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
2
Q
why is it important to keep the apical opening as small as possible?
A
wound healing
less likelihood of trauma
apical control
3
Q
why is cuspal protection important?
A
prevent microbial ingress
prevent catastrophic fracture
4
Q
what does the pre-tx radiograph need to include?
A
all root
2-3mm of surrounding PR tissue
5
Q
why should dam be used?
A
bacterial contamination inhalation protects Sts access and vision can use disinfectants
6
Q
sizes of SS instruments
A
21/25/31mm
7
Q
taper on SS instruments
A
2%, 0.32mm
8
Q
cutting flutes on SS instruments
A
16mm
diameter at D2 = apical size + 0.32mm
9
Q
ISO colour code - 06
A
pink
10
Q
ISO colour code - 08
A
grey
11
Q
ISO colour code - 10
A
purple
12
Q
ISO colour code - 15
A
white
13
Q
ISO colour code - 20
A
yellow
14
Q
ISO colour code - 25
A
red
15
Q
ISO colour code - 30
A
blue
16
Q
ISO colour code - 35
A
green
17
Q
ISO colour code - 40
A
black
18
Q
ISO colour code - 45
A
white
19
Q
ISO colour code - 50
A
yellow
20
Q
ISO colour code - 55
A
red
21
Q
ISO colour code - 60
A
blue
22
Q
ISO colour code - 70
A
green
23
Q
ISO colour code - 80
A
black
24
Q
ISO colour code - pink
A
06
25
ISO colour code - grey
08
26
ISO colour code - purple
10
27
ISO colour code - white
15
| 45
28
ISO colour code - yellow
20
| 50
29
ISO colour code - red
25
| 55
30
ISO colour code - blue
30
| 60
31
ISO colour code - green
35
| 70
32
ISO colour code - black
40
| 80
33
objectives of irrigants
```
disinfect RC
dissolve organic debris
flush out debris
lubricate instruments
remove smear layer
```
34
what is used to deliver irrigant to RC?
Luer lock syringe with 27 gauge needle
35
what is recapitulation?
after each file irrigate and use file smaller than MAF
36
what are the aims of recapitulation?
disturbs debris and lifts into solution
| prevents blockages
37
where should RC preparation end?
at the jct of pulpal and PA tissue - as close as possible to CDJ - usually apical constriction
38
EWL
estimated length at which instrumentation should be limited
39
calculating EWL
measure pre-op radiograph from FRP to radiographic apex and -1mm
40
how does the distance of the apical constriction from the radiographic apex vary?
greater in older teeth with secondary cementum
varying anatomy
RR
can give a false reading of where RC terminates
41
CWL
length at which instrumentation and subsequent obturation should be limited
42
when is CWL determined?
after coronal flaring
43
methods of determining CWL
EAL
WL radiograph
PP length discrimination
44
EAL
impedence/resistance drops when you touch PDL
unreliable if wide apical foramen
subtract 0.5-1mm
45
PP length discrimination
wet dry interface
| PR tissues wet, RC should be dry
46
MAF
largest diameter file taken to CWL and therefore represents the final prepared size of the apical portion of the canal at the WL
47
reasons for early flaring of coronal portion
reservoir for irrigant
avoids hydrostatic pressure in canal
early removal of heavily contaminated contents
improved SL access to apical 1/3
48
modified double flare technique
uses BF
1 - enlarge/flare coronal part
2 - apical enlargement
3 - apical taper - step back
49
apical size
small as practicable but large enough to irrigate
| ISO 25 or above
50
mid root prep
step back
increase file size as -1mm each time
until file "falls out"
brush MAF around wall to get rid of steps
51
what is patency filing?
