Dental Implants: Types, Benefits and Complications
Dental implant or “fixture” is an artificial anchor that is surgically placed into the jaw to support a prosthetic tooth. A dental prosthesis, such as crown, bridge or denture, is used to replace missing teeth.
Implants are highly compatible with the human body and are usually made of a special type of titanium alloy that the body does not usually reject as a foreign material. Titanium is extremely strong, resistant to corrosion from acids, salts or oxygen and is practically nonmagnetic. This means it does not interfere with magnetic resonance imaging (MRI).
Types of Dental Implants
The type of dental implant that is best suited for a particular patient will depend on various factors such as location of the implant, jawbone density or gums health and the type of tooth replacement that the implant will support (e.g., crown, bridge or denture). The most commonly used types of dental implants are endosteal (or endosseous) implants, which means they are placed inside the bone. The main types of endosteal implants include:
- Root form Implant is the most common form of dental implant and it 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 has specific advantages depending on the nature of the bone into which it is going to be placed. It can support a denture, crown or bridge but requires jawbone that is wide and deep enough to anchor the implant.
- Blade form Implant has been used for longer than the root form implant but it is not as popular. Instead of a cylindrical artificial root, a flat, rectangular metal structure (a kind of blade) 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, bridge or denture.
- Ramus-frame Implant is inserted in the bone of the back corners of the mouth and at the front, above the chin. A thin metal bar connects it, following the arch of the jaw. This bar is used to support a denture. Ramus-frame implants are recommended for patients with thin jawbones that will not support other types of implants. They also help to prevent the fracturing of a weak jaw.
The aforementioned endosteal implants are the most common but not the only types of dental implants we have. Two other types that may also be used in limited circumstances include:
- Subperiosteal implant is the oldest type of implant system but is no longer commonly used since the root form implants were developed. It is placed on top of the bone instead of inside it. The soft tissues grow over it and stabilize it. Subperiosteal implant can be used to support a crown, denture or bridge in patients with very shallow jawbone which cannot be rebuilt.
- Transosseous (or transmandibular) implant is inserted from the underside of the chin and through the jawbone. It is the only dental implant that requires extensive surgery under general anesthesia with hospitalization. The posts of the implant rise through the jawbone into the mouth where they are used to support a denture. Transosseous implant can only be used on the lower jawbone, especially in cases when there has been serious loss of bone. However, bone grafting followed by root-form implants is the preferred restoration method in patients with substantial bone loss.
Benefits and Potential Complications of Dental Implants
Replacing missing teeth is necessary to enable the patient to chew properly, avoid bone loss, and help them to form proper sounds in words as well as to maintain their original shape of the face.
Although dental implants are successful most of the time, they may occasionally be associated with various complications and may even fail. The failure usually occurs when the bone does not fuse with the implant. Sometimes, the bone may deteriorate from around the implant, causing it to loosen and fail. This may in some cases happen even years after the implant has been placed. Too much trauma experienced during surgery, periodontal disease, uncontrolled diabetes, an allergy to titanium, heavy smoking, habitually clenching or grinding the teeth or an infection following the surgery may also increase the risk of implant failure.
A good candidate for dental implants must be physically fully grown up and generally healthy with healthy gums. Patients with certain medical conditions, such as high blood pressure, immune system deficiency or haemophilia (as well as those mentioned in the previous paragraph), may not be good candidates for implants, although this depends on the severity of their condition. Furthermore, dental implants may not be recommended for patients taking corticosteroids or immunosuppressant medications or those receiving high-dose radiation therapy on the head or neck.