What is the minimum axial reduction required for a crown?

The minimum axial reduction required for a crown is generally accepted to be 1.5 mm. This amount of reduction is necessary to ensure adequate space for the crown material, which allows for sufficient thickness to provide strength, durability, and aesthetic appeal, particularly with all-ceramic and metal-ceramic restorations.

Insufficient axial reduction risks compromising the crown's structural integrity and could lead to issues such as fractures, wear, or a lack of proper adaptation to the tooth preparation. Additionally, proper reduction facilitates effective bonding and enhances the overall fit of the crown, which is essential for long-term success in restorative dentistry.

The other options either provide insufficient reduction or exceed the optimal amount required, which could unnecessarily remove more tooth structure, leading to potential sensitivity or other complications. Thus, 1.5 mm represents a balanced approach that maintains both tooth vitality and restorative efficacy.