Dental Anatomy: Face Bow Overview

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Questions and Answers

What is the purpose of adjusting the condylar rods on the maxillary face-bow?

To enhance the aesthetic design of dentures.

To create a mold of the patient's teeth.

To ensure equal calibrations and slight tension. (correct)

To measure the patient's jaw width.

When using the ear piece face-bow, where should the ear pieces be placed?

On the external auditory canal. (correct)

On the top of the patient's head.

On the cheekbone.

On the patient's nose bridge.

Why may face-bow orientation not be necessary for most complete denture cases?

It is always less accurate than traditional methods.

It complicates the denture fabrication process.

The occlusal vertical dimension is unchanged. (correct)

Patients commonly report discomfort with face-bows.

What is the effect of using a face-bow during denture fabrication?

It minimizes errors in maxillary cast orientation. Signup and view all the answers

How do arbitrary face-bows achieve their accuracy?

By utilizing facial and anatomical landmarks. Signup and view all the answers

What factor influences the need for interocclusal records when programming the condylar inclination?

The type of occlusal scheme used. Signup and view all the answers

What is the maximum distance the articulator hinge axis can be from the true hinge axis using an arbitrary face-bow?

6 mm. Signup and view all the answers

What benefit does the use of a face-bow in the denture process provide?

It simplifies the articulating of the maxillary cast. Signup and view all the answers

What is the primary function of an articulator?

To simulate different mandibular movements Signup and view all the answers

Which class of articulator is capable of accepting three-dimensional dynamic registrations?

Class IV articulator Signup and view all the answers

What characterizes a Class II articulator?

It permits horizontal and vertical motion without joint orientation Signup and view all the answers

Which articulator type does NOT accept a facebow?

Class I articulator Signup and view all the answers

What is a primary feature of simple hinge articulators?

They consist of upper and lower members held apart by a screw Signup and view all the answers

The mean value articulator is based on average measurements recorded by which of the following?

Bonwill's measurements Signup and view all the answers

In a Class III articulator, what type of path does it simulate for the condyles?

An average path using mechanical equivalents Signup and view all the answers

What is the primary movement limitation of a Class I articulator?

It only allows vertical motion without horizontal orientation Signup and view all the answers

What is the primary function of a face bow in dentistry?

To record the relationship between the maxilla and the rotational axis of the mandible. Signup and view all the answers

Which component is NOT part of the kinematic face bow?

Graduated condylar rod Signup and view all the answers

What is the purpose of the infra-orbital pointer in the maxillary face bow?

To relate the base plate and occlusion rim to the horizontal plane of the articulator. Signup and view all the answers

Which of the following describes an arbitrary face bow?

It is used to record the relationship between the maxilla and the mandible arbitrarily. Signup and view all the answers

What is the key difference between kinematic and arbitrary face bows?

Kinematic face bows are used for locating the terminal hinge axis, while arbitrary ones do not require this. Signup and view all the answers

In the context of the maxillary face bow, what does the bite fork do?

Records the relationship between the maxilla and the mandible. Signup and view all the answers

What anatomical landmark is used to position the condylar rods in the arbitrary face bow technique?

The tragus of the ear. Signup and view all the answers

Which component is unique to the kinematic face bow compared to arbitrary types?

Two pointed condylar rods Signup and view all the answers

What is the role of the Bonwill triangle in relation to the articulators?

It is used to mount the upper cast. Signup and view all the answers

How is the angle of the horizontal condylar path adjusted in a semi-adjustable articulator?

Using a protrusive record. Signup and view all the answers

What is the function of Hanau's formula in the context of adjustable articulators?

To adjust the lateral condylar guidance. Signup and view all the answers

What is a distinguishing feature of fully-adjustable articulators compared to semi-adjustable ones?

They can adjust both horizontal and lateral inclinations based on patient records. Signup and view all the answers

What additional record is required to adjust the left lateral condylar path inclination in a fully-adjustable articulator?

Right lateral record. Signup and view all the answers

What does the term 'incisal guidance plate' refer to in the context of semi-adjustable articulators?

A mechanism that can be modified for different patients. Signup and view all the answers

What does the term 'condylar path' refer to in the context of articulators?

The path followed by the condyle during jaw movement. Signup and view all the answers

Which of the following articulators allows for precise adjustments using a variety of patient records?

Fully-adjustable articulator. Signup and view all the answers

What is a primary reason for the use of an articulator in complete denture patients?

To assist in achieving proper occlusal and esthetic placement of artificial teeth. Signup and view all the answers

Why is extreme accuracy in programming articulators difficult for complete denture patients?

