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A face bow is a tool used in dentistry to determine the positional relationships of the jaws and teeth, and can also refer to an appliance worn by patients to correct bite or jaw problems. It consists of a U-shaped frame, condylar rods, bite fork, and locking mechanism. There are two types of face bows: arbitrary and kinematic. The corrective facebow acts as a splint to hold the jaw and teeth together and is useful for correcting crossbites. It should be worn for 12 hours a day and secured to the headgear for safety reasons.
In dentistry, a face bow can refer to two tools or appliances. One is a tool used by dentists to determine positional relationships, such as for the production of dental casts. A second meaning of the term is an appliance worn by patients to correct bite or jaw problems. This type of facebow is also often called a headdress, referring to the headgear that holds the facebow in place.
Tool that determines the positional relationship of the jaws to the jaw joints
A facebow is an external metal instrument used in dentistry to precisely record the relative positions of the jaws, bones of the upper jaw, against the joints in the jaw called the temporomandibular joints. A dental facebow is typically made from aluminum or thick stainless wire. This bow-shaped, caliper-like device measures the bite character of the patient. It is then detached to transfer the fused impressions of the teeth to an articulator, which makes crowns, bridges and dentures.
A dental facebow determines the relationship between the upper teeth and jaw joints by representing two planes. The plane of the skull is represented by the U-shaped frame, while the fork of the bite represents the plane of the jaw. In order for the planes to be set and angled precisely, the locking device is inserted. Correct alignment of the device is essential for the articulator to obtain accurate impressions of the teeth.
The two types of facebow tools are arbitrary and kinematic. Arbitrary face bows include plank type, ear type, and spring bow type. Other subtypes include slidematic, twirlbow and whipmix. The kinematic type is also called the hinge type. It is used to create fixed partial dentures and for full mouth rehabilitation.
There are four parts to a facebow device: the U-shaped frame, the condylar rods, the bite fork, and the locking mechanism. The frame is the metal arch that holds the entire device up. The condylar rods are inserted into the ends of the frame and anchor it to the jaw joints. The fork of the bite is a U-shaped plate attached to the rims. A rod connecting the fork to the frame acts as a locking device.
Appliance worn to correct bite or jaw problems
A corrective facebow, or headpiece, acts as a splint to hold the jaw and teeth tightly together. The device allows for the transfer of tension from the dental headgear to the teeth through the use of straps attached to the facebow headgear. It is useful for correcting crossbites by pushing the back section or molars far enough back to create extra space for the teeth in the front of the mouth.
Typically, a facebow or headgear is required to be worn 12 hours a day. For safety reasons, it is important to ensure that the facebow is secured to the headgear. The headgear ensures that the instrument is inserted securely inside the buccal holes in the back of the mouth. If the device is bent or twisted, the frame or wire may break and injure parts of the face, such as the eyes.
