Facebow

Question 1

What are facebows

Answer 1

Facebows are devices that record the relationship of the maxillary teeth to the position of the condyle concerning the distances in the horizontal and sagittal planes

Question 2

What is the function of the facebow

Answer 2

allows the relationship (the relationship between the upper arch to the condylar axis) to be transferred to the articulator while mounting the maxillary cast

Question 3

When are facebows used

Answer 3

when restoring a surface that is involved in guidance with an indirect restoration so as to ensure that we don’t create interferences

Question 4

What are the 2 types of facebows

Answer 4

dentitus
denar

Question 5

What is a dentitus facebow

Answer 5

It is used from an arbitrary hinge axis position that is 13mm along an imaginary line from the tip of the tragus of the ear to the outer canthus of the eye

Question 6

What is a denar facebow

Answer 6

The one we were taught how to use in PCS

Used within the external auditory meatus which is on average 6mm of the true hinge axis position

Denar slidematic facebow has a glide mechanism that allows the facebow to open and close along the axis

Question 7

What are the components required for the denar facebow

Answer 7

o Reference plane pointer
o Bubble level
o Slidematic u-shaped earbow
o Dentate bitefork
o Transfer jig
o Mounting shoe
o Reference plane locator
o Marker pen

Question 8

What are the 13 steps to recording the facebow registration

Answer 8

1. Locating and marking a reference point on the patient’s face
2. Trying the dentate bitefork on the patient’s upper teeth
3. Loading the upper surface of the bitefork with a suitable bite registration material
4. Placing the bitefork with the bite registration material on the patient’s upper anterior teeth
5. Stabilise the fork by instructing the patient to hold it steady using the thumbs
6. Engaging the transfer jig in the earbow
7. Engaging the earbow into the patient’s ears
8. Raising or lowering the bow so that the pointer aligns with the anterior reference point on the patient’s face
9. Ensure that numbers 1 and 2 are correct way up and facing you
10. Looking at the patient from the front, verify that the bow is horizontal to the horizon and the patient’s pupils
11. Slide open and remove the entire assembly, transfer jig and bitefork from the patient & detach the earbow from the transfer jig assembly
12. Transfer jig after detachment from the earbow (no picture
13. Trimming regiration material on the fork after disinfection

Question 9

How do we locate and mark the reference point on the px face

Answer 9

Anterior reference point is recorded 43mm from the incisal edge of the lateral/central incisor towards the inner corner of the eye

the notched out area of the reference plane locator is used to make this measurement

Question 10

How do we try the dentate bitefork on the px

Answer 10

Bite-fork arm should be on patient’s right
Fork should be placed against upper teeth aligning centreline with bite fork index notch to orientate it correctly and ensure it is parallel with the horizontal and coronal planes

Question 11

What do we use for the bite registration

Answer 11

rigid silicone bite registration material

Question 12

Why should rigid silicone be placed on the upper and under surface of the bite fork

Answer 12

to prevent the registration coming off the fork during disinfection/transportation

Question 13

What do we achieve when taking the bite registration

Answer 13

a light indexing impression of the maxillary teeth

Question 14

How do we engage the transfer jig in the earbow

Answer 14

Attach vertical shaft to the bow and make sure the flat surface of the jig is facing the patient

Tighten the finger screw to secure the vertical shaft to the measuring bow and to avoid any movement

Ensure number 1 and 2 are the correct way up and facing the operator

Question 15

How do we engage the earbow in the patient’s ears

Answer 15

Put earbow in patient’s ear using their help

Pull earbow together and tighten centre wheel

Ensure even placement in both ears

Question 16

How do we align the bow with the anterior reference point on the patient’s face

Answer 16

Tighten centre wheel on bow
Loosen finger screw on anterior reference pointer
Raise or lower bow so pointer aligns with anterior reference point on face

Question 17

When ensuring that numbers 1 and 2 are correcting the face way, what should you do

Answer 17

tighten them

Question 18

How do you detach the earbow from the transfer jig assembly

Answer 18

by loosening centre screw

Question 19

What are the 5 steps to transferring the facebow recording to the semi-adjustable articulator

Answer 19

1. Securing the transfer jig to the lower member of the articulator using the mounting shoe
2. Aligning the flat surface on the transfer jig with the hole in the mounting shoe and securing
3. Making grooves on the base of the cast to help them relocate when needed
4. Mount upper cast to articulator
5. Mounting the lower cast using the jaw registration

Question 20

What does the mounting shoe replace

Answer 20

o Mounting shoe replaces the incisal table and is where the transfer jig sits in

Question 21

How do we mount the upper cast

Answer 21

o Place upper cast on bitefork
o Ensure incisal post is at 0
o Use mounting plaster mixed with water
o 50ml of water with a crust of powder on the surface of the water (similar to mixing stone for dentate casts)

Question 22

How do we mount the lower cast

Answer 22

using the jaw registration

o Detach the transfer jig and bitefork
o Place the incisal table back
o Ensure incisal post still at zero
o Occlude casts (using jaw registration if required)
o Turn articulator upside down and mount with mounting plaster
o Once finished mounting, ensure incisal post is at 0 & the casts are in ICP