during 3/4 crown preparation on premolar, bur used to add retentive grooves is:
- a. radial fissure.
- b. Tapered fissure.***
The correct answer is b. Tapered fissure.
A tapered fissure bur is the preferred instrument for adding retentive grooves in a 3/4 crown preparation on a premolar. It has a conical shape that allows for precise placement and creation of grooves that provide additional mechanical retention for the crown.
Here's why the other option is incorrect:
a. Radial fissure:
A radial fissure bur has a cylindrical shape with a rounded end. While it can be used for some crown preparations, it is not ideal for creating retentive grooves in premolars due to its lack of precision and potential for creating undercut areas.
Therefore, the tapered fissure bur is the optimal choice for adding retentive grooves in this specific scenario.
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