Costa Rica Implant Dentistry


Dental implants are an artificial tooth root replacement and is used in Prosthetic Dentistry to support restorations that resemble a tooth or group of teeth. There are several types of dental implants. The major classifications are divided into osseointegrated and fibrointegrated implants. The most widely accepted and successful type today is the osseointegrated implant. Titanium can be successfully fused into bone when osteoblasts grow on and into the rough surface of the implanted titanium. This forms a structural and functional connection with the living bone. A variation on the procedure is the implant-supported bridge or denture. The composition of a typical implant consists of a titanium screw (resembling the root of a tooth) with a roughened or smooth surface. The majority are made out of commercially pure titanium and it is believed to offer similar Osseo integration levels as pure titanium. Today, most are still made out of commercially pure titanium, but some may be fabricated out of the alloy. Implant surfaces may be modified either by plasma spraying, anodizing, etching or sandblasting to increase the surface area and the integration potential.

Implants Surgery

Surgery may be performed as an outpatient under general anesthesia, oral conscious sedation, nitrous oxide sedation, intravenous sedation or under local anesthesia by trained and certified clinicians including general Implantologists and prosthodontists. The legal training requirements for dentists who carry out such treatments differ from country to country.

Surgical planning

Prior to commencement of surgery, careful and detailed planning is required to indentify vital structures such as the inferior alveolar nerve or the sinus, as well as the shape and dimensions of the bone to properly orientate the implants for the most predictable outcome. In most instances, a panoramic x-ray or a CT Scan will be obtained to plan the case. Whether CT-guided or manual, a 'stent' may sometimes be required to facilitate proper placement. A surgical stent is an acrylic wafer that fits over the teeth, the bone surface or the mucosa (when all the teeth are missing) with pre-drilled holes to show the position and angle of the implants to be placed. The surgical stent may be produced using stereolithography following computerized planning of a case from the CT scan.

Basic procedure

In its most basic form the placement of osseointegrated implants requires a preparation into the bone using either hand osteotomes or precision drills with highly regulated speed to prevent burning or pressure necrosis of the bone. After the proper amount of time to allow the bone to grow on to the surface of the implant (Osseo integration) a tooth or teeth can be placed on top. The amount of time required to place an implant will vary depending on the experience of the practitioner, the quality and quantity of the bone and the difficulty of the individual situation. At edentulous (without teeth) jaw sites, a pilot hole is bored into the recipient bone, taking care to avoid the vital structures (in particular the inferior alveolar nerve or IAN and the mental foramen within the mandible). 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). A cooling saline or water spray keeps the temperature of the bone to below 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 osteo necrosis, which may lead to a failure to fully integrate or bond with the jawbone). Typically in most implant systems, the osteotomy or drilled hole is about 1mm deeper than the device being placed, due to the shape of the drill tip.

Healing time

The amount of time that practitioners allow for healing before placing a restoration varies widely. In general, practitioners allow 2–6 months for healing, but preliminary studies show that early loading may not increase early or long term complications. If the implant is loaded too soon, it is possible that it may move and result in failure. The subsequent time to heal, possibly graft and eventually place a new device may take up to eighteen months.

One-stage and two-stage surgery

When implants are placed either a healing abutment, which comes through the mucosa is placed or a 'cover screw' which is flush with the surface where its located. When a cover screw is placed the mucosa covers the implant while it integrates then a second surgery is completed to place the healing abutment. Two-stage surgery is sometimes chosen when a concurrent bone graft is placed or surgery on the mucosa may be required for esthetic reasons. Some implants are one piece so that no healing abutment is required. In carefully selected cases patients can be treated in a single procedure called "Immediate Loading". In such cases a provisional prosthetic tooth or crown is shaped to avoid the force of the bite transferring to the implant while it integrates with the bone.

Immediate placement

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. However, the chances of the implant failing in these cases may be as high as 50%.

Use of CT scanning

When computed tomography, also called cone beam computed tomography or CBCT (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 and production of a surgical drilling and angulation guide.

Considerations

For dental implants procedures to work, there must be enough bone in the jaw, and the bone has to be strong enough to hold and support the device. If there is not enough bone, more may need to be added with a bone graft procedure, also referred-to as bone augmentation. Also natural teeth and supporting tissues near the implant’s location must be in good health.

In all cases careful consideration must be given to the final functional aspects of the restoration, such as assessing the forces which will be placed on the implant. Implant loading from chewing and parafunction (abnormal grinding or clenching habits) can exceed the biomechanic tolerance of the implant bone interface and/or the titanium material itself, causing failure. This can be failure of the implant itself (fracture) or bone loss, a "melting" or resorption of the surrounding bone.

The dentist must first determine what type of prosthesis will be fabricated. Only then can the specific device requirements including number, length, diameter, and thread pattern be determined. The procedure must be reverse engineered by the restoring dentist prior to the surgery. If bone volume or density is inadequate, a bone graft procedure must be considered. The implant surgeon makes his own plan or relies upon advanced computer-assisted tomography or a cone beam CT scan to achieve the proper treatment plan.

Computer simulation software based on CT scan data allows virtual implant surgical placement based on a barium impregnated prototype of the final prosthesis. This predicts vital anatomy, bone quality, implant characteristics, the need for bone grafting, and maximizing the implant bone surface area for the treatment case creating a high level of predictability.

The success rate of dental implants is related to doctor’s skill, quality and quantity of the bone available at the site, and the patient's oral hygiene. The general consensus of opinion is that implants carry a success rate of 95%. One of the most important factors that determine implant success is the achievement and maintenance of implant stability. The stability is presented as an ISQ (Implant Stability Quotient) value. Other contributing factors to the success of dental implant placement, as with most surgical procedures, include the patient's overall general health and compliance with post-surgical care.

The failure of dental implants is often related to failure to Osseo integrate correctly. The procedure is considered a failure if it is lost, mobile or shows peri-implant (around the implant) bone loss of greater than 1.0 mm in the first year and greater than 0.2mm a year after.

Dental implants are not susceptible to cavities but can develop a condition called peri-implantitis. This is an inflammatory condition of the mucosa and/or bone which may result in bone loss and eventual loss of the implant. The condition is usually, but not always, associated with a chronic infection. Peri-implantitis is more likely to occur in heavy smokers, patients with diabetes, patients with poor oral hygiene and cases where the mucosa around the implant is thin.

Risk of failure is higher in smokers and are recommended only after a patient has stopped smoking, as the treatment is expensive. More rarely, an implant may fail because of poor positioning or may be overloaded initially causing failure to integrate. If smoking and positioning problems exist prior to implant surgery, clinicians often advise patients that a bridge or partial denture may be a better solution.

In the majority of cases where implants fails to integrate with the bone and is rejected by the body the cause may be unknown and can occur in about 5% of cases. Many theories have been postulated over the last five decades and the most recent theory argues that rather than being an active biological tissue response, the integration of bone with an implant is the lack of a negative tissue response. Thus for unknown reasons the usual response of the body to reject foreign implanted objects does not function correctly with titanium implants. It has further been postulated that an implant rejection occurs in patients whose bone tissues actually react as they naturally should with the 'foreign body' and reject the implant in the same manner that would occur with most other implanted materials.