What are Dental Implants?
Dental implants may be thought of as replacement tooth roots. Although they are available in many shapes and sizes, depending on the specific problem to be solved, by far the most common type in use today is the “root-form” implant. Dental implants are among the most significant advancements in the history of dentistry for their versatility at replacing one tooth, several teeth — even all of the teeth.
Implants are a viable treatment option for most patients, regardless of how many teeth are missing.
The process of placing a dental implant
Before a dental implant is placed, your dentist will review your medical and dental history thoroughly to rule out any contraindications to the procedure. These are discussed more fully below. If you have replacement joints (for example, total knee replacement, hip replacement, etc.), you may be pre-medicated with specific antibiotics for the procedure. If you have certain types of heart murmurs or replacement heart valves, you may also need to take a specific antibiotic pre-medication prior to the procedure. Due to the risks and complications of infections with dental implants, your dentist may place you on antibiotic medication a day or two prior to the procedure, and for a week or so afterwards.
If you are anxious about dental procedures, your dentist may recommend sedating you for the procedure. There are several methods of relaxing patients for dental treatment, including oral anti-anxiety pills; inhaled anti-anxiety medication like nitrous oxide; and intravenous anti-anxiety medication. Your dental plan may not pay benefits toward sedation.
If you decide to be sedated with oral medication (pills), you will arrive at the dentist’s office with some degree of sedation already having taken effect. This may inhibit your ability to understand the “informed consent” paperwork you will be required to read and sign. Therefore, the dentist will likely have you read and sign the paperwork ahead of the surgical appointment. You will be given an opportunity to discuss any questions you may have ahead of time, so that you are not signing consent forms while under the effects of sedation. If you are sedated, you will also be required to have an escort to and from the dental office.
When you arrive at the dentist’s office for placement of the implant(s), you will rinse your mouth thoroughly with an antiseptic rinse, and wash your face with an antibacterial scrub.
If you are to be sedated by a method other than ingestion of a pill, the sedation procedure will be performed next.
Local anesthetic will be given in the area of implant placement, both to numb the surgical area and to minimize bleeding for good visibility of the implant site. Bleeding from an implant surgical site is normally insignificant anyway, but can be reduced even more by the vasoconstricting ingredients found in certain local anesthetics.
With traditional implant surgery, an incision through the gums is generally made, exposing the underlying bone. Implants are currently available which are designed to be placed without the need for an incision, but they are meeting with mixed success. Your dentist will be able to provide more information on such techniques.
A series of successively larger drills are used to establish and enlarge the hole into which the implant is placed. The hole is called the “osteotomy”. Depending on the type of implant being placed, and the density of the bone, a bone tap (thread forming device) may or may not be used to establish threads in the osteotomy. The implant is then inserted into the osteotomy. A “single-stage” implant is one that extends through the gums, and is not covered by them during the healing and osseointegration period (while the implant is fusing to the bone).
A “two-stage” implant (the traditional kind) will have a very thin cover screw inserted into the implant at the time of placement, and the gums will be closed over it with stitches (sutures). The cover screw keeps the gums from growing down into the center of the implant during the healing phase. Several radiographs may be exposed during the surgery, to allow your dentist to visualize the depth and angulation of the implant as it goes into place.
About four to six months after placement into the jaw (depending on the density of the bone and other factors), the implant will be ready to be restored. There are several variations on implant placement that your dentist will discuss with you. When the implant is ready to be restored, it is uncovered, and a temporary crown may be placed on the implant to sculpt the gums to proper shape. Crowns, fixed bridges and removable dentures are attached to implants by means of “abutments.”
Abutments can be made of white ceramic or metal. The abutment is attached to the implant with a retaining screw. Generally, silicone, wax, or other soft compound will be placed in the head of the retaining screw to keep cement from the crown from filling it. Crown cement dries extremely hard, and can be difficult to remove from the retaining screw if this step is not done.
In the case of single tooth replacement, the final crown will generally be made in a lab and cemented onto the abutment. Implant crowns can also be screw-retained, with the advantage of easy retrievability and the possible disadvantages of bulkiness and compromised esthetics. With screw-retained implants, the screw head extends through to the surface of the crown. Your dentist can help you decide which type would work best for you.
Some advantages and benefits of dental implants
Dental implants offer many advantages:
- They preserve the tooth-bearing (alveolar) bone.
- They avoid cutting healthy teeth to support fixed bridgework.
- They prevent drifting of adjacent teeth, preserving the patient’s normal bite.
- They restore normal chewing function.
- They can provide excellent cosmetic results.
- They are not susceptible to tooth decay (caries).
Potential disadvantages and risks of dental implants
The biggest disadvantage of dental implants is the amount of time that must elapse from surgical placement to placement of the final dental restoration. Typically three to six months are necessary to allow the implant time to heal (osseointegrate) into the bone, although the timeline can sometimes be reduced. In appropriate cases, an implant may be placed and restored with a temporary crown the same day, with an increased chance of the implant failing in the first two years.
Cost can be another concern with dental implants, although given their excellent track record for long term success, is usually justifiable.
Risks of placing dental implants into the jaws include the usual risks of having a surgical procedure accomplished: pain (usually mild), post-operative infection, bleeding, swelling, and bruising. Most people do not experience severe pain, swelling or bruising.
Depending on where in the jaws the implants are being placed, other risks may include nerve injury, resulting in partial to complete numbness (which may be temporary or permanent) of the tissues innervated by the injured nerve; sensory changes in the lip, chin or tongue; temporary muscle trismus (inability to open your mouth fully) secondary to swelling; jaw joint pain (normally temporary), and poor healing, which may result in loss of the implant. Most of these complications are avoidable by careful treatment planning and appropriate diagnostic imaging.
Dental implant failure
Although the failure rate of dental implants is low, failures do occur. What defines failure may not always be intuitive. The implant itself may break (very small chance) or may integrate into the bone in an un-restorable position. It may also integrate into the bone in a position that would provide non-ideal function or esthetics. Any of these situations may require surgical removal of the implant at a later date. Failure of the implant to integrate into the bone, while unfortunate and inconvenient is typically not complicated to resolve. In most such cases, the implant may be easily removed, the site grafted with bone, and another implant may be attempted (if desired by the patient), either at the time of implant removal, or two to four months later.
In general, two things cause implants to fail: Heavy bite stresses on the implant (especially if the implant(s) is/are placed into function too soon); and infection. Smoking reduces the prognosis for success with implants, mainly because it impairs good circulation that is essential to good healing and immune response. Bruxing (grinding your teeth) reduces the success rate of dental implants. Implants should not be placed in a patient with active periodontal disease. Poorly controlled diabetes and poor general health are two of the few medical contraindications to the placement of dental implants.
Bisphosphonate medication / radiation
If you take bisphosphonate medications, or have undergone radiation to the head or neck, you may not be a good candidate for dental implants without significant medical interventions. However, there are protocols for altering medications, and methods of avoiding jaw bone necrosis secondary to radiation which may allow dental implants to be considered. You should check with your dentist and primary care physician before ruling them out as an option.
Your unique dental and medical situation may introduce other specific risk factors which you should discuss thoroughly with your dentist and/or physician prior to undergoing implant dentistry. It’s important to understand the risks, benefits and consequences of not replacing your teeth before deciding with your dentist on the most appropriate course of treatment.
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