Living with Dentures

Implant-retained removable dentures (snap-on dentures): how many implants, which attachment, and what upkeep?

A lower denture held by two implants has been the standard for over twenty years; the real issues are the choice of attachment and upkeep over the years

For someone whose removable denture moves, an implant-retained removable denture is often the first solution discussed. The denture is still taken out and cleaned, but it now sits on attachments on top of the implants; it does not lift when you eat or speak. In Turkish it is known as a 'snap-on denture', and in the literature it appears as an 'overdenture'. The McGill consensus statement of 2002 and the York consensus statement of 2009 defined a lower denture held by two implants as the first-choice standard for people with no teeth. This standard still holds. But which attachment to choose, how many implants are needed in the upper jaw and how much upkeep the denture will need over the years are questions that are rarely discussed at the quote stage.

Short answer

An implant-retained removable denture is a full denture that clips onto and off attachments on top of implants. A lower denture held by two implants is defined in consensus statements as the first-choice standard for people with no teeth. In the upper jaw, at least four implants are generally discussed. The attachments can be Locator, ball or bar types; the plastic or rubber parts inside them are replaced as they wear. It is easier to clean than fixed teeth, but its retention and stability are lower.

Lower jaw standard: Two implants (McGill 2002 and York 2009 consensus statements)
Upper jaw: Higher implant survival with at least four implants in a review
Attachment types: Locator, ball, bar, telescopic, magnet
Upkeep: Replacing attachment inserts and relining; complications are unavoidable, and follow-up reduces them

How the denture holds on to the implants, and what each choice changes

The system has two halves. One half is the attachment screwed onto the implant: a short cap, a ball-shaped tip or a metal rod connecting the implants to each other, that is, a bar. The other half is the housing fitted into the inner surface of the denture: a small metal cup containing a nylon, plastic or rubber insert. When the denture is pressed into place, this insert clips over the attachment, and the 'click' you hear is where the Turkish name comes from. The denture is removed by lifting it with your fingers. What wears is usually this insert, and replacing it takes a few minutes.

The standard of two implants in the lower jaw is not a random number. The McGill consensus meeting held in Montreal in 2002 and the British Society for the Study of Prosthetic Dentistry meeting held in York, England, in 2009 defined a removable denture held by two implants in the lower jaw as the first-choice standard for people with no teeth. The emphasis of the York statement was on patient-centred outcomes: satisfaction, being able to eat and being able to take part in social life with a denture. We have explained separately why a lower full denture does not stay in place on our page about a lower jaw with no teeth; two implants stand out as the solution to this problem with the least surgery.

A single implant means less surgery, but more denture problems. In a meta-analysis pooling 17 randomised studies comparing lower dentures held by one and by two implants, there was no difference in five-year implant survival. On the denture side, however, denture fracture, remaking the denture and the metal housing coming loose and needing to be re-bonded were more common in the single-implant group. In another meta-analysis pooling patient-reported outcomes, significantly better results were also reported with two-implant dentures than with a single implant. A single implant is possible, but 'one instead of two' is not a cheap simplification.

The upper jaw is a separate calculation. Because an upper denture rests on the palate, it already holds better; implants are often wanted to open up the palate or make the denture smaller. This puts a greater share of the load on the implants. In a review of 28 studies examining the number of implants for the upper jaw, implant survival was found to be higher with four or more implants; denture survival and patient satisfaction, however, were not significantly affected by the number of implants. The authors concluded that at least four implants in the upper jaw is the prevailing trend.

The choice of attachment is the most debated topic, but the evidence is not as clear as people think. A Cochrane review found insufficient evidence to establish the superiority of any attachment system over another in the lower jaw in terms of denture success, maintenance needs, satisfaction or cost; for the upper jaw there are no randomised studies at all. In the same review, ball attachments needed repair more often than bars in the short term, but the certainty of the evidence is very low. A more recent meta-analysis examined 2,154 implants and 737 dentures in 25 randomised studies: implant loss was 2.0% and denture loss 4.2%. Denture complications were least common with Locator attachments, followed by telescopic, bar and ball attachments; with magnetic attachments, complications were about 7.4 times those of the others. Connecting the implants with a bar did not significantly change biological complications.

Upkeep is unavoidable, and knowing this from the start prevents disappointment. A review of maintenance for lower removable dentures states that calculating an average complication rate is not possible because of the large number of factors, but that denture complications are unavoidable and can be kept at the expected level with close follow-up. In an older review of 49 studies, the housing loosening, wearing or coming out was found to be more common with ball attachments after the first year; insert replacement increased in both jaws after five years. The same review concluded that the effect of the attachment system on the denture outcome is negligible.

The comparison with fixed teeth is most patients' real question. In a meta-analysis pooling 28 studies and 1,457 patients with no teeth, both fixed teeth and removable dentures brought a large improvement in oral health-related quality of life, and the difference between the two was not significant. The only heading on which fixed teeth were significantly ahead was the stability of the prosthesis. The authors sum it up like this: for a patient who wants high stability, fixed teeth may be preferred. Where the removable denture stands out is cleaning: the denture is taken out and brushed by hand, and the areas around the implants can be reached directly.

