Orthodontics PCPC

Question 1

What are the goals of an orthodontic retainer?

Answer 1

1. Allow for reorganisation of gingival / periodontal tissues after ortho treatment
2. Minimise changes due to growth
3. Neuromuscular adaptation to new tooth position
4. Maintain teeth in unstable position

Question 2

What factors does a dentist need to consider when deciding which type of orthodontic retainer to prescribe to a patient?

Answer 2

Pre Treatment Scenario
Treatment Result
Post Treatment Growth Potential
Oral Hygiene
Aesthetic Requirements
Patient Compliance
Ease of retainer fabrication
Cost Effectiveness
Durability

Question 3

What are the 3 main types of orthodontic retainers?

Answer 3

1. Hawley Retainer: acrylic + stainless steel wire
2. Bonded Fixed Retainers (BRs)
3. Vacuum Formed Retainers (VFRs)

Question 4

What are the 2 main ways to fabricate vacuum formed retainers (VFRs)?

Answer 4

1. Pressure Machines: heat + positive pressure

2. Vacuum Machines: heat + negative pressure

Question 5

What are the 2 main VFR materials?

Answer 5

1. Essix Type A Co-Polyester: Aesthetic
   Fracture/Cracks easier
2. Essix Type B Polypropylene / Ethylene Co-Polymer: More Resilient, Less Retentive

Question 6

What coverage is typically done with a VFR?

Answer 6

1. Original Essix: 3-to-3 (Still Popular in USA)

2. Modern VRF: Full Occlusal Coverage

Question 7

How should VFRs be cleaned?

Answer 7

1. Avoid Toothpaste: dull plastic
2. Soapy Cotton Tip
3. Denture Cleaners

Question 8

What are advantages of VFRs?

Answer 8

Aesthetic Appearance
Patient Comfort / Acceptability
Speed, Ease and Low Cost of Fabrication

Question 9

What are disadvantages of VFRs?

Answer 9

Can’t use with Gingival Hyperplasia
Contraindication for poor oral hygiene
Loss / Breakage
Inability to maintain expanded arches - in severely unstable orthodontic positions
Demineralisation if sugar/fizzy drinks consumed with VFR in
Reliance on patient compliance

Question 10

According to Meade and Millett, what type of orthodontic retainer is the most effective in preserving orthodontic treatment?

Answer 10

Bonded Retainers have the lowest Irregularity Index

BR > VFR > Hawley

Question 11

According to Meade and Millett, what type of orthodontic retainer has the most patient complaints?

Answer 11

Hawley > VFR > BR

Question 12

According to Meade and Millett, what type of orthodontic retainer has the most breakages?

Answer 12

Hawley > VFR > BR

Question 13

According to Meade and Millett, what type of orthodontic retainer is the most cost effective?

Answer 13

VFR > Hawley

Question 14

Are VFRs adequate to maintain expanded maxillary arches?

Answer 14

No, a more robust material is needed