This section provides a general introduction to the use of dental implants in individuals with hypodontia. The techniques described do not include every variation which may be employed in a given situation.
The use of dental implants has been attempted for many centuries with little long-term success, however in the mid 1900s the discovery in Sweden of the ability of titanium to bond to living bone revolutionised the procedure.
Modern dental implants can, in appropriate circumstances, be inserted into regions of the jaw where there are no teeth to provide a long-term anchorage for fixed or removable prosthetic replacements. They are typically precision tapered screws made from commercially pure titanium. Their designs are manufacturer specific and comprised of a system of components and instrumentation designed to aid surgical insertion and subsequent restoration.
Natural teeth attach to the surrounding bone via a periodontal ligament (PDL). This is made up of thousands of fibres which fasten the cementum (a layer of bone-like tissue covering the root) to the jaw bone and act as shock absorbers for the tooth, which is subjected to heavy forces during chewing. The PDL is not only capable of change as the face and jaw grow, but it also allows for tooth movement as teeth react to naturally applied forces, for example when eating, or those applied in orthodontic treatment.
In contrast, dental implants attach directly to the bone and are incapable of movement. This can result in significant potential problems if they are placed in a growing jaw or near to developing teeth, which may have their growth and eruption affected.
Treatment using dental implants in appropriate circumstances has revolutionised the management of hypodontia. Remember however that inserting implants is not in itself treatment but only a part of a treatment journey involving many factors, typically over an extended period. It is not a cure for every dental problem, and certainly not instantaneous.
Factors which are important in potential treatment with implants include:
1 The patient’s current and projected oral problems?
2 Whether the oral problems can be optimally treated with crowns, bridges and removable prostheses rather than implant stabilised prostheses?
3 The patient and carer’s wishes and consent to treatment are crucial and should be based on a detailed discussion with the responsible clinician who must ensure that the patient and carers are fully informed. A range of treatment options are usually available, and the patient and carers may not at that time necessarily choose the most complex, for example implant treatment. It must be remembered that in the UK minors are able to provide consent to treatment provided the clinician considers that they are sufficiently mature and able to understand and agree to what is being proposed. This obviously has increasing significance in the case of older minors.
Treatment of hypodontia may extend over many years, especially where implant treatment is planned, and must therefore be considered when deciding how best to proceed.
4 While there are few general health conditions which preclude implant treatment or increase the risk of treatment failure, this does need to be considered and is one of the reasons for taking the patient’s medical history.
5 There is an ongoing professional debate concerning the use of dental implants in children who are still growing and has been increasing interest in using these devices in younger age groups. Many clinicians subscribe to the general principle that implants may be placed in the front of the lower jaw at a younger age provided there are no other teeth. It should, however, be noted that in these circumstances the amount of bone at potential implant sites is often reduced and the bone is harder than normal, making implant insertion and subsequent healing more challenging. Implant placement in the upper jaw and other areas of the lower jaw should be deferred until skeletal maturity at roughly age 21 years.
The reason we say to wait for growth is because natural teeth move, grow and shift their positions as the jawbone continues to grow, whereas dental implants can’t move as they are fused in one position to the bone. Should an implant be fitted into a jawbone that is not fully mature then, as the jaw continues to grow, the implants would appear to sink and get left behind the neighbouring teeth which grow harmoniously together with the jaw bone. Therefore, as with most things in life, timing can be everything.
Each patient’s needs will be reviewed on a case-by-case basis so that the optimal time can be determined to place implants while maintaining self-esteem which is usually 16-18 in girls and 18-21 in boys, with the exception of the edentulous (lacking teeth) lower jaw as described above. However, the good news is that there are some temporary tooth replacement techniques available until the timing is right for implants.
6 Treatment is driven by a patient’s oral problems, the impact which the problems have on them, and their wishes as to how they should be managed. These can embrace a wide spectrum from enthusiasm for complex treatment involving a number of dental specialities to a wish for little or no active treatment of their hypodontia, although accepting the need for maintenance of the existing dentition. Where treatment could include the use of dental implants then this would be factored into discussions.
