Retention And Stability

Question 1

What malocclusions are more likely to relapse?

Answer 1

• spacing/
• rotations
• deep overbite
• arch form changes e.g expansion
• altered LLS position
• periodontal involved teeth

Question 2

What are the 3 divisions of relapse?

Answer 2

• physiological recovery - return to original malocclusion
• unfavourable growth
• ‘true relapse’ - due to treatment choices e.g. expanding lower inter canine width

Question 3

How long does it take for periodontal fibres to remodel?

Answer 3

1-2 months

Question 4

How long does it take for supra-crestal gingival fibres to remodel?

Answer 4

6 months

Question 5

How long does it take for free gingival fibres to remodel?

Answer 5

12 months

Question 6

How long does it take for osteoid bone to remodel?

Answer 6

3 months

Question 7

What are the advantages of vacuum formed retainers?

Answer 7

Good aesthetics
Cheap and easy to construct
Superior retention of lower incisors 
Preferred by patients
Less affect on speech

Question 8

What are the disadvantages of vacuum formed retainers?

Answer 8

Less effective at maintaining expansion
Less occlusal/posterior settling
Risk of decalcification/caries of worn when eating and drinking

Question 9

What are the advantages of hawley retainers?

Answer 9

Simple to construct
Robust 
Easy to add a Pontic tooth 
Can be worn when eating
Allows posterior settling
Rigid to maintain transverse corrections
Labial bow - simple incisor movements

Question 10

What are the disadvantages of hawley retainers?

Answer 10

Difficult to tolerate - in particular the lower
Expensive compared to VFR
Takes time to make
Effects speech more than VFR

Question 11

What are the advantages of fixed retainers?

Answer 11

Less demand for patient compliance

Discreet

Question 12

What are disadvantages of fixed retainers?

Answer 12

High failure rate
OH - difficult
Long term maintained
Patient may not know it is broken - risk of caries and tooth movement

Question 13

What specific problems are fixed retainers used for?

Answer 13

Rotations
Diastema 
Spacing 
Displaced teeth 
Periodontal issues

Question 14

What are vacuum formed retainers Made out of?

Answer 14

Polyvinyl chloride sheets

Question 15

What are relapse causes/factors?

Answer 15

• pro-facial soft tissues
• post treatment facial growth
• occlusion
• age related changes

Question 16

What is retention?

Answer 16

Holding of teeth following orthodontic treatment, in treated position for a period of time necessary for maintaining result

Question 17

What is relapse?

Answer 17

• the return, following correction, of the original features of malocclusion
• unfavourable changes, from the final tooth positions achieved at the end of orthodontic treatment

Question 18

How can relapse be minimised?

Answer 18

• consider extraction of rotated or displaced teeth
• maintain arch form and inter canine width
• minimal alteration of lower labial segment
• consider IPR

Question 19

What is dual retention?

Answer 19

Fixed retainers used with removable retainers

Question 20

What are the potential causes of late lower incisors crowding in an untreated patient?

Answer 20

• inter canine width reduces
• eruption of 3rd molars
• growth in lower jaw

Question 21

What is the stability of treating a patient with Bimaxillary proclination?

Answer 21

Variable
• retroclining the labial segment causes infringement on the tongue space
• space will want to re open if they were present pre treatment