Clinical Skills Flashcards
aetiology of endo disease
- Bacterial invasion bacteria and fungi
- Development of bacterial ecosystem
- Biofilm formation
clinical objectives of RCT
- Removing canal contents
- Eliminating infection
- Spectrum of possibilities exist from Non-instrument technique to Extraction
chemomechanical disinfection
- Used to manage RCS complexity
- Use of mechanical means of shaping and debriding root canal space and chemical means to further disrupt biofilm and disinfect RCS
Dr Herbert Schider
design objectives (3)
- Create a continuously tapering funnel shape
- Maintain apical foramen in original position
- Keep apical opening as small as possible
Create space for introduction irrigants whilst maintaining sufficient structure
pre endo tx need
An undistorted peri-apical radiograph must be taken to show all the root and 2-3mm of surrounding peri-radicular tissue
Use light box and magnifier in dark room to view X-ray
what to look for in a pre-endo tx radiograph?
(6)
- Is there peri-radicular pathology and how far does it extend?
- The anatomy of the root canal system
- Canal calcifications – is pulp chamber compressed, due to layer down of tertiary dentine
- Check angulation of root in relation to adjacent teeth
- Number, length and morphology of roots
- Proximity of vital structures
before deciding on endo tx definitely what must be done to the tooth in Q
All caries and defective restorations must be removed from the crown
- Allows assessment of restorability and creates an environment suitable for obtaining adequate isolation
pre-endo build up when
Assess restorability
- Clamp placement good
- Four walled access cavity
- Control irrigant
- Control saliva
dental dam needed in endo?
Mandatory for all procedures involving the pulp
- To eliminate bacterial contamination
- To prevent inhalation of instruments etc
- Retracts and protects soft tissues and tongue
- Prevents patient from rinsing, chatting
- Reduces chairside time and operator stress
5 reasons for dental dam use in endo
- to eliminate bacterial contamination
- To prevent inhalation of instruments etc
- Retracts and protects soft tissues and tongue
- Prevents patient from rinsing, chatting
- Reduces chairside time and operator stress
when to place your dental dam in regards to cutting access cavity
can place your dental dam after cutting most of your access cavity to avoid losing orientation
7 instruments in endo kit
- Mirror – front facing, single shot to improve visulisation
- Locking tweezers
- Probe
- DG 16
- Excavator
- Flat plastic
- Burnisher
DG16
dull ended probe, long tip to allow exploration of pulp chamber and orifices/access RCS
equipment needed for endo access cavity prep
endo kit
local anaesthetic equipment
examination kit
handpieces and burs
- air rotor, fissure burm Endo-Z or similar
- slow speed - long shanked round bur
basic armentarium
- file holders (clean K files)
- rulers
slow speed bur type used in endo
long shanked round bur
root of upper central incisor
23mm
little apical curvature
root of uppper lateral incisor
21-22mm
1 canal inclined palatally
distal apical curvature
root upper canine
26.5mm
distal and labial curvature
narrow apex
root lower central incisor
21mm
41% hhhave 2 canals
distal apical curvature
root of lower lateral incisor
21mm
41% have 2 canals
distal apical curvature
root lower canine
22.5mm
14% have 2 canals
distal and sometimes labial apical curvature
access cavity driven by
need to gain access – roof of pulp chamber.
Instrument needs to be able to pass unhindered into root canal – to reduce chance of instrument fatigue and failure.
Can be variation in shape/position depending on what you are aiming to achieve
why is a good access cavity important
Instrument needs to be able to pass unhindered into root canal – to reduce chance of instrument fatigue and failure.
access cavity maxillary central
2 pulp horns – triangular access cavity,
- start with single point of access until drop into pulp chamber then shape into triangle,
- long flat end tapered bur
(Middle third of tooth)
access cavity maxillary lateral
smaller triangular access for smaller 2 pulp horns
access cavity maxillary canine
single pulp horn - oval shape access cavity
access cavity mandibular incisors (central and lateral)
Single canal – ovoid access,
can be moved more incisal – more mid crown and slightly up.
