium mandibular opening <5mm work by stimulating muscle stretch- Bionator appliance or twin block (simulation of Masticatory muscle ).
  • Myotonic e.g. Harvold - Large mandibular opening 8-10mm work by passive muscle stretch.

At some degree this classification cross over that why is not used very often

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4
Q

In which malocclusion are they used?

A
  • Functional appliances are designed to change the anterior- posterior relationship of the upper and lower arches
  • They are most commonly used to correct Class 2 malocclusions ( class 2/1 or class2/2)
  • There are functional appliances designed to correct class 3 malocclusion but they are not used very often
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5
Q

Functional Appliance Aim

A
  • Correction of OJ
  • Correction of buccal segment , anterior posterior and Transverse relationship
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6
Q

Functional appliance
Indications

A
  • growing pt - utilise growth potential
  • Motivated patient
  • Classic case
  • Uncrowded class 2 div 1 mild / moderate SK class 2 base ( no need of Fixed appliances
  • Moderate / severe SK CL 2 with normal MMPA
  • CLASS 2/2 cases once converted CL 2/1
  • CL 3 cases (rarely)
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7
Q

How can you convert class 2/2 to Class 2/1

A
  • URA z spring Upper 2s’
  • Sectional upper fixed appliance
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8
Q

How do Functional appliances work?

A
  • Dento alveolar change
  • Skeletal change
  • Soft tissue change
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9
Q

Dentoalveolar change

A

70%

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10
Q

Skeletal (growth) change

A
  • 30%
  • Mandibular growth enhanced 1-2 mm
  • Maxillary growth inhibit 1mm.

There is wide range of skeletal response. This could be account for some of our cases going particularly well and other struggling for class 2 correction

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11
Q

Soft tissues

A
  • Soft tissue stretch produced forces
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12
Q

What’s best time for Functional appliance?

A
  • Optimum during pubertal growth spurt
    Girls 10-12years , Boys: 12-14 years. +/- 2 years
  • When eruption of permanent teeth allows
  • Psychological development
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13
Q

What Dentoalveolar effects with Functional appliance?

A
  • Upper incisors retroclined
  • Lower incisors proclined
  • Upper premolar and molar distal movement
  • Lower premolar/ molar mesial movement
  • bilateral open bite
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14
Q

Functional appliance - Mode of action

A
  • It is appliance posturing mandible forward , causing soft tissue stretch , Force created by soft tissue stretch result Dentoalveolar and sk change
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15
Q

Why do we wait for Best time factors for functional appliance?

A
  • Since we want to move permanent teeth best time to start in relation to dental development is when Permanent teeth have erupted specially with Fixed appliance to follow
  • If we start early, longer tx waiting for permanent teeth to erupt
  • Can be difficult with deciduous teeth are being shed due to appliance retention, discomfort or complaince
  • A potential advantage of early start increase risk of trauma and bullying.
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16
Q

OJ and Risk of trauma ?

A

-Overjet greater than 9mm double risk of trauma

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17
Q

Why wait for peak puberty growth spurt?

A
  • Jaws may grow 2-5 mm more per year but it’s hard to predict individual growth.
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18
Q

How can we check Growth?

A
  • Asking parents about change in shoe size.
  • Regular height measurement - prediction can still be incorrect in 33% cases (Sullivan 1983)
  • Cervical spine maturity- can be accurately recorded once puberty spurt is in full swing.
  • Hand wrist radiograph - not ethical - no longer used.
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19
Q

Timing of treatment- Psychological factor

A
  • Best age for when pt has ability for compliance
  • same operator with same appliance decrease risk of failure to finish :Study by OBrien 2003
  • Also reported on psycho- social effects of early twin block treatment and found significant benefit from tx in terms of increased self confidence (bullying)
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20
Q

Timing of tx

A
  • Skeletal response seems to be marginally related to growth , so we usually wait for Permanent dentition or mixed dentition.
  • Starting earlier tx can be helpful for trauma Class 2 Sk discrepancies but it can also have drawbacks back long tx , loss of pt motivation , slower growth
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21
Q

Example of Functional appliances (Removable)

A
  • Twin block
  • Anderson activator ( It’s loose/ mono bloc)
  • Bionator
  • Functional regulator (Frankel)
  • Harvold
  • Dynamax
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22
Q

Example of Functional appliance (Fixed)

A
  • Fixed twin block -
  • Herbst
  • Advan Sync
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23
Q

Class 3 Functional

A
  • Only Two types of Functional appliance

1- FRANKEL’s Functional Regulator 3
2- Class 3 twin blocks

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24
Q

Anderson Activator

A
  • Monobloc appliance (single block of acrylic)
  • Mandible postured forward and upward to seat appliance
  • It is loose fit and patient must bite together to keep it in place
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25
Q

Harvold Activator

A
  • It has Increased bite opening of 1cm
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26
Q

Functional regulator appliance (Rolf Frankel)

