Why All-on-6 bridges are screwed in, not glued

Two ways to fix teeth to implants

The British Society of Periodontology explains that a crown or bridge can be either cemented or, ideally, screwed onto implants. Both are used in dentistry. For a single crown, either can work well. For a full-arch bridge like All-on-6, which replaces a whole row of teeth on six implants, screws are the standard choice, and for good reasons.

• Screw-retained: each implant has a small screw that passes through the bridge and tightens into the implant or into an abutment on top of it. The bridge can be unscrewed by a dentist at any time.
• Cement-retained: the bridge is glued onto abutments attached to the implants, much like a crown on a natural tooth. Removing it later is difficult and can damage it.

What the research shows

A 2014 systematic review, part of an international consensus conference, analysed 73 studies of screw-retained and cement-retained implant restorations. Its main findings:

• Survival was similar overall: about 96% at five years for cemented and about 95.5% for screw-retained restorations, with no significant difference.
• Full arches did well screwed: five-year survival for screw-retained full-arch reconstructions was about 96.7%.
• Fewer complications with screws: screw-retained reconstructions showed fewer technical and biological complications overall. Differences included loss of retention, abutment loosening, porcelain chipping and signs of infection such as fistulas or pus.

The authors concluded that, although survival rates did not differ, screw-retained reconstructions had fewer technical and biological complications, and they favoured screw retention where it is practical.

Why screws suit All-on-6 especially well

Cleaning and checks

The British Society of Periodontology notes that fixed prostheses occasionally need to be removed for professional cleaning. With All-on-6, that means unscrewing the bridge so the hygienist can clean the implants and the underside thoroughly, and the dentist can check the implants and gums. With a cemented full arch, that is rarely practical. More on what happens at those visits in hygienist visits with All-on-6.

Repairs

Over the years, teeth on the bridge may chip, acrylic may wear, or a screw may loosen. If the bridge can be removed, it can be repaired in a laboratory and refitted, or replaced, without touching the implants. See broken or loose bridge.

No hidden cement

When a bridge is cemented, a small amount of excess cement can be squeezed under the gum and is hard to see and remove. Retained cement is a known cause of inflammation around implants. Screws avoid it entirely.

If an implant has a problem

If one implant ever needs treatment, the bridge can be removed to give access. With six implants, a plan can sometimes continue on the remaining five while the problem is dealt with.

The screw access holes

The one cosmetic trade-off of screw retention is that each screw needs a channel through the bridge. On the back teeth these usually come out on the biting surface; on the front teeth, behind them. After the bridge is tightened, the channels are sealed with a soft material over the screw head and a tooth-coloured filling on top. From the front, they are usually invisible. Your tongue may notice them at first.

Modern planning, including angled screw channels in some systems, helps keep access holes out of sight. Where implants are tilted, as at the back of some full-arch plans, a type of abutment called a multi-unit abutment corrects the angle so the screws line up. See the parts of an All-on-6 bridge.

Screw loosening: the trade-off

Screws are designed to hold firmly, but under heavy biting or grinding they can occasionally loosen. A loose screw usually shows up as a slight movement, clicking or a bad taste. It is not usually serious if dealt with promptly: the dentist removes the filling, re-tightens or replaces the screw and seals it again. Left alone, a loose screw can break or put strain on the other implants. That is why any looseness should be checked straight away.

In a sense, the screw is designed to be the weak point. It is much better for a small, replaceable screw to loosen than for an implant or bridge to fail.

Tightening: torque matters

Each screw is tightened to a specific force set by the implant manufacturer, using a calibrated torque wrench. Too loose, and it may work free; too tight, and it can be damaged. This is one reason a bridge should only be removed and refitted by a dentist, and why the brand and type of your implants should be recorded. Your implant passport lists these details.

What it means for you day to day

• The bridge stays in all the time. You do not remove it to clean or sleep.
• Clean under it daily with interdental brushes or a water flosser; see cleaning and care.
• Report movement, clicking or a lost filling over a screw promptly.
• Keep your records: implant brand, type and screw details, so any dentist can maintain the bridge.
• Attend maintenance visits, where the bridge may be removed for a deep clean.

Questions to ask your dentist

• Will my bridge be screw-retained, and where will the access holes be?
• Which abutments will be used, and why?
• How often do you recommend removing the bridge for cleaning?
• Can any dentist with the right tools remove and refit it?

How the bridge is fitted

Fitting a screw-retained final bridge is usually straightforward and does not need anaesthetic. The dentist checks that the bridge seats fully on all the abutments, often with an X-ray to confirm there are no gaps, then inserts and tightens each screw in turn to the manufacturer's recommended force. The bite is checked and adjusted. Finally, each screw head is covered with a soft material and the access holes are sealed with tooth-coloured filling. Some dentists wait a short time and re-tighten the screws at a follow-up visit, because screws can settle slightly after they are first tightened.

Removing the bridge: what it feels like

When the bridge is removed for cleaning or repair, the dentist drills out the small fillings over the screws, unscrews each one and lifts the bridge off. It is not usually painful. Seeing your implants without the bridge can be surprising at first: they look like small metal posts in the gum. The hygienist cleans around each implant and the dentist checks the gum and bone. Before refitting, the screws are often replaced with new ones. The whole process usually takes one longer appointment.

Screws and cost

Screws and the sealing fillings are small parts, but they are part of long-term maintenance. Over the life of a bridge, screws may be replaced several times. Ask whether routine screw replacement is included in maintenance visits or charged separately, and whether your guarantee covers screws. Our sister guide allon6cost.co.uk covers lifetime costs.

When cement is used

Cement is not unusual in implant dentistry overall; it is common for single crowns where the screw channel would come out in a visible place, or where the implant angle makes screws awkward. For full-arch bridges it is uncommon because of the difficulty of removal. If a clinic proposes a cemented full-arch bridge, ask why, and how they would remove it for cleaning or repair.

Common questions

Can I take my All-on-6 bridge out myself?

No. The screws need special tools and the correct tightening force, so only a dentist removes and refits the bridge.

What are the small holes on the back of my teeth?

They are the access holes for the screws, usually on the biting surface of the back teeth or behind the front teeth. They are filled with a tooth-coloured material that can be removed when the bridge needs to come off.

Can the filling over the screw fall out?

Occasionally. It is not an emergency, but see your dentist so it can be replaced, to keep food out of the screw channel.

Why not just cement the bridge so it never comes off?

A cemented full-arch bridge is very hard to remove for cleaning or repair without damaging it, and cement left under the gum can cause inflammation around implants.

How often is the bridge taken off?

It depends on your cleaning and gum health. Many dentists remove it periodically for a deep clean and to check the implants; your dentist will set the interval.

Sources

1. Wittneben, Millen & Brägger (2014), Int J Oral Maxillofac Implants — Clinical performance of screw- versus cement-retained fixed implant-supported reconstructions: systematic review
2. British Society of Periodontology — Patient FAQs: dental implants (crowns and bridges screwed or cemented; prostheses removed for cleaning)
3. Bidra et al. (2017), Eur J Oral Implantol — Clinical outcomes of full-arch fixed implant-supported zirconia prostheses

Checked October 2026. Where we give our own view as a clinic, we say so.