Three types of endosseous implants

The term implant refers to a medical device that replaces a missing body part. Implants, as the name implies, are placed or implanted inside the body and function much like the missing body part that it is replacing. Medical technology has advanced to the point where implants are commonly used to improve not only the physical well-being but also the quality of life of a vast number of patients. A good example of this is the use of an artificial hip joint to replace a painful, worn-out arthritic hip. 

Typically implants are constructed from materials that are biocompatible. Biocompatible materials are not recognized by the body as foreign and therefore, the body does not reject them. The term dental implantrefers to a dental device that is used to replace the root portion of a missing tooth or teeth. These artificial root replacements can then be used to support natural looking teeth that enable patients who are missing some or all of their natural teeth to smile and speak with confidence and to chew their food well and more comfortably.

Dental implants come in a variety of designs. However, the most common type of implants are threaded titanium cylinders that are placed into the jaw bones (Figure 1). Titanium is one of the biocompatible materials that is not recognized by the body's immune system and, therefore, allows dental implants to be placed without undergoing rejection.

Simply put, any person who has had the misfortune to lose one or more teeth, or even a part of the jaw bone, is a candidate for dental implants. This includes those individuals who have congenitally missing teeth (i.e., some or all or their teeth have been missing since birth). As an aside, if you fall into any of these categories you are not alone as it has been estimated that approximately 125 million Americans are missing one or more teeth for one reason or another!

Once we have established the absence of one or more teeth, as the basic criteria for placing dental implants, we must consider two additional factors that may ultimately affect the outcome of treatment.

First, patients need to be in a good state of health, and we would expect that any systemic illnesses or condition that may adversely affect healing is well under control. The diabetic patient, as an example, may be an acceptable candidate for dental implants provided that their disease process has been addressed, and they are carefully monitoring their medications and level of blood sugar. If not and the patient is unstable, then we would need to work with the patient's physician to correct the situation prior to proceeding with treatment. Any concerns that you may have regarding your medical history should be discussed with your doctor at a consultation appointment. 

Second, the patient must have enough high quality bone within which the implant(s) can be placed. Whenever a tooth is lost, bone in the surrounding area begins to remodel and slowly disappears. This physiological process is called resorption. Consequently, patients who have been missing teeth for a period of time may also present with resorption of the jaw bones. If the degree of resorption is slight then it is usually possible to place dental implants without any further treatment. However, if the resorption process is extensive there may be insufficient bone available to support the implant.

In the not too distant past patients who presented with insufficient bone were simply classified as non-candidates, and were left untreated. Fortunately we are now able to transform the majority of non-candidate patients, with deficient bony support in either the upper or lower jaw, into good candidates for dental implants with the use of a variety of simple grafting procedures. Often the grafting can be done in conjunction with the placement of implants in a single surgical procedure. This minimizes patient inconvenience and decreases the treatment time.

Some patients present with more significant bone loss and may require more extensive grafting procedures that need to be accomplished prior to the placement of implants. In any case, it is important to remember that almost any patient can receive dental implants as long as they are committed to treatment. Again, your doctor should discuss the necessity of any grafting procedures at the consultation appointment.

The actual process of placing the implant into the jaw involves two straightforward surgical procedures. These procedures are so simple that they are usually performed in the office with local anesthesia (Novocain or Lidocaine). The first procedure involves creating a precision channel in the jawbone into which the implant is firmly threaded. The implant then remains undisturbed for a period of two to six months. During this initial healing phase the surrounding bone heals tightly to the implant's surface giving it firm support. This healing process is termed osseointegration, which literally means bone connection.

The implant typically has a protective cover on it during this phase and the patient is only mildly aware of its presence. You can often wear your existing denture, a temporary crown or a bridge over the area while the healing takes place. Once the implant is firmly attached to the bone, the restorative process can begin. The surgeon or your restorative dentist will then select and place an abutment on the implant to which teeth can be attached (Figure 2).

At this point, the restorative dentist will fabricate the appropriate crown, bridge or denture type restoration. There are other special circumstances that also bear mentioning. For example, in some cases, an implant can be placed immediately into a tooth extraction site. The tooth site must be free from active infection and sufficient bone must be present to allow for initial stabilization of the implant. Here the advantage is that the overall treatment time is minimized. In most cases, however, the extraction socket needs to heal for anywhere between four to six months before implants can be placed.

Your doctor will discuss the specific sequencing of treatment in your case if you are a candidate. For those individuals who are very anxious or in situations where a lengthy procedure is anticipated, sedation is available and often encouraged. 

With all the recent advances in dental implantology, patients should expect their implants to remain in function for many years. The individual success rate for an implant is determined in part by a number of patient factors that may include the amount and quality of the existing bone when the implant was placed, the type of restoration and the patient's hygiene or maintenance program, to name a few.

Although implants are made of metal, they are not bulletproof and occasionally a problem may arise. Unlike natural teeth, however, if a dental implant needs to be removed it can usually be replaced once the bone in the area has healed. Once again, implants have proven to be a reliable treatment alternative for patients with missing teeth with the ability to significantly improve the patient's the quality of life while restoring their physical well being.