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Restorative > CSL Book 2 Blue > Flashcards

CSL Book 2 Blue Flashcards

1
Q

2 things that can lead to class IV restoration

A
  • trauma

- progression of class III caries

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2
Q

who is most at risk for trauma injuries to teeth

A

children

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3
Q

normal angle of fracture across crown

A

45 degrees towards palatal surface

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4
Q

3 special investigations with trauma cases

A
  • clinical exam/history: discolouration of crown, mobility of tooth, position of tooth in occlusion
  • vitality: at least 2 methods inc pulp tests to eliminate concussion
  • radiographs: 2 views periapicals with different angulations to identify fracture lines
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5
Q

2 complications of trauma leading to class IV

A
  • root fracture

- damage to adjacent teeth

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6
Q

is enamel bevelling usual for class IV restorations? why?

A

no because it removes more tooth structure.

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7
Q

what bevel is normal for class IV and how is it done

A

labial margin only is bevelled so composite can be blended with tooth structure
use D&Z850 at 45 degrees or greater to long axis of tooth –> 1mm bevel
not to edges to avoid damage to adjacent teeth

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8
Q

what lining to use for class IV cavities

A
  • total etch and bond (shallow -moderate depth cavities, this is enough to seal dentine tubules)
  • light-cured GIC (bonds to dentine AND composite)
  • setting calcium hydroxide (when deep cavity nr pulp)

usually use GIC or setting calc hydroxide

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9
Q

type of wax used to box the impression in lost wax technique and why this is done 2

A

ribbon wax

  • contain die stone, prevent distortion
  • ensure the model has sufficient thickness for drilling in to its base
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10
Q

what type of gypsum is used for cast metal restoration

A

modified alpha hemi-hydrate (artificial/die stone)

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11
Q

thickness of model and why 2

A

15mm gingival margin to base

  • avoids fracture during drilling
  • ensures base is flat for next stage
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12
Q

are labial/lingual pins longer and colour of sleeve

A

LONG, WHITE, LIPS
labial: longer, white sleeve
lingual: shorter, grey sleeve
LONG LIPS, WHITE IS LONGER WORD

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13
Q

what is used to base the model

A

50:50 plaster stone mix

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14
Q

3 advantages of pindex system

A
  • PRECISE location in to plastic sleeves
  • DURABLE- plastic sleeves prevent wear
  • STABLE (twin pin system- 2 pins per area –> no danger of rotation)
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15
Q

what can be applied to die and adjacent teeth to prevent damage/distortion, how do they work

A

stone die and plaster hardeners (resins in soln)
absorb in to die stone material –> seal/waterproof surface while protecting definition of margins (don’t create another layer, just blend in to surface)

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16
Q

what material is the plastic coping made of

A

polythene

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17
Q

thickness and positions of pieces of plastic foils

A

thicker 0.6mm below thinner 0.1mm (thinner one contacts the die)
0.6-0.1-die

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18
Q

how far above margin to trim plastic coping

A

1mm

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19
Q

size and angle of sprue

A

2mm

45 degrees to thickest section of wax pattern

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20
Q

why must sprue be fairly large

A

allow free flow of molten alloy

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21
Q

where should sprue be positioned in crucible former and why

A

no less than 7mm from upper edge

prevents molten alloy from breaking through when entering the mould

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22
Q

when is wetting agent applied and why

A

prior to investing

reduce surface tension–> smooth cast surface

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23
Q

why must investment be mixed under vacuum

A

eliminate air inclusions that may result in air pockets forming against pattern surface

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24
Q

% shrinkage of casting gold and what compensates for it

A

1.5%

compensated for by 3 EXPANSIONS: setting, hygroscopic and thermal of investment material

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25
Q

4 requirements of an investment

A

SERS

  • produce smooth Surface to casting
  • permit Escape of gases to casting
  • facilitate easy Removal of casting
  • sufficient Strength to withstand temps in furnace
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26
Q

order, time and temp of casting

A 
-1 hour: allowed to set
crucible removed
-30 mins (min), 250C hotplate
-10 mins 740C furcace
-few minures: allowed to cool
-cold water
*the hotter the process, the shorter the time*
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27
Q

details of gold alloys

A

types I-IV. contain Au,Ag,Cu,Pt/Pd,Zn
I:85% gold
IV: 65% gold
melting point 950-980C

