Biomaterials Lecture 4

Question 1

• What are waxes? And what are they derived from?

Answer 1

• Thermoplasmic materials with a hydrocarbon structure

* Derived from mineral, plant, and animal sources

Question 2

• What is used for the base of all dental waxes? Where is it from?

Answer 2

• Paraffin (sometimes Ceresin) from mineral source

Question 3

• What is added to dental wax to increase the melting temperature and make it harder and tougher.

Answer 3

• Carnauba

Question 4

What is an undesirable property of ALL dental waxes?

Answer 4

• High CTE (Thermal expansion coefficient) low melting point

* (200-600ppm/C)

Question 5

• Three basic classes of dental waxes

Answer 5

• Pattern, Impression, Processing

Question 6

• What is a necessary characteristic of all casting and inlay waxes and why?

Answer 6

• Pyrolysis because it leaves no residues in the investment

Question 7

• What is the correlation between a wax having a higher molecular weight and its physical characteristics?

Answer 7

• Higher density and higher melting temperature

Question 8

• How does the molecular weight effect the CTE (thermal expansion coefficient)?

Answer 8

• Has no effect on it

Question 9

• Why are colorants used?

Answer 9

• Used so that margins can be seen clearly when adjusting wax