As an alternative to removable dentures, there are essentially three fixed options available for restoring a space with teeth:
1. Adhesive Bridges
These are bridges that are held in place by metal wings bonded to the back of teeth adjacent to the missing tooth or teeth.
These are usually quick to complete and only a small amount of tooth preparation is required. They can however sometimes be unreliable as the wing holding the bridge in place can become loose and the bridge can fall off. They are best used as medium to longterm temporary bridges.
2. Porcelain Bonded Bridges
For many years conventional bridges were seen as the ideal solution for filling spaces where teeth were missing. Teeth either side of the gap are prepared (cut down) for crowns, impressions taken and the bridge cemented into place 7-10 days later.
The advantages of bridges are that they are permanent and feel and look like natural teeth. One disadvantage is that natural teeth have to be cut down, which can cause a reaction from the tooth leading to possible tooth death in the future. Bridges can also become loose and decay can start to form around their edges.
Nonetheless they can be very predictable way of restoring spaces in many situations.
3. Dental Implant(s) supporting a Porcelain Crown or Bridge
These are tooth-root shaped titanium insert that are placed into the bone at sites once occupied by a tooth root. Once positioned under sterile conditions bone fuses to the implant surface in a process known as osseointegration. The procedure is carried out under local anaesthetic and although some soreness afterwards can be expected it is usually minimal.
Once the implant has become osseointegrated it can be considered long lasting. At this stage, which is normally three – four months after the implant was placed, it is uncovered and a special post called an abutment attached. A porcelain crown can then be made for the post and subsequently cemented into position. In some situations a post and provisional crown can be attached to the implant when it is initially placed.
The main advantages of dental implants are that they are permanent and the adjacent teeth are not touched in any way. Dental implant treatment is extremely predictable with success rates in excess of 95% and is now seen as the ideal solution and first choice for replacing missing teeth.
The phases of implant treatment are as follows:
Models, further x-rays and photographs may be taken so that a diagnostic stent can be made. This stent shows the ideal positions of the proposed dental implants.
The dental implants are placed very carefully into the appropriate positions as planned. The procedure is carried out under local anaesthetic with strict sterile conditions. Healing is rapid and usually on slight discomfort or pain (managed by paracetamol or ibuprofen) occurs after the procedure.
When the implants have become fully integrated, which usually takes approximately three to four months, they will be uncovered and posts (abutments) connected.
After a further few weeks for healing, the final impressions are taken and then the definitive porcelain crowns cemented into place, after allowing for try in of colour, shape and fit.
Occasionally bone defects exist adjacent to proposed dental implant sites. In these circumstances it is frequently possible to supplement for the missing tissue in a procedure termed guided bone regeneration.
In this a combination of biomaterials are used around the defect area and build it up.
The real advantage of guided bone regeneration is that only one area is involved. It is frequently possible to use the guided bone regeneration technique at the same time as implant placement, but usually a final decision is taken at the time of implant placement itself or after healing of the extraction site.
We use biomaterials in adjunct to bone grafting or to create volume around an implant site. These materials can ‘plump’ out soft tissue to create a more natural emergence of a crown from the gum.
Materials of bovine origin are used which is gradually replaced by bone over a period of time. Collagen membranes of porcine (pig) origin are also used to cover the graft material. This excludes the soft tissues so enabling bone to grow in the protected space. Sometimes an inorganic hydroxyapatite material is used.
Biomaterials are excellent for repairing small defects in bone. They are not however recommended for replacing large deficiencies in of bone.
Benefits and Risks of Dental Implant Treatment
There is a risk of failure of approximately 1% to 5% depending on specific circumstances. Generally an implant can be replaced should it fail either at the same time or at a later stage, occasionally additional procedures may be required.
There is a risk of accidental damage to adjacent anatomic structures, such as teeth and sinus spaces although with accurate planning this should be avoidable. There is a low risk of failure of implants after the first year in function as long as health, both general and around the implant is maintained and no excessive forces are exerted. Excessive forces may result in some of the component parts fracturing.
Implants and teeth are subject to wear and tear as time goes on and, depending upon the amount of wear, the need to replace the crown may arise.
There is a risk of gum recession around the implants. Although this may not affect its survival it may require treatment for aesthetic reasons.
It is essential that the implants are monitored and maintained after completion of treatment and 3-6 monthly hygienist treatments are advised.