endo Flashcards
features of loss of vitality
discolouration
sinus presene
gross caries
large restorations
PA radiolucency
dentine hypersensitivty
short sharp pain arising from exposed dentine in response to thermal or osmotic stimulus
thought to occur due to hydrodynamic theory - due to dentinal fluid movement in tubules stimulating pulpal pain receptors (A- delta and C-fibres)
management of dentine hypersensitivity
OHI
erosion prevention - straws, not swilling
densensitising tooth pastes (strontium fluroide, potassium nitrate)
Fluoride varnsihes
indications for RCTx
irrversible pulpitis
pulp necrosis
apical periodontitis
contraindications for RCTx
unrestorable tooth
aims of RCTx
treat inflamed/infected RCS by controlling infection via eliminating microorganisms and remove pulp system and filling with a material
to prevent Reinfection
dam purposes
prevent contamination
protect airway
impve access and vision
improve safety
improve isolation and moisture control
improve pt comfort
allows use of approp dsinfectants
access features
removal of existing restoration
removal of entire roof of pulp chamber -
removal of all coronal pulp and locate orifices of canals
finish cavity to have unimpeded STRAIGHT LINE access
aims of canal shaping
removal of pulp debris and microbes
produce ideal shape and space for effective irrigant penetration and reception of root filling material to working length
* continuously tapering funnel shape
* maintain apical formaten in original position
* keep apical foramen as small as possible
NiTi hand files
adv
disadv
adv - inc flexibility, inc cutting efficacy, so user friendly
disadv - instrument #, expensive,
benefits of rotary systems
predictability
easier to use
less time consuming
less files needed
EWL
estimated length at which instrumentation should be limited
obtained by measuring a pre op radiograph to determine distance between radiographic apex and coronal reference point, minus 1mm
CWL
length at which instrumentation and obturation should be limited to
defined by use of electronic apec locator after inital shaping
master apical file
largest diameter file taken to CWL
represents final size of apical portion of canal
recapitulation and patency filing
reintroducing smaller files to WL to re-establish ape and help prevent ledges
modified double flare technique
adv
3
coronal third preparation first
* improves straight line access
* avoid hydrostatic pressure build up in canals
* allows early removal of heavily contaminated contents
negotiation of apical third with smaller file
apical and mid third prep by step back technique
causes of instrument separation
torsional stress
flexural stress
RCT issues with hand files
6 common
incomplete debridement - inabilility to completely clean canal
ledges - internal transportation of canal. when working short of WL
blockages - caused by dentine debris packing into apical portion of root
apical transportation - transportation of apical foramen occurs as tendency of instruments to straighten inside a curved canal
perforation - when straight line access not complete and care not taken when intrumenting
zipping - over prep of outercurvature of canal and under prep of inner curvature of canal
aims for chemomechanical disinfection
disinfect root canal
flush out debris
eliminate microorganisms
dissolve organic debris and remove smear layer
key irrigants and concentrations
3% NaOCl
17% EDTA
0.2% CHX
NaOCl properties
dissolves organic material
disadv - unable to remove smear layer, irritant to soft tissues/tissue necrosis, allegry, bleach to fabrics
factors to improve NaOCl function
concentration
contact time
volume
mechnical agitation
possible reasons for NaOCl accident
4
- excessive pressure during irrigation - use of forefinger and slow flow rate
- needle locked in canal - use manual dynamic irrigation
- larger apical constrictions
- needle beyond apical constriction - not using rubber stop
- poor seal - test with CHX prior, give pt PPE
symptoms of NaOCl accident
pain
swelling
bruising
haemorrhage
airway obstruction
smear layer
formed during preparation
contains organic pulpal material and inorganic dentinal debris
prevents sealer prenetration nad causes bacterial contamination
how to remove smear layer
EDTA 17%
irrigate and recap throughout instrumentation
then penultimate 3% NaOCl for 10mins per canal (30mls) througholy dry EDTA for 1min, thoroughly dry then 3% NaOCl
intracanal medicaments functions
destroy MO and prevent reinfection
reduce inflammation and control root resorption
e.g. Ledermix or nsCaOH
objective of obtruation
provide a 3D hermetic seal to the RCS that will prevent ingress of bacteria and tissue fluids
aims
* fill/seal entire RCS
* eliminate infection
* prevent reinfection
* incarcerate any remaining microbes
aims of obturating
4
- fill/seal entire RCS
- eliminate infection
- prevent reinfection
- incarcerate any remaining microbes
gutta percha constituents
7
GP 20%
Zinc oxide 59-75%
Radiopacifiers – barium salts
Waxes, colouring agents, anti-oxidants, plasticiers
properties of obturating materials
GP
non irritant
