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Endo > Endo third year > Flashcards

Endo third year Flashcards

1
Q

Schilder’s design objectives

A

continuously tapering funnel shape
maintain apical foramen in original position
keep apical opening as small as possible

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2
Q

why is it important to keep the apical opening as small as possible?

A

wound healing
less likelihood of trauma
apical control

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3
Q

why is cuspal protection important?

A

prevent microbial ingress

prevent catastrophic fracture

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4
Q

what does the pre-tx radiograph need to include?

A

all root

2-3mm of surrounding PR tissue

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5
Q

why should dam be used?

A 
bacterial contamination
inhalation
protects Sts
access and vision
can use disinfectants
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6
Q

sizes of SS instruments

A

21/25/31mm

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7
Q

taper on SS instruments

A

2%, 0.32mm

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8
Q

cutting flutes on SS instruments

A

16mm

diameter at D2 = apical size + 0.32mm

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9
Q

ISO colour code - 06

A

pink

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10
Q

ISO colour code - 08

A

grey

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11
Q

ISO colour code - 10

A

purple

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12
Q

ISO colour code - 15

A

white

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13
Q

ISO colour code - 20

A

yellow

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14
Q

ISO colour code - 25

A

red

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15
Q

ISO colour code - 30

A

blue

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16
Q

ISO colour code - 35

A

green

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17
Q

ISO colour code - 40

A

black

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18
Q

ISO colour code - 45

A

white

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19
Q

ISO colour code - 50

A

yellow

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20
Q

ISO colour code - 55

A

red

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21
Q

ISO colour code - 60

A

blue

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22
Q

ISO colour code - 70

A

green

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23
Q

ISO colour code - 80

A

black

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24
Q

ISO colour code - pink

A

06

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25
Q

ISO colour code - grey

A

08

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26
Q

ISO colour code - purple

A

10

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27
Q

ISO colour code - white

A

15

45

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28
Q

ISO colour code - yellow

A

20

50

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29
Q

ISO colour code - red

A

25

55

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30
Q

ISO colour code - blue

A

30

60

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31
Q

ISO colour code - green

A

35

70

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32
Q

ISO colour code - black

A

40

80

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33
Q

objectives of irrigants

A 
disinfect RC
dissolve organic debris
flush out debris
lubricate instruments
remove smear layer
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34
Q

what is used to deliver irrigant to RC?

A

Luer lock syringe with 27 gauge needle

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35
Q

what is recapitulation?

A

after each file irrigate and use file smaller than MAF

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36
Q

what are the aims of recapitulation?

A

disturbs debris and lifts into solution

prevents blockages

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37
Q

where should RC preparation end?

A

at the jct of pulpal and PA tissue - as close as possible to CDJ - usually apical constriction

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38
Q

EWL

A

estimated length at which instrumentation should be limited

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39
Q

calculating EWL

A

measure pre-op radiograph from FRP to radiographic apex and -1mm

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40
Q

how does the distance of the apical constriction from the radiographic apex vary?

A

greater in older teeth with secondary cementum
varying anatomy
RR
can give a false reading of where RC terminates

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41
Q

CWL

A

length at which instrumentation and subsequent obturation should be limited

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42
Q

when is CWL determined?

A

after coronal flaring

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43
Q

methods of determining CWL

A

EAL
WL radiograph
PP length discrimination

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44
Q

EAL

A

impedence/resistance drops when you touch PDL
unreliable if wide apical foramen
subtract 0.5-1mm

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45
Q

PP length discrimination

A

wet dry interface

PR tissues wet, RC should be dry

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46
Q

MAF

A

largest diameter file taken to CWL and therefore represents the final prepared size of the apical portion of the canal at the WL

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47
Q

reasons for early flaring of coronal portion

A

reservoir for irrigant
avoids hydrostatic pressure in canal
early removal of heavily contaminated contents
improved SL access to apical 1/3

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48
Q

modified double flare technique

A

uses BF
1 - enlarge/flare coronal part
2 - apical enlargement
3 - apical taper - step back

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49
Q

apical size

A

small as practicable but large enough to irrigate

ISO 25 or above

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50
Q

mid root prep

A

step back
increase file size as -1mm each time
until file “falls out”
brush MAF around wall to get rid of steps

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51
Q

what is patency filing?

A

ISO 10 or smaller 0.5-1mm through apical constriction

passive placement

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52
Q

purpose of patency filing

A

prevent apical blockage

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53
Q

risk of patency filing

A

risk of extrusion of infected debris into PA tissues

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54
Q

resin sealers

A

2 pastes - AH plus
8hr set
good seal and flow
initial toxicity decreases after 24hours

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55
Q

GP components

A

20% GP
65% ZnO (filler)
10% radiopacifiers
5% plasticisers

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56
Q

is the outcome affected if GP goes through apex?

A

yes

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57
Q

CLC advantages

A

good length control
gold standard
removable filling

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58
Q

CLC disadvantages

A

does not allow good adaptation to canal irregularities

doesn’t produce homogeneous mass of GP

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59
Q

finger spreaders

A

tapered, smooth-sided

lateral pressure

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60
Q

checking for tug back with master cone

A

should have slight resistance when tug back
corresponds to size of MAF - good apical seal
apical portion must remain undistorted when at length

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61
Q

altering fit of master cone

A

trim apically with scalpel
try another
confirm prep

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62
Q

accessory cones

A

greater taper
corresponding FSs
all interfaces filled with sealer

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63
Q

excess GP removal

A

heated instruments to sever at ACJ/level of attachment
plug GP to compact
remove excess sealer
RMGI primary seal

