Why Implant Screws Loosen, and How to Prevent It

A patient calls a few months after you seated an implant crown: it clicks on biting, or it turns. Screw loosening is the most frequently reported technical complication of single implant crowns, and each episode means an unplanned visit and a retrieval.

Most causes are mechanical and predictable. This guide covers what holds an implant screw tight, what loosens it, what manufacturers' instructions say about torque and screws, and what to do when one comes loose.

Quick Answer

Implant screws loosen when the screw's clamping force (preload) falls below the forces trying to open the joint. Preload is lost to under-torquing, settling of the contact surfaces in the first minutes, repeated tightening and framework misfit; opening forces come from off-axis loads, cantilevers, heavy contacts and bruxism. Prevent it with a calibrated torque wrench at the manufacturer's value, a re-torque where the instructions call for it, a new final screw, passive fit and light, axial occlusion.

How Often Do Implant Screws Loosen?

Definitions differ between reviews, so compare loosely.

With proper torque, connection type matters modestly: 97.3% of 586 external-connection and 97.6% of 1,113 internal-connection single crowns were free of abutment screw loosening at three years (Theoharidou et al., 2008), though a 60-study review found more loosening with external connections (Pjetursson et al., 2018). Newer screw designs have cut loosening by almost half, and cemented crowns loosen less often than screw-retained ones (Sailer et al., 2022).

What Holds an Implant Screw Tight?

Preload

Tightening stretches the screw slightly, and its pull clamps the abutment or crown against the implant. That clamping force, the preload, keeps the joint closed (Cantwell and Hobkirk, 2004). A 2020 review puts the share of applied torque that becomes preload at only about 10%; the rest overcomes friction (Vinhas et al., 2020).

Settling (embedment relaxation)

No machined surface is perfectly smooth. At first only the high spots touch; within seconds to minutes they flatten and preload drops, by 2% to 10% in the studies it summarizes. ZimVie's manual gives the same reason for its ten-minute re-torque: clamping force lost to screw embedment.

Joint separation

Every bite tries to tip or lift the abutment. When lateral loads, a cantilever or a heavy contact exceed the preload, the parts rock microscopically, the threads wear and the screw backs off or fatigues. Under cyclic loading in lab studies, abutment screws lost 16.1% to 39% of their torque (Pardal-Peláez and Montero, 2017).

What Causes Implant Screws to Loosen?

Every cause either lowers the preload or raises the forces that open the joint.

With cantilevers, technical complications, mostly porcelain chips and bridge-screw loosening, reached a weighted mean of 20.3% versus 9.7% without in one review (Zurdo et al., 2009); another found no increase (Romeo and Storelli, 2012). A 2017 review found misfit only slightly raised the risk of screw complications, but advised the least misfit possible (Katsoulis et al., 2017). A compatible CAD/CAM abutment group had 8.5% abutment screw loosening over a mean 7.2 years, more than original abutments (Hsiao et al., 2021), and a 40-study review recommends originals (Rizvi et al., 2022); see Implant Abutments Explained. Surface-treated screws reached higher preload at the same torque (Martin et al., 2001).

How Do You Prevent Screw Loosening?

Torque to the IFU value with a calibrated wrench

Use the value for the exact screw. Straumann specifies 35 Ncm for Variobase restorations and warns that more than 35 Ncm can damage its angled-channel Screw AS. ZimVie specifies 30 Ncm for Tapered Screw-Vent abutment screws with a calibrated torque wrench. Neodent lists 20 Ncm for the GM Exact abutment and 32 Ncm for the GM Mini Conical abutment.

Wrenches drift. New spring-style wrenches deviated 2.36% from target on average versus 13.74% for friction-style ones (Vallee et al., 2008), a difference a 16-study meta-analysis confirmed (Wang et al., 2024). After simulated aging, over half of friction-style readings were more than 10% off (Saboury et al., 2013). ISO 6789 recommends testing torque tools periodically (Wadhwani et al., 2020).

Re-torque after a few minutes where the IFU says so

ZimVie is explicit: "Wait ten minutes, then retighten." The Straumann and Neodent documents we reviewed include no re-torque step. Lab studies favor a second tightening after 10 minutes (Siamos et al., 2002) or 2 minutes (Varvara et al., 2020); loosening and immediately retightening worked as well as waiting 10 minutes (Sun et al., 2024). Clinically it is less clear: in 158 patients, a 10-minute re-torque made no difference, preload loss was found in 10.13% of cases at one month, and the authors recommend re-torquing then (Xu et al., 2021).

