Mastering the "Push Button" of Spring Spindles
If you are used to KaVo-style (Carbide) handpieces, you might find that NSK-style (Spring) handpieces require a slightly different technique to change the bur.
A common issue dentists face is "The bur won't come out" or "The bur won't go in fully." Often, the handpiece is not broken — the button is simply not being pressed deep enough.
❌ The Common Mistake: "Partial Press"
Spring chucks have a safety mechanism. When you feel the first resistance, the chuck is NOT open yet. Many users stop here, thinking the button is fully depressed.
Result: The internal spring is not compressed enough to release the grip. Forcing the bur out at this stage can damage the spindle.
✅ The Correct Way: "Deep Press"
To fully open a Spring-type chuck, you must press past the initial resistance.
- Step 1: Place your thumb specifically on the center of the back cap.
- Step 2: Apply firm pressure until the button sinks deeply into the head cap.
- Step 3: You will feel a distinct "click" or a second level of depth. Hold it there while changing the bur.
Result: The chuck jaws open completely, allowing the bur to slide in and out smoothly.
💡 Pro Tip: Check Your Bur Length
Always ensure the bur is inserted all the way to the back. A partially inserted bur can cause vibration and damage the bearings. Once inserted, give the bur a gentle "tug" to confirm it is locked in place before stepping on the pedal.