A 2% taper on an endodontic (endo) file refers to the gradual increase in the diameter of the file from its tip to the end of its cutting surface. **The “2%” indicates that for every millimeter of length along the file, the diameter increases by 2% of the starting diameter at the tip.**

The taper of these files is critical for their function, as it influences how they enlarge the canal, remove debris, and prepare the canal for filling.

To put it simply, if you have an endo file with a 2% taper and the tip diameter is 0.20mm, after 1mm of length from the tip, the diameter of the file will be 0.20mm plus 2% of 0.20mm (which is 0.004mm), making it 0.204mm in diameter. This gradual increase allows for a progressive and controlled enlargement of the root canal.

## How do you calculate endodontic taper?

To calculate the taper of an endodontic file, you can use the formula that describes the increase in diameter of the file over its length. The taper is usually given as a percentage, indicating how much the diameter increases per millimeter of length from the tip of the file. Here’s a step-by-step way to calculate the taper:

**Understand the Taper Percentage**

As we said, the taper percentage (e.g., 2%, 4%, 6%) indicates the increase in diameter of the file for each millimeter of length. A 2% taper means the file’s diameter increases by 2% of its starting diameter at the tip for every millimeter you move along the length of the file.

**Calculate Diameter Increase Per Millimeter**

To find out how much the diameter increases per millimeter, multiply the starting diameter of the file at its tip by the taper percentage. If the taper percentage is not directly given but you have the diameters at two points along the length and the distance between those points, you can calculate the taper percentage.

**Formula:** Diameter increase per mm= Starting diameter × (Taper percentage/100)

**Calculate Taper Over a Specific Length**

If you want to know the increase in diameter over a specific length, multiply the diameter increase per millimeter by the length in millimeters.

**Formula:** Total increase in diameter=Diameter increase per mm×Length in mm

**Determine Final Diameter**

To find the final diameter of the file at a certain point along its length, add the total increase in diameter to the starting diameter of the file.

**Formula:** Final diameter=Starting diameter+Total increase in diameter

**Example Calculation**

For a 2% taper file with a starting tip diameter of 0.20mm, to find its diameter after 10mm of length:

- Diameter increase per mm=0.20×(2/100)=0.004
- Total increase in diameter over 10mm=0.004×10=0.04
- Final diameter after 10mm=0.20+0.04=0.24