Who a snap-on denture is a good choice for, and for whom it falls short

The distinction below shows which expectation a removable denture meets, and in which a fixed solution comes out ahead.

When it fits

People whose lower denture moves but who are happy with the denture itselfIf the only problem is retention, two implants and a well-made denture largely solve it. This is the standard the consensus statements recommend for the lower jaw.
People who prefer to clean by hand, or whose manual dexterity is limitedThe denture is taken out and brushed at the sink, and the implant heads are easily cleaned in the mouth. If cleaning under a fixed bridge every day with special brushes would be difficult, this ease can be decisive.
People who want to make do with a small number of implantsIn the lower jaw, two implants are often enough. This means less surgery, a shorter procedure and less need for bone.
People who want to regain lost lip and cheek support with a dentureThe pink part and the edges of the denture support the lips and cheeks from inside. In patients who have been without teeth for a long time and whose facial contours have collapsed, this can give a fullness that is hard to achieve with fixed teeth.

When it doesn't

People who never want to take their denture outA removable denture is taken out at night and cleaned every day. If you want teeth that stay in your mouth all the time, fixed teeth, which come out ahead on stability in patient-reported studies, are what is discussed.
People who want a palate-free upper denture but can only have a few implantsIn the upper jaw, opening up the palate transfers the load to the implants. In the review, implant survival in the upper jaw was found to be lower with fewer than four implants; opening up the palate is thought of as a factor that increases this risk.
People who will not be able to come for regular check-upsReplacing the attachment inserts, relining and adjusting the bite are the normal upkeep of this denture. When upkeep is put off, the denture moves and the load falls unevenly on the implants.
People who do not have enough height for the dentureThe attachment and housing take up space inside the denture. If the distance between the jaws is small, the denture becomes thinner at these points and is prone to fracture; bar attachments need more space.

How an implant-retained removable denture is made

The sequence below shows the general course. Whether the existing denture is used and when the implants are loaded vary with the clinic and the patient.

1
Assessing the denture and the bone
The fit of the existing denture, wear of its teeth and the bite are checked. The bone is measured with a CBCT scan, and the positions of the implants are planned according to the position of the denture teeth.
2
Placing the implants
In the lower jaw, the two implants are usually placed at the front, near the canine teeth. In the upper jaw, the number and positions are decided by the bone.
3
Choosing the attachment system
How parallel the implants are to each other, the distance between the jaws and the patient's manual dexterity affect the choice of attachment. Separate attachments are simpler to clean; a bar needs more space but shares the load between the implants.
4
Making the denture or converting the existing one
If a new denture is made, the housings are fitted in the laboratory. If the existing denture is suitable, the housings are fixed inside the denture in the mouth.
5
Fitting and learning to put it in and take it out
How to put the denture in and take it out is shown in the mouth. The denture should not be seated by biting it into place; it is seated with the fingers. Biting it into place strains the attachments and housings.
6
Check-ups and insert replacement
When retention decreases, the insert is replaced. As the tissue under the denture changes, relining is needed. Reviews report that a close follow-up protocol keeps complications at the expected level.

Options discussed instead of a snap-on denture

The decision is made along two axes: how many implants can be placed, and whether the row of teeth will be removable or fixed.

Conventional full denture

It needs no surgery and is easy to clean. In the lower jaw, the retention problem often continues; this is why the consensus statements recommend two implants as the standard.

Denture held by mini implants

In lower jaws with narrow bone, four mini implants can be used instead of two standard implants. The results are good in the lower jaw and markedly weaker in the upper jaw; the details are on our mini implant page.

Lower denture held by a single implant

Implant survival at five years is similar to two implants, but denture fracture and housing problems are more common. Patient-reported outcomes improve significantly with a second implant.

Fixed bridge on implants

The prosthesis is screwed to the implants and the patient does not take it out. In patient-reported studies it comes out ahead on stability and is similar to a removable denture in overall satisfaction. It needs more implants and more painstaking daily cleaning.

Final fixed teeth in 3 days

The route we work with in full-mouth cases: the implants and the fixed teeth are completed within 3 days, that is 72 hours, and the teeth fitted on the third day are the final teeth. For patients who do not want to live with a removable denture but have been without teeth for years, this option is assessed on the basis of a CBCT scan.

The problems most often met over the years

The problems with a removable denture usually concern the denture rather than the implant; they are small but recurring upkeep jobs.

Loss of retention

The inserts wear a little each time the denture is put in and taken out. If the denture does not sit as firmly as before, the job to be done is often replacing this insert. In the review, insert replacement increases after five years.

The housing loosening or coming out

With ball attachments, the housing loosening, wearing or separating from the denture after the first year is more common than with other systems. With single-implant dentures, the housing needs to be re-bonded more often than with two-implant dentures.

Denture fracture

The points where the housings are cut in are the thinnest parts of the denture. Fracture and remaking of the denture were reported more often with single-implant dentures than with two-implant ones.

