Dental Implants
..................................

Dental implants are artificial tooth replacements that are used to counter tooth loss. Crowns and conventional bridges or dentures may not be only options when replacing missing teeth. Dental implants offer a smile that looks and feels very natural. Surgically placed below the gums over a series of appointments, implants fuse to the jawbone and serve as a base for individual replacement teeth, bridges or a denture.

Candidates for dental implants need to have healthy gums and adequate bone to support the implant. A thorough evaluation by dentist will help determine whether you are a good candidate for dental implants.

Advantages of Implant Dentistry

Dental implants are stronger and more durable than their restorative counterparts (bridges and dentures). Implants offer a permanent solution to tooth loss. Additionally, implants may be used in conjunction with other restorative procedures for maximum effectiveness. For example, a single implant can serve to support a crown replacing a single missing tooth. Implants can also be used to support a dental bridge for the replacement of multiple missing teeth, and can be used with dentures to increase stability and reduce gum tissue irritation.

Procedure

A typical implant consists of a titanium screw (resembling a tooth root) with a roughened surface. Implant surgery is typically performed with local anesthesia.

A single implant procedure that involves an incision and "flapping" of the gum or gingiva (to expose the jawbone) takes about half an hour, sometimes longer; multiple implants can be installed in a single surgical session lasting few hours.

Healing and integration of the implant(s) with jawbone occurs over several months in a process called osseointegration. At the appropriate time, the restorative dentist or prosthodontist uses the implant(s) to anchor crowns or a prosthetic restoration containing several "teeth". Since the implants supporting the restoration are integrated, which means they are biomechanically stable and strong, the patient is immediately able to masticate (chew) normally.

There are different approaches to place dental implants after tooth extraction. The approaches are:

1. Immediate post-extraction implant placement.
2. Delayed immediate post-extraction implant placement (2 weeks to 3 months after extraction).
3. Late implantation (3 months after tooth extraction).

After several months the implant is uncovered in another surgical procedure, usually under local anesthetic, and a healing abutment and temporary crown is placed onto the implant. This encourages the gum to grow in the right scalloped shape to approximate a natural tooth's gums and allows assessment of the final aesthetics of the restored tooth. Once this has occurred a permanent crown will be fabricated and placed on the implant.

An increasingly common strategy to preserve bone and reduce treatment times includes the placement of a dental implant into a recent extraction site. In addition, immediate loading is becoming more common as success rates for this procedure are now acceptable. This can cut months off the treatment time and in some cases a prosthetic tooth can be attached to the implants at the same time as the surgery to place the dental implants.

In all of these approaches, computer-based guidance has thrust itself onto the treatment stage. Not only will 3D digital imagery yield critical treatment guidance, the digital data can be used to manufacture precision drilling guides, virtually eliminating surgical errors.

Complementary procedures

Sinus lifting is a common surgical intervention. Surgeon thickens the inadequate part of atrophic maxilla towards the sinus with the help of bone transplantation or bone expletive substance and as a result creates a better quality bone site for the implantation.

Bone grafting will be necessary in cases where there is a lack of adequate maxillary or mandibular bone in terms of front to back (lip to tongue) depth or thickness; top to bottom height; and left to right width. Sufficient bone is needed in three dimensions to securely integrate with the root-like implant.

Typically, surgeons try to place implants at least as deeply into bone as the crown or tooth will be above the bone. This is called a 1:1 crown to root ratio. This ratio establishes the target for bone grafting in most cases. If 1:1 or better cannot be achieved, the patient is usually advised that only a short implant can be placed and to not expect a long period of usability.

A wide range of grafting materials and substances may be used during the process of bone grafting / bone replacement. They include the patient's own bone (autograft), which may be harvested from the hip (iliac crest) or from spare jawbone; processed bone from cadavers (allograft); bovine bone or coral (xenograft); or artificially produced bonelike substances (calcium sulfate with names like Regeneform; and hydroxyapatite or HA, which is the primary form of calcium found in bone).