ISO 10 or smaller 0.5-1mm through apical constriction
| passive placement
52
purpose of patency filing
prevent apical blockage
53
risk of patency filing
risk of extrusion of infected debris into PA tissues
54
resin sealers
2 pastes - AH plus
8hr set
good seal and flow
initial toxicity decreases after 24hours
55
GP components
20% GP
65% ZnO (filler)
10% radiopacifiers
5% plasticisers
56
is the outcome affected if GP goes through apex?
yes
57
CLC advantages
good length control
gold standard
removable filling
58
CLC disadvantages
does not allow good adaptation to canal irregularities
| doesn't produce homogeneous mass of GP
59
finger spreaders
tapered, smooth-sided
| lateral pressure
60
checking for tug back with master cone
should have slight resistance when tug back
corresponds to size of MAF - good apical seal
apical portion must remain undistorted when at length
61
altering fit of master cone
trim apically with scalpel
try another
confirm prep
62
accessory cones
greater taper
corresponding FSs
all interfaces filled with sealer
63
excess GP removal
heated instruments to sever at ACJ/level of attachment
plug GP to compact
remove excess sealer
RMGI primary seal
64
upper incisors access cavity
triangular palatal
65
upper incisors RCs
1 canal
66
upper canines access cavity
oval palatal
67
upper canines RCs
1 canal
68
upper 1st premolar access
oblong
69
upper 1st premolar RCs
1 - 6%
2 - 93%
3 - 1%
70
upper second premolar access
oval
71
upper second premolar RCs
1 - 75%
2 - 24%
3 - 1%
72
upper 1st molar access
rhomboid
73
upper 1st molar RCs
4 - 93% (MB2)
| 3 - 7%
74
upper 2nd molar access
triangle
75
upper 2nd molar RCs
4 - 37%
| 3 - 63%
76
lower incisors access
palatal similar shape to crown
77
lower incisors RCs
1 - 59%
| 2 - 41%
78
lower canine RCs
1 - 86%
| 2 - 14%
79
lower premolars access
oval
80
Lower first premolar RCs
1 - 73%
| 2 - 27%
81
lower second premolar RCs
1 - 85%
| 2 - 15%
82
lower first molar access
oval/square
83
lower first molar RCs
3 - 67%
| 4 - 33%
84
lower second molar RCs
2 - 13%
3 - 79%
4 - 8%
85
radix entomolaris
additional root in mandibular molars - DL
86
radix paramolaris
additional root in mandibular molars - DB
87
accessing posterior teeth
not vertically due to bulbosity of crown
| need distal inclination
88
Anatomy of the pulp chamber floor - laws
```
laws of symmetry
law of colour change
laws of orifice location
law of centrality
law of concentricity
law of the CEJ
```
89
laws of symmetry
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
90
law of colour change
colour of floor always darker than walls
91
laws of orifice location
always at jct of walls and floor
always at angles in floor wall jct
at terminus of root developmental fusion lines
92
law of centrality
floor always at centre of tooth at level of CEJ
93
law of concentricity
walls of pulp chamber are always concentric to the external surface of the tooth at the level of the CEJ
94
law of the CEJ
the CEJ is the most consistent repeatable landmark for locating the position of the pulp chamber
95
what is the most reliable landmark for locating the pulp chamber floor?
ACJ - pulp chamber floor central and concentric to shape of tooth at ACJ
96
what may you find when accessing the pulp chamber?
```
healthy pulp
necrotic pulp
empty
pus
GP
```
97
straight line access
instrument relatively passive in canal until 1st curvature
| protects canal and instrument
98
what to put in table in notes
```
canal
EWL
ref point
CWL
MAF
```
99
pulpal physiology
```
hydrodynamic theory (AB, Ad, C)
generation of movement of tubular fluid leading to activation of the nerve fibres
```
100
pulpal physiology - AB and Ad fibres
short sharp pain
101
pulpal physiology - C-fibres
long dull throbbing pain
102
which MOs predominate in necrotic untreated cases?
gram - anaerobes
103
which MOs predominate in failed and persisting infection?
mostly gram + anaerobes
104
biofilm
protein matrix with bacterial cells embedded
105
SOCRATES
```
Site
Onset
Character
Radiation
Association
Time course
Exacerbating/Relieving factors
Severity
```
106
clinical endo notes for a tooth
```
buccal soft tissue
palatal/lingual mucosa
colour
palpation
restoration
TTP
sinus
mobility
EPT
ethyl chloride
radiograph
diagnosis
```
107
what do CN5 branches mostly transmit pain in response to?
thermal, mechanical or chemical stimuli
108
referred pain
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
109
what does vitality testing mean?
