Setting teeth

Question 1

What is the aim when setting artificial teeth for partial dentures?

Answer 1

• aim is to have teeth set in a position that will complement the existing teeth, thus restoring the arch, aesthetics and function

Question 2

Is there a difference when setting teeth for a Co/Cr base or a PMMA base?

Answer 2

• no, although for Co/Cr bases the scheme for mechanical retention for the PMMA to metal base must be considered (post or mesh depending on available space)

Question 3

Why are teeth sometimes set so that they are not in perfect alignment?

Answer 3

• It can look more natural

Question 4

What are the 2 materials used for artificial teeth?

Answer 4

• Acrylic

- Porcelain

Question 5

What are the properties of plastic/acrylic teeth? (7 points)

Answer 5

• Chemical bond with the denture base
• Natural appearance and feel - silent in function
• Tough
• Soft-flow abrasion resistance
• Easily trimmed and polished/customised
• Cold flow under pressure
• Insoluble in mouth fluids - some dimensional change

Question 6

What are the properties of modified acrylic/composite/polymers? (3 points)

Answer 6

• Chemical bond with the denture base
• partial bonding - recommended mechanical and/or bonding agent (4-meta)
• Higher abrasion resistance

Question 7

What are the properties of porcelain teeth? (7 points)

Answer 7

• Mechanical attachment with the denture base (silane coupling agent)
• Natural appearance - possible noise function
• Brittle
• Friable - grinding removes surface glaze
• Hard-high resistance to abrasion
• Inert in mouth fluids - no dimensional change
• High heat distortion - no permanent deformation under forces of mastication

Question 8

What is important when choosing a shade for the teeth?

Answer 8

• Have to determine this on clinic under natural light

Question 9

What are the different general shapes of the teeth? (3 points)

Answer 9

• Square
• Ovoid
• Tapered

Question 10

What information can you get about the tooth from a tooth/mould chart? (4 points)

Answer 10

• Shape of tooth
• Length of anterior teeth
• Height of central incisor
• Width of central incisor

Question 11

How do acrylic teeth bond with the denture base?

Answer 11

• Chemical bond with the denture base

- Can also have hollowed areas

Question 12

How do porcelain artificial teeth bond with the denture base? (2 points)

Answer 12

• Mechanical bond with the denture base is provided by a metal retention pin incorporated within the tooth on anterior teeth
• Posterior teeth have a hollowed area that will fill with the denture base

Question 13

What is the first thing you want to establish when placing artificial teeth?

Answer 13

• Want to establish the midline

Question 14

What should be done to prevent teeth from de-bonding? (4 points)

Answer 14

• Try to avoid heavy contact on the denture teeth - cuspal interface
• No wax or grease
• No mould seal
• Add a drop of monomer onto before acrylic