Abutment Screws: Why They Loosen and How to Remove a Loose or Broken Screw

The abutment screw is the small screw that holds the abutment to the dental implant. It is also the most common mechanical complication in implant dentistry: a screw that loosens, a driver slot that strips, or, worst case, a screw that fractures inside the implant. This guide explains how the screw works, why it loosens, how to prevent it, and what to do when it fails.

What an abutment screw does

The abutment screw passes through the abutment and threads into the implant body. When it is tightened, it stretches very slightly. That stretch creates preload, a clamping force that pulls the abutment onto the implant platform and keeps the joint closed under chewing forces.

Every implant system uses its own screw design, thread and driver. Use the screw made for your implant and abutment, and keep spares from the same system.

Abutment screw or prosthetic screw? The terms overlap. “Abutment screw” usually means the screw that fixes an abutment to the implant. “Prosthetic screw” also covers the screws that fix a bridge or bar to multi-unit abutments. Both work the same way and fail for the same reasons.

Why abutment screws loosen

A screw loosens when the forces trying to open the joint exceed the preload holding it closed. The common causes:

• Under-tightening. Hand tightening rarely reaches the intended preload. A screw that starts with too little clamping force is the most likely to work loose.
• Settling. Microscopic high spots on the threads and seating surfaces flatten in the first hours and days after tightening, and some preload is lost.
• Misfit. A restoration that doesn’t seat passively puts the screw under constant load.
• Occlusal overload. Heavy contacts, long cantilevers and lateral forces bend the joint with every bite. The implant and abutment instructions for use list severe bruxism, clenching and overloading as causes of screw loosening.
• Connection design. Connections that share lateral load with the implant walls, such as internal hex and conical designs, generally loosen less than external hex. See internal hex vs conical connection.

How to prevent screw loosening

1. Use a torque wrench. Tighten to the torque stated in the instructions for use for that component, never by feel. A torque ratchet wrench gives the same preload every time. See dental torque wrench accuracy for how wrench designs compare.
2. Use the right driver, fully seated. A worn or wrong-size driver slips and damages the screw head before full torque is reached. Replace drivers that show wear.
3. Re-tighten after settling if the instructions for use call for it, typically a few minutes after the first tightening.
4. Check the fit and the bite. Verify passive seating, reduce heavy lateral contacts and keep cantilevers short.
5. Use a new screw for the final restoration if the screw has been tightened and loosened repeatedly during lab and try-in stages. Keep spare prosthetic screws on hand.

What to do when a screw is loose

A loose crown or bridge that rocks or clicks usually means a loose screw. Act early: a loose screw puts load on the threads and the connection, and that is how screws fracture.

1. Access the screw through the access hole, or remove a cemented crown if needed.
2. Remove the screw and inspect it, the abutment and the implant connection for damage.
3. Check the fit and the occlusion to find the cause.
4. Replace the screw with a new one and tighten it to the IFU torque with a torque wrench.

If the same screw keeps loosening, the cause is usually the bite or the fit, not the screw.

Removing a stripped or broken abutment screw

Stripped driver slot

When the driver spins in a damaged screw head, the screw can’t be unscrewed normally.

• A screw release key (hand or machine version) is used to loosen and release stuck prosthetic and abutment screws from the implant.
• The Corkskey extractor (Corkskey) can remove a prosthetic screw with a damaged driver slot.

Screw fractured inside the implant

If the screw breaks and the fragment sits below the top of the implant, first try to rotate the fragment counter-clockwise with a fine probe or explorer. A fractured fragment is often no longer under load and may turn out freely.

If it won’t move, use a dedicated retrieval set. Surcam’s S.O.S Screw Out Set uses a guide that seats in the implant hex to center a reverse drill on the fragment. The drill runs counter-clockwise at low speed with a light tapping action until the fragment backs out. Follow the instructions for use exactly. Too much pressure can damage the instrument or the implant’s internal threads.

All retrieval tools are on the implant screw removal and extraction tools page.

Frequently asked questions

What is an abutment screw?

The screw that fixes an abutment to a dental implant. Tightening it creates a clamping force (preload) that holds the joint closed.

Why does my implant abutment screw keep loosening?

Usually because of too little preload, settling, a restoration that doesn’t fit passively, or heavy biting forces. Tighten with a torque wrench to the IFU value and check the fit and the occlusion.

Can you reuse an abutment screw?

Use a new screw for the final restoration if the screw has been tightened and loosened several times during try-ins. A used screw may not reach the same preload.

How do you remove a broken abutment screw from an implant?

Try to turn the fragment counter-clockwise with a fine probe first. If it is stuck, use a retrieval set with a guide and a reverse drill, following its instructions for use.

Are abutment screws universal?

No. Thread, length and head design differ between implant systems. Use the screw made for your implant and abutment.

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