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64
Q

upper incisors access cavity

A

triangular palatal

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65
Q

upper incisors RCs

A

1 canal

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66
Q

upper canines access cavity

A

oval palatal

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67
Q

upper canines RCs

A

1 canal

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68
Q

upper 1st premolar access

A

oblong

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69
Q

upper 1st premolar RCs

A

1 - 6%
2 - 93%
3 - 1%

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70
Q

upper second premolar access

A

oval

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71
Q

upper second premolar RCs

A

1 - 75%
2 - 24%
3 - 1%

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72
Q

upper 1st molar access

A

rhomboid

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73
Q

upper 1st molar RCs

A

4 - 93% (MB2)

3 - 7%

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74
Q

upper 2nd molar access

A

triangle

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75
Q

upper 2nd molar RCs

A

4 - 37%

3 - 63%

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76
Q

lower incisors access

A

palatal similar shape to crown

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77
Q

lower incisors RCs

A

1 - 59%

2 - 41%

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78
Q

lower canine RCs

A

1 - 86%

2 - 14%

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79
Q

lower premolars access

A

oval

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80
Q

Lower first premolar RCs

A

1 - 73%

2 - 27%

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81
Q

lower second premolar RCs

A

1 - 85%

2 - 15%

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82
Q

lower first molar access

A

oval/square

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83
Q

lower first molar RCs

A

3 - 67%

4 - 33%

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84
Q

lower second molar RCs

A

2 - 13%
3 - 79%
4 - 8%

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85
Q

radix entomolaris

A

additional root in mandibular molars - DL

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86
Q

radix paramolaris

A

additional root in mandibular molars - DB

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87
Q

accessing posterior teeth

A

not vertically due to bulbosity of crown

need distal inclination

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88
Q

Anatomy of the pulp chamber floor - laws

A 
laws of symmetry
law of colour change
laws of orifice location
law of centrality
law of concentricity
law of the CEJ
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89
Q

laws of symmetry

A

1 - except maxillary molars, orifices of canals are equidistant from a line MD direction through floor
2 - except maxillary molars, orifices of canals lie on line perpendicular to a line drawn in a MD direction across centre of floor

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90
Q

law of colour change

A

colour of floor always darker than walls

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91
Q

laws of orifice location

A

always at jct of walls and floor
always at angles in floor wall jct
at terminus of root developmental fusion lines

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92
Q

law of centrality

A

floor always at centre of tooth at level of CEJ

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93
Q

law of concentricity

A

walls of pulp chamber are always concentric to the external surface of the tooth at the level of the CEJ

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94
Q

law of the CEJ

A

the CEJ is the most consistent repeatable landmark for locating the position of the pulp chamber

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95
Q

what is the most reliable landmark for locating the pulp chamber floor?

A

ACJ - pulp chamber floor central and concentric to shape of tooth at ACJ

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96
Q

what may you find when accessing the pulp chamber?

A 
healthy pulp
necrotic pulp
empty
pus
GP
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97
Q

straight line access

A

instrument relatively passive in canal until 1st curvature

protects canal and instrument

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98
Q

what to put in table in notes

A 
canal 
EWL
ref point
CWL
MAF
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99
Q

pulpal physiology

A 
hydrodynamic theory (AB, Ad, C)
generation of movement of tubular fluid leading to activation of the nerve fibres
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100
Q

pulpal physiology - AB and Ad fibres

A

short sharp pain

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101
Q

pulpal physiology - C-fibres

A

long dull throbbing pain

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102
Q

which MOs predominate in necrotic untreated cases?

A

gram - anaerobes

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103
Q

which MOs predominate in failed and persisting infection?

A

mostly gram + anaerobes

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104
Q

biofilm

A

protein matrix with bacterial cells embedded

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105
Q

SOCRATES

A 
Site
Onset
Character
Radiation
Association
Time course
Exacerbating/Relieving factors
Severity
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106
Q

clinical endo notes for a tooth

A 
buccal soft tissue
palatal/lingual mucosa
colour
palpation
restoration
TTP
sinus
mobility
EPT
ethyl chloride
radiograph
diagnosis
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107
Q

what do CN5 branches mostly transmit pain in response to?

A

thermal, mechanical or chemical stimuli

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108
Q

referred pain

A

perception of pain in one part of body distant from source of pain
difficult to discriminate location of pulpal pain
provoked by intense stimulation of C-fibres - intense, slow, dull pain
radiates to ipsilateral side
rare anteriors
posteriors (esp mandibular) - to opp arch or periauricular area but rarely to anteriors

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109
Q

what does vitality testing mean?

A

if it has an intact blood supply

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110
Q

sensibility tests

A

thermal

electric

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111
Q

problems with sensibility tests

A

subjective
testing nerve not blood
problems with multi-rooted teeth

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112
Q

other sensibility tests

A 
laser doppler flowmetry
pulse oximetry
bite test
test cavity
staining and transillumination
selective anaesthesia
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113
Q

pulpal diagnoses

A 
normal pulp
reversible pulpitis
irreversible pulpitis
 - asymptomatic
 - symptomatic
pulp necrosis
prev. treated
prev. initiated
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114
Q

normal pulp

A

symptom free

normally responsive to pulp testing

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115
Q

reversible pulpitis

A

sharp transient, only lasts a few secs
reactive to stimulus - not spontaneous pain
not TTP
no significant radiographic changes

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116
Q

management of reversible pulpitis

A

manage aetiology

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117
Q

what is the nature of the pulp in irreversible pulpitis?