Too lingual access will only be able to instrument labial area and not all of canal system
(lower incisors often fail as not properly irrigated
care needed in access cavity prep to ensure
not go beyond pulp chamber - perforation
objectives of access cavity preparation (4)
- Remove entire roof allowing complete removal of pulpal tissue
- Allow visualisation of root canal entrance
- Produce smooth walled preparation with no overhangs
- Allow unimpeded straight-line access of instruments
- If severely curved whilst working, risk will start to fatigue and failure or damage root canal along walls -> ledge formation, perforation
initial access cavity prep with
long tapered high speed flat ended diamond bur
extends working distance improvng visualisation
when to switch from high to slow speed handpiece in access cavity prep
when breach pulp
chamber switch to long neck round bur on slow speed
with the long neck round slow speed bur - aim to
de roof pulp chamber
once de roofed the pulp chamber with slow speed
switch to
ultrasonic
safely remove remainder of pulp chamber roof so can see full access
good straigh line access enables
dropping into RCS from access cavity
conventional instruments for developing canal shape
- Made from stainless steel
- The lengths of ISO instruments, (International Organisation for Standardisation) are 21, 25 or 31mm
- The handles of ISO instruments are colour-coded according to file tip size
- 02 Taper or 2% Taper
ISO tools shape
tapered with flutes along (02 taper/2%)
ISO colour code
handles colour coded to file tip size
ISO-sized instruments
stainless steel
- All have 16mm cutting flutes
- Each file is named according to its diameter at the first rake angle – D1
- Taper is 0.32mm over the 16mm, or 0.02mm per millimetre from tip (2%)
Diameter at D2 = apical size + 0.32mm
hand instrumentation by (2)
K files
- Flexible therefore useful in curved canals
- Available in stainless steel
- Cut when used in rotation
Flexible K Files (Flexofiles)
- Cross-sectional shape allows greater flexibility
- Stainless steel or nickel titanium
- Used in rotation or filing motion
4 types of file motion
- Filing
- Reaming
- Watch-winding
- Balanced Forced Motion
watch winding motion
- Back and Forward Oscillation of 30°-60 °
- Light apical pressure
Effective with K files
Useful for passing small files through canals
balanced forced techniques
- insert file and engage clockwise into the dentine 1/4 turn
- with continued pressure, go counter-clockwise 1/2 turn to strip the dentine away
- do this 1-3 times before removig the file to remove debris and check the file
- remove, clean, reintroduce, working way to working length
root canal preparation needs
to be undertaken with copious irrigation
objectives of irrigants (5)
- To disinfect root canal
- Dissolve organic debris
- Flush out debris
- Lubricate root canal instruments
- Remove endodontic smear layer
luer lock syringe
- 27 gauge endodontic-tipped needle
- Ensure needle is tightly screwed onto syringe
- But should be loose and free to move inside canal
- Always placed short of working length
Get NaOCl from galley pot (1/2 -2/3 full)
reason for coronal flaring (3)
- Avoids hydrostatic pressure in canal
- Early removal of heavily contaminated contents
- Improved straight line access to apical 1/3
3 methods for coronal flaring
step down technique
double flare technique
crown done pressureless technique
modified double flare technique for coronal flaring
Uses the balanced force technique
- to enlarge/flare the coronal part of root canal
- to negotiate the narrower apical part of canal
- to flare the apical part of canal by step-back technique
The aim is to create a continuously tapering, funnelled root canal without forcing debris apically whilst respecting original canal anatomy
gates glidden bur
bur with tear drop, long shank placed in motor
- too small – fragile
- too large – remove too much
- break just below shank to allow tip to be retrieved