A
  • Rolf Frankel
  • Acrylic shield holds cheeks and lips away from teeth and aim to stretch the Periosteum to cause tooth movement and develop bone growth.
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27
Q

Functional regulator 2

A
  • Single piece construction
  • No retentive component
  • Useful in mixed dentition
  • Not well tolerated
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28
Q

Bionator

A
  • Single piece
  • Reverse labial bow
  • mıxed dentition
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29
Q

Dynamax

A
  • Upper removable appliance with fixed lower lingual arch
  • no need to postured bite
  • less vertical opening
  • spur from upper interlock with lower arch
30
Q

Read fixed twin block

A
  • Small
  • Less effect on speech
  • Fixed appliance but lower premolar bands are potential weak point, increased chance of breakages
31
Q

HEBRST - Fixed Funtional appliance

A
  • Adv - decrease Overjet in 6 months rather than 9month on average. Less patient compliance

Disadv - breakage , expensive

32
Q

Advan sync - Fixed Functional appliances

A
  • Adv - no lab work required , can use fixed appliance at same time, less pt compliance ,

Dis adv: Expansion not possible , expensive, breakage chance higher (yawning)

33
Q

CLARK TWIN BLOCK Advantages

A
  • William Clark described
  • Relatively well tolerated by pt
  • Robust and easy to repair
  • Fairly easy to advance - add acrylic button
  • Compensatory expansion is easy- midline screw
  • Suitable for mixed / permanent dentition
  • Most commonly prescribed functional appliance in uk
34
Q

William Clark - Twin Block
Disadvantage

A
  • Retention of lower part of functional appliance can be tricky - less undercut for cribs
35
Q

What is key to success rate of functional appliance?

A
  • Encouragement at every visits
36
Q

Problem with Twin block type appliances? Specially in young children

A
  • Retention of lower part of functional appliance as it has less under cuts for cribs to hug compared to upper arch (specially in young age group)
37
Q

Factors which reduce problem?

A
  • Cribs on 4s and 6s. Wait until these teeth are there.
  • Avoid treating in presence of multiple loose deciduous teeth- wait little or remove them.
  • Excellent impression and technician
  • short internal between impression and fit
  • Lower incisor capping / ball ended incisor clasps aids retention and stability of
38
Q

Success rate in prospective of RCT( randomised controlled trial) with TB?

A
  • 83% favourable mand growth in functions group
  • 31% favourable mand growth in control group
39
Q

Failure rate in older patient?

A

34%

40
Q

Failure rate in younger patient ?

A

19%

41
Q

Ideally functional appliance therapy to patient with?

A
  • Mild to moderate increased OJ upto 11mm
  • Increased OB
  • Active facial growth
  • Compliance
  • start at age of less than 12.3 significantly improves co operation.
42
Q

Use of WILLIAM CLARK functional appliance in uk?

A
  • 75% of Clark’s TB
    -Clark’s twin block associated with compliance
43
Q

How many % Orthodontist use CTB to treat CLASS 2/1 ?

A

99%

44
Q

How many Ortho use CTB for CLASS 2/2?

A
  • 63%
45
Q

What % of ortho use CTB for class 3?

A

16%

46
Q

Compliance problem can be resolve if?

A
  • Comparison 3x better before age of 12.3 yrs old
  • As 34% older pt failure and 19% younger pt failure
47
Q

How to take bite for CTB?

A
  • Take bite horizontally either edge to edge incisor relationship or at max -2 mm forward posture.
  • Take account the variation in patients ability to protrude mandible.
  • Blocks height advised 5mm for separation of buccal teeth.
  • Small height of block risk - Pt can avoid posturing
  • Taller height of Blocks risk- Intrude unnecessary pt freeway space, reduce comfort and ability to close lips.
48
Q

Taking posture bite what can we use?

A
  • Project bite forks
49
Q

Taking postured bite what should we look for?

A
  • Dental centre lines .
    They should be same relationship in protrusion and ICP.
50
Q

Common CTB design?

A
  • ACTIVE - Acrylic bite blocks - Inclined 70 degree midline screw for upper buccal segment expansion
  • RETENTIVE - Adam’s crib U6s 4s and L 6s’ and 4s’.
    Lower labial segment - Acrylic capping or ball clasps.
    Upper labial segment - Labial bow.
  • ANCHORAGE - acrylic base plate
  • BASE PLATE - acrylic with inclined bite blocks and midline split.
51
Q

Problems with Functional appliance?

A
  • compliance
  • More Proclined lower incisors and Retroclined upper incisors
  • lateral open bite created with TB and Harvold due to rapid correction
  • Frankel fragile - breakages
  • No detail finishing allowed
  • May require Phase 2 tx ( fixed appliance) - prolonged tx
  • Does not work in all pts - biological variabilities
  • Relapse
52
Q

Functional appliance construction?

A
  • working model is Mounted on plane articulator using protrude bite.
53
Q

Fit appointment?

