Implants

A typical implant consists of a titanium screw (resembling a tooth root) with a roughened surface. This surface is treated either by plasma spraying, etching or sandblasting to increase the integration potential of the implant.

Implant surgery is typically performed as an outpatient under general anesthesia by trained and certified clinicians such as an oral surgeon or periodontist. A single implant procedure takes about one hour, sometimes longer; multiple implants can be done in a single surgical session lasting several hours. At the conclusion of surgery, the patient goes through a period of recovery, returns to consciousness and is sent home with a spouse or friend.

Before surgery, with the patient fully awake or during an earlier office visit, a prudent clinician planning mandibular implants will conduct a neurosensory examination to rule out altered sensation, thus setting a base line on nerve function. Also prior to surgery, a panoramic X-ray will be taken using a metal ball of known dimension so that calibrated measurements can be made from the image (to locate “vital structures” such as nerves and the position of critical anatomical features such as the mental foramen).

At edentulous (without teeth) jaw sites, a pilot hole is bored into the recipient bone, taking care to avoid vital structures (in particular the inferior alveolar nerve or IAN within the mandible). A zone of safety, usually 2 mm, is the standard of care for avoiding vital structures like the IAN. When computed tomography (3D X-ray imaging) is used preoperatively to accurately pinpoint vital structures, the zone of safety may be reduced to 1 mm through the use of computer-aided design of surgical guides.

Drilling into jawbone usually occurs in several separate steps. The pilot hole is expanded by using progressively wider drills (typically between three and seven successive drilling steps, depending on implant width and length). Care is taken not to damage the osteoblast or bone cells by overheating. A cooling saline spray keeps the temperature of the bone to below 47 degrees Celsius (approximately 117 degrees Fahrenheit). The implant screw can be self-tapping, and is screwed into place at a precise torque so as not to overload the surrounding bone (overloaded bone can die, a condition called osteonecrosis, which may lead to failure of the implant to fully integrate or bond with the jawbone). Typically in most implant systems, the osteotomy or drilled hole is about 1mm deeper than the implant being placed, due to the shape of the drill tip. Surgeons must take the added length into consideration when drilling in the vicinity of vital structures.

Once properly torqued into the bone, a cover screw is placed on the implant, then the gingiva or gum is sutured over the site and allowed to heal for several months for integration to occur between the titanium surface of the implant and jawbone.

After several months the implant is uncovered in another surgical procedure, usually under local anesthetic by the restorative dentist, 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.