run at relatively low level (1000rpm)
only in coronal portion
series of instruments for coronal prep (straigh portion of canal only)
- NaOCl
- # 10 K file
- GG4 (too big)
- GG3
- NaOCl
- GG2
light pressure and brushing movements - irrigate between sizes
working length characteristics
- Preparation should end at the junction of pulpal and periapical tissue
- just shy of apical constriction
- WL should be as close as possible to CDJ
- This is usually the narrowest part of the canal – apical constriction
Corrected working length
CWL
instrument and radiographic interpretation
- K file and with rubber stop at landmark (incisal cusp)
Go into to EWL (from pre-op radiograph)
- 1-2mm of radiographic apex
- But due to potential curvature of root canal need to confirm the length
Put file in at EWL and then take another radiograph to determine CWL
how to determine CWL
Radiographically
- Length should be 1mm from radiographic apex
- Use a sound and reproducible reference point
- Usually the incisal edge or a cusp tip
- Use paralleling technique with film holder
electronic apex locator
radiographic apex -> apical constriction distance
varies
greater in older teeth with secondary cementum - can lead to over extension of preparation
electronic apex locator
Allows better determination of working length, more reliable
- Place instrument in canal with apex locator attached, and to lip of pt
- Current passed through, instrument able to determine when instrument enters PDL
- Reach 0 is the true length from coronal reference point to apex constriction
Want to go 1mm short of where you reach 0 (first red band)
paper point length determination
Determine interface between wet and dry
- Dry canal using paper points
- Place paper point into canal and as it touched PDL, see blood or tissue fluid
Coronal reference point to this point (1mm short of)
apical preparation
- Determine working length with K files, electronic apex locator, paper point
- Use watch winding and balanced force technique working up files to size 20
- Irrigate
- Back to size 10 (lift debris from canal to ensure not packing debris in)
- Then take size 10 just beyond CWL to work as patency file
- Prevents collection of debris at apical portion
- Balanced force technique with next size up file (25) to expand apical preparation
- Want to reach at least size 25
- But in order to ensure sufficient preparation may want to expand to size 30
- Until reach appropriate diameter
- Master apical file
- But in order to ensure sufficient preparation may want to expand to size 30
apical gauging
Get feedback from canal
- Loose feeling – starting diameter wider (greater than point diameter)
apical size determined by
initial size of root canal apex
use apical gauging
Usually at least ISO size 25 (to CWL)
- Want to go at least 2 sizes bigger than initial size of just gauging
Some advocate 30 and larger to allow irrigation (to CWL)
- Canal curvature impacts upon what is achievable safely
apical size aim
Want to go at least 2 sizes bigger than initial size of just gauging
mid root preparation technique
step back
step back technique
mid root preparation
- 25 file taken to CWL
- Insert K files 1 size greater 1mm short of CWL
- 30 at 1mm short
- 35 at 2mm short
- 40 at 3mm short
- Create steps
- Extend coronal and so will join coronal taper that created initially
- Then take master apical file (25) and make filing motions circumferentially in canal to smooth out steps, to create taper from apical to coronal portion
estimated working length
Estimated length at which instrumentation should be limited. Obtained by measuring pre-operative radiograph to determine distance between coronal reference point and radiographic apex then subtracting 1mm.
corrected working length
Length at which instrumentation and subsequent obturation should be limited. Obtained by the use of an electronic apex locator and/or working length radiograph.