A

vital and inflamed

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118
Q

asymptomatic irreversible pulpitis

A

usually normal response to thermal testing

no clinical symptoms

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119
Q

management of asymptomatic irreversible pulpitis

A

RCT

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120
Q

symptomatic irreversible pulpitis

A

lingering, spontaneous, referred pain
sharp pain on thermal stimulus
OTC analgesics typically ineffective
if inflammation hasn’t reached PA tissues - not TTP

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121
Q

management of symptomatic irreversible pulpitis

A

RCT

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122
Q

pulp necrosis

A

non-responsive to pulp testing, asymptomatic
only causes apical periodontitis if canal infected
usually no obvious radiographic changes

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123
Q

other reasons than necrosis for non-responsive to pulp testing

A

calcification
recent trauma
just not responding

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124
Q

apical diagnoses

A 
normal apical tissues
symptomatic apical periodontitis
asymptomatic apical periodontitis
chronic apical abscess
acute apical abscess
condensing osteitis
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125
Q

normal apical tissues

A

not sensitive to percussion/palpation

radiographically LD intact and PDL space uniform

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126
Q

symptomatic apical periodontitis

A

pain on biting/percussion/palpation
may have radiographic changes - PA radiolucency, widened PDL, thinning LD

severe pain to P/P - degenerating pulp - RCT

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127
Q

apical periodontitis

A

inflammation and destruction of apical periodontium of pulpal origin

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128
Q

asymptomatic apical periodontitis

A

no clinical symptoms

apical radiolucency

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129
Q

chronic apical abscess

A

inflammatory reaction to pulpal infection and necrosis
gradual onset
little/no pain
associated sinus tract - intermittent pus discharge
radiographically signs of osseous destruction e.g. radiolucency

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130
Q

acute apical abscess

A 
inflammatory reaction to pulpal infection and necrosis
rapid onset, spontaneous pain
extreme tenderness to pressure
pus
swelling
may be no radiographic signs of destruction
may be mobile
often malaise, fever, lymphadenopathy
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131
Q

condensing osteitis

A

diffuse radiopaque lesion representing a localised bony reaction to a low grade inflammatory stimulus
usually seen at apex
usually symptom free

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132
Q

tx options

A 
RCT
re-RCT
extract
monitor
surgery
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133
Q

purpose of obturation

A

prevent bacteria that are left from accessing any nutrients

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134
Q

endo-restorative interface - purpose of endo

A

provide env that allows healing of PR tissues so the tooth is retained as a functional unit in the dental arch

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135
Q

aims of instrumentation

A

remove infected hard and soft tissue
give disinfecting irritants access to apical canal space
create space for medicaments and obturation
retain integrity of radicular structures

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136
Q

irrigant ideal properties

A

washing action
lubrication
improve cutting of dentine by the instruments
temp control
dissolution of organic and inorganic matter
good penetration within RC system
killing of planktonic and biofilm microbes
detachment of biofilm
non-toxic to PA tissues
non-allergenic
doesn’t negatively react with other dental materials
does not weaken dentine

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137
Q

NaOCl chemistry

A 
ionises in water into Na+ and OCl-
establishes equilibrium with HOCl
acid/neutral HOCl predominates
pH9 and above OCl- predominates
HOCl - antibacterial activity
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138
Q

why NaOCl?

A

potent antimicrobial activity
dissolves pulp remnants and collagen
only RC irrigant that dissolves necrotic and vital tissue
helps disrupt smear layer by acting on organic component

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139
Q

what is the least effective method of irrigation?

A

syringe irrigation alone

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140
Q

what is the ideal irrigation technique?

A

Manual Dynamic Irrigation - GP point - increase efficacy of NaOCl
can also use Endoactivator - mechanical agitation

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141
Q

factors important for NaOCl function

A 
conc 3%
vol
contact - 10mins
mechanical agitation
exchange
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142
Q

problems with NaOCl

A

possible effects on dentine properties
inability to remove smear layer by itself
effect on organic material

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143
Q

when is the smear layer formed?

A

during prep

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144
Q

smear layer

A

organic pulpal material and inorganic dentinal debris

superficial 1-5um with packing into tubules

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145
Q

problems with the smear layer

A

bacterial contamination
substrate
interferes with disinfection
prevents sealer penetration

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146
Q

removal of the smear layer options

A

17% EDTA
10% citric acid
MTAD
S and US irrigation

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147
Q

EDTA concentration

A

17%

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148
Q

EDTA function

A

removes smear layer

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149
Q

what type of agent is EDTA?

A

chelating agent

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150
Q

EDTA contact time

A

1min

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151
Q

why shouldn’t EDTA and NaOCl interact?

A

get ppts which block tubules

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152
Q

irrigant protocol

A

irrigate/dry with PP between
NaOCl 10mins
EDTA 1min
NaOCl final rinse

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153
Q

NaOCl complications

A

fabric discolouration
ophthalmic injuries
apical extrusion - tissue necrosis
allergic reactions

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154
Q

common symptoms of NaOCl extrusion

A 
pain
swelling
ecchymosis - along course of superficial venous vasculature
haemorrhage
neurological complications
airway obstruction
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155
Q

extrusion risk factors

A

excessive pressure - use index finger not thumb
needle locked within canal
loss of control of WL
larger apical diameters/constriction - RR, immature teeth, developmental anomalies
anatomical factors/proximity to sinus
higher NaOCl conc?

156
Q

EndoVac

A

negative pressure system to pull irrigant down canal

157
Q

management of NaOCl extrusion

A 
LA for pain relief
irrigate with saline
relax pt
nsCaOH
cold and warm compresses, analgesics, review in 24hrs, antibiotics?

prognosis of tooth not - affected

158
Q

advantages of CHX digluconate

A

antibacterial activity
dentine medicated with CHX acquires antimicrobial substantivity - prevents colonisation for time beyond application
acceptable biocompatibility

159
Q

how does CHX digluconate have antibacterial activity?

A

+CHX attracted to -phospholipids in cell wall

binds to cell wall - lysis

160
Q

disadvantages of CHX digluconate

A

less antifungal activity
unable to disrupt biofilms
sensitivity possible, risk of anaphylactic reaction

161
Q

NaOCl and CHX interaction

A

forms parachloroaniline
cytotoxic and carcinogenic
uncertain bioavailability
brown ppt - discolours tooth

162
Q

what cases are often done in a single visit?

A

vital cases

163
Q

single vs multi visit

A

case by case

164
Q

which cases may be done over multi visits?