Use a new screw for the final restoration

Straumann's Variobase guide says to ensure "that a new screw is used for the final restoration," and ZimVie's T3 manual swaps the try-in screw for the final one. Repeated tightening costs preload: a 2025 review found significant loss of removal torque after 5 cycles and more after 10 (Shui et al., 2025), and one study recommends a new screw after 10 insertions (Guzaitis et al., 2011). Whether a loosened screw is better replaced or retightened is less settled (Attiah et al., 2020); follow the IFU and replace any damaged screw.

Keep implant occlusion light and axial

Evidence is too thin for firm implant occlusion guidelines (Koyano and Esaki, 2015), but recommendations agree (Stilwell, 2024):

• Graded contact: in light closure only natural teeth hold shimstock, and it should just pull through against an implant crown; in firm closure all posterior teeth and implant crowns hold it.
• No dynamic contacts on posterior implant crowns; wide fossae and shallow cusps.
• Anterior guidance on natural teeth where possible.
• A hard occlusal splint for patients with bruxism.

A crown that arrives high undoes this; see High Crowns and Open Contacts.

What Should You Do When a Screw Loosens?

Confirm it and get to the screw

Patients often notice a slight click when biting or chewing (Stilwell, 2024). Check for movement, a gap or fluid at the margin and excursive marks; take a radiograph. On a screw-retained crown, remove the access filling. A cement-retained crown is harder to retrieve, one reason retrievability matters (see Screw-Retained vs. Cement-Retained Implant Crowns).

Suspect a fracture or misfit

If the driver turns without tightening, the crown stays mobile after torquing or the screw comes out in pieces, assume a fractured screw or damaged threads. Start with the least invasive retrieval: a 2026 review found 86% success in lab studies, higher with ultrasonic methods (97%) and external rather than internal connections (100% vs. 80%) (Arshad et al., 2026). A gap on the radiograph, or a framework that seats only as the screws pull it down, points to misfit.

Fix the cause, not only the screw

Clean the connection, place and torque a screw as the IFU directs, and protect the screw head with PTFE tape before sealing (Stilwell, 2024). Correct the occlusion and recheck. Send the restoration to the lab if the screw loosens again despite correct torque, a new screw and an occlusal check; if you see misfit or chipping; or if the design must change, for example a shorter cantilever.

Checklist

• Rx: implant system, platform, connection; bruxism, cantilevers, limited space.
• Components: original or documented compatible parts; try-in screw for try-ins.
• Torque: the IFU value for that screw, with a calibrated, serviced wrench.
• Re-torque: as the IFU directs; recheck at the first follow-up.
• Multi-unit: all screws hand-tight, then torque in sequence; radiograph to confirm seating.
• Occlusion: graded contacts, no posterior excursive contacts, night guard for bruxers.

Implant Restorations at Elegant Dental Laboratory

• Screw-retained and cement-retained implant restorations, custom screw-retained abutments and full-arch cases. See our implant restorations.
• Up to a 20-year warranty on screw-retained implant abutments and up to 7 years on final restorations (policies and warranties).
• Every case is made in house in Brooklyn, New York, by more than 35 technicians; digital scans are reviewed before production.
• 5 business day standard turnaround on most restorative cases, rush options available. Submit a digital case or send a case: our own drivers pick up in the New York area (call to confirm), and UPS labels work anywhere. Call 877-335-5221.

Related Guides

• How to Scan Implants: Scan Bodies, Common Mistakes and What to Send the Lab
• Full-Arch Implant Prosthesis: Zirconia vs. PMMA vs. Metal-Acrylic (Hybrid)
• Dentures in America, Then and Now: From Hippopotamus Ivory to Digital Dentures

FAQ

How often do implant abutment screws loosen?

In a review of 46 studies, 8.8% of single crowns within five years; full-arch reviews report 5% to 15%.

Should I re-torque an implant screw after 10 minutes?

Yes, if the IFU says so; ZimVie's does. One clinical study found no benefit at one month, so also recheck at follow-up.

Can I reuse an abutment screw?

Use a try-in screw for try-ins; Straumann calls for a new final screw, and every tightening cycle lowers removal torque.

Is hand tightening enough for a final abutment screw?

No. Clinicians aiming for 32 Ncm by hand delivered 8.2 to 36.2 Ncm. Use a calibrated torque wrench.

How do I know a loose screw is actually broken?

When the driver spins without tightening, the crown stays mobile after torquing, or the screw comes out in pieces.

Reviewed by Gary Fingerman, founder and CEO of Elegant Dental Laboratory, Brooklyn, New York (founded 2007). Last reviewed: September 28, 2026. Torque values and protocols come from the manufacturer documents listed above; always follow the current instructions for use of the exact implant system and screw you are restoring.