master apical file
The largest diameter file taken to working length and therefore represents the final prepared size of the apical portion of the canal at the working length
resin sealer
- Epoxy Resin
- Paste-Paste mixing
- Slow setting - 8 hours
- Good sealing ability
- Good flow
- Initial toxicity declining after 24 hours
GP cones
- 20% Gutta-percha
- 65% Zinc Oxide
- 10% Radiopacifiers
- 5% Plasticizers
- Standardised, non-standardised and size-matched
cold lateral compaction
Common method for filling root canals in 3D
- Can be used in most clinical situations
Good length control – GP is semi-solid
Does not allow good adaptation to canal irregularities
cold lateral compaction materials and equipment
- GP points
- size correspond to master apical file
- finger spreaders (A, B, C, D)
- not hand spreaders - too great a force
cold lateral compaction inital step
Get master point (correspond to master apical file)
- grasp cone at CWL – compress GP cone
- place into damp canal – should go to CWL
Check for “Tug Back” with Master Cone
Take a “cone fit” radiograph
- place master cone into RCS and take radiograph, should reach approximately the CWL
- Too short – modify so goes to CWL
- Too long
- Either increase size of cone
- Trim off excess GP
Needs to sit snuggly
accessory points
Cones that fit around the master cone
- A, B, C, D correspond to space left by finger spreaders
how to dry canal
paper points
cold lateral compaction cycles
Master cone that goes to CWL
- Coat with thin layer of sealer
Place finger spreader alongside master cone
- Insert apically and apply apical pressure – create space for accessory cone
Go through rounds of compaction and additions of accessory cones
Each addition will go to a shorter length
Until fill RCS
what to do once fill pulp chamber with GP points
remove excess
DON’T FILL PULP CHAMBER
NO NEED TO PUT ACCESSORY CONES IN PULP CHAMBER
- Traverse it
Cut using a heater cutter, sever off GP
- Compact GP into the space
Finish obturation at level of ADJ
issue here
Not appropriate
- GP should reach orifice but should not coat the walls of pulp chamber
- Sealer – white substance
Pulp chamber space needs to be cleaned
Circle of GP evident in the orifice
what goes on top of the orifice
a secondary sealer (vitrebond, RMGI)
- protect thr orifice from ingress of bacteria
summary of obturation
- Complete preparation
- Try finger spreader in, should go to CWL (just shy 1-2mm)
- Master apical cone
- Accessory cone
- Spread laterally
- Additional rounds of adding accessory cones
- Compaction with accessory cone placement
- Sever off at level of ACJ, allow thin layer of vitrebond/RMGI and opportunity to place definitive restoration (amalgam, composite or GIC until it can be done if no time)
manual dynamic irrigation
- Introduction of GP cone towards CWL, with inward and outward movement
- Agitate hypochlorite
- Lift debris
Go through rounds of manual dynamic irrigation and irrigation until 10 mins up
what should be used before the final rinse of NaOCl before GP placement
EDTA for 1 min
maxillary 1st premolar acccess cavity
2-3 canals
ovoid access cavity
maxillary 2nd premolar access cavity
1-3 (mostly single rooted)
oval
maxillary 1st molar access cavity
3-4 canals
mesial quadrangle
maxillary 2nd molar access cavity
3 canals
mesial quadrangle
mandibular first premolar access cavity
1 root (73%)
oval
mandibular 2nd premolar access cavity
1 root (85%)
oval
mandibular 1st premolar access cavity
2-3 roots
3 canals
central quadrangle
mandibular 2nd molar access cavity
2 roots
2-4 canals (3 most common)
central quadrangle
how to determine access cavity for posterior teeth
look at radiograph - where likely to find root canal
fissure bur to most easy access
pre op assessment before initial access cavity cut
consider
- angle of bur
- size of pulp chamber
- pulp horns
reason to have a pre op assessment and have a plan
to try and avoid problems - perforation
and ID them if they occur
(bur penetration too deep, angulation wrong)
additional possible step in access prep
may need deconstruct tooth to ensure gaining access to correct area
- remove crowns, restorative materials
how to safely de roof pulp chamber
safe ended bur (not damage floor of pulp)
- diamond coated
- tungsten carbide
tip of instrument is not cutting
- insert into hole made in pulp chamber roof and it will cut laterally to remove the roof
e. g. EndoZ
dentine below pulp chamber roof is
very homogenous
Anatomical features – developmental fusion lines
what to ensure before completing access cavity stage and moving onto prep
- Check that roof of pulp chamber has been removed
- Complete and direct vision of canal openings
straight line access
often lip of dentine at opening of orifice, will interfere with endodontic straight line access
- Need to modify dentinal wall so can get straight line access to first point of curvature or apex (whichever is first)