inert
radiopaque
doesn’t discolour tooth
easy removal upon pretreatment
moisture resistant
bacteriostatic
functions of sealer
3
- seal space between dentinal wall and GP
- fill voids and irregularities between GP points, canal walls and seal lateral canals
- TO MAKE A FLUID TIGHT SEAL
common sealers
4
resin based
ZOE
calcium hydroxide
calcium silicate (MTA)
properties of ideal root canal sealer
establish hermetic seal
radiopaque
no setting shrinkage
non staining
bacteriostatic
soluble on retreatment
methods for obturations
cold lateral compaction
warm lateral compation
vertical compaction
continous wave compaction
carrier based obturation
cold lateral compaction
check for tug back with master GP point (matches to MAF) at CWL
dry with paper points
apply sealer to GP point (lightly) and place in canal to CWL
try and place finger spreader in canal short of CWL and if room, leave for 20secs and then place corresponding accessory files in same manner
cut GP at ACJ
want no GP in pulp chamber so ensure cut and condense before RMGIC for coronal seal
success RCTx
asymp
normal PDL radiographically
no loss of function of totoh
success with incomplete healing
success but scar tissue formation
rather than resoluation of lesion
unceratin RCTx outcome
radiographic lesion same size or only slightly reduced 4yrs post endo
unfavourable outcome
symptoms persist after endo
radiographic lesion inc in size or same size or new lesion 4 yrs post endo
continued resorption of root
risks in endo tx
perforation of RCS
instrument separation
failure of tx - unable to reach working length
pain after tx
NaOCl accident
material extrusion beyoud apex
methods to prevent instrument failure
correct instrument use
create manual glide path
crown down technique
possible reTx options
orthograde RCT
periradicular surgery
XLA
what is periradicular surgery
surgical shortening of root apex (2-3mm)
and retrograde sealing with MTA
law of centrality
floor of the pulp chamber is always located in the centre of the tooth at the level of the ACJ
low of concentricity
wall of the pulp chamber are always concentric to the external surface of the tooth at the level of the ACJ
law of the ACJ
ACJ is the most consistent repeatable landmark for locating the position of the pulp chamber
Law of symmetry
2
1 - orifices of the canals are equidistant from a line drawn in the mesial-distal direction through the pulp floor
2 - orifices of canals lie on a line perpendicular to a line drawn in a MD direcction across the centre of the floor of the pulp chamber
except maxillary molars
law of colour change
colour of the pulp chamber floor is always darker than the walls
law of orifice location
3
1 - orifices are always located at the junction of the walls and the floor
2 - orifices of the root canals are always located at the angles in the floor wall junction
3 - origicies are located at the terminus of the root developmental fusion lines
pathogenesis of endo disease
?
glide path
sequential introduction of smaller diameter files WL to prevent fracture of larger diameter insturments
modified double flare
technique
access identified and straigh line comfirmed (DG16 then 10K to 2/3 EWL)
GG to create coronal flare
* GG4 to 2/3 EWL with light apical pressure and brushing motion
* then GG3 and GG2 to further prep coronal portion more apicaly
after coronal prep, establish CWL with apex locator (10K)
apical prep
* 15K file set to CWL and watch winding motion
* 20K file set to CWL with balanced force motion
* then work up files till get apical gauging (MAF)
stepback (apical taper)
* take file size larger than MAF to 1mm less than CWL
* do this 3x
then irrigation protocol, dry, obturate
irrigation and patentcy throughout with 10K
% taper of K files
2%
hand file motions
watch winding - forward and backwards osscilating 30-60
balanced force - 90 one way, 180 other way x3
envelop of motion - brush up sides of canal?
protaper hand files
access and achieve straigh line
glide path to 2/3 EWL to ensure straight line access then use apex locator to work out CWL
use 10K and 15K to CWL with balanced force technique
then
S1 to CWL (shape coronal 1/3)
S2 to CWL (shape mid 1/3)
F1 to CWL (apical 1/3)
F2 to CWL (apical 1/3)
check is 25K has apical gauging (corresponds to F2)
irrigation and patentcy throughout with 10K
reciproc
access and straight line (check with glide path 2/3 EWL with 10K)
R25 to 2/3 EWL
pecking motion - 3x light pressure
once reached 2/3 EWL - establish CWL with apex locator and 10K
then R25 to CWL
check tugback with 25K file
irrigation protocol
irrigation and patentcy throughout with 10K
reciproc
access and straight line (check with glide path 2/3 EWL with 10K)
R25 to 2/3 EWL
pecking motion - 3x light pressure
once reached 2/3 EWL - establish CWL with apex locator and 10K
then R25 to CWL
check tugback with 25K file
irrigation protocol
irrigation and patentcy throughout with 10K
size reciproc to use
canal narrow or partially/completely invisible = R25
canal medium/wide
* 30K can be inserted passivley to EWL = R50
* 20K can be inserted passively to EWL = R40
