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.