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Year 3 Operative and endo > Online stuff > Flashcards

Online stuff Flashcards

1
Q

type of glass in compomers

A

fluoroaluminosilicate glass

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2
Q

5 components of porcelain

A 
Kaolinite/kaolin
Quartz
Feldspar
Metallic oxides
Borax
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3
Q

polymer of silicone impression materials

A

Polydimethyl siloxane

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4
Q

difference between condensation and addition cured silicones

A

POLYMER TERMINAL GROUPS:
Addition cured silicones: vinyl
condensation: hydroxyl (OH –> alcohol)

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5
Q

What is present in addition cured silicones

a. catalyst and base paste 2
b. catalyst paste
c. base paste 3

A

a,Polyvinyl siloxane (VINYL TERMINAL GROUP)
Filler
b. platinum catalyst
c. silanol

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6
Q

typical detail reproduction of a light bodied silicone impression material

A

20 microns

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7
Q

define astringent solution, when to use it and 3 examples

A

causes muscle contraction –> tissue shrinks. This is useful in situations such as when impressions of a tooth/teeth need to be made and the gingivae is preventing a clear impression being taken.

  • ferric sulphate
  • aluminium chloride
  • aluminium sulphate.
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8
Q

what does trim consist of

A

Polyethyl methacrylate acrylic (PEMA)

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9
Q

how many ppm chlorine in disinfectant soln

A

1000

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10
Q

how to prepare disinfectant soln

A

dissolving Correct Sodium Dichloraisocyonurate tablets (Actichlor plus) in water = 1 tablet per 1 litre of cold water.

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11
Q

which impression materials to leave in disinfectant soln for

a. 10s
b. 10 mins

A

a. 10s: Alginate, Correct Zinc Oxide/Eugenol Impressions and Laboratory Work with Metal Components
b. 10 mins: Rubber, Correct Compo Impressions and Laboratory Work without Metal Components Silicone

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12
Q

5 components of maxitemp

A 
Urethane dimethacrylate UDMA
Aromatic dimethacrylate ADMA
Glycol methacrylate GMA
Glass powder
Silica
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13
Q

types of temp crown

A

Preformed crowns
Matrices
Direct syringing
Lab made temporary crowns

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14
Q

functions of temp crown 5

A 
Protecting tooth vitality if not root filled
Preventing movement of teeth
Maintaining function
Aesthetics
Diagnostic purposes
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15
Q

difference between maxitemp HP and Directa crowns

A

Maxitemp HP: automix crown and bridge acrylic, made on clinic
Directa: pre-formed in lab polycarbonate crowns

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16
Q

advantages/ disadvantages of maxitemp over directa drowns

A

advantages maxitemp 3: No need to have different sized crowns
Can use different shades
May be used for a greater variety of uses such as bridges, inlays, onlays and veneers

disadvantage: need impression

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17
Q

size/use of ultrapak retraction cords

A 
#00: Preparing and cementing veneers; restorative procedures with thin, friable tissues
#0: Lower anteriors; luting near gingival and subgingival veneers; Class III, IV and V restorations; second cord or double-cord technique
#1: Non-impreganted are effective for tissue control and/or displacement when soaked in hemostatic solution prior to and/or after crown preparations; as a protect pre-preparation cord on anteriors
#2: Upper cord for double-cord technique; as a protective pre-preparation cord
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18
Q

define galvanic corrosion

A

When two dissimilar metals are combined, resulting in the corrosion of one of the metals being significantly increased

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19
Q

density of dentine tubules per mm squared in

a. young fully formed premolar
b. at ADJ of premolars

A

a. young fully formed premolar: 50 000

b. at ADJ of premolars: 20 0000

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20
Q

alternatives to amalgam in large posterior cavity

A

Adhesive amalgams
Onlay
Crowns
Indirect resin composite restoration

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21
Q

auto matrix system. how to

a. adjust
b. remove

A

a. adjust: hand wrench

b. remove: cutting the top from the retaining flange e.g Maun’s Cutters

22
Q

what matrix band is suitable for use on all teeth

A

seqviland

23
Q

disadvantage of tofflemire

A

Contact surface usually located incorrectly near the marginal ridge leading to an abnormal embrasure space and unnatural look

24
Q

5 types of composite available. which is used here

A 
Conventional
Fine particle
Microfilled (used here)
Packable
Hybrid
25
Q

main bacteria with

a. caries
b. periodontal disease

A

a. caries SAL: strep, actinomyces, lactobacilli

b. periodontal disease FP: fusobacteria, prevotella

26
Q

how do plaque adhere to teeth

A

van der waals and electrostatic forces –> proteins and bacteria create BIOFILM on teeth pellicle

27
Q

can plaque form without food? explain

A

yes. it is looser

sugar causes gelatinous texture

28
Q

explain how plaque leads to caries

A

bacteria release acid –> demineralisation of tooth surface

29
Q

enamel crystal dimensions

A

arge crystals 100 nm long, 70 nm wide and 25 nm thick

30
Q

unit cell of enamel crystallite

A

1 OH surrounded by 3 Ca3+ ions

31
Q

% composition of

a. enamel
b. dentine
c. pulp

A

a. enamel: 96% inorganic, 1% organic, 3% water
b. dentine: 70% inorganic,
c. pulp: 75% water 25% organic

32
Q

4 reasons for class V lesions

A

Abrasion
Abfraction
Caries
Erosion

33
Q

2 ways to increase crown height in order to be able to do FVG

A

-composite build up

crown-lengthening

34
Q

minimum height for FVG RETENTION

a. non-molars
b. molars

A

a. non-molars: 3mm

b. molars:4mm

35
Q

composition of FVG

A 
10% Gold
45.9% Silver
24% Palladium
18% Indium
2% Zinc
36
Q

Where should a bevel be placed on a class IV restoration?

