Fixed Prosthodontics

Question 1

What is the occlusal reduction for ceramic or composite?

Answer 1

Between 1 and 1.5mm occlusal reduction

Question 2

How do diamond burs remove tooth tissue?

Answer 2

By abrasion

Question 3

What are the similarities of luting cements and adhesive cements? (4)

Answer 3

• good flow properties
• thin film thickness
• sets hard
• broken down by shearing force

Question 4

What are the indications for GI as a core material?

Answer 4

If there are 2+ intact tooth walls remaining and they must be 1-2mm thick (the material does not have sufficient strength on its own)

Question 5

What are the advantages of amalgam as a core material? (2)

Answer 5

• not technique sensitive

- can be bonded

Question 6

What are the disadvantages of amalgam? (2)

Answer 6

• low tensile/compressive strength

- not adhesive

Question 7

What are the disadvantages of GI and RMGI as a core material? (2)

Answer 7

• low compressive/tensile strengths

- deteriorate at low pH

Question 8

What is the technique for doing a bonded amalgam?

Answer 8

• complete cavity prep
• place lining if necessary in deep aspects
• etch enamel 20 secs, dentine 10 secs
• rinse and dry
• dentine bonding agent and light cure
• place adhesive resin cement on base and walls of the cavity
• pack amalgam onto unset cement and wipe away excess panavea

Question 9

What are the uses of an average value articulator? (3)

Answer 9

• posterior restorations where obvious canine guidance
• multiple restorations with obvious guidance on other teeth
• complete removable prosthesis

Question 10

What are the uses of semi adjustable articulators? (5)

Answer 10

• multiple units
• re organised occlusion
• group function
• anterior guidance
• occlusal analysis

Question 11

What are the components of a face bow? (4)

Answer 11

Bite fork- records the position of the teeth
Bow- records the position of the terminal hinge axis to the condyle
Jig- connects the bow and bite fork
Pointer for 3rd reference point- to align teeth to horizontal access

Question 12

What material do you use for the mono phase impression technique?

Answer 12

Polyether or med viscosity silicone

Question 13

What are the methods used to create a provisional restoration? (5)

Answer 13

• pre operative putty impression
• pre formed crown
• pre operative wax up followed by duplication and vacuum formed stent
• free hand bis acrylic resin
• use the old crown if there is one

Question 14

What goes into the pre operative putty?

Answer 14

Chemically cured bis acrylic composite resin e.g pro temp or integrity

Question 15

What are the advantages of polycarbonate? (3)

Answer 15

• bonds to inside of crown
• doesn’t fall apart when trimmed
• can be polished

Question 16

Why should a non-eugenol cement be used to place a resin provisional crown?

Answer 16

Eugenol is thought to inhibit polymerisation

Question 17

What are the advantages of fixed moveable bridgework? (3)

Answer 17

• good track record
• solution for alignment problems
• use of different materials possible

Question 18

What are the disadvantages of fixed moveable bridgework? (4)

Answer 18

• limited areas of use
• complicated
• expensive
• increased stress on major abutment

Question 19

What are the functions of poetics? (4)

Answer 19

• replacing the function of the lost tooth
• achieve an aesthetic appearance
• enable adequate oral hygiene
• prevent tissue irritation

Question 20

What is the anterior pontic design?

Answer 20

Modified ridge lap

Question 21

How can you assess undercuts in conventional fixed fixed bridge preps? (4)

Answer 21

• direct monocular vision
• indirect monocular vision
• take an alginate impression and cast in quick setting plaster
• paralleling mirror

Question 22

Is it best to preserve or remove the cingulum when preparing anterior teeth for indirect restorations?

Answer 22

Leave the cingulum

Question 23

What are the requirements of current day resin retained bridges? (3)

Answer 23

• wing retainer must be rigid
• wing must fit closely to abutment tooth
• porcelain fused to metal

Question 24

What are the indications for current day resin retained bridges? (4)

Answer 24

• unrestored or minimally restored abutment teeth
• sufficient good quality enamel on abutment tooth
• sufficient interocclusal space
• good alveolar bone shape

Question 25

What cements give the most retention? (2)

Answer 25

- zinc phosphate cements give more retention than polycarboxylate cements - composite resin luting cements can give superior retention if the smear layer is removed from the walls of the post space preparation

Question 26

When would you use a customised incisal guidance table?

Answer 26

- class I and class II div II (as they are involved in anterior or lateral guidance) - when need to customise palatal surfaces of upper anteriors - would use it when doing restorations on all anterior upper teeth, wouldn't just use it if doing if doing a bridge on a central

Question 27

If you are doing a crown or bridge on a tooth that is not the guidance tooth do you need a face bow and semi adjustable articulator?

Answer 27

No

Question 28

What is a RRB cemented with?

Answer 28

Panavia

Question 29

What would you use to cement a cast metal post or fibre post?

Answer 29

Rely x unicem

Question 30

What cement would you use to cement a post core and crown, MCC, all ceramic crown or crown with a reinforced core?

Answer 30

Rely x luting cement

Question 31

What is used to cement veneers?

Answer 31

Colebra

Question 32

Why is RMGI not good for cementing?

Answer 32

Absorbs water and could fracture restorations

Question 33

What are the ideal characteristics of cements?

Answer 33

- thin - flowable - not too acidic - insoluble - easy to use