Vacuum Formed Retainers

Question 1

What is the rationale for maintaining teeth in their treated position?

Answer 1

Allow for reorganisation of gingival and periodontal tissues

• Minimise changes from growth
• Permit neuromuscular adaptation to the corrected position
• Maintain teeth in unstable positions (sometimes)

Question 2

What factors should be considered in choice of post treatment retainer?

Answer 2

• Pre-treatment situation
• End of treatment result
• Post treatment growth potential
• Oral hygiene
• Aesthetic requirements
• Patient compliance
• Ease of retainer fabrication
• Durability
• Cost Effectiveness

Question 3

What types of machines can be used to manufacture VFR’s?

Answer 3

• Pressure machine: “superior”, force heat softened plastic over end of treatment plaster mould using positive pressure
• Vacuum machine: adapt heat softened plastic to mould by negative pressure

Question 4

What are the two materials used for VFR’s?

Answer 4

• Essix type ‘A’ co-polyester: More aesthetic but tend to fracture more easily
• Essix type ‘C+’ polypropylene or ethylene co-polymer: More resilient but less retentive

Question 5

What is the most common extension of VFR margins?

Answer 5

1-2mm buccal and 3-4mm lingual to gingival margins

Question 6

How is a VFR retained?

Answer 6

Undercuts gingival to the contact points of the teeth

Question 7

How can a VFR be adjusted?

Answer 7

Increasing or reducing depth of undercuts by scissors or greenstone slow speed

Question 8

What can be used to clean a VFR? Why is toothpaste not recommended?

Answer 8

Toothpaste can dull appearance

Regular cleaning with soapy cotton tip swap and/or propriety cleaning agent is recommended

Question 9

What are some advantages of a VFR?

Answer 9

• Aesthetic
• Patient comfort and acceptability
• Speed, ease and low cost of manufacturing

Question 10

What are some disadvantages of a VFR?

Answer 10

• Compromised retention if hyperplastic gingiva, poor oral hygiene, or spaced dentition
• Loss, breakage, poor wear resistance (concern with bruxism)
• Possible inability to maintain expanded arch due to lack of rigidity
• Inhibits any desired vertical ‘settling in’ of occlusion subsequent to treatment
• Potential for demin and poor gingival health if detrimental dietary lifestyle (e.g. frequent soft/fizzy drink) while retainers worn
• Reliance of patient compliance as VFR removable

Question 11

Does the evidence suggest that there is significant difference between full time and part time wear of VFR’s?

Answer 11

No, although patient factors such as severe crowding may warant alternative wear protocol

Question 12

What is used to measure incisor regularity and also commonly used to assess relapse?

Answer 12

Little’s Irregularity Index

Question 13

What does the evidence suggest the effectiveness of a VFR is compared to a Hawley and Bonded Retainer?

Answer 13

• At least as effective as Hawley in maintaining post-treatment stability
• Less effective than BR at maintaining lower incisor alignment, but no significant difference in upper incisors

Question 14

What does the evidence suggest in terms of the problems related to a VFR is compared to a Hawley and Bonded Retainer?

Answer 14

• More problems in VFR compared to BR
• Less problems in VFR compared to Hawley
• VFR’s have no detrimental effect on dental and periodontal health and more cost effective than Hawley