Fixed Prosthodontics Flashcards
What is the occlusal reduction for ceramic or composite?
Between 1 and 1.5mm occlusal reduction
How do diamond burs remove tooth tissue?
By abrasion
What are the similarities of luting cements and adhesive cements? (4)
- good flow properties
- thin film thickness
- sets hard
- broken down by shearing force
What are the indications for GI as a core material?
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)
What are the advantages of amalgam as a core material? (2)
- not technique sensitive
- can be bonded
What are the disadvantages of amalgam? (2)
- low tensile/compressive strength
- not adhesive
What are the disadvantages of GI and RMGI as a core material? (2)
- low compressive/tensile strengths
- deteriorate at low pH
What is the technique for doing a bonded amalgam?
- 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
What are the uses of an average value articulator? (3)
- posterior restorations where obvious canine guidance
- multiple restorations with obvious guidance on other teeth
- complete removable prosthesis
What are the uses of semi adjustable articulators? (5)
- multiple units
- re organised occlusion
- group function
- anterior guidance
- occlusal analysis
What are the components of a face bow? (4)
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
What material do you use for the mono phase impression technique?
Polyether or med viscosity silicone
What are the methods used to create a provisional restoration? (5)
- 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
What goes into the pre operative putty?
Chemically cured bis acrylic composite resin e.g pro temp or integrity
What are the advantages of polycarbonate? (3)
- bonds to inside of crown
- doesn’t fall apart when trimmed
- can be polished
Why should a non-eugenol cement be used to place a resin provisional crown?
Eugenol is thought to inhibit polymerisation
What are the advantages of fixed moveable bridgework? (3)
- good track record
- solution for alignment problems
- use of different materials possible
What are the disadvantages of fixed moveable bridgework? (4)
- limited areas of use
- complicated
- expensive
- increased stress on major abutment
What are the functions of poetics? (4)
- replacing the function of the lost tooth
- achieve an aesthetic appearance
- enable adequate oral hygiene
- prevent tissue irritation
What is the anterior pontic design?
Modified ridge lap
How can you assess undercuts in conventional fixed fixed bridge preps? (4)
- direct monocular vision
- indirect monocular vision
- take an alginate impression and cast in quick setting plaster
- paralleling mirror
Is it best to preserve or remove the cingulum when preparing anterior teeth for indirect restorations?
Leave the cingulum
What are the requirements of current day resin retained bridges? (3)
- wing retainer must be rigid
- wing must fit closely to abutment tooth
- porcelain fused to metal
What are the indications for current day resin retained bridges? (4)
- unrestored or minimally restored abutment teeth
- sufficient good quality enamel on abutment tooth
- sufficient interocclusal space
- good alveolar bone shape
What cements give the most retention? (2)
- 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
When would you use a customised incisal guidance table?
- 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
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?
No
What is a RRB cemented with?
Panavia
What would you use to cement a cast metal post or fibre post?
Rely x unicem
What cement would you use to cement a post core and crown, MCC, all ceramic crown or crown with a reinforced core?
Rely x luting cement
What is used to cement veneers?
Colebra
Why is RMGI not good for cementing?
Absorbs water and could fracture restorations
What are the ideal characteristics of cements?
- thin
- flowable
- not too acidic
- insoluble
- easy to use
