Fixed Prosthodontics

Question 1

Why may a face bow record be required?

Answer 1

To allow casts to be mounted on a semi or fully adjustable articulator

Question 2

Why is a semi-adjustable articulator required for face-bow recording? Give two main reasons.

Answer 2

1. To allow the relationship of the casts to be visualised in a number of functional positions during the planning stage of treatment.
2. To allow the relationship to be reorganised by the waxing up or fabrication of restorations.

Question 3

Define a confirmative relationship.

Answer 3

Same occlusion before and after placement of a restoration.

Question 4

What does a face bow record?

Answer 4

The relationship of the maxillary teeth to the condylar head in a retruded position (i.e. a posterior superior position)

Question 5

Why are there indentations on the bite fork component of a face bow recording?

Answer 5

This is for mechanical retention of the wax onto the bite-fork

Question 6

What are the 4 types of articulators?

Answer 6

1. Simple hinge (e.g. plane line)
2. Average value (e.g. free plane)
3. Semi-adjustable (e.g. denar or dentatus)
4. Fully adjustable

Question 7

What articulator is described:
1. equivalent to holding casts in your hand
2. Occlusal relationship only correct when casts are together

Answer 7

Simple hinge articulator

Question 8

What articulator is described:
1. Sufficiently accurate for reproducing ICP
2. Suitable for posterior restorations where there is guidance from other teeth
3. Suitable for a complete removable prosthesis

Answer 8

Average value articulator

Question 9

What articulator is described:
1. Mandibular condyle (arcon)
2. Used for fixed pros
3. Multiple units
4. Reorganised occlusion

Answer 9

Denar semi-adjustable articulator

Question 10

What articulator is described?:
1. Maxillary condyle (non arcon)
2. Used for rem pros
3. Multiple units
4. Re-organised occlusion

Answer 10

Dentatus semi-adjustable articulator

Question 11

Define the terminal hinge axis.

Answer 11

An axis through both condyles when they are in most retruded unstrained position in the glenoid fossa. The terminal hinge axis coincides with the position of central relation.

Question 12

As part of a facebow recording, what does the bite-fork record?

Answer 12

The position of the teeth

Question 13

As part of a facebow recording, what does the bow record?

Answer 13

The position of the condyle

Question 14

What 4 factors MUST be determined prior to preparing teeth for laboratory fabricated restorations?

Answer 14

1. Pain from TMD
2. Unexplained facial pain
3. Chronic dental pain
4. Discomfort from mobile teeth

Question 15

What 3 ways can the “comfortable closed position where the maximum number of natural teeth meet.” Be addressed?

Answer 15

1. ICP
2. Centric occlusion (CO)
3. Maximum intercuspation

Question 16

In the case of a complete denture case, what position can be used where there is memory of the ICP from when natural teeth remained?

Answer 16

Muscular position

Question 17

What are the 5 different terms used for a retruded position? Not all of these terms mean that the retruded position has tooth contact.

Answer 17

1. Centric relation (CR)
2. RCP
3. Ligamentous position
4. Centric relation contact position (CRCP)
5. Retruded axis position (RAP)

Question 18

Define, “a maxillomandibular relationship, independent of tooth contact, in which the condyles articulate in the anterior-superior position against the posterior slopes of the articular eminences.”

Answer 18

Centric relation

Question 19

Why is centric relation important clinically?

Answer 19

It is a repeatable, unstrained, physiological maxillomandibular relationship where the patient can make vertical, lateral or protrusive movements.

Question 20

Define, “when the condyle is in its most superior, anterior position within the glenoid fossa (terminal hinge axis position) and the mandible is elevated.”

Answer 20

Retruded position

Question 21

How many mm is the anterior slide from RCP to ICP?

Answer 21

1-2mm

Question 22

If a patient has a class 1 incisal relationship what would you expect to see in regards to incisal movement upon protrusive excursion?

Answer 22

If mandible slides forward, incisors and canines should guide mandible forward.

Question 23

If a patient has a class 2 div 2 incisal relationship what would you expect to see in regards to incisal movement upon protrusive excursion?

Answer 23

An increased overbite, when the patient tries to slide forward they will just hinge open.

Question 24

If a patient has a class 2 div 1 incisal relationship what would you expect to see in regards to incisal movement upon protrusive excursion?

Answer 24

When the mandible slides forward, it is the posterior teeth instead of the anterior guiding the movement.

Question 25

Why is it advantageous to smear Alginate on occlusal surfaces of teeth when taking impressions for fixed pros?

Answer 25

It will aim to avoid air blows which will give excess amount of stone on cast which could alter occlusion.

Question 26

When upper anterior fixed restorations involves palatal morphology, what is advantageous to do?

Answer 26

Customise the incisal guidance table

Question 27

How is a customised anterior guidance table recorded?

Answer 27

Movement of pin as it rises of table is recorded using a cold cure acrylic

Question 28

Why is recording an anterior guidance table so important when making fixed restorations such as anterior crowns?

Answer 28

Because it is the only record of pre-existing guidance, this must be copied when the shape of the crowns is developed by the technician.

Question 29

Describe the three main steps to fabrication of an indirect restoration incorporating a removable prosthesis.

Answer 29

1. design the denture until special tray stage 2. Prepare the tooth for the indirect restoration plus additional prep for the rest seat 3. Prescribe to lab with words diagrams and verbal instructions

Question 30

Roughy how long should a set of dentures last and why?

Answer 30

Around 3-5 years, because of physiological resorption of edentulous areas

Question 31

In what % of the population is ICP coincident with RCP?

Answer 31

10%

Question 32

In what % of the population is ICP 1mm anterior to RCP?

Answer 32

90%

Question 33

What is the major muscle that pulls back the mandible when going into RCP?

Answer 33

Genioglossus

Question 34

Define, the bilateral simultaneous occlusal contact of the anterior and posterior teeth in excursive movement.

Answer 34

Balanced articulation

Question 35

What is the Daal approach for tooth wear in natural dentition to try and establish an appropriate FWS?

Answer 35

Where teeth with tooth wear are built up so that FWS is 0mm, expect to find that the FWS re-establishes itself.

Question 36

What articulator is used if a face bow recording is to be taken for making a removable prosthesis?

Answer 36

Dentatus semi-adjustable articulator