A
  • Check correct appliance for patient and design prescribed
  • check fit upper and lower appliances.
  • Adjust retentive components are necessary.
  • Ensure patient can posture forward to engage the bite blocks relatively comfortably with suitable amount of vertical opening.
54
Q

Instructions for TB?

A
  • 22 hours a day
  • Remove when cleaning teeth and playing sports
  • Eat with it if you can. Dietary advise . Some patient can eat with it.
  • Clean it with soft tooth brush under tap water specially back of appliance when it sits.
  • Anti bacterial tablets use 2x a day.
  • keep in box when you take it out. Charges applies for replacement.
55
Q

How can you tell patient wearing appliance? Patient compliance present?

A
  • Is patient wearing it?
  • Are they confident to remove it.
  • No lisping and drooling. How’s their speech.
    -Does appliance look as if it has been worn regularly.
  • Do crib need adjusting to increase retention?
  • Is there an improvement in their occlusion.
56
Q

What measurements can you take?

A
  • Over jet
  • Molar relationship
  • Reverse Overjet

Compare it with orignal measurements

57
Q

When is functional phase complete?

A
  • Aim to over correct OJ to prevent relapse.
  • Cause of return to OJ include : uprighting tipped teeth. All upper teeth will frequently be distally angulated/ Retroclined relative to their starting angulation / inclination and the consequent uprighting with fixed appliances can result in relapse of Overjet.
  • A false condylar position. If the functional appliance has caused a temporary but undetected, anterior position of condyles, rebound of this effect will put additional demand on Anchorage at this stage.
  • Therefore we usually aim for 0-2mm final Overjet and molar relationship approaching no Class 3.
  • OJ 0-2mm
  • Molar relationship class 3.
58
Q

Causes of return of Overjet?

A

-We Aim to overcorrect it to protect from relapse

  • Uprighting of distally tipped teeth with fixed appliance
  • False condyler position - if TB caused temporary but undetected position of condyles, the rebound affect will put additional demand on Anchorage at this stage.
59
Q

Managing the transition from functional to fixed appliance
Reason?

A
  • During Twin block functional phase there is tendency for lateral open bites to develop.
  • The reason of this Overjet reduction happens far more quickly than bite opening. This can be worsened by extrusion of upper incisors that are accompanies their retroclination.
60
Q

Managing the transition from functional to fixed appliance?
Solution for lateral open bite?

A
  • Trimming / undermining blocks.
  • A period of nights only wear after overjet reduction - usually 3 months
  • When overjet reduced, place URA with very steep anterior bite plane to reduce overbite and hold mandible and lower incisor forward.
  • Subsequent fixed appliances
61
Q

Why Extractions Post functional Phase?

A
  • To limit amount of lower incisor Proclination . During functional appliance, lower incisor proclination occurs 4-8 degrees. If lower arch crowded and incisor proclined orthodontist consider extractions to prevent proclination during alignment phase of fixed braces for stability reason.
  • To maintain class 1 buccal segment relationship achieved during functional phase . Extractions in lower and upper arch . Most commonly second premolars.
62
Q

Why orthodontist take lateral ceph after functional phase?

A
  • Orthodontist often takes lateral Ceph following functional phase to asses amount of proclination compared with start of Lateral Ceoh.
63
Q

Contradictions for Functional appliance?

A
  • Non growing patient
  • High angle cases with backward mand growth rotation
    -AOB
    -cases with lower proclined incisors. Further proclination minimised incisor capping
64
Q

Wear timing - of TWIN block, Herbst, Frankel

A

FULLTIME

65
Q

Wear time of Andresen, Harvold Bionator

A
  • 12-14hrs
66
Q

Why Lateral open bite develope?

A
  • Overjet reduction happens far more quickly than bite opening. This can be worsened by extrusion of upper incisors that accompanies their retroclination.
67
Q

Solution of lateral open bite?

A
  • Trimming the blocks
  • Period of URA only wear after OJ reduction - usually 3months
  • when OJ reduced , URA places with bite plane for OB reduction and hold lower incisors forward.
  • Subsequent with fixed appliances
68
Q

Extraction after TB phase

A
  • For stability reason Orthodontist plan their treatment to limit amount of lower incisor Proclination.
  • Therefore if patient with lower arch crowding has already experienced lower proclination may consider extractions to prevent further proclination during the alignment phase of fixed appliances.
  • To maintain the Class 1 buccal segments relationship during TB phase achieved. This usually means extraction of upper and lower second premolar most common.
  • ORTHO often takes lateral Ceph following functional phase to assesses Proclination compared with start Ceph.
69
Q

Class 3 functional appliances?

A
  • There are only 2 types
  • Fr3 Frankel function Regulator 3
  • Class 3 twin block
70
Q

How does functional appliance work?

A

3 effects
- Dentoalveolar - 70% OJ reduction 60-% molar change
- Skeletal - 30% for final result but variable - 1-2mm mandible enhancement 1mm maxilla growth inhibit. (Depends on individual growth)
- Soft tissue - Stretch and produce force

Orthodontics (53 decks)

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