Chrome

Question 1

What is the basic set up of a chrome denture?

Answer 1

• Chrome frame supports + provides scaffold
• Pink acrylic used to cover part of the chrome to form base
• Tooth coloured acrylic used to cover tooth part of chrome

Question 2

What are the advantages of chrome?

Answer 2

• Strong (thus can come thinner)
• Clasps have longer lifespan
• Harbours less plaque

Question 3

What are the disadvantages of chrome?

Answer 3

• Expensive
• Difficult to add teeth (restricted by the framework, e.g. clasps are cast onto metal frame and can’t move around, so can not add teeth to clasp areas. Also if framework does not extend to certain areas, teeth can not be added there. However, if there is an area of framework free and no clasps or rests, then it is just as easy as adding to acrylic)
• Conducts hot and cold

Question 4

What clasps are used for chrome dentures? How much undercut is required for retention?

Answer 4

• Chromium/cobalt

- 0.25mm undercut

Question 5

Can clasps in chrome dentures be adjusted?

Answer 5

-Yes, but not too often or will cause work hardening

Question 6

What are the different clasp designs available? What influences clasp selection? When are each one generally indicated?

Answer 6

Location of survey line influences clasp selection

• Circumferential clasp: Most common, provides good posterior retention
• Butterfly clasp: double circumferential for extra retention
• Ring clasp: Tilted teeth
• I-Bar: Hidden behind tooth (thus used for purposes such as distal clasp on anterior abutment in bounded saddles)
• L-clasp: I Bar clasp but with labial extension
• Reverse action: want circumferential but can’t find undercut so reverse to locate it

-T Clasp: Struggling to find undercuts (not often used)

Question 7

What are the requirements for an Lingual bar?

Answer 7

• Bar should be 3mm deep, 1.5mm thick
• Upper border 2mm below gingival margin
• Lower border 2mm above floor of mouth
• Thus total of 7mm space between gingival margin and floor of mouth required, otherwise use lingual plate

Question 8

What is the advantage of using a lingual plate over a lingual bar and vice versa?

Answer 8

Lingual plate: easier to add teeth to, does not require 7mm space but harbours more plaque

Lingual bar: more difficult to add teeth to (just don’t do it) and requires 7mm space, but harbours less plaque