Dental implants are artificial substitutes for the root(s) of a missing natural tooth (Fig 1) or teeth. They may be used to support a single crown, a series of crowns, a removable partial denture, or a complete denture.

When Should Implants Be Used?

There are several situations where implants may be considered.
(1) To replace a single tooth;
(2) To replace several teeth in the same general area;
(3) To replace all the teath in a jaw.

1. To replace a single tooth
The most common method for replacing a single missing tooth is with a fixed bridge that is cemented to the teeth on either side of a missing tooth. With all fixed bridges the teeth adjacent to the space must be reduced to properly hold the bridge. The most conservative bridge is a Resin-Bonded Bridge (RBB), sometimes called a Maryland bridge(Fig 1-1). The resin-Bonded Bridge offers the advantage of minimal reduction of adjacent teeth to support the missing tooth. This type of bridge can only be used under certain circumstances.

A conventional bridge requires that the teeth on either side of the space be reduced in size to take room for crown which are then cemented onto the prepared teeth. The artificial replacement tooth is attached to these crowns prior to cementation(Fig 1-2). When properly maintained, the resin bonded bridge and the conventional bridge can last many years.

Implants can be considered to replace a single tooth(Fig 1-3). Often when the teeth on either side of the space are in good health, an implant may be the most conservative means of replacing the missing teeth because the adjacent teeth do not have to be reduced.

2. Replacement of several teeth in the same general area
When two or three adjacent teeth are missing, a bridge may be the treatment of choice depending on the condition of the teeth next to the space and the bone supporting these teeth. The more missing teeth to be replaced, the greater the force that is placed on the remaining teeth which support the artificial teeth(Fig 2-1).

In some cases, when there are not enough teeth, a conventional bridge is not possible and a removable partial denture will have to be considered to replace the missing teeth(Fig 2-2,3). A partial denture spreads the force to the adjacent teeth as well as to the underlying bone and gum tissue. A removable partial denture is less expensive than a conventional bridge. However, a partial denture is more bulky and less stable than a bridge and often times metal clasps will be seen when smiling. In some cases, the partial denture may cause deterioration of the natural teeth due to excessive forces.

When an implant is placed in the space where the teeth are missing, it can help by absorbing some of the load created by chewing forces and therefore make it easier for the adjacent natural teeth to withstand the forces. When an implant is placed in the space where the teeth are missing, a bridge may be considered instead of a removable partial denture(Fig 2-4,5).

3. Replacement of all the teeth in a jaw

The conventional method of replacing all the teeth in a jaw is with a complete denture(Fig 3-1). If the jaw bone does not provide sufficient support, sometimes surgical procedures can be done to improve support and retention for the complete denture. These surgical procedures can include moving the position of muscle attachments or placing bone grafts.

A complete denture rests on the gums. In the upper jaw it also rests on the roof of the mouth. In addition to chewing forces being spread over a larger area, forces that might tend to dislodge the denture are offset by a suction which forms between it and the roof of the mouth. This suction helps to keep the denture in place. Most people are able to adapt reasonably well to an upper complete denture. However, a lower complete denture is considerably more difficult to wear. The forces are applied over a smaller area and due to the movements of the tongue a suction usually cannot be developed.

The constant pressure on the gums under the dentures can cause slow changes in the underlying bone which result in the dentures losing their fit. For this reason complete dentures should be professionally examined at regular intervals, and when the tissues show sufficient change, the dentures should be relined, re-based, or re-made, depending on the specific conditions. When improperly fitted dentures continue to be worn, the pressure may result in excessive bone loss. Eventually, so much bone loss can occur that a well fitting complete denture can not longer be made. Under these circumstances, implants may be the treatment of choice.

Implants may be placed at selected sites to help retain a denture. The implants can be connected by a bar(Fig 3-2) or left standing along to give the denture the added retention required. In selected cases it may also be possible to attach a permanent bridge to these implants(Fig3-3).

Procedures Involved in Replacement of Missing Teeth With Implants

1. Diagnostic evaluation
In addition to the routine dental exam, an examination of your gum and jawbone will be performed. This may necessitate having special x-rays taken that will give a better indication of bone quantity and quality.

