Dental Implants – Types, Risks and benefits

Dental Implants

Also called: Tooth Implants

Reviewed By:
Kenneth Cheng, D.D.S.

Summary

An implant is an anchor for a prosthetic tooth or teeth (e.g., crown, bridge, denture) that is surgically placed in the jaw. It becomes fused with the jawbone as the bone heals around it. Implants are most commonly made of titanium, a special type of metal that bone fuses to and does not reject as a foreign body.

Implants are used to replace missing or lost teeth. A missing tooth can affect the jaw and lead to bone loss. It may also affect surrounding teeth by causing them to shift and affect a person’s bite.  People with missing teeth may also have difficulty chewing or be dissatisfied with their appearance. Bridges and dentures are also used to take the place of missing teeth.

Before implants can be placed, the patient will need to undergo a comprehensive oral examination to determine if he or she is a good candidate for the procedure. The dentist will evaluate the patient’s medical and dental history. Good candidates must be generally healthy and must be old enough that the jawbones have finished developing. Their gums must be healthy to ensure the success of the implants and they must practice diligent oral hygiene.

Implants require multiple surgeries and appointments spread out over months. The first surgery is performed to place the implant in the jawbone. Then the bone is allowed to grow around and fuse with the implants, firmly anchoring them. The second surgery takes place three to eight months later, depending on the bone’s growth and fusion around the implant. In this surgery, an abutment that will support the restoration is attached. However, in some cases, the abutment is attached to the implant when it is initially placed, condensing the two-step process into a single step (single step). Finally, the restoration (e.g., crown, bridge, denture) is attached to the implant.

Implants are anchored in the bone, so restorations using implants generally do not involve neighboring teeth for support, which can place stress on them. This also means that the neighboring teeth may not need to be cut down and crowned. It may also help to reduce or eliminate costly re-fitting and adjustments. However, they can be expensive and may not be covered by insurance. The surgeries involved in placing implants may be associated with various complications, such as bleeding and infection.

While implants are successful the vast majority of time, they may occasionally fail. If the implant is loose or becomes loose, it is considered to have failed and will be removed. The dentist may attempt to immediately insert another implant or may graft the area with bone chips to allow it to heal before making another attempt. Practicing diligent oral hygiene, refraining from smoking and seeing a dentist regularly for dental examinations and cleaning can help to reduce the risk of implant failure.

About implants

An implant is an artificial tooth root that supports a prosthetic tooth or teeth (e.g., crown, bridge, denture). It is surgically placed in the jaw, where it becomes fused with the jawbone as the bone heals around it in a process called osseointegration. Implants have a high rate of success and have become increasingly more common in modern dentistry. However, they cost more than traditional reconstructions due to the degree of surgery and materials involved.

Implants are used to replace missing or lost teeth with stable, well-anchored, natural-looking artificial teeth. Replacing missing teeth is important for a number of reasons. The teeth are necessary to chew properly and help form the sounds in words. They also help to establish and maintain the shape of the face.

Missing teeth can place increased stress on the jaw that can lead to problems with the muscles and the temporomandibular joint (jaw joint). Finally, teeth preserve the positions of neighboring teeth. If a tooth is missing, the nearby teeth may move into the open area. A missing tooth can affect the jaw and lead to bone loss. People with missing teeth may also be dissatisified with the appearance of their mouth. Bridges and dentures are also used to take the place of missing teeth.

Implants are highly compatible with the human body and are most commonly made of titanium, a special type of metal alloy that the body does not usually reject as a foreign material. It is extremely strong, resistant to corrosion (e.g., from acids, salts, oxygen) and is practically nonmagnetic. This can be important for a number of reasons. For instance, patients with nonmagnetic implants can usually undergo magnetic resonance imaging (MRI) with fewer problems regarding resolution or safety. However, it is important to inform hospital staff of any implants before undergoing imaging tests (e.g., x-ray, MRI, CAT scan).

The surface of the implant is generally rough. This creates more surface area for bone to bond to. It may be coated with hydroxyapatite, which is a substance found in natural bone. Scientists are also researching other substances for coating implants, such as special proteins that further encourage osseointegration.

Good candidates must be generally healthy and must be old enough that their jawbones have finished developing. Their gums must be healthy to ensure the success of the implants and they must practice diligent oral hygiene. Both before and after the implants are placed, the patients must see a dentist regularly for a dental examination and cleaning.

