New Zealand Association of Prosthodontists and Restorative Dentists

Implant Overdentures

When implants are used to secure a denture to your jaw bone, they are called 'implant overdentures'. This name has been used because the denture sits on top of the implants. Implant overdentures can help people with severe jaw-bone loss to have a secure denture wearing experience. The procedure involves placing two or three implants usually into the lower jaw bone. Once the implants integrate into the bone, a denture is then made to fit over the top of the implants.

Small clips are used to join the implants to the dentures. The implant overdenture can still be removed from your mouth like a normal set of dentures to be cleaned and to give your gums a rest at night. The biggest difference is that they hold much better to your lower jaw compared with a conventional set of complete dentures. This will give you more confidence that your dentures will remain secure when eating and speaking.

What are the advantages of Implant Overdentures?

Implants are fixed to your jaw bone and do not move. For people that have lost all their teeth, their jaw bone may shrink over time, making it increasingly difficult to function comfortably with complete dentures. Removable dentures are not permanently fixed in place, they can move around when you eat and speak. Implant overdentures can help to stabilise an upper or lower denture by using clips that attach to the implants that are anchored in your jaw bone. Implant overdentures can initially be more cost effective than fixed implant bridges (fixed bridges on four or more implants).

A significant amount of research has demonstrated that implant overdentures can significantly improve the quality of life of those who cannot manage conventional dentures. People treated with implant overdentures often mention that they can eat a greater range of foods than they could previously and they also have more confidence with speaking and interacting in social situations.

What are the disadvantages of Implant Overdentures?

Disadvantages include the surgical procedure that required to place the implants into your jawbone and the long-term maintenance that is needed to keep them working well. Maintenance requirements will vary between different people, however we know that the majority of maintenance is usually required within the first year of service. This is most likely because it takes time to get used to wearing the new dentures and once you learn how to use them, there is less stress placed on the clips that hold the dentures to the implants.

It is impossible to accurately predict how much maintenance you will require over time as every person will have a different denture wearing experience. Common maintenance issues include: Tightening/replacement of the clips, relining the overdenture, easing sore spots, denture tooth wear, fracture of the denture base. You could expect over a 5 year span, to see some sort of wear and tear on the overdentures. Often teeth may need replacing after 5-6 years or a reline of the denture base may be necessary.

How successful are the implants once they have been placed into my jaw?

While implants are highly successful, the likelihood of success depends on several factors. The amount of bone available to support the implant, the patient’s health, whether or not the patient smokes and the quality of ongoing home care all effect long-term success. If an implant fails to integrate in your bone, it can be removed under local anaesthetic. The site is left to allow healing to occur before placing another implant into the same site. In general, implants placed into the front of the lower jaw, have the highest rate of survival (95%+). The upper jaw and the back of the lower jaw have traditionally had lower survival rates (88%+), however there are indications from recent research that these survival rates have improved to above 90%.

No matter where an implant is placed, there is always a small risk that the implant can fail and you must be aware of this prior to commencement of treatment. Most failures are seen within the first year. The bone and soft tissue repair rapidly and it is often possible to place another implant in the same site after a few months of healing at no extra cost to you. There is also a risk of the margin between the implant and the crown becoming exposed over time if the gum receeds. We will do everything we possibly can to ensure that the implant crowns appear as natural as possible and that the implants integrate with your bone successfully.

Once the implants are placed, how long will my treatment last?

It is important that you understand that implant restorations consist of two parts, the titanium implant and the superstructure that is placed on top of the implant head (abutment and implant crown). Research has demonstrated that dental implants may remain integrated with bone in excess of 25 years and many implants will remain integrated for life. The limiting factor for the survival of implant restorations is usually the overdenture or crown that is placed on top. The most common maintenance issue of an overdenture is the clips coming loose and needing activation or tightening. Clips can come loose from the denture base, the abutment can come loose from the implant and all of the overdenture components will wear over time. After 5-6 years you will begin to notice wear on the false teeth themselves.

Often the decision to replace or reline implant overdentures will rest on the individual and their ability to cope with wearing the implant overdentures. It is difficult to give an accurate estimate of exactly how long the implant overdenture will last, as this is dependant on many factors within and beyond our control. Most complications with materials tend to occur within the first year of service. The implants need to be brushed regularly to keep them clean and prevent plaque from building up on them. Provided the Implant Overdenture is maintained in a meticulous manner you should get many years of satisfactory service.

Are there any other things that we need to know?

Implant overdentures can certainly improve the quality of life for those who cannot manage wearing conventional dentures, however over time some people forget how well they fit compared to a conventional denture. It has been well documented that the expectations of people wearing implant overdentures may increase over time and they still feel as if the lower denture is loose.

The upper denture may also begin to feel loose as the lower denture becomes firm due to the improved tightness of the lower denture from the implants. However, overall, implant overdentures are often a significant improvement when compared with conventional dentures.

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