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28
Q 
other name for class V
2 materials used to fill class V cavity
A

abrasion cavity

GIC, compomer

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29
Q

3 causes of class V cavities

A
  • caries due to poor plaque control
  • abrasion due to horizontal scrubbing when brushing
  • abfracture (occlusal stresses concentrate at thin enamel near enamo-cemental junction –> fracture of enamel)
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30
Q

what to clean class V cavity with and why

A

clean to remove pellicle and surface plaque
oil, glycerine, fluoride-free prophylaxis paste (would decrease bonding,use a pumice slurry)
rubber polishing cup (not brush-may break rubber dam and damage gingivae)

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31
Q

what to do after washing/drying class V cavity and why 2

A

CONDITION: 25% polyacrylic acid with cotton wool, leave for 30s, wash for 30s,dry gently

  • remove smear layer
  • improve bond strength for GIC
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32
Q

what matrix to use for class Vcavity and why 3

A

cervical matrix

  • forms missing surface –> contains filling material
  • compresses filling material while it sets
  • smooth finish surface
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33
Q

how long to amalgamate gic

A

10s

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34
Q

how long to press gic for and why

A

2 secs

rupture membrane –> polyalkenoic acid contacts aluminosilicate glass

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35
Q

2 advantages of encapsulated gic

A
  • viscosity and quality are reproducible

- can be injected directly in to cavity

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36
Q

ratio of gic powder to liq

A

2:2

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37
Q

mixing time of gic

A

max 25 secs

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38
Q

how long to leave class 5 gic (cervical)

A

5 mins to ensure fully set

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39
Q

when to finish gic restorations and why

A

24hours after unless gross excess present. allows second ion exchange (with aluminium) to take place

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40
Q

what is used to protect gic for first 24hrs and why. how to apply

A

light-cured bis GMA resin (best) or varnish
stop it gaining/ losing water –> weaker
resin: leave for 30s to penetrate voids in material, light cure 20s

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41
Q

what to use to polish gic/compomer class v

A

prisma glosses

felt polishing cup (NOT rubber)

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42
Q

contents of compomer and why

A
  • aluminosilicate glass (gic filler)
  • acid polymerisable resin (TCB tetracarboxylic acid butate, allows methacrylate groups to polymerise in to long chains while pendant acid groups react with glass surface)
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43
Q

does gic or compomer have better aesthetics

A

compomer

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44
Q

why must dentine not be desicated

A

will prevent hydrophilic bonding resin from wetting the tooth surface

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45
Q

prime and bond contents

A

elastomeric resins and penta

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46
Q

contents of penta and why

A

phosphate ester of methacrylate. it is polar – wets surface (hydrophilic) and forms ionic bonds with apatite crystals

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47
Q

what matrix is used with compomer class v and what is it made of

A

hawe neos cervical matrix (must use transparent matric with light cured material)
cellulose actate

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48
Q

2 ways to increase bond strength of compomer

A
  • non rinse conditioner: maleic and polyacrylic acids , leave for 20s then air dry
  • phosphoric acid etchant: same as always, leave for 30s, water 30s, gently air dry,
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49
Q

what to use to remove excess compomer from class v

A

excavator

50
Q

3 parts of porcelain-metal bond

A
  • chemical (tin/indium oxides come to the surface for passivation)
  • mechanical
  • shrinkage/compression bonding (this is the reason there must be no pits/hollows on buccal surface
51
Q

5 indications for porcelain fused to metal pfm crown

A
  • improve strength/appearance of heavily filled teeth
  • where porcelain crown repeatedly fractures
  • where occlusion unfavourable (deep overbite, minimal overjet)
  • conjunction with bridge of partial denture construction
  • occlusal reconstruction (crowning all standing teeth to re-establish correct clinical height)
52
Q

how much occlusal reduction to do where and why

A

buccal: 1.5mm (room for porcelain and metal)
lingual: 1mm (bonding alloy better than gold, less reduction needed, even for functional cus)

