Glossary

A facebow is a special instrument used by dentists when fitting a patient for dental prosthodontics. The facebow lines up with the patient exactly and allows the dentist or periodontist to accurately measure important parts of the patient’s facial structure, like the maxillary arch and its relationship to the temporomandibular joint, and transfer that data to where it can be used to create dental prosthetics. With the rise of computer-generated dental prosthetics, the facebow has been phased out by many dentists and periodontists and is no longer used to take important measurements. However, the facebow still plays an important role in transferring functional and aesthetic components from the mouth of the patient to the dental articulator. Without a facebow, the measurements taken by a dentist or periodontist may not be as accurate as they assume. This results in having to make multiple adjustments for the esthetics and occlusions later.

A facial prosthesis is a maxillofacial or craniofacial artificial replacement for a part of the face that is missing due to:

• Traumatic injury
• Surgical intervention for carcinoma-related lesions
• Congenital defects

Facial prostheses may include the use of a prosthetic mask. They can require prosthetic nose surgery to replace the affected facial features. A prosthetic facial mask can be used to replace more than one feature as well as larger portions of missing or damaged tissue on various parts of the face. A nose prosthesis has a more limited function as it only replaces the lost or damaged nose and surrounding tissue. Such prostheses can provide confidence for those who have been affected. Prosthesis training is required for those in the medical and dental professions to ensure patients are properly fitted. Prostheses can be attached to the affected areas in a variety of ways, with some requiring stabilizing or fixing with the support of specially-designed dental implants.

A facing is more commonly known in cosmetic dentistry as a veneer. They are most commonly used to achieve a perfectly straight, white smile and can restore the look of chipped, broken, cracked, stained, and gapped teeth. Veneers are thin pieces of porcelain that are used to recreate the surface of the teeth, or the “face.” Porcelain is preferable to other materials because it has a similar density and durability as natural tooth enamel, however, some veneers are crafted from resin. Resin is a similar material to composite, or “white” fillings. Each veneer is custom made to the shape of the tooth it will be placed on and is permanently bonded to the tooth with a special procedure. Veneers are not removable and require the surface of the natural tooth to be altered to place the veneer. Patients interested in veneers should discuss the benefits and risks of permanent tooth alteration.

Unfortunately, all dental implants carry a risk of failure and a periodontist’s primary job is to use a wide variety of available tools and techniques to reduce that risk. A dental implant can include one or more teeth, either separate or joined together. They are generally made out of alloplastic materials like titanium or titanium alloy, but ceramics, bioglass, hydroxyapatite, and aluminum oxides may also be used. Osseointegration, or fusing to the bone, is the measure of success for a dental implant and what material the implant is made from and its surface texture plays a significant role in that success. Other factors for dental implant failure include but are not limited to: the location of the implant in the mouth and its placement in bone; what kind of implant screw is placed over the implant body, and the type of abutment used and how it is placed.

Like any medical procedure, dental implants can fail. The failure rate of implants is low, with only about 5-10% of patients experiencing failure. Dental implant failure can be mitigated by taking into account factors of success. The chances of implant failure are higher in patients who have gum disease, who smoke, who have insufficient or weak jawbone, or who have conditions like diabetes or rheumatoid arthritis that can impede healing. Dental implant failure can occur early after the procedure or much later. Early failure factors include an infection at the surgical site, insufficient bone to support the implant hardware, allergic reaction, poor adherence to post-op instructions, and micromovements of the hardware. Late failure factors include tissue and nerve damage at the implant site, foreign body rejection, and injury to the face or jaw that physically dislodges the implant. Signs of failure include problems chewing, pain, swelling, and gum recession.

Dental implants can fail for several reasons, including lack of osseointegration (fusion to the surrounding bone) or peri-implantitis (a post-op infection causing inflammation of the surrounding bone and gum tissues). However, dental implant failure in the long term can be caused by what is known as the fatigue phenomenon. This phenomenon was first discussed in a 1964 article called General Principles for Fatigue Testing of Metals, published in the International Organization for Standardization. The article describes the changes that can occur to metal materials when under intense “cycles” of stress or pressure for a significant period of time. This is most applicable to implant dentistry when dental professionals are considering a dental implant for a patient with bruxism. Bruxism is the repeated grinding or clenching of the teeth, usually at night, that can cause teeth to crack or cause temporomandibular joint disorder (TMJ). Patients with bruxism are more likely to experience implant failure due to fatigue.