Tooth Replacement Using Dental Implants

An implant is an artificial tooth root that is surgically placed into the jaw bone. Implants provide support and stability for dentures and act as roots for artificial teeth. The best studied and most successful implants are titanium screw shaped implants and we use these. They are rather small (about ¼ inch diameter x ¾ inch long), but carefully designed, very strong and extremely well made.

Figure 1: Replacing teeth with implants involves three parts; the implant in bone, the abutment which passes through the gums, and the artificial tooth itself (above left). The components are made of titanium, a metal which is well tolerated by your body. They look like simple screws, but are carefully engineered and machined to high tolerances so the parts fit together and stay together well. All of the fixtures and abutments used are FDA approved devices and have undergone careful testing. The AstraTech implant and abutment pictured here (above right) are representative of current technology.

After titanium screw shaped implants are placed into the jaw bone by a gentle, simple and precise procedure, bone actually grows onto the implant. This process is called "osseointegration." We use osseointegrated implants. While there are other types of dental implants, their lower success rates and the complications reported discourage our using them.

Figure 2: The x – ray shows a successful AstraTech dental implant with an abutment and crown attached (most of the crown is invisible to the x – ray). Success is indicated by the direct contact of bone to the implant. The microscopic picture to (right) demonstrates the typical result of osseointegration. Healthy bone (purple and blue stained material) has grown directly onto the implant surface (black). There is the absense of inflammation or infection at the tissue / implant interface. This result takes several months to fully develop.

Because the dental implant is placed into the bone, it can only be placed in jaws that are of the sufficient size. Fortunately, this includes many people. But, some injuries and infections that cause tooth loss may also destroy the bone needed for successful implants. When there is not enough bone for implant placement, the periodontist or oral surgeon can create more bone by augmenting or grafting procedures.

Implants cannot be placed into the nerves in your lower jaw or into your upper jaw sinuses. Implants cannot be placed into existing infected areas or next to teeth with infections.

Figure 3: Dental implants can be placed in regions of the upper and lower jaws where there is sufficient dimension and quality of bone. The above panoramic x –ray shows the upper and lower jaws of an individual missing all teeth. Five AstraTech implants were placed in the lower jaw. The green arrow indicates the position of the nerve that must be avoided in the back of the lower jaw. The 6 AstraTech implants in the upper jaw are also surrounded by healthy, dense bone. They are placed away from the sinuses ( red arrow ). If teeth were present, the same restrictions and avoiding natural teeth must be observed.

Sometimes a dental implant can be placed immediately following tooth removal, but better results are often obtained when healing of the extracted tooth has been carefully monitored and directed. It is best not to wait a long time after extraction either. Bone is frequently lost after tooth removal and this decreases the amount of bone to support the implant. If your teeth were removed a long time ago, you are still a candidate for implants. Remember, enough bone can be created for many otherwise - deficient sites.

Figure 4: The placement of a dental implant after extraction must be carefully planned. Above left, the x –ray demonstrates that the single tooth AstraTech implant is not touching the roots of the healthy neighboring teeth and is oriented parallel with the natural teeth. The height of bone at the implant and the natural teeth is similar because bone resorption was prevented by careful tooth removal and ideal timing for implant placement. On the right, the abutment that will support the artificial tooth is emerging through healthy gums at the level of a natural tooth. This relationship is important for optimum esthetics.

Whether you are missing one tooth or all of your teeth, you can benefit from dental implants. Dental implants add health value to your existing oral health status. If you are missing only one tooth, the placement of an implant provides an esthetic replacement and prevents damage to the other teeth that can occur when conventional bridges are used.

Figure 5: After years of bonding a malformed tooth, this patient elected to have a single implant placed. Above left, the AstraTech abutment is seen through the gum four months after surgery. On the right, a all – ceramic crown is shown cemented onto the abutment after four weeks. This life – like restoration does not affect the adjacent teeth and is expected to function for many years.

If you are missing all of your teeth, dental implants support, retain and stabilize dentures. More importantly, they may prevent further bone loss associated with missing all of your teeth. You may chew better with implant - supported dentures than with conventional dentures. Without implants, lower dentures function poorly. Every patient missing all lower teeth should consider dental implants.

Figure 6: Often only two implants with simple ball attachments in the lower jaw are needed to dramatically improve denture function and comfort (above left). The denture clips onto the two ball attachments. Here, two AstraTech implants were placed in the dental office using local anesthetic. After healing, the abutments were placed and adapted to a complete denture made to provide excellent function and esthetics (above right).

Figure 7: Dentures can be replaced with artificial teeth that are not removed. These "fixed" dentures are placed on many ( 5 or more) implants per jaw (arrows, above left). The functional benefits can be great, however, they are difficult to clean and are much more expensive. They often can resemble natural teeth (above right).

If you are missing just a few teeth, implants will support the artificial teeth without needing to risk the other teeth in your mouth. In fact, a most gratifying use for dental implants is the replacement of a failed fixed bridge. In addition, one or two dental implants can also be used to retain a dysfunctional partial denture, often without replacement of the removable partial denture.