53
Q

2 functions of functional cusp bevel pfm

A
  • provides clearance between upper and lower teeth

- brings cusp tip back in to line with unprepared cusp position

54
Q

order of pfm crown prep

A
  1. occlusal reduction
  2. functional cusp bevel
  3. axial wall reduction
  4. interproximal reduction
  5. palatal/lingual surface
55
Q

axial wall prep buccal and lingual/palatal pfm crown

A

buccal: shoulder, 1.3mm reduction

lingual/palatal: 135 degree chamfer, max 5 degree taper 1mm reduction

56
Q

width of straight enamel chisel and why

A

1.5mm; used to check buccal reduction of PFM is 1.3mm

(also used to

57
Q

2 stages of interproximal reduction pfm

A
  • break contact with adjacent teeth

- chamfer prep of margin

58
Q

on which side of the tooth is wing position critical and why

A

mesial- metal must not be visible

59
Q

mesial and distal position of wings

A

mesial: interface position, midway between buccal embrasure and midpoint of contact area
distal: buccal embrasure point
[mesial wing is more palatal than distal]

60
Q

chamfer position of pfm crown prep

same but when restoration present

A

just above gingival level

restoration present: just cervical to margin of filling

61
Q

3 things used to smooth surfaces and line angles

A
  • superfine diamond burs
  • multi-fluted tungsten carbide burs
  • green stones
62
Q

2 instruments used to smooth and define shoulder and why

A
  • enamel chisel (moves unsupported enamel but v sharp –> tissue damage)
  • shoulder file (safer, only cuts in 1 direction)
63
Q

pfm crown prep function of:

a. shoulder
b. chamfer
c. buccal reduction
d. wings
e. bevel

A

a. shoulder: structural durability
b. chamfer: marginal integrity
c. buccal reduction: retention, resistance
d. wings: retention, resistance
e. bevel: structural dirability

64
Q

advantages of wingless design

A
  • easier to prepare

- less chance of undercut

65
Q

disadvantages of wingless design

A
  • less resistance form

- less conservative of tooth structure

66
Q

which tooth has a canine fossa

A

maxillary first premolar

67
Q

which cusp is thin for extensive amalgam restoration

A

buccal

68
Q

symptoms of cracked tooth syndrome

A

pain on release from biting

69
Q

how to cut buccal wall for EAR

A

45 degrees towards occlusal plane

70
Q

with of buccal shoulder in EAR. bur used

A

1mm, 554

71
Q

when to line EAR and why

A

before drilling hole/ groove (or lining may block holes)

+before pin placement (or pins get in the way)

72
Q

where to place pins and why

A

1mm in from EDJ –> no perforation of periodontal ligament and pulp
1mm of amalgam should be placed around pins

73
Q

where to line EAR

A

horizontal pulpal floor and vertical axial walls

74
Q

what is used to make dimples for pins EAR

A

number 1 round bur (slow handpiece)

75
Q

thicknesses of dentine/amalgam required for EAR and why

A 
(grooves/ holes max 1mm depth)
1mm in from ADJ
1-2mm of amalgam covering
1mm dentine around pins
2.5mm overall thickness of dentine
max 2mm protruding in cavity
--> room for 2mm overlying amalgam (may need to reduce height of pins with diamond coated bur)
protect against pulpal or periodontal perforation
76
Q

how far apart should pins be EAR

A

5mm

77
Q

how to make holes for pins EAR

A

twist drill in speed reducing handpiece –> less speed, more torque
bur aligned with outer surface of tooth
pushed down in one firm movement, taken out while still rotating
DO NOT put twist drill back in- will make hole too big

78
Q

where is widened seat on EAR pin and where should it sit

A

midway along length. should sit on dentine surface

79
Q

how far out of tooth should pin be and why

A

no more than 2mm -doesnt help retetion of amalgam

allow for 2mm of amalgam covering pin (may have to shorten pin with diamond coated bur)

80
Q

speed of handpiece when inserting pin and why

A

slow-moderate

too fast –> threads will strip from dentine wall, retention compromised

81
Q

what to use to alter position of pin

A

pickle fork shaped pin bender

82
Q

how to make groove / size in EAR

A

701 fissure bur

1.5mm deep

83
Q

disadvantage of siqveland matrix band for EAR. better alternative

A

cannot be removed from holder while still attached to tooth –> hinders removal, risks fracturing amalgam while trying to remove band
tofflemire is better

84
Q

advantages/disadvantages of copper band matrix

A
  • advantages: can be left in situ until pt returns

- disadvantages: not flared–> poor shape of tooth, thicker–> poor contact point

85
Q

3 ways heavily restored tooth can interfere with occlusion

A
  • centric occlusion
  • lateral excursions
  • protrusion of mandible
86
Q

use/ contents of kalsogen

A

temp dressing

zinc oxide-eugenol

87
Q

3 ways to stop kalsogen adhering to flat plastic

A

water
alcohol
kalsogen powder

88
Q

what accelerates setting reaction of zinc oxide-eugenol cements

A

contact with water

89
Q

what is added to kalsogen to strengthen it

–> modified use

A

cotton wool

–> onlay cavity dressing, hold occlusal contacts/stops

90
Q

compare strengths of GIC and zinc polycarboxylate cements

A

similar

91
Q

suggest use of zinc polycarboxylate

A

where strength and no bond to overlying restorative necessary and need to see difference between cement and tooth eg v deep cavities pulp capping

