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Undercut desirable for wrought wire clasp:

 # Undercut desirable for wrought wire clasp:
A. 0.02 inches with clasp length 8 mm
B. 0.01 inches with clasp length 8 mm
C. 0.02 inches with clasp length 5 mm
D. 0.01 inches with clasp length 5 mm



The correct answer is A. 0.02 inches with clasp length 8 mm.

• Undercuts on the master cast may be measured with an undercut gauge, such as those provided with the Ney and Jelenko surveyors. 
• The amount of undercut is measured in hundredths of an inch, with the gauges allowing measurements up to 0.03inch. Theoretically the amount of undercut used may vary with the clasp to be used up to a full 0.03 inch. However, undercuts of 0.01 inch are often adequate for retention by cast retainers.
• Tapered wrought-wire retention may safely use up to 0.02 inch without inducing undesirable torque on the abutment tooth, provided the wire retentive arm is long enough (at least 8mm). 
• The use of 0.03inch is rarely, if ever, justified with any clasp. When greater retention is required, such as when abutment teeth remain on only one side of the arch, multiple abutments should be used rather than increasing the retention on any one tooth. 


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