if it has an intact blood supply
110
sensibility tests
thermal
| electric
111
problems with sensibility tests
subjective
testing nerve not blood
problems with multi-rooted teeth
112
other sensibility tests
```
laser doppler flowmetry
pulse oximetry
bite test
test cavity
staining and transillumination
selective anaesthesia
```
113
pulpal diagnoses
```
normal pulp
reversible pulpitis
irreversible pulpitis
- asymptomatic
- symptomatic
pulp necrosis
prev. treated
prev. initiated
```
114
normal pulp
symptom free
| normally responsive to pulp testing
115
reversible pulpitis
sharp transient, only lasts a few secs
reactive to stimulus - not spontaneous pain
not TTP
no significant radiographic changes
116
management of reversible pulpitis
manage aetiology
117
what is the nature of the pulp in irreversible pulpitis?
vital and inflamed
118
asymptomatic irreversible pulpitis
usually normal response to thermal testing
| no clinical symptoms
119
management of asymptomatic irreversible pulpitis
RCT
120
symptomatic irreversible pulpitis
lingering, spontaneous, referred pain
sharp pain on thermal stimulus
OTC analgesics typically ineffective
if inflammation hasn't reached PA tissues - not TTP
121
management of symptomatic irreversible pulpitis
RCT
122
pulp necrosis
non-responsive to pulp testing, asymptomatic
only causes apical periodontitis if canal infected
usually no obvious radiographic changes
123
other reasons than necrosis for non-responsive to pulp testing
calcification
recent trauma
just not responding
124
apical diagnoses
```
normal apical tissues
symptomatic apical periodontitis
asymptomatic apical periodontitis
chronic apical abscess
acute apical abscess
condensing osteitis
```
125
normal apical tissues
not sensitive to percussion/palpation
| radiographically LD intact and PDL space uniform
126
symptomatic apical periodontitis
pain on biting/percussion/palpation
may have radiographic changes - PA radiolucency, widened PDL, thinning LD
severe pain to P/P - degenerating pulp - RCT
127
apical periodontitis
inflammation and destruction of apical periodontium of pulpal origin
128
asymptomatic apical periodontitis
no clinical symptoms
| apical radiolucency
129
chronic apical abscess
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
130
acute apical abscess
```
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
```
131
condensing osteitis
diffuse radiopaque lesion representing a localised bony reaction to a low grade inflammatory stimulus
usually seen at apex
usually symptom free
132
tx options
```
RCT
re-RCT
extract
monitor
surgery
```
133
purpose of obturation
prevent bacteria that are left from accessing any nutrients
134
endo-restorative interface - purpose of endo
provide env that allows healing of PR tissues so the tooth is retained as a functional unit in the dental arch
135
aims of instrumentation
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
136
irrigant ideal properties
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
137
NaOCl chemistry
```
ionises in water into Na+ and OCl-
establishes equilibrium with HOCl
acid/neutral HOCl predominates
pH9 and above OCl- predominates
HOCl - antibacterial activity
```
138
why NaOCl?
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
139
what is the least effective method of irrigation?
syringe irrigation alone
140
what is the ideal irrigation technique?
Manual Dynamic Irrigation - GP point - increase efficacy of NaOCl
can also use Endoactivator - mechanical agitation
141
factors important for NaOCl function
```
conc 3%
vol
contact - 10mins
mechanical agitation
exchange
```
142
problems with NaOCl
possible effects on dentine properties
inability to remove smear layer by itself
effect on organic material
143
when is the smear layer formed?
during prep
144
smear layer
organic pulpal material and inorganic dentinal debris
| superficial 1-5um with packing into tubules
145
problems with the smear layer
bacterial contamination
substrate
interferes with disinfection
prevents sealer penetration
146
removal of the smear layer options
17% EDTA
10% citric acid
MTAD
S and US irrigation
147
EDTA concentration
17%
148
EDTA function
removes smear layer
149
what type of agent is EDTA?
chelating agent
150
EDTA contact time
1min
151
why shouldn't EDTA and NaOCl interact?