7 Potential implant sites in the jaws need to be:
- Suitably located in the dental arch.
- Appropriately shaped to enable optimal implant positioning and orientation.
- Sufficiently large to accommodate an implant of an adequate size.
- Have suitable bone quality and gum quality.
- Provide enough space for the placement of teeth (a superstructure) on the implant.
During the consultation and planning stage, the dental surgeon will visually examine the site in the mouth where dental implants are being considered as well as look at x-rays, panoramic films, and/or CT scans to assess the quality and quantity of jawbone to determine if more bone is needed at the site. Lack of jawbone is typical in individuals affected by Ectodermal Dysplasia who have many missing teeth. In these circumstances bone grafting may be required.
Bone can be harvested from a number of sources, sometimes it is taken from the hip or shinbone (tibia), but usually from behind the back teeth in the lower jaw or from the chin to provide a scaffold into which new bone will grow in order to be ready to receive dental implants a few months later.
A bone graft not only replaces lost bone, it also stimulates the jawbone to regrow and eventually replaces the bone graft with the patient’s own, healthy bone. Some patients do not have sufficient baseline bone to allow successful bone grafting, some patients may not be suitable for grafting at all and some may need multiple grafts to gain enough bone.
When there is not enough bone height in the upper jaw, or the sinuses are too close to the jaw for dental implants to be placed, a sinus lift, that is lifting the floor of the sinus, will be required. This is done by gently pushing up the lining membrane of the sinus from the jaw and packing bone graft material into the space created. Once the bone graft material has fully integrated with the jawbone, implants can be placed.
New bone can take anything from three to twelve months before it is ready to receive dental implants. Do not be in a hurry to move to the next stage. If you need a large volume of bone it will take longer to mature than a small amount.
8 Implant treatment is expensive as it requires specially trained staff, expensive components and typically extended treatments. There can also be ongoing maintenance costs. Currently funding is available in the NHS however, it is perhaps wise to consider the possible implications of evolving funding schemes.
Once adequate, strong bone is present, the site is ready for the implants. At the implant placement appointment, the dental implant (titanium post) is placed into the bone with a special drill and tools. A “healing cap” is placed over the implant, the gum is stitched up, and the healing phase begins. During this healing phase, usually a temporary denture can be made to replace missing teeth for aesthetic purposes. The healing time depends greatly on the quality of bone present and is usually anywhere from two to six months. During this time, the implant becomes integrated with the bone. It’s important to avoid placing any force or stress on the dental implant as it heals.
After the required healing period, the dental implant is tested to determine whether it has been successfully taken up by the surrounding bone. Once this has been confirmed, a prosthetic component, which can be fixed or removeable, is connected to the dental implant via a screw. This component is called an “abutment.” It will serve to hold the replacement tooth or “crown.” The dentist will take an impression (mould) of this abutment in the mouth and have the implant crown, fixed or removable prosthesis custom-made to fit. An implant crown or bridge is either cemented on or secured with a screw(s) to the abutment(s). After review of implant placement success, the impressions to make the teeth are needed. Depending on the complexity of the implant supported teeth multiple appointments may be needed which can take two to six months to complete.
Restored dental implants require regular professional review at typical intervals of 6-12 months, although these vary with individual circumstances. Your dentist will need to check the health of the tissues around the implants as well as the integrity of the superstructure, which may need adjustment. It is also essential that patients maintain scrupulous oral hygiene around their devices, and keep any implant stabilised removable prostheses clean so as to minimise the risk of infections. Any untoward performance of an implant restoration, such as pain or looseness, must be reported to your dentist at once. Where appropriate dental implants can provide dramatic results, however they are definitely not ‘fit and forget’ items!
Take a look at the article “Clinical advice on treatment with dental implants in HED”
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