Waxes Tutorial

Which of the following is true of residual stress?

• Is developed in wax when it is cooled under stress

• Results in a uniform dimensional change that can be compensated for in the casting process

• Can be minimized by the manipulation of a wax at a temperature as high as is practical

• Can cause warpage that increases at higher storage temperatures and during longer storage times

A pattern wax might be used to do which of the following?

• Make a corrective impression

• Form a mold around an impression

• Form the general size and contour of a restoration

Casting waxes possess useful properties, such as which of the following?

• Tackiness

• No residue other than carbon

• Minimum values of flow at mouth temperaturemperature

• Specified values of coefficient of thermal expansion

Which of the following statements are true?

• Boxing wax is used for forming a mold around an impression before a gypsum cast is poured

• Utility wax must stick to itself

• Utility wax is used to prevent sad and distortion of alginate impression

• Sticky wax is used to assemble metallic or resin pieces in a fixed temporary position and is brittle at room temperature

Which of the following statements apply to bite-registration waxes?

• They are used to articulate models of opposing quadrants accurately.

• Formulations are made from carnauba wax.

• The flow of these waxes at 37^O C if from 5% to 80%.

• These waxes may distort when removed from the mouth.

You are treating a patient on a hot day, and the office temperature is significantly higher than normal. You notice that when you use a wax bite record to mount cast on your articulator, the occlusal relationship is not correct. Which properties of wax were most likely to be responsible for this problem?

Answer explanation

Flow and residual stress

Described the techniques that can be used to limit the problems of residual-stress incorporation in wax?

Answer explanation

Carve at warm temperature

Add wax in small increments

Redo critical areas if time passes

Avoid elevated temperatures

Flow of dental wax increases as the temperature increases.

• True

• False

As wax is heated, a significant expansion occurs, but upon cooling, contraction occurs reversibly.

• True

• False

Warm temperatures and long storage times increase the possibility of release of residual stress in wax patterns.

• True

• False