get ppts which block tubules
152
irrigant protocol
irrigate/dry with PP between
NaOCl 10mins
EDTA 1min
NaOCl final rinse
153
NaOCl complications
fabric discolouration
ophthalmic injuries
apical extrusion - tissue necrosis
allergic reactions
154
common symptoms of NaOCl extrusion
```
pain
swelling
ecchymosis - along course of superficial venous vasculature
haemorrhage
neurological complications
airway obstruction
```
155
extrusion risk factors
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
EndoVac
negative pressure system to pull irrigant down canal
157
management of NaOCl extrusion
```
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
advantages of CHX digluconate
antibacterial activity
dentine medicated with CHX acquires antimicrobial substantivity - prevents colonisation for time beyond application
acceptable biocompatibility
159
how does CHX digluconate have antibacterial activity?
+CHX attracted to -phospholipids in cell wall
| binds to cell wall - lysis
160
disadvantages of CHX digluconate
less antifungal activity
unable to disrupt biofilms
sensitivity possible, risk of anaphylactic reaction
161
NaOCl and CHX interaction
forms parachloroaniline
cytotoxic and carcinogenic
uncertain bioavailability
brown ppt - discolours tooth
162
what cases are often done in a single visit?
vital cases
163
single vs multi visit
case by case
164
which cases may be done over multi visits?
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
purpose of intracanal medicaments between appts
destroy MOs
prevent reinfection
decrease inflammation and exudate
control of RR
166
antimicrobial paste
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
how long should nsCaOH be left?
7days
168
properties of nsCaOH
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
inter-appt temp dressing
CaOH
cotton wool
Coltosol
3mm GI
170
file motions
```
filing
reaming
WW
balanced force
envelope of motion
```
171
filing motion
up and down
172
reaming
repeated clockwise rotation
| if bind too far breaks
173
WW
back and forward oscillation 30-60 degrees with light apical pressure
174
balanced force technique
```
LAP
clockwise
anticlockwise a bigger degree of rotation
x1-3 then remove
safer for canal and file
```
175
envelope of motion
evenly strip
176
what is a glide path?
path along which tip of subsequent instrument will pass, protects that tip
"smooth radicular tunnel from canal orifice to apical constriction"
177
importance of a glide path
confirm SL access
| explore anatomy
178
creating a glide path
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
what is apical gauging?
technique to best determine the size of the apical constriction and the taper of the apical portion closest to the foramen
180
how to determine apical gauging
2 sizes bigger than one that originally bound at length
181
protaper hand use properties
superelasticity
| variable taper
182
protaper hand use properties - superelasticity
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
protaper hand use properties - variable taper
more specific shape
larger taper apically so more control
not whole way up
184
S shaping files - where are they used?
coronal and mid root
185
S shaping files
S1
S2
SX
186
S shaping files - S1
purple
17
coronal flare
2/3 BF technique
187
S shaping files - S2
white
20
mid-root shaping
188
S shaping files - SX
red
19
only for short canals
189
F finishing files - F1
yellow
| 20
190
F finishing files - F2
red
| 25
191
F finishing files - F3
blue
| 30
192
F finishing files - F4
black
| 40
193
F finishing files - F5
yellow
| 50
194
protaper colours mnemonic
```
Please
Will
You
Read
Books
By
Yourself
```
195
summary of Protaper process
```
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
barbed broach
extirpating only
do not engage dentine
tapered round shaft with portions lifted almost at a right angle
extremely fragile
197
Hedstrom (H) files
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
K reamers
made by twisting a tapered triangular shaft
| must be in contact with walls, but must not bind or may break
199
C+ files
similar to K-files but has a cutting tip and slightly more rigid
200
K files
flexible so useful in curved canals
SS
cut when used in rotation
twisting a square shaft
201
flexible K files (flexofiles)
cross-sectional shape allows greater flexibility
SS/NiTi
filing/rotation motion
202
complications of SS hand instrumentation
mishaps - ledges, canal blockage, zipping of apical foramen
| debris extrusion with filing motion
203
blockage
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
ledges
an internal transportation of the canal
205
when do ledges occur?
when working short of length
206
management of a ledge
hard to bypass - need to curve tip of a small file
207
what happens if curved canals are instrumented as if they were straight?