A

non-vital cases more complex with greater resistance to endo tx - inter-appt dressing may be important
may not always want to fill teeth on first visit e.g. if huge abscess filled with pus

165
Q

purpose of intracanal medicaments between appts

A

destroy MOs
prevent reinfection
decrease inflammation and exudate
control of RR

166
Q

antimicrobial paste

A

paste containing corticosteroid and tetracycline
good for hot pulps = when can’t get numb due to extent of inflammation
not gold standard otherwise
can facilitate follow-up treatment
effective for 5-7 days e.g. odontopaste

167
Q

how long should nsCaOH be left?

A

7days

168
Q

properties of nsCaOH

A

bactericidal and bacteriostatic, antimicrobial
hydrolysis of LPS therefore reducing its inflammatory potential
effective in removing tissue debris
high pH - stimulates fibroblasts for reparative dentine formation
adheres directly to dentine
doesn’t dissolve in biological liquids
neutralises low pH from acidic restorative materials

169
Q

inter-appt temp dressing

A

CaOH
cotton wool
Coltosol
3mm GI

170
Q

file motions

A 
filing
reaming
WW
balanced force
envelope of motion
171
Q

filing motion

A

up and down

172
Q

reaming

A

repeated clockwise rotation

if bind too far breaks

173
Q

WW

A

back and forward oscillation 30-60 degrees with light apical pressure

174
Q

balanced force technique

A 
LAP
clockwise
anticlockwise a bigger degree of rotation
x1-3 then remove
safer for canal and file
175
Q

envelope of motion

A

evenly strip

176
Q

what is a glide path?

A

path along which tip of subsequent instrument will pass, protects that tip
“smooth radicular tunnel from canal orifice to apical constriction”

177
Q

importance of a glide path

A

confirm SL access

explore anatomy

178
Q

creating a glide path

A

always introduce files 10-25 to resistance only
coronal flare
size 10 with WW establish apex
irrigate and repeat using 15 (WW) and 20 (BF)

179
Q

what is apical gauging?

A

technique to best determine the size of the apical constriction and the taper of the apical portion closest to the foramen

180
Q

how to determine apical gauging

A

2 sizes bigger than one that originally bound at length

181
Q

protaper hand use properties

A

superelasticity

variable taper

182
Q

protaper hand use properties - superelasticity

A

NiTi alloy - v flexible
shape memory effect after heat tx
lowers risk of ledges and perforation - doesn’t apply much force at its tip

183
Q

protaper hand use properties - variable taper

A

more specific shape
larger taper apically so more control
not whole way up

184
Q

S shaping files - where are they used?

A

coronal and mid root

185
Q

S shaping files

A

S1
S2
SX

186
Q

S shaping files - S1

A

purple
17
coronal flare
2/3 BF technique

187
Q

S shaping files - S2

A

white
20
mid-root shaping

188
Q

S shaping files - SX

A

red
19
only for short canals

189
Q

F finishing files - F1

A

yellow

20

190
Q

F finishing files - F2

A

red

25

191
Q

F finishing files - F3

A

blue

30

192
Q

F finishing files - F4

A

black

40

193
Q

F finishing files - F5

A

yellow

50

194
Q

protaper colours mnemonic

A 
Please
Will
You
Read
Books
By
Yourself
195
Q

summary of Protaper process

A 
10 - to 2/3 EWL
15 - to 2/3 EWL
S1 - no deeper than 15
(SX)
10 - EWL/0 with EAL

find CWL

15 - glide path to CWL
S1
S2
F1
F2
...
K25 to length
196
Q

barbed broach

A

extirpating only
do not engage dentine
tapered round shaft with portions lifted almost at a right angle
extremely fragile

197
Q

Hedstrom (H) files

A

use in filing motion - cuts on withdrawal
can cause iatrogenic damage - no longer used for canal prep
useful for removing GP or fractured instruments for re-tx

198
Q

K reamers

A

made by twisting a tapered triangular shaft

must be in contact with walls, but must not bind or may break

199
Q

C+ files

A

similar to K-files but has a cutting tip and slightly more rigid

200
Q

K files

A

flexible so useful in curved canals
SS
cut when used in rotation
twisting a square shaft

201
Q

flexible K files (flexofiles)

A

cross-sectional shape allows greater flexibility
SS/NiTi
filing/rotation motion

202
Q

complications of SS hand instrumentation

A

mishaps - ledges, canal blockage, zipping of apical foramen

debris extrusion with filing motion

203
Q

blockage

A

dentine debris packed into apical portion of root
when packed tightly can be as hard as dentine
attempts to remove it can lead to false canal and perforation
irrigate

204
Q

ledges

A

an internal transportation of the canal

205
Q

when do ledges occur?

A

when working short of length

206
Q

management of a ledge

A

hard to bypass - need to curve tip of a small file

207
Q

what happens if curved canals are instrumented as if they were straight?

A

get ledging and the apical few mm will remain uninstrumented and infected

208
Q

apical zipping/transportation

A

occurs due to the tendency of the instrument to straighten inside a curved canal

209
Q

management of minor apical zipping/transportation

A

canal can be reshaped to a new level just above the foramen

210
Q

severe apical zipping/transportation issues

A

bleeding is a problem and attempting to reshape can weaken/perforate root

211
Q

consequences of apical zipping/transportation

A

over enlargement along outer side of curvature
under prep of inner aspect at apical end point
main axis of canal is transported
results in a teardrop/hourglass shape

cases tend to be over-extended and poorly filled = fails to provide resistance for packing of GP

212
Q

how to avoid apical transportation

A

always pre-curve initial small sized hand instruments
don’t skip instruments in sequence
never rotate the instruments in curved canals

213
Q

diagnosis of root perforation

A

persisting bleeding into canal
multiple radiographs - can do with a file in to see if perforation
EAL
dental operating microscope

214
Q

what does prognosis of perforation depend on?

