Which bur is specifically designed to establish retention in tooth preparation?

The inverted cone bur is specifically designed for establishing retention in tooth preparation due to its unique shape, which allows for the creation of undercuts in the cavity preparation. This design helps to lock the restorative material in place once it has been applied, enhancing the stability of the filling or other restorative work.

The inverted cone bur features a tapered end that can reach into the tooth structure, helping to create a specific cavity shape that promotes retention. This characteristic makes it particularly useful in situations where it is essential to hold the restorative material securely within the prepared dental area, reducing the likelihood of dislodgement over time.

In contrast, other burs like the tapered fissure plain cut bur are primarily aimed at creating precise cavity walls or refining internal angles, while the pear-shaped bur is often used to create broader, rounded shapes in preparations. The round bur generally serves for removing caries or creating openings but does not provide the same retention features found in the inverted cone bur. Understanding the designated purposes of each type of bur helps in making informed choices during dental procedures.