get ledging and the apical few mm will remain uninstrumented and infected
208
apical zipping/transportation
occurs due to the tendency of the instrument to straighten inside a curved canal
209
management of minor apical zipping/transportation
canal can be reshaped to a new level just above the foramen
210
severe apical zipping/transportation issues
bleeding is a problem and attempting to reshape can weaken/perforate root
211
consequences of apical zipping/transportation
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
how to avoid apical transportation
always pre-curve initial small sized hand instruments
don't skip instruments in sequence
never rotate the instruments in curved canals
213
diagnosis of root perforation
persisting bleeding into canal
multiple radiographs - can do with a file in to see if perforation
EAL
dental operating microscope
214
what does prognosis of perforation depend on?
```
location
time elapsed
size
PD irritation
material used for repair
```
215
MTA for perforation
only works well for small - not strong in CS
| dentine fibres and cementum will bind to MTA
216
importance of superelasticity
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
components of an endo rotary instrument
```
taper
flute
leading/cutting edge
land
relief
helix angle
```
218
taper
diameter change along working surface
219
flute
groove to collect dentine and ST
220
leading/cutting edge
forms and deflects dentine chips
221
land
surface extending between flutes
222
relief
reduction in surface of land
223
helix angle
angle cutting axis makes with LA of file
224
advantages of NiTi vs SS
increased flexibility in larger sizes and tapers
increased cutting efficiency
if used appropriately good safety in use
more user friendly
225
Protaper gold
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
disadvantages of NiTi
```
instrument fracture
£
access can be difficult in posteriors
unsuitable for complex canal anatomy
effect of prion decontamination protocols on NiTi rotary surfaces?
```
227
true reciprocation
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
rotary instrumentation guidelines
```
straight line access
CS diameter (ISO 15 or more)
RC system anatomy
speed and sequencing
lubrication and light touch
```
229
Rotary NiTi generations
```
1st - K file type helix
2nd - reamer type helix, Protaper
3rd - metallurgy, safer, Protaper Gold
4th - reciprocation movement, safer
5th - offset design
```
230
engine driven systems movement
vertical movement
reciprocation rotation 90/30 degrees
rotation 360 degrees
rotary endo - greater flexibility and taper
231
torsional stress
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
flexural stress
repeated cyclic metal fatigue
| cannot be influenced by clinician
233
cyclic fatigue
freely rotating in a curvature
get tension/compression cycles
failure
234
torsional fatigue
instrument binds, if further rotated - stress in torsion, torque
structure of metal can undergo irreversible changes
each time causes torsional fatigue - eventually fracture
235
how to avoid torsional fatigue in reciprocation
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
in torsional fatigue what determines if the metal structure changes are reversible or irreversible?
amount of rotation when instrument is binding
237
what is between the elastic and plastic phases?
elastic limit
238
protaper size matched cones
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
what is the outcome if good endo and good restoration?
91%
240
disadvantages of radiographs
2D
magnification/distortion
radiographic apex could be different from the actual terminus
241
evaluation of pt - case assessment
medical
psychological
social factors
242
case selection
pt evaluation
tooth evaluation
self-evaluation of clinician
243
case assessment - medical findings
```
no absolute contraindication to endo - if in doubt speak to physician
pregnancy
CV disease
cancer
diabetes mellitus
bisphosphonate therapy
allergies
```
244
pregnancy
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
cancer
history
chemo and radio to head and neck can compromise healing
consult with oncologist
246
CV disease
contraindication - MI in last 6m
consult cardiologist re emergency tx
Stress Reduction Protocol - short appts, sedation, pain and anxiety control
247
diabetes
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
bisphosphonates
IV>oral
preventive care - avoid extractions
non-surgical endo tx of teeth that might otherwise be extracted
249
allergies
latex allergy - use vinyl dam
| GP not a risk as non-cross reactive
250
dental evaluation
```
PD considerations
restorative considerations
calcifications, dilacerations, resorption
inability to isolate tooth
unusual anatomy
ledges and perforations
posts
separated instruments
developmental abnormalities
```
251
endo perio lesion
do endo first then PD therapy later if necessary
252
calcifications
usually coronal to apical
isolated/continuous - can make tx vvv difficult
may consider surgery
253
restorative considerations
```
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
effect of resorption on RCT
harder to control irrigants
255
when would you consider CBCT?