A 
location
time elapsed
size
PD irritation
material used for repair
215
Q

MTA for perforation

A

only works well for small - not strong in CS

dentine fibres and cementum will bind to MTA

216
Q

importance of superelasticity

A

can be strained more than others before permanent deformation
can place in curved canals with less lateral forces exerted
- less transportation, zipping and ledging
- more centrally placed prep in harmony with original canal shape

217
Q

components of an endo rotary instrument

A 
taper
flute
leading/cutting edge
land
relief
helix angle
218
Q

taper

A

diameter change along working surface

219
Q

flute

A

groove to collect dentine and ST

220
Q

leading/cutting edge

A

forms and deflects dentine chips

221
Q

land

A

surface extending between flutes

222
Q

relief

A

reduction in surface of land

223
Q

helix angle

A

angle cutting axis makes with LA of file

224
Q

advantages of NiTi vs SS

A

increased flexibility in larger sizes and tapers
increased cutting efficiency
if used appropriately good safety in use
more user friendly

225
Q

Protaper gold

A

NiTi wire plus gold tx
triangular in CS
active length 16mm
impacts the metallurgy in a favourable way to provide a higher flexibility and a higher resistance to cyclic fatigue

226
Q

disadvantages of NiTi

A 
instrument fracture
£
access can be difficult in posteriors
unsuitable for complex canal anatomy
effect of prion decontamination protocols on NiTi rotary surfaces?
227
Q

true reciprocation

A

mimics manual movement
lower risks associated with continuously rotating a file through canal curvatures
decreased cutting efficiency
requires increased inward pressure
limited capacity to auger debris out of a canal

228
Q

rotary instrumentation guidelines

A 
straight line access
CS diameter (ISO 15 or more)
RC system anatomy 
speed and sequencing
lubrication and light touch
229
Q

Rotary NiTi generations

A 
1st - K file type helix
2nd - reamer type helix, Protaper
3rd - metallurgy, safer, Protaper Gold
4th - reciprocation movement, safer
5th - offset design
230
Q

engine driven systems movement

A

vertical movement
reciprocation rotation 90/30 degrees
rotation 360 degrees
rotary endo - greater flexibility and taper

231
Q

torsional stress

A

extensive instrument surface encounters excessive friction on canal walls
instrument tip is larger than canal section to be shaped, tip may lock, torque exceeds critical level

232
Q

flexural stress

A

repeated cyclic metal fatigue

cannot be influenced by clinician

233
Q

cyclic fatigue

A

freely rotating in a curvature
get tension/compression cycles
failure

234
Q

torsional fatigue

A

instrument binds, if further rotated - stress in torsion, torque
structure of metal can undergo irreversible changes
each time causes torsional fatigue - eventually fracture

235
Q

how to avoid torsional fatigue in reciprocation

A

clockwise and anticlockwise angles of rotation should be set lower than the elastic limit
the lower the angles of rotation the safer the procedure, as long as instrument can still cut dentine, advance apically in canal and remove cutting debris in coronal direction

236
Q

in torsional fatigue what determines if the metal structure changes are reversible or irreversible?

A

amount of rotation when instrument is binding

237
Q

what is between the elastic and plastic phases?

A

elastic limit

238
Q

protaper size matched cones

A

complement file size and shape so leave v little space for accessory cones
check for tug back
spreader won’t go as deep as before

239
Q

what is the outcome if good endo and good restoration?

A

91%

240
Q

disadvantages of radiographs

A

2D
magnification/distortion
radiographic apex could be different from the actual terminus

241
Q

evaluation of pt - case assessment

A

medical
psychological
social factors

242
Q

case selection

A

pt evaluation
tooth evaluation
self-evaluation of clinician

243
Q

case assessment - medical findings

A 
no absolute contraindication to endo - if in doubt speak to physician
pregnancy
CV disease
cancer
diabetes mellitus
bisphosphonate therapy
allergies
244
Q

pregnancy

A

1st trimester emergency intervention only - when foetus most at risk from env factors
balancing act - if don’t tx infection could make them systemically unwell
pain and infection managed in collaboration with physician

245
Q

cancer

A

history
chemo and radio to head and neck can compromise healing
consult with oncologist

246
Q

CV disease

A

contraindication - MI in last 6m
consult cardiologist re emergency tx
Stress Reduction Protocol - short appts, sedation, pain and anxiety control

247
Q

diabetes

A

endo infection can affect their glycemic control
monitor carefully
schedule appts around insulin and meal schedule
minimise stress
may also impact on their outcome - RCT prognosis worse

248
Q

bisphosphonates

A

IV>oral
preventive care - avoid extractions
non-surgical endo tx of teeth that might otherwise be extracted

249
Q

allergies

A

latex allergy - use vinyl dam

GP not a risk as non-cross reactive

250
Q

dental evaluation

A 
PD considerations
restorative considerations
calcifications, dilacerations, resorption
inability to isolate tooth
unusual anatomy
ledges and perforations
posts
separated instruments
developmental abnormalities
251
Q

endo perio lesion

A

do endo first then PD therapy later if necessary

252
Q

calcifications

A

usually coronal to apical
isolated/continuous - can make tx vvv difficult
may consider surgery

253
Q

restorative considerations

A 
sub-osseous caries
poor crown/root ratio
misalignment
pre-existing full coverage restorations
restorability - remove all decay so extent of healthy tooth structure can be determined
254
Q

effect of resorption on RCT

A

harder to control irrigants

255
Q

when would you consider CBCT?

