What is the width of a 330 bur in millimeters?

• A. 0.5 mm
• B. 1.0 mm
• C. 1.2 mm
• D. 0.8 mm

Answer: (D)

Understanding bur sizes helps you predict how much tooth will be removed and how the cavity walls will form. The 330 inverted cone bur is defined by its cutting end width, which is 0.8 millimeters. This specific size provides a small, controlled diameter that’s ideal for shaping internal walls and creating retention features without removing excess tooth structure. It’s the smaller option among common inverted cones, with other sizes like 1.0 mm used when a larger width is needed. So the width of a 330 bur is 0.8 mm.