Figure 8: In this case, a fixed bridge failed and the remaining tooth roots were not restorable (arrows, above left). The tooth roots were extracted and allowed to heal. Then, three AstraTech implants were placed. After several months, the abutments were connected to the implants. An impression of the abutments was made and new porcelain bridge was made and cemented onto the implant abutments (arrows, above right). Following a proscribed time line for healing (see figure 13), function and esthetics were restored.

Implants are for all fully grown patients, irrespective of your age. Young teenagers are not good candidates for implants because their jaws may continue to grow and their teeth move for several years. Aging adults are frequently missing many of their teeth and are good candidates for dental implant therapy. Most diseases associated with aging are not absolute contraindications for dental implant therapy. What is important is a careful individual evaluation by the team of dentists contributing to your dental implant care.

Figure 9: When there is enough bone, implants can often be placed to prevent or replace the use of a removable partial denture. For this patient, a partial denture was not satisfying and implants were requested. The x – ray shows the successful placement of five AstraTech implants in the upper jaw of a patient missing all upper back teeth. Artificial teeth made from porcelain and gold alloy were placed on the implants to restore function and appearance.

In general, the titanium screw shaped implants are very successful. Your individual success depends on careful treatment planning, your health, your cooperation, and the status of the supporting bone for the implant. In places where there is dense and abundant bone (typically the front of your lower jaw), implants are most successful. In places where there is sparse and limited bone (often the back of your upper jaw), implants are least successful. However, even in these limited situations, dental implants are often placed with good results. If you are a smoker, the success of dental implants is greatly reduced.

Because dental implants are placed by a surgical procedure, there can be some pain. To everyone’s surprise, pain is not a major factor in the process of implant placement. Local anesthetic and sedation prevent discomfort during implant placement. The procedure is relatively short and is done in such a careful and precise manner that the procedure is not uncomfortable. Post - operative pain is frequently compared with having a tooth removed. Our patients are provided with medication to limit soreness and discomfort after surgery; many report not requiring any medication at all. Associated with the discomfort is the possibility of swelling and bruising. You probably will not return to work the day of surgery. Other time taken away from work is a personal decision.

When you leave the clinic after implant placement, we often ask that the temporary denture is not used for several days. In trying to achieve the best healing and least discomfort, keeping the temporary denture away from the implant site prevents pressure or actual displacement of the newly forming tissues.

In the rare event that an implant does not osseointegrate, this is not commonly associated with the complaint of pain. As healing progresses beyond the first week, symptoms of pain should be immediately reported to the periodontist, oral surgeon or prosthodontist. Pain is an uncommon event in the healing of dental implants.

It is safe to say that dental implants are not inexpensive. But, when 350 patients were surveyed after completion of their treatment, they stated that it was worth the investment and they would happily do it again.

When dental implant treatment was recently compared to conventional denture treatment, the mathematical analysis revealed that over several years, the cost was not dramatically different because of the many repairs, replacements and adjustments made to the conventional dentures (just ask yourself what you might spend over 5 years f or dental adhesive?).

When comparing the cost of a conventional fixed bridge to replace a missing tooth with the cost of a single tooth implant, the total cost for initial placement of the fixed bridge and the single tooth implant are not dramatically different. These simple financial comparisons do not consider important benefit and risk factors that favor the use of dental implants.

If you are interested in discussing the use of dental implants for replacement of one or more teeth or to dramatically improve the function of your denture, please speak with one of our graduate prosthodontics residents or faculty. The actual process is simple.

If you choose to be a dental implant patient, you are selecting a treatment that is associated with high probability of success and longevity. However the process of implant placement and restoration requires weeks of planning, months of healing and a life-time of follow - up care. Consider implant treatment in six stages:

1. Diagnostic phase - After a general assessment of your systemic health and a careful clinical oral examination, you can discuss possible treatment options that may or may not include implants. This first stage involves meeting with several different specialists. Should you be a candidate and have further interest in pursuing dental implant therapy, you should be prepared for a comprehensive examination by the prosthodontist that will include making casts of your teeth and jaws, taking special x-rays by the radiologist, and an initial consultation with a periodontist. If teeth need to be moved to allow for better implant placement and esthetics, then you will also meet with an orthodontist. Other preparatory visits may be required to remove decay, replace broken fillings and treat periodontal infections and gingivitis. While each meeting may be brief, it is likely that several trips are necessary to gather all of the useful information.

 

 

2. Planning phase - This second stage is the joint consideration of your medical and dental information obtained by history, examination, the measurement of casts of your teeth and x - rays. Together, the prosthodontist, radiologist, and periodontist or oral surgeon plans the best possible surgery and restoration for your individual needs. Any decay or periodontal disease will be treated before the next phase, implant surgery.