92
Q

most common method used for casting gold from dies

A

centrifugal force

93
Q

2 ways to melt gold during casting

A
  • melted over casting ring (over reducing zone of flame, middle triangle)
  • in a crucuble (torch/induction melting)
94
Q

2 reasons investment is washed in cold water

A
  • enable easier deflasking

- produce fine grain structure

95
Q

newly made cast gold crown: what is used to smooth

a. axial surfaces
b. angular primary casting
c. fissure pattern

A

a. axial surfaces: white flexi rubber wheel

b. angular primary casting, c. fissure pattern: rubber points

96
Q

position of contact point in relation to marginal ridge

A

1mm below marginal ridge

97
Q

how porcelain is built up for

a. crowns
b. veneers

A

a. crowns: build up on platinum foil (foil removed after glazing)
b. veneers: build up on refractory model

98
Q

what is tinners joint

A

fold in TIN foil to make incisal edge in porcelain crown build up

99
Q

POLISHING:

faster or slower better and why

A

faster better: shallower scratches
reduces wear of abrasive practicals
quicker result

100
Q

compare coarse and fine abrasives

A

coarse: fast removal of material, deep scratches
fine: slower abrasion, smoother surface

101
Q

compare abrasion and polishing

A 
abrasion= producing gradually finer scratches --> smooth reflective surface
polishing= producing smooth reflective surface with surface flow and BEILBY LAYER (molecular disorganised, shiny layer)
102
Q

examples of dental abrasives 7

A

-pumice
-sand
-diamond
-carbides
-Kieselguhr
-garnet
emery

103
Q

examples of polishing agents 5

A 
whiting 
rouge
tripoli
tin oxide
chromium oxide
104
Q

rubber dam thickness

A

0.15-0.35mm

105
Q

is liquid or gel etch preferable for class IV restorations and why

A

gel- easier to control where it goes

106
Q

function of applying copal ether varnish to adjacent teeth during class IV restoration

A
  • prevent composite sticking

- prevent inadvertent etching

107
Q

type of composite to use for initial part of class IV restoration and why

A

opaque, dentine shade

stops restoration looking too translucent

108
Q

for what materials does oxygen prevent polymerisation of surface during setting reaction

A

composite

bond

109
Q

when may it be desirable to leave the surface layer of composite uncovered so that it is not cured due to oxygen inhibition

A

all except the last layer, so the overlying composite bonds to the non-fully-set composite

110
Q

2 techniques used to make wax pattern

A
  • wax addition (PK thomas instruments)

- carve down technique (Ney)

111
Q

during investment furnacing, which way should the sprue face and why

A

downwards -> allow wax to escape

112
Q

what force makes casting work

A

centrifugal

113
Q

why must investment be cooled before deflasking 2

A
  • easier deflasking

- fine grain structure

114
Q

3 substances that may decrease bonding of restorative material to tooth

A

-oil (eg from compressor)
-glycerine
-fluoride
in prophylactic pastes

115
Q

what is ketac and when is it used

A

unfilled bis GMA resin

used to cover GIC for first 24 hours to reduce water gain/ loss

116
Q

what restorative material do you NOT etch with

A

compomer (uses prime and bond), amalgam

composite uses etch, gic uses conditioner (polyacrylic acid

117
Q

depth of cure of compomer, cure time

A

3mm, 40s

118
Q

function in EAR of

a. pin
b. groove

A

a. pin: resistance form

b. groove: resistance and direct retention

119
Q

order of procedures in restoration stages of EAR

A
  • cavity varnish (3 layers)
  • matrix application
  • amalgam insertion
  • carving
  • occlusion check
120
Q

EAR lecture: adhesives to use for EAR

A
  • 4META (amalgam bond)

- MDP (methacryloxydecyl dihydrogen phosphate)

121
Q

advantages of EAR over cast restoration

A

quicker
cheaper
less invasive

Restorative (5 decks)

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