Changes in the tissue under the denture

The back part of the denture still rests on the gum. As the bone in this area changes, the denture is left with a gap underneath and starts to rotate around the implants. Relining is done for this reason.

Inflammation around the implants

If the areas around the implant heads are not cleaned, they can become inflamed. No significant difference in biological complications was found between implants joined by a bar and those standing separately; in both cases the implant heads need daily cleaning.

From implants to living with the denture: what to expect

Healing from implant surgery is short; the real adjustment is to putting the denture in and taking it out, and to the rhythm of upkeep.

The first few weeks after the implants
The denture is hollowed out so that it does not press on the implants and is used with a soft liner. The denture can still be worn while the implants fuse with the bone.
Connecting the attachments
Once fusion is complete, or earlier depending on the dentist's protocol, the attachments are fitted to the implants and the housings are fitted into the denture. This is when the patient first feels the denture 'click into place'.
The first few months
Putting the denture in and taking it out becomes a habit. Points on the denture that rub or cause sores are adjusted. At night the denture is taken out and stored clean.
Over the years
The inserts are replaced as they wear, the underside of the denture is relined when needed, and the denture teeth are renewed as they wear. According to the reviews, these jobs are unavoidable; regular check-ups turn each of them into a planned appointment.

Don't wait if

If the denture does not hold as well as it used to. Often the insert has worn and replacing it is a short procedure. But a loose attachment cap or a problem with an implant can give the same sign.
If the denture rotates or rocks on an implant. The tissue under the denture may have changed, and it may be time for relining. In this situation the load falls unevenly on the attachments.
If an attachment cap is loose or the area around an implant is bleeding. If a cap that has come loose is not tightened, the screw or the implant can be damaged. Bleeding and swelling can be an early sign of inflammation around the implant.
If there is a crack or break in the denture. If a small crack in the housing area is repaired early, the denture can be prevented from breaking altogether. Do not repair the denture yourself with glue.
Difficulty breathing or swallowing after surgery, or swelling spreading quickly to the face or neck. Call 112 straight away or go to the nearest A&E. Do not wait with these signs.

What shapes a snap-on denture quote

You will not find figures here. These are the headings to look at when comparing two quotes:

Number of implants and which jaw: Two implants in the lower jaw, usually four or more in the upper jaw. A quote for the upper jaw is not read with the same logic as one for the lower jaw.
Attachment system: Separate attachments and a bar mean different laboratory work and a different cost. A bar needs more denture height and is more painstaking to clean.
The denture: new or converted: There is a marked difference between fitting housings inside the existing denture and making a new one. If the denture fits poorly, converting it can be cheap in the short term and expensive in the long term.
Maintenance items: Ask from the start how insert replacement, relining and denture repair will be charged. With this denture, these jobs are expected upkeep.

Frequently asked questions about snap-on dentures

How many implants are needed for the lower jaw?

According to the consensus statements, two implants are the standard. It can also be done with a single implant; five-year implant survival is similar, but denture fracture and housing problems are more common. In jaws with narrow bone, four mini implants can also be used instead of two standard implants.

How many implants are needed for the upper jaw?

In the review, implant survival was found to be higher with four or more implants, and the prevailing trend is at least four implants. There are no randomised studies of attachment systems for the upper jaw, so the choice of attachment rests largely on the dentist's experience.

Locator, ball or bar?

According to the Cochrane review, there is not enough evidence in the lower jaw to declare one superior to another. In a meta-analysis pooling 25 randomised studies, denture complications were least common with Locator attachments and most common with magnets. The choice is also affected by how parallel the implants are, the denture height and your manual dexterity.

How often does the insert in the attachment need replacing?

There is no fixed interval; it varies with use and the system. In the review, insert replacement increased in both jaws after five years. When the denture becomes noticeably loose, it is time for a replacement.

Can my existing denture be turned into a snap-on denture?

If the denture fits well, its teeth are not worn and its bite is correct, it can be used by fitting housings inside it. Connecting an ill-fitting denture to implants does not solve the problem; it transfers the load to the implants.

Should I take my denture out at night?

The NHS recommends taking dentures out every night and keeping them somewhere moist, unless your dentist advises otherwise. When you take it out, brush the denture and clean the implant heads as well.

Which is better, a snap-on denture or fixed teeth?

In a meta-analysis pooling 28 studies, both bring a large improvement in quality of life, and the difference between them is not significant. Fixed teeth are significantly ahead only on stability. A removable denture stands out for someone who wants an easy-to-clean solution with few implants, and fixed teeth for someone who wants teeth that stay in the mouth all the time. If you have a panoramic X-ray or a CBCT scan, you can send it through the application form; the image is assessed by the dentist who would carry out the treatment.

Which is sturdier, a bar or separate attachments?

Joining the implants with a bar did not significantly change biological complications. A bar shares the load, but it needs more space and cleaning underneath it is more painstaking. Separate attachments are simpler and easier to clean.

Sources

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