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?

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Answer explanation

Flow and residual stress

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

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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