Functional appliances

Question 1

What are they?

Answer 1

a specialist type of removable appliance made of acrylic + stainless steel components + worn in both arches at the same time, the most common being a ‘twin block’

Question 2

Used for?

Answer 2

correct skeletal class II where mandible is further back from ideal position, + work by holding mandible forwards in ideal class I + allowing mandibular growth to correct malocclusion naturally.

Question 3

As their success is dependent on mandibular growth:

Answer 3

can only be used while pt is still growing but after premolars have erupted (used for retention of appliance) so ideal age is up to 14.

Question 4

The materials, instruments + advice

Answer 4

are as for removable ortho appliances

Question 5

The wearing of any ortho appliance

Answer 5

demands high degree of motivation + cooperation from pts. their diet has to be restricted to minimise risk of caries developing + is more likely to happen with prolonged COT

Question 6

Cooperation + motivation need to be assessed at each adjustment appt + reinforced. Warning signs include:

Answer 6

failed appts, recurrent breakages, continual reporting of problems which cannot be detected by dentist resulting in non wear, falling standards of OH (evidence of carious damage), obvious disinterest, requests of early removal + failure to wear during day showing little improvement

Question 7

Any combination of these signs

Answer 7

should alert OH team that trt may fail, so cooperation reinforced + decision taken to abandon trt.
A system of discontinuation of trt must be in place so pts aware that non compliance means early removal + malocclusion may remain.

Question 8

If pt persistently fails to wear or attend appts

Answer 8

trt is best discontinued at an early stage before too much surgery time has been wasted.
Pts who have discontinued trt once + then re-present for continuation should be treated with caution, as likelihood of second failure is greater still.