Use of Facebow in Fabrication of Complete Denture

Use Of Facebow in Fabrication Of Complete Denture

Question. Define the face bow, and its use, and enumerate the steps in the use of a face bow in complete denture fabrication.
Answer:

Face-bow is a caliper-like device that is used to record the relationship of the jaws to the temporomandibular joints or the opening axis of the jaws and to orient the casts in this same relationship to the opening axis of the articulator.

Complete denture fabrication Uses Of Face-Bow

1. When cusp-form teeth are used.
2. When balanced occlusion in the eccentric positions is desired.
3. When a definite cusp fossa or cusp tip-to-cusp incline relation is needed.
4. Interocclusal check records after face-bow transfer aid in verifying of jaw positions.
5. If the occlusal vertical dimension is changed and the alterations of tooth occlusal surfaces are necessary to accommodate the change.

Read And Learn More: Complete Dentures Question and Answers

Complete denture fabrication  Face-Bow Transfer Procedure

Complete denture fabrication  Preliminary Steps

1. The patient’s head should be in an upright position and well-supported.
2. Mark on skin or on adhesive tape the axis points by measuring 12 mm anterior to the middle of the tragus of the ear on a line drawn from the outer canthus of the eye to the middle of the tragus of the ear.
3. Contour the maxillary occlusion rim, establish the occlusal plane, mark the point of low lip line on the occlusal rims, and a mounting index on the occlusal surface in the regions of the first molars.
4. Apply a thin layer of petrolatum to the occlusion rims to facilitate separating from the wax on the bite fork.
5. Reduce the mandibular occlusion rim to allow space for the fork and attached wax.
6. Adjust the condyle rods to the face for centering the bow by placing the ends over the marked points on the skin. Secure either the right or left condyle rod; lock and remove the bow from the face.

Complete denture fabrication  Face-bow Record

1. A 6 mm thick horseshoe-shaped soft baseplate wax is rolled together and the prongs of the bite fork are embedded in it.
2. Fold the wax over at the margins to secure it to the fork.
3. Place the prongs of the bite fork with the attached soft wax between the occluding surfaces of the occlusion rims. Adjust the midline of the fork to coincide with the midline on the occlusion rim. Extend the stem of the fork forward and parallel to the sagittal plane.
4. Slide the stem of the fork through the opening in the clamp of the bow and adjust the width of the condyle rods equidistant bilaterally and secure the clamp of the bow to the stem of the bite fork.
5. Slide the condyle rods from the skin. Extend the condyle rods back to the axis points to countercheck.
6. If the infraorbital notch is used as the anterior point of reference, the infraorbital notch is located and marked. Place the point of the pointer over the mark and secure the clamp to the pointer. Remove the assembly from the face and allow the wax to set hard before removing the bite fork and face-bow record from the occlusion rims.

Complete denture fabrication  Face-bow Mounting

1. Set the sliding condylar rods symmetrically on both sides over the articulator condyle shaft.
2. Raise or lower the face-bow to adjust until the low lip line, which was recorded on the labial surface of the occlusion rim, is on a level with the groove marked around the incisal pin.
3. Adjust the infraorbital pointer to touch the pointer plate attached to the maxillary bow of the articulator.
4. Support the face-bow securely in position with the face-bow support.
5. Soak the maxillary cast in water for at least five minutes.
6. Secure the incisal guide pin with its top flush with the top of the maxillary bow of the articulator. Open the maxillary bow of the articulator and apply dental plaster to the top of the articulator until the incisal guide pin is stopped on the guide table and the mounting plate on the maxillary bow is embedded in the plaster.
7. Remove the excess plaster. After the plaster hardens remove the face-bow assembly. The maxillary cast is related to the opening axis in the articulator in the same anteroposterior and horizontal position as the maxillae in the skull are related to the arbitrarily located opening axis in the temporomandibular joints.
8. When the record bases, occlusion rims, and interocclusal relations are satisfactory a tentative centric relation record with the jaws at the vertical dimension of occlusion is made and other records as right and left lateral records and protrusive records are made later.