Chapter 9: Articulators and face bows

Question 1

What is an articulator?

Answer 1

It is a mechanical instrument that stimulates mandibular movement.
It relates the lower model to the upper model in its exact position, which will have been transferred due to the face bow.

Question 2

The articulator reproduces the lower teeth’s displacement concerning the upper ones. True or False

Answer 2

True

Question 3

What does the face bow allow?

Answer 3

The orientation of the upper model similarly as it is related to the base of the skull

Question 4

What are the 3 types of articulators?

Answer 4

• Not adjustable
• Semi-adjustable
• Fully adjustable

Question 5

Not adjustable articulator characteristics:

Answer 5

• Hinge type: very inaccurate
• Fixed guidance articulators:
  Opening/closing and laterality
  Inaccurate because the condylar guidance cannot be adjusted

Question 6

Semi-adjustable articulator characteristics:

Answer 6

• It admits a face bow
• It allows adjustment and individualisation
• They reproduce condylar movements in a straight line

Question 7

What is the articulator that is not acceptable?

Answer 7

The not adjustable articulator

Question 8

What is the most commonly used articulator?

Answer 8

The semi-adjustable articulator

Question 9

Classification of condylar mechanism:

Answer 9

1. Arcon type:
   - Condylar spheres at the lower frame (same as the patient)
   - Mechanical glenoid fossa attached to the upper frame
   - Most semi-adjustable and fully adjustable
2. Non-Arcon type:
   - Condylar spheres at the upper frame
   - Mechanical glenoid fossa at the lower
   - Lower accuracy reproducing CPI

Question 10

Fully adjustable articulator characteristics:

Answer 10

• Kinematic face-bow –> locate the actual hinge axis
• They are adjusted with a pantograph

Question 11

Requirements for an articulator:

Answer 11

• Accept a face bow
• The articulator must be rigid and stable and have a defined and safe position for CR in opening and closing
• Adaptable condylar mechanisms
• Adjustable incisal stem that allows changes in the VD
• Adjustable incisal table –> Customise the anterior guidance
• It should have an adjustable intercondylar distance

Question 12

What are the objectives of the articulator?

Answer 12

1. Diagnosis:
   - Evaluate the occlusal status
   - Mounting in CR
2. Planning:
   - The necessity of selective occlusal grinding
   - Diagnosis waxing-up
   - Design
3. Performing:
   - Manufacture of different prostheses

Question 13

Indicate if the information is true or false regarding the non-adjustable articulator:

1. They cannot be adjusted so they are inaccurate
2. They reproduce the mandibular biodynamic properly
3. They only reproduce the MI
4. They are correct in opening and closing

Answer 13

1. True
2. False, they do not reproduce the mandibular biodynamic properly
3. True
4. They are not correct in opening and closing

Question 14

Advantages and disadvantages of a non-adjustable articulator:

Answer 14

Advantages:
- Cheap
- Less mounting time

Disadvantages:
- Poor occlusal result