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
how to decide whether to tx or refer
simple formula - e.g root number/chronic or acute
AAE endo case difficulty assessment form
Restorative dentistry IOTN - complexity assessment
257
options for tx
```
no active tx with review
extract
orthograde RCT
surgical endo
referral
```
258
factors that affect tx decision
```
pt assessment
dental assessment
pt motivation
pt time
cost
```
259
AAE endo case difficulty assessment form - categories
minimal
mod
high
260
AAE endo case difficulty assessment form - minimal
routine complexity
| predictable tx outcome should be attainable by competent with limited experience
261
AAE endo case difficulty assessment form - mod
complicated
| challenging for competent, experienced practitioner
262
AAE endo case difficulty assessment form - high
exceptionally complicated
| challenging for even the most experienced practitioner with extensive history of favourable outcomes
263
AAE endo case difficulty assessment form - considerations
pt
diagnostic tx
additional
264
AAE endo case difficulty assessment form - pt considerations
```
MH
anaesthesia
pt disposition
ability to open mouth
gag reflex
emergency condition
```
265
AAE endo case difficulty assessment form - diagnostic tx considerations
```
diagnosis
radiographic difficulties
position in arch
isolation
radiographic appearance of canals
resorption
crown, canal and root morphology
```
266
AAE endo case difficulty assessment form - additional considerations
trauma history
endo tx history
perio-endo condition
267
NHS IOTN complexity assessment
complexity 1/2/3
modifying factors that are relevant to RCT
MH that significantly affects clinical management
268
prognosis of orthograde RCT
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
importance of filling the RC system
prevent passage of MOs and fluid
block apical foramina, dentinal tubules and accessory canals
chemomechanical disinfection can't get to it all
270
properties of obturation materials
```
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
disadvantages of CLC
voids
spreader tracts
incomplete fusion of GP cones
lack of surface adaptation
272
disadvantages of single cone obturation
quality
microleakage
bacterial penetration
similar/lower to others
273
warm vertical compaction
3D obturation
need continuously tapering funnel and small apical diameter
repeated heating and compaction of GP
274
yellow Buchanan hand plugger
25
275
red Buchanan hand plugger
40
276
blue Buchanan hand plugger
70
277
continuous wave obturation
```
downpack, apical pressure
cool reactivate separate tip
have apical plug - forced into lateral canals
backfill
uses heat
```
278
carrier based obturation
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
what is a potential disadvantage of thermal obturation techniques?
less apical control?
280
bio ceramic cements
may be good in some complex canals
root perforations
MTA
comparable filling quality to GP and sealer
281
how to measure sealing ability
```
dye penetration
isotope penetration
EC technique
bacterial penetration
salivary penetration
```
282
resilon
resin based system
dentine bonding technology
"monoblock"
much higher failure than GP
283
ideal sealer properties
```
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
ZOE based sealers
```
e.g. Tubliseal
antimicrobial
cytotoxic
free eugenol - irritant
lose vol with time due to dissolution - resins can modify
```
285
GI sealers
dentine bonding properties
minimal antimicrobial activity
soluble
difficult to remove upon re-tx
286
EndoRez
```
MDMA resin-based sealer
hydrophillic
good penetration into tubules
biocompatible
good radiopacity
```
287
calcium silicate sealers
```
high pH initial 24hrs
hydrophillic
biocompatible
doesn't shrink
non-resorbable
excellent sealing ability
quick set 3-4hrs - needs moisture
easy to use
```
288
sealer placement
file
lentulospiral
US files
master GP cone
289
sealer functions
seal space between dentinal wall and core
fills voids and irregularities
lubricated
290
what type of sealers are not recommended?
ones containing organic materials e.g. aldehydes
291
why is RC culturing not always done?
assays not always reliable/relevant
292
timing of obturation
```
S/S - don't want to obturate while patient still has symptoms i.e. swelling
pulp status
PA status
difficulty
pt management
```
293
is length a prognostic determinant?