A

only if the additional information from 3D reconstructed images will potentially aid formulating a diagnosis/enhance the management of a tooth with an endo problem

256
Q

how to decide whether to tx or refer

A

simple formula - e.g root number/chronic or acute
AAE endo case difficulty assessment form
Restorative dentistry IOTN - complexity assessment

257
Q

options for tx

A 
no active tx with review
extract
orthograde RCT
surgical endo
referral
258
Q

factors that affect tx decision

A 
pt assessment
dental assessment
pt motivation
pt time
cost
259
Q

AAE endo case difficulty assessment form - categories

A

minimal
mod
high

260
Q

AAE endo case difficulty assessment form - minimal

A

routine complexity

predictable tx outcome should be attainable by competent with limited experience

261
Q

AAE endo case difficulty assessment form - mod

A

complicated

challenging for competent, experienced practitioner

262
Q

AAE endo case difficulty assessment form - high

A

exceptionally complicated

challenging for even the most experienced practitioner with extensive history of favourable outcomes

263
Q

AAE endo case difficulty assessment form - considerations

A

pt
diagnostic tx
additional

264
Q

AAE endo case difficulty assessment form - pt considerations

A 
MH
anaesthesia
pt disposition
ability to open mouth
gag reflex
emergency condition
265
Q

AAE endo case difficulty assessment form - diagnostic tx considerations

A 
diagnosis
radiographic difficulties
position in arch
isolation
radiographic appearance of canals
resorption
crown, canal and root morphology
266
Q

AAE endo case difficulty assessment form - additional considerations

A

trauma history
endo tx history
perio-endo condition

267
Q

NHS IOTN complexity assessment

A

complexity 1/2/3
modifying factors that are relevant to RCT
MH that significantly affects clinical management

268
Q

prognosis of orthograde RCT

A

predictable and usually successful
outcome rates up to 90% over 10 years for teeth with irreversible pulpitis
up to 80% over 10 years for necrotic teeth
many tx modalities yet v little difference in outcome

269
Q

importance of filling the RC system

A

prevent passage of MOs and fluid
block apical foramina, dentinal tubules and accessory canals
chemomechanical disinfection can’t get to it all

270
Q

properties of obturation materials

A 
biocompatible
dimensionally stable
able to seal
insoluble
unaffected by tissue fluids
non-supportive of bacterial growth
radiopaque
removable from canal if re-tx needed
271
Q

disadvantages of CLC

A

voids
spreader tracts
incomplete fusion of GP cones
lack of surface adaptation

272
Q

disadvantages of single cone obturation

A

quality
microleakage
bacterial penetration
similar/lower to others

273
Q

warm vertical compaction

A

3D obturation
need continuously tapering funnel and small apical diameter
repeated heating and compaction of GP

274
Q

yellow Buchanan hand plugger

A

25

275
Q

red Buchanan hand plugger

A

40

276
Q

blue Buchanan hand plugger

A

70

277
Q

continuous wave obturation

A 
downpack, apical pressure
cool reactivate separate tip
have apical plug - forced into lateral canals
backfill
uses heat
278
Q

carrier based obturation

A

solid (flexible) plastic/cross-linked GP core, coated with molten GP
good for curved canal
but easy to extrude beyond apex
low void incidence

279
Q

what is a potential disadvantage of thermal obturation techniques?

A

less apical control?

280
Q

bio ceramic cements

A

may be good in some complex canals
root perforations
MTA
comparable filling quality to GP and sealer

281
Q

how to measure sealing ability

A 
dye penetration
isotope penetration
EC technique
bacterial penetration
salivary penetration
282
Q

resilon

A

resin based system
dentine bonding technology
“monoblock”
much higher failure than GP

283
Q

ideal sealer properties

A 
tackiness - good adhesion
hermetic seal
radiopaque
easily mixed
no shrinkage on setting
non-staining
bacteriostatic
slow set
insoluble in tissue fluids
biocompatible
soluble on re-tx
284
Q

ZOE based sealers

A 
e.g. Tubliseal
antimicrobial
cytotoxic
free eugenol - irritant
lose vol with time due to dissolution - resins can modify
285
Q

GI sealers

A

dentine bonding properties
minimal antimicrobial activity
soluble
difficult to remove upon re-tx

286
Q

EndoRez

A 
MDMA resin-based sealer
hydrophillic
good penetration into tubules
biocompatible
good radiopacity
287
Q

calcium silicate sealers

A 
high pH initial 24hrs
hydrophillic
biocompatible
doesn't shrink
non-resorbable
excellent sealing ability
quick set 3-4hrs - needs moisture
easy to use
288
Q

sealer placement

A

file
lentulospiral
US files
master GP cone

289
Q

sealer functions

A

seal space between dentinal wall and core
fills voids and irregularities
lubricated

290
Q

what type of sealers are not recommended?

A

ones containing organic materials e.g. aldehydes

291
Q

why is RC culturing not always done?

A

assays not always reliable/relevant

292
Q

timing of obturation

A 
S/S - don't want to obturate while patient still has symptoms i.e. swelling
pulp status
PA status
difficulty
pt management
293
Q

is length a prognostic determinant?

A

yes - >2mm short of apex harboured bacteria

294
Q

how to asses obturation

A

post-op radiograph including root apex and at least 2-3mm of PA region

295
Q

criteria for successful obturation

A

completely filled (unless space for post)
prepped and filled canal should contain original canal
no spaces
to length
to facial CEJ anteriors and canal orifice in posteriors

296
Q

what is the most important factor for apical PD health?

A

coronal seal

297
Q

orifice closure

A

ZnO/Eugenol
RMGIC/flowable composite
GP rapidly infected if exposed

298
Q

future - regenerative endo?

