Restorative - Crowns and treatment planning

Question 1

Outline the overall assessment stages? (from when you first see the patient)

Answer 1

C/0
HPC
PMD
PDH
SH/FH
E/O
I/O

Question 2

What is contained within the E/O?

Answer 2

You are checking for abnormalities as soon as you first see the patient.
symmetry 
TMJ 
M.O.M
Lymph nodes 
Smile

Question 3

What does a high lip line mean?

Answer 3

When the patient smiles you can see the gingivae all the way up to the apex of the tooth.

Question 4

What is the vermillion zone?

Answer 4

The sharp demarcation between the lips and the skin

Question 5

Outline the steps in an I/O?

Answer 5

Checking of all the soft tissues
Soft palate, hard palate, lateral border of the tongue, tongue and floor of the mouth.
Perio - BPE 
Dentition - Charting of the teeth 
Occlusion - If GF or CG
If the teeth retrude or protrude and their lateral movements.
Incisal relationship.
Inter arch and inter tooth space.

Question 6

Special investigation?

Answer 6

Study casts 
photographs 
Radiographs 
Sensibility tests - EPT and thermal 
6PPC 
Facebow

Question 7

When are face bows utilised in fixed pros?

Answer 7

Facebows are important for any pros work involving the canines or where the vertical dimension is being altered.

Question 8

Radiographic assessment?

Answer 8

Grade radiograph 
Tooth present 
Apical pathology
bone levels 
Caries 
Large restorations and RCT 
Assess possible abutment teeth

Question 9

What are the 5 stages of overall treatment planning?

Answer 9

IIRRM
Immediate 
Initial (disease control)
Re-elevaluation 
Re-constructive 
Maintenance

Question 10

What treatment is carried out in the immediate phase of treatment?

Answer 10

Relief of symptoms
Consider endo
Consider immediate denture/bridge

Question 11

What treatment is carried out in the initial phase of treatment?

Answer 11

OHI and diet advice 
HPT 
Ex of hopeless teeth
management of caries and failed restorations 
endodontics
denture design and wax-up for FP

Question 12

What treatment is carried out in the re-evaluation phase of treatment?

Answer 12

Re-evaluation of periodontal status

Confirm denture/ bridge design

Question 13

What treatment is carried out in the re-constructive phase of treatment?

Answer 13

Perio surgery (if OH is good)
Fixed and removable prosthodontics

Question 14

What treatment is carried out in the maintenance phase of treatment?

Answer 14

Supportive periodontal care and review of restorations

Question 15

Why do patients need to have good OH before they can think about FP?

Answer 15

As if they don’t arrest the disease in the mouth and have good OH then the chances of restoration failure are much greater

Question 16

Alternatives to FP?

Answer 16

Implants
Internal bleaching of teeth (colouration problem)
RPD

Question 17

Why is over the preparation of a crown bad?

Answer 17

It weakens the tooth increases the chances of failure

Also increases the chances of pulpal damage or exposure.

Question 18

What are the problems with under preparation of crowns?

Answer 18

Aesthetically won’t look as good and functionally will make it feel bulking in the mouth.
Also makes plaque control difficult as cleansing of the teeth isn’t as good.

Question 19

What can you include in your design to increase retention of the crown?

Answer 19

Taper - 6’ on opposing wall
One path of insertion
grooves
Long walls

Question 20

Name some key qualities of good crown margins?

Answer 20

Smooth and fully exposed to allow cleansing action
Should be clearly visible to the dentist to allow for any finishing and so the patient can easily clean.
Should be 0.5mm supragingival

Question 21

Define biological width?

Answer 21

It is the Junctional epithelium + Connective tissue length about the alveolar crest.

Question 22

What would happen if the margins of the crown encroached on the biological width?

Answer 22

There would be possible bone loss as the gingivae would become inflamed as an inflammatory response
Would also make it very difficult to clean this area

Question 23

At what landmark does the tooth become unrestorable if caries reaches it?

Answer 23

The crestal bone.

The patient should be informed if they are close to this point and told about the poor prognosis.

Question 24

For a crown preparation, what are the 3 types of reductions?

Answer 24

Axial
Occlusal (functional cusp)
occlusal (non-functional cusp)
Finishing line

Question 25

What are the two main types of finishing lines?

Answer 25

Chamfer

Shoulder

Question 26

What crown material is best suited for bruxists?

Answer 26

MCC

Question 27

What material is worst for bruxists and why?

Answer 27

All ceramics are harder than tooth tissue and won’t be worn down but the opposing teeth will. Affecting the ICP relationship

Question 28

When considering what crown material to use what should you consider?

Answer 28

Aesthetic (anterior or posterior)
Amount of tooth tissue reduction
If you’re a bruxist
Lip line

Question 29

What kind of preps require the most amount of tooth reduction?

Answer 29

All ceramic -porcelain bonded to zirconia or alumina framework

Question 30

What is the axial reduction on metal crowns?

Answer 30

0.5mm

Question 31

What is the axial reduction on MCC?

Answer 31

1.5mm