yes - >2mm short of apex harboured bacteria
294
how to asses obturation
post-op radiograph including root apex and at least 2-3mm of PA region
295
criteria for successful obturation
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
what is the most important factor for apical PD health?
coronal seal
297
orifice closure
ZnO/Eugenol
RMGIC/flowable composite
GP rapidly infected if exposed
298
future - regenerative endo?
vital pulp therapies with SCs
| pulp regenerative therapies
299
defining success
means different to researchers, clinicians and patients
| technical vs biological outcome
300
ESE success - assessment of outcome
RCT should be assessed at least after 1 year and subsequently as required
successful
uncertain
unfavourable
301
successful outcome
no pain, swelling, other symptoms
no sinus tract
no loss of fct
radiological evidence of a normal PDL - intact LD
302
uncertain outcome
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
exceptions to outcome - scar tissue formation
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
unfavourable outcome
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
definitions of outcome - how success is defined
strict criteria - ESE guidelines, strict radiographic criteria for success 74.7%
loose criteria 85.2%
retention only 97.1%
306
pre-op factors affecting success
presence/absence of lesion - PA radiolucency pre-tx - outcome worse
presence of sinus
increased lesion size
307
operative factors affecting success
```
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
how does instrument fracture affect outcome?
may do - depends on when fracture occurs - how much disinfection has already occurred
e.g. F3 better than S2
309
instrument fracture management options
```
remove
bypass
obturate up to instrument
surgical removal
extract
```
310
iatrogenic factors leading to failure
```
poor planning
poor access
poor length control
forcing instruments
failure to observe sequence
failure to maintain patency
```
311
biological reasons for failure
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
periapical cysts
form from mature granuloma, inflammatory mediators acting on epithelial cell rests - proliferate
313
true cyst
epithelial lined cavity that is distinct from the root
314
pocket cyst
cyst cavity continuous with RC space
315
how can you tell if it is a cyst?
only histologically
316
periapical cyst prevalence
about 15%
317
retreatment options
KUO
orthograde retx - but can you change something?
surgical tx - periradicular surgery
extract
318
what are 3 key points before retx?
establish cause of failure
assess restorative prognosis
re-tx complexity
319
when is KUO a risk?
CV disease/diabetes
320
removing insoluble resins
US
321
removing soluble pastes
handfiles +/-solvent - Protaper, D/Reciproc
322
removing poorly condensed GP
generally easier
| Hedstroem files
323
removing well-condensed GP
generally harder
| need to create space
324
removing GP
handfiles
solvent
Protaper D1
325
removing GP - handfiles
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
removing GP - solvents
eucalyptus oil or chloroform
327
removing GP - Protaper D1
active tip - better initial penetration
but perforates teeth easily
good for coronal GP ONLY
328
Reciproc blue
"increased resistance to cyclic fatigue, increased flexibility"
good for re-tx
329
what could PAP be (in order of likelihood)?
granuloma
abscess
true cyst
pocket cyst
330
what speed should you use for protaper re-tx?
lowest speed that engages obturation material
| 500-700 rpm
331
Protaper retx D1
coronal removal
| 16mm, ISO30, 9%
332
protaper retx D2
middle 1/3 removal
| 18mm, ISO25, 8%
333
protaper retx D3
apical 1/3 removal, stop 2-3mm short of apex
| 22mm, ISO20, 7%
334
how to bypass ledges in protaper retx
pre-curved C+ files
335
PR surgery
surgical shortening of the root apex +/- retrograde sealing
336
is PR surgery ideal?
no - retx almost always preferable to or at v least better to use in conjunction with root end surgery
337
reciproc system for retx
reciprocating movement
R25 red
R40 black
R50 yellow
v efficient
remove bulk of GP (US, heat carrier)
brushing
338
why should you delay the use of solvents for as long as possible?