2. Surgical phase
If, after the diagnostic evaluation, it is determined that implants are a suitable treatment alternative, the case will move to the surgical phase. During the surgical phase the implants will be placed in the bone and then covered by the gum tissue.

The implants will remain covered for a period of three to six months as determined by the surgeon. When the healing phase is completed, the implants are uncovered and the dentist can begin to fabricate teeth on top of the implant. In some cases, the amount of bone available to place the implant needs to be supplemented using a bone graft.

3. Restorative phase
After uncovering, the implant is used as the foundation to restore the mouth to a functional state. This can be done in various ways as previously discussed:
1) A single tooth replacement
2) Replacement of several teeth in the same general area
3) Replacement of all the teeth in the jaw

4. Maintenance phase
After completion of the restorative phase, patients will be recalled at intervals determined by the implant team. It is recalled at intervals determined by the implant team. It is mandatory that patients follow the recall schedule, all oral hygiene instructions, and any special instructions given to them by implant team members. Failure to do so can lead to implant failure.

Risk
All surgical procedures pose risks. If surgery is proposed, the patient must weigh the risks versus the benefits before choosing to have the surgery performed. There is a risk of bruising or damaging adjacent nerves which are responsible for sensation to the lips, chin, gum, any remaining teeth and tongue. The change in sensation may vary from a tingling feeling to a hot or burning feeling or complete numbness. When the nerve is bruised, it is rare that the change in nerve sensation becomes permanent. However, temporary changes may last from a few months to a year or longer. When the sinuses are in close proximity to the surgical site a patient may develop a sinus perforation or an infection, especially when there is preexisting sinus disease.

In some cases, bone surrounding an implant may shrink away from the implant as the tissues are allowed to heal. This may result in the undesired exposure of a portion of the implant. In some cases, the exposed implant would need to be covered by bone and gum with additional surgical procedures. Rarely , the replacement of an implant may damage an adjacent tooth and the adjacent tooth may then require root canal treatment.

An implant may not heal well or adhere to the bone. As a result, the implant may need to be removed either during the healing phase or when the restorative phase has begun. Failure of an implant to heal properly may lead to a change in the restorative treatment plan.

The implant procedure can be performed under local anesthesia, sedation or general anesthesia, depending on the patient's medical history and anxiety level.

How long will an implant last?
Dental implants are made from dependable materials, almost pure titanium. The implants are engineered to withstand heavy forces with a considerable margin of safety. Therefore, fracture of an implant seldom occurs, but is possible when excessive forces applied. In many cases, if the forces applied to the implants are too great, the bone surrounding the implant begins to deteriorate. Three conditions can result in the loss of tissue around an implant. These are local conditions, systemic conditions, and overloading of the implant.

Local Conditions: Bacteria can accumulate around a dental implant just as they can around a tooth. When bacteria are allowed to remain around a tooth, the gum becomes infected and there is eventual destruction of the bone supporting the tooth. We call this process periodontal disease. This same process can occur around an implant. Therefore, the implant must be kept thoroughly cleaned.

Systemic Conditions: Any medical condition that prevents the body from repairing bone or other supporting tissues can result in the eventual loss of support for the implant. Certain medical conditions such as osteoporosis, collagen diseases, uncontrolled diabetes, frequent use of tobacco, excessive use of alcohol or drugs may result in early loss of an implant.

Overloading: When Excessive forces are applied to an implant, the implants are said to be overloaded. In some cases the bone can respond to the excessive forces and no damage to the implant or surrounding bone occurs. In other cases, the implant can fracture of the bone begins to resorb and the implant loosens. Certain habits such as grinding or clenching of the teeth, biting on pencils or pens, and gum chewing can apply excessive forces. Excessive forces can cause loosening or breaking of the screw that connects the bridge to the implant, fracture of the actual bridgework and possible loss of the implant.

Financial Obligation

As the implant materials are expensive, patients are required to pay half the surgical fee prior to the day of surgery and the remainder is due the day of surgery. For the restoration of the implants, half must be paid before the impression appointment and the remainder must be paid in full prior to final placement. Due to the high cost of implant parts and materials, we ask that you understand the need for us to request payment at these times.