The record bases rest on movable tissues. Signup and view all the answers

What is the importance of indexing casts before mounting them on an articulator?

It allows for the accurate replacement and removal of the cast. Signup and view all the answers

Which of the following statements about occlusal errors in dentures is correct?

Remounting procedures are important for correcting occlusal errors after curing. Signup and view all the answers

During the mounting of master casts on a fixed condylar path articulator, what should be aligned with the incisal indicator pin?

The midline of the occlusion rim. Signup and view all the answers

What role does a separating medium play during the mounting of casts?

It allows for easy removal of the cast. Signup and view all the answers

Why are complex articulators not indicated for the treatment of edentulous patients?

They require higher accuracy than necessary for these patients. Signup and view all the answers

What is the purpose of temporarily fixing the wax rim to the occlusion plane table?

To ensure alignment before applying the separating medium. Signup and view all the answers

Study Notes

Face Bow

Definition: A caliper-like device that records the relationship between the maxilla and the rotational axis of the mandible. It then transfers this relationship to the articulator.
Types
- Mandibular Face Bow (Kinematic Face Bow): Used to locate the exact terminal hinge axis before using the maxillary face bow. Consists of:
  - U-shaped bow
  - Clamp - attaches the bow to the mandible.
  - Universal joint - attaches the clamp to the bow.
  - Two pointed condylar rods - attached to the bow.
  - Two screws - used to adjust the position of the condylar rods.
- Maxillary Face Bow (Arbitrary Face Bow): Records the relationship between the maxilla and the rotational axis of the mandible.
  - Consists of a U-shaped bow, a bite fork (attached to the bow), and condylar rods.
  - Types of maxillary face bows:
    - Facial Face Bow: Uses facial landmarks for orientation.
    - Ear Piece Face Bow: Uses the external auditory canal as a posterior reference point.
  - Orientation on Patient's Face: Condylar rods are positioned 13 mm in front of the tragus on a line called the canthus-tragus line.
  - Orientation on the Articulator: The bite fork is placed on the articulator aligning the condylar rods with the articulator's condylar housing.

Articulators

Definition: A mechanical device that represents the temporomandibular joints (TMJs) and jaw members. Maxillary and mandibular casts are attached to it to simulate different mandibular movements.
Types
- Simple Hinge Articulator (Plain Line Articulator): A simple holding device that allows for vertical movement but no horizontal movement.
- Mean Value Articulator (Average Value Articulator): Simulates condylar pathways using average measurements. Has a fixed condylar path angle of 33 degrees.
  - Examples: Gysi Simplex Articulator
- Adjustable Articulator: Allows for customization based on patient-specific records.
- Semi-Adjustable Articulator: The horizontal condylar path is adjusted using a protrusive record, and the lateral condylar path is adjusted using Hanau's formula.
  - Examples: Hanau (Model H) Articulator, Denar 5a
  - Hanau's Formula: Determines the lateral condylar path: L=H/8+12 (where L is the lateral condylar path and H is the horizontal condylar path).
- Fully-Adjustable Articulator: All horizontal and lateral inclinations are adjusted using patient-specific records.
  - Examples: Hanau Kinoscope, Dentatus Articulator, Denar 2
Mounting the Master Cast on the Articulator:
- The cast is positioned with the midline of the occlusion rim aligned with the incisal indicator pin and the midline marker on the articulator.
- Cast is placed on the occlusion plane table and secured with wax until the mounting process.

Benefits of Using a Face Bow and an Articulator

Accuracy: While not perfectly replicating the TMJ movement, articulators provide sufficient accuracy for most cases, improving denture placement, occlusal harmony, and esthetics.
Mobility: Using an articulator is preferable to making final occlusal adjustments solely intraorally, as dentures rest on movable tissues.
Easier Adjustment: Face bows and articulators simplify the procedure by providing a stable platform for adjusting occlusal schemes, especially for complete denture cases.
Occlusion: Articulators aid in proper occlusal schemes with balanced and nonbalanced techniques.

Indexing the Cast

Indexing allows for accurate remounting of the cast to the articulator for adjustments.
It is achieved with grooves, notches, or remounting plates.

Conclusion

Articulators are fundamental tools in complete denture fabrication. Though not perfect replicas of the TMJ, they provide necessary accuracy for proper denture placement and occlusal adjustments.

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Description

Explore the functionality and types of face bows in dentistry. This quiz covers the relationship between the maxilla and the mandible, detailing both mandibular and maxillary face bows. Test your knowledge on their components and uses in dental practice.