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.
2
Q
Which soft tissue generate forces?
A
- Muscle of mastication
- facial muscles
- Oro facial
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
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
5
Q
Functional Appliance Aim
A
- Correction of OJ
- Correction of buccal segment , anterior posterior and Transverse relationship
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)
7
Q
How can you convert class 2/2 to Class 2/1
A
- URA z spring Upper 2s’
- Sectional upper fixed appliance
8
Q
How do Functional appliances work?
A
- Dento alveolar change
- Skeletal change
- Soft tissue change
9
Q
Dentoalveolar change
A
70%
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
11
Q
Soft tissues
A
- Soft tissue stretch produced forces
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
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
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
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.
16
Q
OJ and Risk of trauma ?
A
-Overjet greater than 9mm double risk of trauma
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.
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.
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)
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
21
Q
Example of Functional appliances (Removable)
A
- Twin block
- Anderson activator ( It’s loose/ mono bloc)
- Bionator
- Functional regulator (Frankel)
- Harvold
- Dynamax
22
Q
Example of Functional appliance (Fixed)
A
- Fixed twin block -
- Herbst
- Advan Sync
23
Q
Class 3 Functional
A
- Only Two types of Functional appliance
1- FRANKEL’s Functional Regulator 3
2- Class 3 twin blocks
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
25
Harvold Activator
- It has Increased bite opening of 1cm
26
Functional regulator appliance (Rolf Frankel)
- 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.
27
Functional regulator 2
- Single piece construction
- No retentive component
- Useful in mixed dentition
- Not well tolerated
28
Bionator
- Single piece
- Reverse labial bow
- mıxed dentition
29
Dynamax
- Upper removable appliance with fixed lower lingual arch
- no need to postured bite
- less vertical opening
- spur from upper interlock with lower arch
30
Read fixed twin block
- Small
- Less effect on speech
- Fixed appliance but lower premolar bands are potential weak point, increased chance of breakages
31
HEBRST - Fixed Funtional appliance
- Adv - decrease Overjet in 6 months rather than 9month on average. Less patient compliance
Disadv - breakage , expensive
32
Advan sync - Fixed Functional appliances
- 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
CLARK TWIN BLOCK Advantages
- 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
William Clark - Twin Block
Disadvantage
- Retention of lower part of functional appliance can be tricky - less undercut for cribs
35
What is key to success rate of functional appliance?
- Encouragement at every visits
36
Problem with Twin block type appliances? Specially in young children
- 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
Factors which reduce problem?
- 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
Success rate in prospective of RCT( randomised controlled trial) with TB?
- 83% favourable mand growth in functions group
- 31% favourable mand growth in control group
39
Failure rate in older patient?
34%
40
Failure rate in younger patient ?
19%
41
Ideally functional appliance therapy to patient with?
- 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
Use of WILLIAM CLARK functional appliance in uk?
- 75% of Clark's TB
-Clark's twin block associated with compliance
43
How many % Orthodontist use CTB to treat CLASS 2/1 ?
99%
44
How many Ortho use CTB for CLASS 2/2?
- 63%
45
What % of ortho use CTB for class 3?
16%
46
Compliance problem can be resolve if?
- Comparison 3x better before age of 12.3 yrs old
- As 34% older pt failure and 19% younger pt failure
47
How to take bite for CTB?
- 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
Taking posture bite what can we use?
- Project bite forks
49
Taking postured bite what should we look for?
- Dental centre lines .
They should be same relationship in protrusion and ICP.
50
Common CTB design?
- 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
Problems with Functional appliance?
- 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
Functional appliance construction?
- working model is Mounted on plane articulator using protrude bite.
53
Fit appointment?
- 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
Instructions for TB?
- 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
How can you tell patient wearing appliance? Patient compliance present?
- 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
What measurements can you take?
- Over jet
- Molar relationship
- Reverse Overjet
Compare it with orignal measurements
57
When is functional phase complete?
- 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
Causes of return of Overjet?
-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
Managing the transition from functional to fixed appliance
Reason?
- 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
Managing the transition from functional to fixed appliance?
Solution for lateral open bite?
- 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
Why Extractions Post functional Phase?
- 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
Why orthodontist take lateral ceph after functional phase?
- Orthodontist often takes lateral Ceph following functional phase to asses amount of proclination compared with start of Lateral Ceoh.
63
Contradictions for Functional appliance?
- Non growing patient
- High angle cases with backward mand growth rotation
-AOB
-cases with lower proclined incisors. Further proclination minimised incisor capping
64
Wear timing - of TWIN block, Herbst, Frankel
FULLTIME
65
Wear time of Andresen, Harvold Bionator
- 12-14hrs
66
Why Lateral open bite develope?
- Overjet reduction happens far more quickly than bite opening. This can be worsened by extrusion of upper incisors that accompanies their retroclination.
67
Solution of lateral open bite?
- 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
Extraction after TB phase
- 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
Class 3 functional appliances?
- There are only 2 types
- Fr3 Frankel function Regulator 3
- Class 3 twin block
70
How does functional appliance work?
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