Clenching or grinding the teeth can place too much stress on the implants, so patients who habitually do either are not good candidates. Similarly, patients who smoke, drink excessive amounts of alcohol or abuse other substances may not be good candidates for implants. All of these habits can increase the risk of implant failure.Patients with certain medical conditions (e.g., diabetes, high blood pressure, hemophilia, immune deficiency) may also not be good candidates, although this depends on the severity of their condition. Implants may also not be recommended for patients receiving high-dose radiation therapy on the head or neck or those taking corticosteroids or immunosuppressant medications.

Types and differences of implants

There are several different types of implants. The type that is best for a particular patient can be determined by an oral surgeon, periodontist or dentist. The type chosen will also depend on the type of tooth replacement that the implant will support (e.g., crown, denture, bridge). The most commonly used types of implants are endosseous (also called endosteal), which means they are placed inside the bone. The main types of endosseous implants include:

  • Root form. This is the most common form of dental implant. A root form implant is placed into the jaw like the root of a tooth. Some are cylindrical in shape, with threads like a screw, while others are smooth. Some are straight walled while others are tapered. Each type of implant may have specific advantages depending on the nature of the bone into which it will be placed. It can support a crown, denture or bridge, but requires bone that is wide and deep enough to anchor the implant.
  • Blade form. Instead of a cylindrical artificial root, a flat, rectangular metal structure with posts rising from one side is inserted into the jawbone. It may have one or multiple posts, which serve as abutments to support a crown, denture or bridge. It is not as popular as the root form implants.
  • Ramus-frame. These implants are inserted in the bone of the back corners of the mouth and at the front, above the chin. A thin metal bar connects them, following the arch of the jaw. This bar is used to support a denture. Ramus-frame implants can be used with thin jawbones that will not support other types of implants. They also help to prevent the fracturing of a weak jaw.

While these types of implants are the most common, they are not the only types that may be used. Two other types of implants may also be used in limited circumstances:

  • Subperiosteal. This type of implant is placed over the bone (on top of it) instead of inside it. The soft tissues grow over it and stabilize it. It can be used to support a crown, denture or bridge, but is no longer commonly used since the root form implants were developed. This was a popular implant system before the advent of root form implants.
  • Transosseous. Also called transmandibular. This form of implants is inserted from the underside of the chin and through the jawbone using extensive surgery that typically requires general anesthesia and hospitalization. The posts of the implants rise through the jawbone into the mouth, where they are used to support a denture. It can only be used on the lower jawbone. Transosseous implants can be used when there has been serious loss of bone. However, bone grafting followed by root-form implants are the preferred method.

Before the implant procedure

Implants require a team composed of a surgeon (e.g., oral and maxillofacial surgeon, periodontist) and a restorative dentist (e.g., general dentist, prosthodontist). The surgeon is responsible for placing the implants while the restorative dentist is responsible for the crown, bridge or denture that the implant supports.

Before implants can be placed, the patient will undergo a comprehensive oral examination to determine if he or she is a good candidate for the procedure. The dentist will evaluate the patient’s medical and dental history. X-rays and sometimes a computerized axial tomography scan (CAT scan) will be ordered to evaluate the condition of the jawbone and the location of nerves and sinuses.There are also a number of surgeries that may be performed prior to placing implants, depending on the individual needs of the patient. For example, patients must have the proper bone structure in the jaw to support the implants. Bone grafting may be used to increase the bone available in the jaw in patients with insufficient bone mass. Inferior alveolar nerve transposition may be used to move a nerve that may be in the way. Maxillary sinus lifts may allow the surgeon to avoid drilling into low-set sinus cavities.

During and after the implant procedure

Implants may require multiple surgeries and appointments spread out to allow for plenty of time to heal and adjust. The entire process can take nine months or more. Individual surgeries can take one to several hours, depending on factors such as the type of implant used, how many implants are being placed and if any other procedures (e.g., tooth extraction) are occurring at the same time.

The surgery to place the implant in the jawbone may occur in the dental office or in a hospital. It may be performed under local anesthesia, intravenous (I.V.) sedation or, in some cases, general anesthesia. During this surgery, an incision is made in the gums and a hole for the implant is drilled into the bone. The implant is inserted and x-rays may be taken to ensure that it is properly located. Then, a cover screw is placed over the implant and the gum tissue is sutured (stitched) over the implant and bone. The stitches may be resorbable, which means that they dissolve into the gum, or they may need to be removed. If they need to be removed, this usually occurs around 7 days after the surgery.