creates things which get pushed into tubules and into accessory canals - affects ability to get into RC space
339
indications for PR surgery
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
contraindications for PR surgery
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
microsurgery
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
haemostasis in PR surgery - pre-op
LA - 1:50 000 adrenaline and 2% lidocaine
343
haemostasis in PR surgery - intra-op
examine bone crypt at high magnification
epinephrine pellets
ferric sulphate (cytotoxic - affects osseous healing)
CaSO4 - mechanically blocks open vessels
344
haemostasis in PR surgery - post-op
pressure
| sulcular full thickness flap or mucogingival flap
345
mucogingival flap
crowned anteriors
scalloped incision in middle of attached gingiva at 45 degrees
vertical relieving incisions
346
microsurgical instruments
```
blades
ST elevators
curettage instruments
US tips
inspection mirrors
carriers and pluggers
needles and holders
```
347
osteotomy - clinical possibilities
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
PRS - osteotomy
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
PRS - root end resection
3mm resected perpendicular to long axis of tooth
350
PRS - why is 3mm resected?
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
what is the aim of the root end filling in PRS?
seal apex so bacteria/products can't enter/leave canal
352
PRS - US root end prep
```
low magnification
US tip at apex
coolant
3mm depth
inspect with micro mirror at high magnification - remnants of GP, recondense GP
```
353
other ways to inspect resected root surface
PP
| stroptko device - low pressure 10psi
354
isthmus
communication between 2 separate canals in one root
355
isthmus frequency
anteriors 15%
premolars 30%
M roots of L6s - 70%
MB roots of U6s - 45%
356
clinical significance of isthmus
untreated is one of the main causes of surgical failure
357
management of isthmus
identify with microscope
| US prep - cut hole along isthmus so you can debride, disinfect and seal root properly
358
properties of ideal root end filling material
```
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
amalgam as a root end filling material
no longer used - slow set, biocompatibility, leakage, corrosion and staining
will see in pts historically
360
MTA chemistry
powder of fine hydrophilic particles
tricalcium silicate/oxide/aluminate, silicate oxide, bismuth oxide
mix water - slurry
361
MTA properties
```
long setting time
antimicrobial
alkaline
superior sealing ability
moisture tolerant
radiopaque
excellent biocompatibility
regeneration of cementum - bioinductive
```
362
clinical applications of MTA
```
pulp capping
RR
apexification
root end filling
perforation repair
furcal repair
```
363
root end filling - MTA placement
```
protect bone crypt
sterile water - putty
MTA gun/carrier
micropluggers/burnishers to lightly condense material
wipe excess with moist cotton pellet
```
364
regenerative procedures
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
PRS suturing
interrupted suture
ideally monofilament
remove 72hrs
366
PRS post op paraesthesia
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
outcome of endo surgery
```
classification of healing
- healed
- incomplete healing (scar)
- uncertain healing
- failed
follow up 1yr, then up to 4 yrs
```
368
preventing lacerations in PRS
vaseline lips
| avoid careless flap elevation
369
PRS prognostic factors
```
age
tooth position (L ants and L7s hard)
root end filling material
presence of co-existing PDD
apical seal
coronal seal
crypt size
```
370
PRS success
1yr post op 96.8%
5-7yrs 91.5%
endodontists higher than oral surgeons - microscopes
1/3 success for repeat surgery
371
PPV
positive test result (no response) are truly non-vital
372
NPV
probability teeth with negative response are truly vital
373
mnemonic for ISO colour code
```
Please
Give
Peter
Why
Yelling
Red
Because
Green
Blacked out
```
374
most common number of canals - maxilla
```
1
1
1
2
1
4
3
```
375
most common number of canals - mandible
```
1
1
1
1
1
3
3
```
376
reaming
repeated clockwise rotation
377
what dictates the access cavity shape?
shape of pulp chamber
378
Endo Z bur
non-cutting tip
make access wider
funnel shape
379
GG bur
non-cutting tip
brush strokes
remove ledges and widen
SL access
380
aims of access cavity prep
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
why shouldn't you use hand spreader?
too much force - may fracture tooth
382
are side vented needles good?
yes they are safer
383
indications for endo tx
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
contraindications for endo tx
```
unrestorable tooth
poor OH
insufficient PD support
root fracture
bizarre anatomy
internal resorption
```
385
why obturate?
seal remaining bacteria - prevent them from accessing any nutrients
provide apical and coronal seal
prevent reinfection