A

1 mm along the labial margin only in enamel

37
Q 
how to polish amalgam 
a. pressure
b.speed
abrasive agents wet/dry
air or no
A

Use light, intermittent pressure with rotary instruments
Use slow to moderate speed with rotary instruments
Use abrasive agents that are wet
Use compressed air directed at the amalgam surface during polishing

38
Q

2 reasons heating amalgam is dangerous

A

heat to pulp

mercury to surface

39
Q

order of smoothing amalgam

A

Smooth occlusal cavosurface margins

  1. Smooth occlusal surface
  2. Smooth interproximal cavosuface margin and surface
  3. Smooth buccal and lingual surfaces
40
Q

define

a. flashing

b. ditching

A

Flashing:excess of amalgam which extends over the cavosurface margin of the cavity preparation
b. ditching is a deficiency of amalgam along the margin, preventing the margin of the cavity preparation from being flush

41
Q

instrument changes when making apical stop

A 
10
15
10
20
15
etc (always capitulate with 1 file size smaller)
42
Q

advantages of crown down technique 5

A

Early organic debris removal from coronal part of canal
Allows greater penetration of irrigant
Straighter access to the apical region of curved canals
Shortens the preparation time
Elimination of the coronal and middle dentine resistance

43
Q

3 things used as temp dressing over root filling

A

zinc oxide eugenol
gic
cotton wool dressing

44
Q

reasons for incomplete casting when constructing gold crowns

A

Pattern positioned incorrectly to allow gases to escape
Incomplete wax elmination
Incorrect investment W/P ratio
Insufficient casting pressure
Pattern damage during investing stage
Sprue becoming unattached from wax pattern

45
Q

common reasons for surface roughness when casting gold crown

A 
roughness= TOO MUCH (pressure/ temp/ surface tension)
Breakdown of investment 
Overheating of alloy
Excessive casting pressure
Incorrect investment W/P ratio
Surface tension reducing agent not used

*not enough –> incomplete casting
too much –> surface roughness

46
Q

order of processes in casting FVG

A
  1. Make a thermoplastic coping to fit the die by pushing the die through heated blanks into the putty well to mould
  2. Mark 1 mm above the margin of the preparation using a marker, then cut the cap using scissors
  3. Apply separating medium to surface of die, replace cap and using blue inlay wax around the preparation margin to ensure a close marginal fit of the crown
  4. Using the PKT waxing method wax up the crown reproducing the anatomy including the cusps and marginal ridges and axial contours by wax addition (PKT)
  5. Sprue the wax pattern to the thickest section of the pattern and secure into the crucible former
  6. Invest the wax pattern (INVESTING IS GOLD ONLY, NOT PORCELAIN)
  7. Place the casting ring into a furnace and slowly bring to the correct temperature to allow burn out of the wax
  8. Cast the molten alloy using centrifugal or induction casting machine
  9. Allow investment to cool before quenching in cold water, and devesting
  10. Remove the sprue close to the casting using a high speed grinding wheel
  11. Check the fit surface for debris or nodules using a small round bur if necessary
  12. Create a highly polished gold restoration using rotary instruments
47
Q

PFM: reasons for irregularities in the casting alloy during the casting process?

A 
Investment heated too rapidly
Investment heated too slowly 
insufficient investment around wax pattern 
Length of sprue used
Metal over/underheated 
Debris in the investment mould
48
Q

anterior PFM lab stages

A
  1. Construct accurate sectional model from impression and check occlusion with opposing arch
  2. A wax shape is made of the core substructure for the crown leaving space for the porcelain
  3. The wax pattern is sprued, and invested in a casting ring
  4. Molten metal is cast into the mould
  5. Sprue is removed
  6. Metal surface is prepared ready to add the porcelain
  7. Opaque porcelain is applied over the metal coping to mask the metal
  8. The opque porcelain is placed in a furnace
  9. Build up crown using Dentine and Enamel effect porcelain
  10. The Dentine and Enamel effect porcelain is fired in a furnace
  11. The porcelain is trimed and shaped using rotary instruments
  12. The porcelain is glazed in the furnace
  13. Any exposed metal is polished
49
Q

reasons for porosity casting defects when casting metal alloys

A 
Incorrectly sprued
Entrapped air during casting procedure
Incomplete wax elimination
Overheating of alloy
Debris in investment mould
NOT ENOUGH PRESSURE
50
Q

reasons for controlled investing and casting PFM

A

Prevent air pockets being formed on metal surfaces of PFM crown
Prevent the cast metal surface irregularities
To allow for the expansion and contraction of the materials

51
Q

disadvantages of pfm

A

Metal may show through
Wear of opposing dentition
Expensive laboratory procedures
Difficult to repair

Year 3 Operative and endo (6 decks)

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