The area will be sore and the gums will be tender and swollen after the surgery. Dentists generally prescribe pain medication to ease this discomfort. Antibiotics may also be prescribed to prevent infection. The patient will need to eat soft foods while the gums are healing and the area needs to be treated very gently. It is typically recommended that the patient does not attempt to clean the immediate area for a week or two while it heals. Dentists may provide an antibacterial rinse to help with oral hygiene and generally advise the patient against spitting, drinking with straws or smoking. Patients may be given a temporary bridge or denture to wear so that they do not have to be without teeth during the healing process.

The next surgery takes place from two to six months later, after the jawbone has fused with the implant, firmly anchoring it. In this surgery, the abutment that will support the restoration is attached. This surgery is less invasive than the first, but still requires  local anesthesia. An incision is made in the gum to expose the head of the implant. Then, the cover screw is replaced with a healing abutment, which protrudes above the gum. This allows the gum to heal in the correct shape around the abutment before the crown, bridge or denture is attached. Since this is not as extensive as the surgery to place the implant, the patient will typically feel less discomfort. However, the dentist will still usually prescribe pain medications and recommend soft food during the healing process.

Lately, some surgeons have been using a one stage technique where a healing abutment is attached to the implant at the time of insertion, thereby eliminating the need for a second uncovering procedure. After a period of healing, the restoration (e.g., crown, bridge, denture) is attached to the abutment. Sometimes, the restoration is immediately attached to the implant (immediate loading)  but this may not be feasible in all cases

If the implant appears to be loose during this surgery, it is considered to have failed and will be removed. The dentist may attempt to immediately insert another implant (after widening the hole in the bone slightly) or may seal the area to allow it to heal before making another attempt.

Patients with implants should continue to have regular dental examinations and be diligent about their oral hygiene. With such maintenance, implants can last a very long time.

Risks and benefits of implants

Implants are anchored in the jawbone, instead of on neighboring teeth. This makes them more stable and secure and increases strength and comfort. It may also help to reduce or eliminate costly re-fitting and adjustments. Since they incorporate no metal clasps or hooks, they look and feel like natural teeth. They can be cleaned like natural teeth, without additional solutions or brushes. It may also be easier to speak or chew with implants than with dentures, which can translate into better nutrition and satisfaction. Finally, implants help retain the jawbone over time because they are fused to the bone like natural teeth.

However, implants have disadvantages. They can be very expensive and may not be covered by insurance. The surgeries involved in placing implants may be associated with various complications, such as bleeding and infection. During drilling, the surgeon may pass through the jawbone and into sinus or nasal cavities, increasing the risk of infection. Also, a nerve that runs along the lower jawbone may be injured during drilling, resulting in pain or numbness that may be temporary or permanent. However, nerve damage is not common.

While implants are successful the vast majority of the time, they may occasionally fail. This generally occurs when the bone does not fuse with the implant. It is typically discovered during the second surgery, when the implant is uncovered to attach the abutment. If the implant is loose at this point, it is considered to have failed and will be removed. The dentist may attempt to immediately insert another implant (after widening the hole in the bone slightly) or may seal the area to allow it to heal before making another attempt.

In some cases, the bone may deteriorate from around the implant, causing it to loosen and fail. This may even occur years after the implant has been placed. The risk of failure is greater in patients who smoke or have diabetes, especially uncontrolled diabetes. If too much trauma occurred during surgery or an infection set in following the surgery, the implant may also fail. Some patients may have an allergy to titanium, the material that most implants are made from, although this is extremely rare. Patients with periodontal disease, including those who developed the disease after the implants have been placed, also have an increased risk of implant failure. Practicing diligent oral hygiene and seeing a dentist regularly for dental examinations and cleaning can help to reduce the risk of implant failure.

Questions for your doctor regarding implants

Preparing questions in advance can help patients to have more meaningful discussions regarding their treatment options. Patients may wish to ask their doctor the following implant-related questions:

  1. Am I a good candidate for implants?
  2. How high is my risk for implant failure?
  3. What type of implant is best for me?
  4. Will I need to undergo any other surgeries, such as a bone graft, before getting implants?
  5. What type of dental restoration, such as crowns or dentures, will my implants support?
  6. How can I care for this type of restoration?
  7. How long will the implantation process take?
  8. Will I have to go without teeth while my gums heal? If so, for how long?
  9. What type of pain medications will I be given after the surgery?
  10. When can I resume my normal diet following surgery?
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