A

vital pulp therapies with SCs

pulp regenerative therapies

299
Q

defining success

A

means different to researchers, clinicians and patients

technical vs biological outcome

300
Q

ESE success - assessment of outcome

A

RCT should be assessed at least after 1 year and subsequently as required
successful
uncertain
unfavourable

301
Q

successful outcome

A

no pain, swelling, other symptoms
no sinus tract
no loss of fct
radiological evidence of a normal PDL - intact LD

302
Q

uncertain outcome

A

radiographic changes same size/smaller
doesn’t have intact PDL - radiolucency, widened etc
clinically and radiographically assess every 12m for 4yrs/until resolved
if persists >4yrs - associated with post-tx disease - unfavourable

303
Q

exceptions to outcome - scar tissue formation

A

an extensive radiological lesion may heal but leave a locally visible, irregularly mineralised area
defect may be scar tissue formation rather than a sign of persisting apical periodontitis
should continue to assess tooth

304
Q

unfavourable outcome

A

tooth associated with S+S of infection
a radiologically visible lesion has appeared subsequent to tx or a pre-existing lesion has increased in size
lesion remained same size/only diminished in size over 4 year assessment period
signs of continuing RR

advise further tx for tooth

305
Q

definitions of outcome - how success is defined

A

strict criteria - ESE guidelines, strict radiographic criteria for success 74.7%
loose criteria 85.2%
retention only 97.1%

306
Q

pre-op factors affecting success

A

presence/absence of lesion - PA radiolucency pre-tx - outcome worse
presence of sinus
increased lesion size

307
Q

operative factors affecting success

A 
fill to within 2mm of radiographic apex
but not extruded
well-condensed, no voids
good quality coronal restoration
no perforation
patency
penultimate rinse with EDTA (re-RCT)
avoid mixing CHX and NaOCl
no flare up between visits
instrument fracture
missed canal - failed biological objective - MB2
308
Q

how does instrument fracture affect outcome?

A

may do - depends on when fracture occurs - how much disinfection has already occurred
e.g. F3 better than S2

309
Q

instrument fracture management options

A 
remove
bypass
obturate up to instrument
surgical removal
extract
310
Q

iatrogenic factors leading to failure

A 
poor planning
poor access
poor length control
forcing instruments
failure to observe sequence
failure to maintain patency
311
Q

biological reasons for failure

A

persistent intraradicular infection - canal complexities, biofilm, resistant bacteria
extra-radicular bacteria - actinomycosis, extruded biofilm
cyst formation
cholesterol crystals
foreign body reactions - delayed healing
scar tissue ‘healing’

312
Q

periapical cysts

A

form from mature granuloma, inflammatory mediators acting on epithelial cell rests - proliferate

313
Q

true cyst

A

epithelial lined cavity that is distinct from the root

314
Q

pocket cyst

A

cyst cavity continuous with RC space

315
Q

how can you tell if it is a cyst?

A

only histologically

316
Q

periapical cyst prevalence

A

about 15%

317
Q

retreatment options

A

KUO
orthograde retx - but can you change something?
surgical tx - periradicular surgery
extract

318
Q

what are 3 key points before retx?

A

establish cause of failure
assess restorative prognosis
re-tx complexity

319
Q

when is KUO a risk?

A

CV disease/diabetes

320
Q

removing insoluble resins

A

US

321
Q

removing soluble pastes

A

handfiles +/-solvent - Protaper, D/Reciproc

322
Q

removing poorly condensed GP

A

generally easier

Hedstroem files

323
Q

removing well-condensed GP

A

generally harder

need to create space

324
Q

removing GP

A

handfiles
solvent
Protaper D1

325
Q

removing GP - handfiles

A

30/40 , few clockwise turns then pull
not on PD compromised teeth
C+ files - wind tip in WW, try to make space
if you can - back to 30 and remove. if can’t - solvent

326
Q

removing GP - solvents

A

eucalyptus oil or chloroform

327
Q

removing GP - Protaper D1

A

active tip - better initial penetration
but perforates teeth easily
good for coronal GP ONLY

328
Q

Reciproc blue

A

“increased resistance to cyclic fatigue, increased flexibility”

good for re-tx

329
Q

what could PAP be (in order of likelihood)?

A

granuloma
abscess
true cyst
pocket cyst

330
Q

what speed should you use for protaper re-tx?

A

lowest speed that engages obturation material

500-700 rpm

331
Q

Protaper retx D1

A

coronal removal

16mm, ISO30, 9%

332
Q

protaper retx D2

A

middle 1/3 removal

18mm, ISO25, 8%

333
Q

protaper retx D3

A

apical 1/3 removal, stop 2-3mm short of apex

22mm, ISO20, 7%

334
Q

how to bypass ledges in protaper retx

A

pre-curved C+ files

335
Q

PR surgery

A

surgical shortening of the root apex +/- retrograde sealing

336
Q

is PR surgery ideal?

A

no - retx almost always preferable to or at v least better to use in conjunction with root end surgery

337
Q

reciproc system for retx

A

reciprocating movement
R25 red
R40 black
R50 yellow

v efficient
remove bulk of GP (US, heat carrier)
brushing

338
Q

why should you delay the use of solvents for as long as possible?

A

creates things which get pushed into tubules and into accessory canals - affects ability to get into RC space

339
Q

indications for PR surgery

A

1 - failure of prev endo tx - retx not possible/won’t correct problem e.g. can’t regain access
2 - anatomical deviations - prevent complete cleaning and obturation - tortuous, curved roots, pulp stones, calcifications
3 - procedural errors - ledges, perforations etc
4 - exploratory surgery - identify root fractures

340
Q

contraindications for PR surgery

A

anatomical factors - proximity to NV bundles
inadequate PD support
unrestorable tooth
medical factors - leukaemia, neutropenia, recent heart/cancer surgery. postpone if recent MI/radio tx
skill and ability of surgeon - refer?

