Bur Choice When Removing Zirconia Restorations.

Area of Science:

• Dental Materials Science
• Biomaterials Engineering
• Restorative Dentistry

Background:

• Zirconia restorations present challenges for removal due to their high strength.
• Iatrogenic complications can arise from inefficient burs during zirconia removal.
• Limited research exists on the comparative cutting efficiency of burs for zirconia.

Purpose of the Study:

• To evaluate the cutting efficiency of a specialized bur against general-purpose burs for zirconia removal.
• To compare the performance of single-use and multiple-use burs on a high-strength zirconia substrate.

Main Methods:

• Four burs were tested: one specialized multiple-use bur (Komet 4ZR), one single-use general-purpose bur (Piranha 837.012), and two multiple-use general-purpose burs (Brassler 6837.31.012C, Komet 6837.314.012).
• Cutting efficiency was measured by the time taken to make serial 2 mm cuts in zirconia blocks.
• Burs were tested until a 50% loss of initial cutting efficiency was observed, under reproducible conditions using a custom rig.

Main Results:

• A statistically significant difference in cutting efficiency was observed among the bur types (p <2.2 × 10^-16).
• The single-use general-purpose bur (Piranha 837.012) exhibited the highest cutting efficiency across all cut numbers.
• All burs showed decreased performance with increased use, though the rate of deterioration varied without statistical significance.

Conclusions:

• Single-use general-purpose burs are significantly more efficient for removing zirconia restorations than multiple-use burs.
• The Piranha 837.012 coarse bur demonstrated superior cutting efficiency on Cerec Zirconia Mono L compared to tested multiple-use burs.
• Single-use burs offer a cost-effective, sterilization-free alternative and should be considered for zirconia restoration removal.