Figure 10: (Above) Implant placement must be carefully planned. First, the implant must be surrounded by healthy bone. Second, the implant and abutment cannot disturb the esthetics of the planned crown. Planning must include an x – ray that shows the location of the planned artificial tooth (white arrow) and the existing bone width (red arrow) and bone height (blue arrow). The estimated location of the gums is obtained too (pink arrow). This type of cross – section x –ray is called a tomogram.

 

 

3. Surgical phase - This third phase is the surgical placement of dental implants into sufficient bone for good implant function. If there is not enough bone, sometimes bone grafting can be performed. These grafting procedures must occur before the implant is placed and several months of healing is required. Otherwise, implant placement can occur in a typical dental chair using local anesthesia. Some anxious patients select sedation in addition to local anesthesia. Surgery for a single implant may take about an hour, while many implants require several hours of treatment time. Patients typically leave the office feeling well accompanied by a friend or family member. You will be given prescription for a special mouth rinse and may be given a prescription for an antibiotic. After a week or so, the dentist will evaluate the healing and remove any sutures.



 

Figure 11: (Above) Implant surgery is a very gentle and precise procedure. Often implants are placed in the jaw and covered with the gum to allow for undisturbed healing. Only after 3 – 6 months is the implant attached to an abutment for restoration with artificial teeth.

 

 

4. Healing phase - This fourth phase is very important. At least 3 months are required for adequate healing of bone at the dental implant (osseointegration) before the bone is actually strong enough to support chewing function. When there is less dense bone, surgeons require longer healing times. 6 months is not unreasonable for implants healing in lesser quality bone.

The implants heal in two ways, depending on the implant design. One type heals beneath the gums. The other heals in or through the gums (you can see it). In both cases, swelling and pain are not usually experienced after the first few days and even then, both swelling and pain are not greater than you may have experienced with a simple single tooth extraction.

 

 

5. Restorative phase - This fifth phase includes all the procedures needed to place a tooth or teeth onto your dental implants. After the implants are placed in bone, other titanium metal pieces must be attached to hold the artificial teeth. These parts are called abutments. If your implant was the type that healed beneath the gums, the abutment is placed through the gums and this requires a small injection of anesthetic. If your implant healed through the gums, the abutment might be placed directly without anesthetic.



Figure 12: A dental laboratory technician produces gold frameworks that are screwed onto the abutment. (above left) The framework can be covered by a typical porcelain bridge. The laboratory also assists in producing esthetic porcelain artificial teeth that can be screwed directly onto the implant abutment. (above right) Implant restorations can be characterized to be lifelike and match neighboring teeth.

 

During this phase, an impression will be made and a dental laboratory will assist the dentist in producing the artificial teeth. Your input is critical to achieving an excellent and pleasing result. However, implants are devices of fixed dimensions and compromise is sometimes needed.

The restorative phase is often completed in just weeks (for single teeth), but can take several months when many teeth are involved or difficulties are encountered. Every attempt is made to produce life - like artificial teeth that will last for many years; patience at this stage is a part of your successful treatment.



Figure 13: Summary and time line for dental implant therapy. Implant – supported artificial teeth can be placed only by following a recommended time line. If bone regeneration is necessary before implant placement, 3 – 12 months may be needed for complete bone healing. Implant placement can occur only after careful assessment of the individual situation and elimination of decay and periodontal disease. After this, implants are placed. Before abutments are placed and teeth restored, at least 3 – 6 months is recommended for healing of bone at the implant itself. For many individuals, implant treatment is at least one year process. Current research is focused on reducing this timeframe.

 

6. Life - long follow up phase - At the completion of your treatment, the treating team of dentists will provide detailed instruction in the process of cleaning your dental implant restorations. Special devices are often given to the patient and check ups are as important for implants as they are for natural teeth.

A number of important dental implant research activities are ongoing at the University of North Carolina. Several detailed investigations are occurring on benchtops in nearby laboratories. The outcomes of these studies may be more rapid and predictable healing of titanium implants in poor quality bone. However, there are also clinical studies that address the use of simplified surgical procedures for placement of implants to support lower jaw dentures. We hope to reduce complexity and cost of implant treatment so more patients needing implants can afford them. Another study is investigating the possibility of combining surgery and restorative procedures so that implant therapy can occur over weeks, not months. These studies have been extremely successful because of the generous participation of many individual patients who are our patients in the various clinics at the University of North Carolina School of Dentistry.

This presentation and many of the implant restorations presented here were, in part, supported by the University of North Carolina AstraTech Research Fellowship. This generous support of implant activities in the Department of Prosthodontics promotes the continued improvement of care for our patients. The implant restorations presented in figure 7 were produced by the 1995 AstraTech Implant Fellow, Dr. Paula Yliheikkilä. The implant restoration presented in figure 8 was produced and documented by the 1997 AstraTech Implant Fellow, Dr. Elin Sigurgeosdottir. These beautiful restorations represent the dedicated efforts of the laboratory technicians at the University of North Carolina School of Dentistry.