Functional appliances

Question 1

what are functional appliances?

Answer 1

Variety of appliances which alter the sagittal
and vertical position of the mandible (when
worn by the patient)
 This repositioning generates muscular forces
which result in orthodontic and possible
orthopaedic changes

Question 2

What are the main functional appliances?

Answer 2

Clarktwin block
Andresen activator

Question 3

Classification of functional appliances?

Answer 3

Fixed functional appliances
Removable functional appliances

Question 4

Fixed functionals?

Answer 4

Fixed twin block
Herbst appliance

Question 5

How does a Herbst appliance work?

Answer 5

 piston mechanism each side
 attached to fixed appliance
 +
◦ less cooperation required
◦ more effective??
◦ use simultaneously with FA
 -
◦ complex design
◦ time consuming to fit
◦ more frequent breakages

Question 6

What are the removable functionals?

Answer 6

 Twin Block (Clark)*
 Andresen activator (Andresen)
 MOA
 Bionator (Balters)
 Dynamax (Bass)
 Functional regulator (Frankel)*

Question 7

Theoretical advantages of functional appliances

Answer 7

improve facial aesthetics
 correct dental relationship
 reduce the need for extractions
 reduce the time needed for fixed appliance
therapy
 reduce chairside time
 reduce incidence of trauma
 reduce need for headgear
 removable – facilitates plaque control

Question 8

Proven advantages
of functional appliances

Answer 8

do produce a clinically significant correction in
the A-P dental relationship
 do provide efficient anchorage reinforcement
prior to functional appliance treatment
 allows for full time wear – thereby more effective than headgear at correcting molar relationship
 can be used during mixed dentition phase
 can attach auxiliaries / expand upper arch etc

Question 9

Disadvantages of functional appliances

Answer 9

 cannot produce detailed tooth movement
 do not produce a clinically significant effect on
skeletal bases
 can cause excessive proclination of lower
incisors
 may cause anterior open bite in patients with increased lower anterior face height / minimal overbite
 demand high level of patient cooperation

Question 10

Advantages of clark twin block vs other functionals

Answer 10

 well tolerated (2 piece design)
 full-time wear possible
 eating possible (in theory)
 versatile appliance
◦ eg. elastics / sectional FA
 expansion of upper arch possible
 can add headgear
 can add fixed appliance
 possible to secure clark twin block to functional appliance

Question 11

Example of what clark twin block does

Answer 11

Carries elastic traction to canine

Question 12

How to functional appliances work

Answer 12

The subject of varying opinion,
but forces arising from the facial soft tissues are
undoubtedly the source of the main tooth
movements.

Question 13

Mode of action

Answer 13

 Orthodontic effect…..dentoalveolar

 Orthopaedic effect…..? jaw growth

Question 14

Mode of action orthodontic effect? upper and lower arch

Answer 14

 Upper arch
◦ retroclination of upper incisors
◦ distal movement of upper molars
 Lower arch
◦ mesial movement of lower teeth, including lower
incisors
◦ vertical movement of lower posterior teeth

this allows class I occlusion to be achieved

Question 15

Mode of action- orthopaedic changes

Answer 15

 Controversial

 maxilla
◦ 1-2mm of long term restriction in growth possible
◦ may more long lasting than mandibular change
 mandible
◦ 1-2mm of extra short term growth possible
◦ evidence for long-term gain is limited

Question 16

what patients are suitable?

Answer 16

Mild, uncrowded Class II with well aligned teeth
◦ uncommon in Western Europe
 As first phase in more severe Class II’s, with
second phase of functional appliance
 Anchorage reinforcement in Class II cases
◦ prior to functional appliance Tx
 Interceptive treatment
◦ early Tx to reduce very large overjet
◦ questionable use in certain countries (stiff private
competition)

Question 17

limitations and contraindications*

Answer 17

 poor cooperation*
 non-growing PTs*
 high angle cases*
 timing of treatment
 individual tooth movements…difficult
 variability of response

Question 18

Timing of treatment

Answer 18

 dental factors
◦ erupted permanent teeth
◦ trauma risk
 psychological factors
 growth
◦ difficult to predict
◦ may not make much difference in any case

Question 19

timing of treatment- growth

Answer 19

 Age
 Height
 Hand-wrist radiographs
 Hormone levels
 Secondary sex characteristics

Question 20

Timing of treatment- dental factors

Answer 20

 can start functional treatment in mixed dentition
phase
◦ await eruption of 1st premolars
 time start of functional phase to allow progression
straight into functional appliances
◦ avoid temptation to start functional Tx too early
◦ avoid significant pause between 2 stages
 aim in general to start functional treatment at
11/12 years of age

Question 21

Stages for a functional appliance
(CTB )

Answer 21

 Assessment
 treatment planning
 consent
 Imps & bite / laboratory prescription
 Fit appliance
 take baseline measurements
 Review visits
 review measurements
 Retention
 night time wear
 plan fixed appliances

Question 22

Bite registration for functional
appliance (CTB )

Answer 22

 Estimate amount of sagittal advancement of
mandible needed
 As rule of thumb this is edge to edge
 Ensure dental centrelines are coincident
 Select and try in ProJet jig
 Colour coded
 Insert with single slot to lower
 Demonstrate to patient
 Soften wax into horseshoe shape
 Wax bite should be 2-3mm thicker than planned vertical
opening
 Carefully apply to ProJet jig
 The softened wax bite and jig are placed against
the upper teeth
 Patient is asked to bite into desired position
 Ask patient to hold face mirror while recording bite
 Wax bite removed from the mouth
 Allow wax bite to cool / cool under running water
 The cooled wax bite is tried in again
 Critical to ensure accurate fit against upper & lower teeth
 If necessary soften and carefully any errors
 Consider retaking if not correct

Question 23

Prescription
- design appliance- upper and lower

Answer 23

upper
◦ clasp 4s and 6s
◦ split baseplate and screw
◦ labial bow?
◦ acrylic blocks
lower
◦ lower incisor capping or ball clasps
◦ clasp lower 4s +/- 6s
◦ acrylic blocks

Question 24

Review visits

Answer 24

 asses cooperation
◦ speech
◦ handling / ease swallowing / hypersalivation
◦ parent
 measure overjet
 record molar relationship
 adjust clasps as necessary
 check / start expansion
 update patient / parent on progress
◦ SMs

Question 25

Advice to patients?

Answer 25

 parent present
 full-time wear essential
 remove appliance for
 eating / cleaning / rough sports / swimming
 use box
 TLC
 OHI
 appliance and dentition
 written instructions
 to back up verbal instructions

Question 26

What is important about retention?

Answer 26

 to assess stability
 over-correct
 night-time wear
 review closely
 explain rational carefully to PT and parent

Question 27

most of the growth in children is

Answer 27

dentoalveolar

there is inc mandibular growth in some children and perhaps reduced maxillary growth

Question 28

functional appliance treatment integrated with fixed appliance treatment is classically used to treat

Answer 28

class II/i cases