341
Q

microsurgery

A

uses “microscopes and miniaturised precision instruments to perform intricate procedures on v small structures”
higher success than contemporary root end surgery
- magnification, instruments, illumination

342
Q

haemostasis in PR surgery - pre-op

A

LA - 1:50 000 adrenaline and 2% lidocaine

343
Q

haemostasis in PR surgery - intra-op

A

examine bone crypt at high magnification
epinephrine pellets
ferric sulphate (cytotoxic - affects osseous healing)
CaSO4 - mechanically blocks open vessels

344
Q

haemostasis in PR surgery - post-op

A

pressure

sulcular full thickness flap or mucogingival flap

345
Q

mucogingival flap

A

crowned anteriors
scalloped incision in middle of attached gingiva at 45 degrees
vertical relieving incisions

346
Q

microsurgical instruments

A 
blades
ST elevators
curettage instruments
US tips
inspection mirrors
carriers and pluggers
needles and holders
347
Q

osteotomy - clinical possibilities

A

intact cortical plate, no radiographic lesion
intact cortical plate, periapical lesion
fenestration through cortical plate leading to apex
- send lesion to histology to confirm just endo lesion

348
Q

PRS - osteotomy

A

remove cortical plate to expose root end
assess
keep small - healing - microscope
use curettes to remove granulation tissue
clean L/P aspect after root end resection

349
Q

PRS - root end resection

A

3mm resected perpendicular to long axis of tooth

350
Q

PRS - why is 3mm resected?

A

terminal 3mm - a delta
- intricate design of canals
- can’t disinfect
- removes most lateral canals and ramifications
may be extraradicular biofilm
- could be initiating factor in inflammation

351
Q

what is the aim of the root end filling in PRS?

A

seal apex so bacteria/products can’t enter/leave canal

352
Q

PRS - US root end prep

A 
low magnification
US tip at apex
coolant
3mm depth
inspect with micro mirror at high magnification - remnants of GP, recondense GP
353
Q

other ways to inspect resected root surface

A

PP

stroptko device - low pressure 10psi

354
Q

isthmus

A

communication between 2 separate canals in one root

355
Q

isthmus frequency

A

anteriors 15%
premolars 30%
M roots of L6s - 70%
MB roots of U6s - 45%

356
Q

clinical significance of isthmus

A

untreated is one of the main causes of surgical failure

357
Q

management of isthmus

A

identify with microscope

US prep - cut hole along isthmus so you can debride, disinfect and seal root properly

358
Q

properties of ideal root end filling material

A 
well-tolerated by apical tissues
bactericidal/static
adhere to tooth
dimensionally stable
easy to handle
do not stain
non-corrosive
non-dissolving
promote cementogenesis
radiopaque
359
Q

amalgam as a root end filling material

A

no longer used - slow set, biocompatibility, leakage, corrosion and staining
will see in pts historically

360
Q

MTA chemistry

A

powder of fine hydrophilic particles
tricalcium silicate/oxide/aluminate, silicate oxide, bismuth oxide
mix water - slurry

361
Q

MTA properties

A 
long setting time
antimicrobial
alkaline
superior sealing ability
moisture tolerant
radiopaque
excellent biocompatibility
regeneration of cementum - bioinductive
362
Q

clinical applications of MTA

A 
pulp capping
RR
apexification
root end filling
perforation repair
furcal repair
363
Q

root end filling - MTA placement

A 
protect bone crypt
sterile water - putty
MTA gun/carrier
micropluggers/burnishers to lightly condense material
wipe excess with moist cotton pellet
364
Q

regenerative procedures

A

quantity of remaining cortical bone influences surgery outcome
GTR
build scaffold on which pts bone can heal
doesn’t seem to have big impact on PR surgery outcome

365
Q

PRS suturing

A

interrupted suture
ideally monofilament
remove 72hrs

366
Q

PRS post op paraesthesia

A

abnormal sensation or numbness caused by impingement/handling/laceration/severance of nerve
often transient caused by swelling due to inflammation
normal sensation returns in 4wks

367
Q

outcome of endo surgery

A 
classification of healing
 - healed
 - incomplete healing (scar)
 - uncertain healing
 - failed
follow up 1yr, then up to 4 yrs
368
Q

preventing lacerations in PRS

A

vaseline lips

avoid careless flap elevation

369
Q

PRS prognostic factors

A 
age
tooth position (L ants and L7s hard)
root end filling material
presence of co-existing PDD
apical seal
coronal seal
crypt size
370
Q

PRS success

A

1yr post op 96.8%
5-7yrs 91.5%
endodontists higher than oral surgeons - microscopes
1/3 success for repeat surgery

371
Q

PPV

A

positive test result (no response) are truly non-vital

372
Q

NPV

A

probability teeth with negative response are truly vital

373
Q

mnemonic for ISO colour code

A 
Please
Give
Peter
Why
Yelling
Red
Because
Green
Blacked out
374
Q

most common number of canals - maxilla

A 
1
1
1
2
1
4
3
375
Q

most common number of canals - mandible

A 
1
1
1
1
1
3
3
376
Q

reaming

A

repeated clockwise rotation

377
Q

what dictates the access cavity shape?

A

shape of pulp chamber

378
Q

Endo Z bur

A

non-cutting tip
make access wider
funnel shape

379
Q

GG bur

A

non-cutting tip
brush strokes
remove ledges and widen
SL access

380
Q

aims of access cavity prep

A

remove entire roof = can remove all of pulpal tissue
visualisation of RC entrance
smooth-walled, no overhangs
SL access
(leave MR if possible to preserve strength)

381
Q

why shouldn’t you use hand spreader?

A

too much force - may fracture tooth

382
Q

are side vented needles good?

A

yes they are safer

383
Q

indications for endo tx

A

irreversibly damaged/necrotic pulp
overdenture - decoronated teeth retained in arch
crowns - prophylactic tx of pulp before crown to reduce complications
PDD - root resection may merit elective devitalisation

384
Q

contraindications for endo tx

A 
unrestorable tooth
poor OH
insufficient PD support
root fracture
bizarre anatomy
internal resorption
385
Q

why obturate?

A

seal remaining bacteria - prevent them from accessing any nutrients
provide apical and coronal seal
prevent reinfection

Endo (5 decks)

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