Correctly performed, a bone graft produces live vascular bone which is very much like natural jawbone and is therefore suitable as a foundation for implants

Considerations

For dental implant procedure to work, there must be enough bone in the jaw, and the bone has to be strong enough to hold and support the implant. If there is not enough bone, more may need to be added with a bone graft procedure discussed earlier. Sometimes, this procedure is called bone augmentation. In addition, natural teeth and supporting tissues near where the implant will be placed must be in good health.

Treatment planning software can also be used to demonstrate "try-ins" to the patient on a computer screen. Software products like Materialise' SimPlant (simulated implant) use the digital data from a CAT scan (such as an iCAT or a NewTom) to provide extremely accurate simulations that are easily understood by patients. When options have been fully discussed between patient and surgeon, the same software can be used to produce precision drill guides.

Success rates

Dental implant success is related to operator skill, quality and quantity of the bone available at the site, and also to the patient's oral hygiene. Various studies have found the 5 year success rate of implants to be between 90-95%. Lower posterior implantation has the highest success rate for all dental implants.

Failure

Dental implants may fail for a number of reasons. The cause is often related to a failure in the osseointegration process. For example, if the implant is placed in a poor position, osseointegration may not take place. Dental implants may break or become infected (like natural teeth) and crowns may become loose.

Dental implants are not susceptible to dental caries but they can develop a periodontal condition called peri-implantitis. The cause may be infection that was introduced during surgery; or failure by the patient to follow correct oral hygiene routines. In either case, inflammation in the bone surrounding the implant causes bone loss (recession) which ultimately may lead to failure, often evidenced by the ability to "spin" an implant.

Risk of failure is increased in smokers.

Contraindications

There are no absolute contraindications to implant dentistry, however there are some systemic, behavioral and anatomic considerations that should be considered.

Lack of sufficient alveolar bone is contraindication to the procedure. Typically, a preoperative in-office panoramic X-ray is taken to establish (with allowances for image distortion, a known problem with panoramic X-rays) in two dimensions (height and width) the amount of available bone. A bone graft or augmentation procedure, sometimes called guided bone regeneration may be performed and allowed to heal several months before implantation surgery. A new panoramic X-ray will help determine if the graft was successful.

Uncontrolled type II diabetes is a significant relative contraindication as healing following any type of surgical procedure is delayed due to poor peripheral blood circulation. Anatomic considerations include the volume and height of bone available. Often an ancillary procedure known as a block graft or sinus augmentation are needed to provide enough bone for successful implant placement.

Implants are contraindicated for some patients who take intravenous bisphosphonates. The many millions of patients who take an oral bisphosphonate (such as Actonel, Fosamax and Boniva) may be advised to stop the administration prior to implant surgery, then resume several months later. The American Dental Association has addressed bisphosphonates in an article entitled "Bisphosphonate medications and your oral health," JADA, Vol. 137, page 1048, July 2006. In an Overview, the ADA stated "The risk of developing BON [bisphosphonate-associated osteonecrosis of the jaw] in patients on oral bisphosphonate therapy appears to be very low...". The ADA Council on Scientific Affairs also employed a panel of experts who issued recommendations [for clinicians] for treatment of patients on oral bisphosphonates, published in June, 2006. The overview may be read online at ada.org.

Bruxism (tooth clenching or grinding) is another contraindication. The forces generated during bruxism are particularly detrimental to implants while bone is healing; micromovements in the implant positioning are associated with increased rates of implant failure. Natural teeth contain a periodontal ligament allowing each tooth to move and absorb shock in response to vertical and horizontal forces. Once replaced by dental implants, this ligament is lost and teeth are immovably anchored directly into the jaw bone. This problem can be minimized by wearing a custom made mouthguard at night.

Dental İmplants(You will be redirected to "www.aaoms.org" web site)