If don’t have
- Additional stress on instrument – risk perforation, fracture, mishaps in canal shaping
gates glidden bur role
- To improve straight line access
- Don’t use gates 1
- Ensure don’t go too deep into canal, otherwise get Coke bottle appearance (over expanded coronal preparation, narrow taper)
GG 2 diameter
0.9
GG3 diameter
1.10
GG bur action
- Dipping into coronal aspect of root canal to improve straight line access
- Remove mesial portion of orifices
- Work away from furcation
- Not into – risk perforation
GG X
- Combination on gates glidden burs
- Tip of gates 1 (0.7)
- Max diameter of gates 4 (1.30)
Create the shape with single instrument
ProTaper Handfiles
- Series of files made from nickle titanium
- Superelasticity – significant flexibility in RCS
- Variable Taper
- Variations in coronal to apical taper with files
ProTaper handfiles allow
Create shape in RCS that would otherwise be very complex to attain
S1 ProTaper
Wide coronally and significant taper to apex
S2 protaper
- Slightly larger tip size
- Taper leads to enhanced diameter of instrument at middle cutting section
- Slightly smaller diameter at coronal portion
Sx ProTaper
- Very short cutting blade
- Significantly increases from apex to coronal portion over short period
- Not typically used in routine endo, can be used in pre-flaring
how to intial create coronal flare with protaper files
Initially pass 10 or 15 file 2/3 of working length
S1 to 2/3 of working length – creating coronal flare due to rapidly increasing taper
Can use Sx but not common place
when to confirm working length
after creating coronal flare (with S1)
glide path
preparation of root canal that allows subsequent instruments to be able to move more freely and safely in the RCS
once establish guide path
Once established Glide Path, use S1 with advanced force to CWL
- Irrigate and recapitulate and patency check
Repeat with S2 file to CWL
Continue till comfortably reach CWL with S1 and S2 file
- create root flare
once created coronal flare and root flare with ProTaper files, then
need to finish preparation using finishing F files
F files
finishing
- colours for different diameters
- apical taper of 3mm slightly differs
use F1 with advanced force and continue until achieve apical diameter wanted
apical diameter needs to reflect
Original size of Root canal
- 2-3 sizes bigger to first file that bites
Dentine looks like
- Needs to be bright and white – clean thus sufficient
Ability to irrigate
- Larger the apical diameter the more efficient irrigation
- F files have wide diameter, F2 does provide sufficient irrigation if provides control
how to know you have control of apical area
apical gauging
Take a file to CWL
It won’t advance any deeper into Root canal
- However F2 can bind more coronal due to taper
- Thus put in equivalent K file, with light apical pressure – should not advance beyond CWL
- F2 = 25 K file
- K file will only bind apically due to tapering made by S and F files (only 2% taper)
get control with 25 K then decide F2 is sufficiently large enough, thus obturation material less likely to lose control when placed
ProTaper tx sequence
use 10 and 15 file for scouting
S1 (and SX) to shape coronally
- Balanced force motion
Irrigate
10 file to EWL and with electronic apex locator determine 0 reading
- May need to go to larger file if apical diameter is large
Establish CWL (0-5-1mm short of 0 reading)
Take S1 to CWL, followed by irrigation, recapitulation and patency filing
- Balanced force
- Repeat several times (irrigation etc in between) to get to CWL
S2 (same process)
F1
- Balanced force to CWL
Bigger – determined by apical gauging
If canal exceptionally curved may only be able to expand to an F2
if master cone is short
consider debris and shape
if master cone is long
cut with scalpel blade (precisely 0.5mm etc)
keep taper the same
multi rooted obturation
Issue for access
Treat one root at a time, unless roots fused
-
Place one cone in a canal and another in the second canal and establish if both go to CWL
- Withdraw the one that has reached CWL
-
And try to navigate the other deeper
- Indication of level of interaction
how to determine level of interaction of multi rooted teeth
Place one cone in a canal and another in the second canal and establish if both go to CWL
- Withdraw the one that has reached CWL
-
And try to navigate the other deeper
- Indication of level of interaction
If they interact, Place master cone in primary and cut the cone for the secondary canal
- So 2 GPs
- Then accessory cones as needed
Typically treat one canal at a time, unless they interact
restoration impact of endo tx
good endo + good restoration = 91%
poor endo + good restoration = 69%
endo impact on final restoration tx
good endo + good restoration = 91%
poor endo + good restoration = 69%
good endo + poor restoration = 44%
poor endo + poor restoration = 18%
