3BDS: Endodontics 11

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cleaning and shaping the root canal system- what are we trying to achieve
maintain healthy periodontal tissues or create environment that will create bony healing
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how do we create an environment that will create bony healing?
cleaning/ disinfection: removal of organic pulp debris, microorganisms and toxins
shaping: controlled removal dentine to produce a tapering shape that can be disinfected and sealed throughout its length with a root canal filling (gutta percha)
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what is the biological objective of endodontics treatment:
confine instrumentation to the root canal
prevent extraction of necrotic debris into periapical tissue
remove all tissue debris and substrate for bacterial regrowth
create sufficient for irrigation and intracanal medication
complete cleaning and shaping
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what are the design objectives of Endodontics treatment
create a continuously tapering funnel shape
maintain apical foramen in original position (without transporting any apical parts)
keep apical openings as soon as possible (instrument constriction)
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what are the instruments and materials needed
 Examination kit (used until rubber dam is placed)
 Local anaesthetic kit
 Handpiece and appropriate burs
 Rubber dam kit, floss, dam, liquid dam, sponge
 RCT kit, paste lubricant (Glyde)
 X2 irrigating syringes/ needles
 X2 galley pots
 Irrig
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when can you use instruments from RCT kit?
after the tooth has been isolated using rubber dam to prevent cross contamination
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what are the stainless steel instruments used for
initial canal negotiation and apical gaging
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what are the nickel titanium instruments used for
canal cleaning/ shaping
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what are the drawbacks of conventional hand stainless steel preparation technique
 Mishaps
 Debris extrusion with fling motion
 Time consuming
 Less predictable shapes in curved canals
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what is the balanced force technique - a stainless steel technique
a stainless steel technique
- Least canal aberrations
- Use without pre-curving files
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how is the balanced force technique performed
Passive CW rotation 60 degrees
CCW rotation with apical pressure 120 degrees
Remove file with another 60 degree CW rotation and clean
Required when preparing canals that have an apical diameter >50 (F5)
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due to what reason would a canal require a file size bigger than 50
inflammatory root resorption, immature non vital teeth
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what are the advantages of rotary
 Less canal transportation
 Less debris extrusion (less post op pain)
 Faster than hand preparation
 More predictable results
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what are the goals of contemporary root canal shaping ?
• Mechanically remove pulp tissue, microorganisms and infected dentine
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what is torque?
describes forces that act in a rotational manner.
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Torque values set are less than ...
the value of torque deformation and at separation of the rotary instruments
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why do motors have precise values ?
that the limit of elasticity is not exceeded
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for what are torque values low?
for smaller, less tapered instruments
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what are the factors that can contribute to instrument fracture ?
• The operator (most important)
• Instrumentation technique
• Instrument design (constant and variable taper)
• Use of torque-controlled motors
• Rotational speed
• Canal geometry (angle of curvature)
• Number of uses (in uk they are single use)
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what is sheer fracture?
An instrument will fail by torsion when the ultimate shear strength is exceeded
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when does sheer fracture occur?
Occurs when the tip or other part of the instrument binds to the canal wall, whereas the hand piece keeps rotating the instrument
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what is flexural fracture caused by?
Caused by continuous rotation in curved canals
Instrument is subjected to tension and compression cycles at point of maximum flexure
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can flexural fracture be influenced by clinician?
no
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what are the advantages of file taper (variable taper)
: each file preferentially cuts a certain part of the canal
Much less likely to have the file stick in the canal (taper- lock) and fracture.
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what happens at end appointment 1
 Pre-treatment radiograph (used to measure ‘tooth length’ or estimated working length + ASSESS root canal morphology)
 LA
 Access cavity
 Rubber dam
 Locate canal
 Flood access cavity with sodium hypochlorite
 Coronal flare with SX instrument
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how is the working length measured ?
measured distance from incisal edge to radiographic apex
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what happens at access cavity stage?
Cut access cavity to appropriate shape and size with central incisors remove pulp horns
Irrigate the pulp chamber with sodium hypochlorite
Locate the canal orifice(s) using a DG16 (endodontic probe) then we do canal flaring etc
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what do you flare the canal orifice with?what are the torque measurements
SX. (ProTaper gold file) rpm 300, torque 4 in endo machine
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what you using the SX ProTaper gold and flooding the canal with sodium hypochlorite.. what do you do
• Using a 10 stainless steel flexofile negotiate the canal
• Place a rubber stop at tooth length
• Coat SX file in Glyde (a paste lubricant) and go down the canal
NEVER USE FORCE could create a ledge- use envelope of motion
Or drop down to 08 or 06 file
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when do you use paste lubricants
Only use with stainless steel files during initial canal negotiation + glide path creation
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how can you determine the working length
can be done radiographically or electronically (electronic apex locator)
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where should preparation end? when determining working length
Preparation should end at the junction of pulpal and periapical tissue
WL should be as close as possible to CDJ
This is usually the narrowest part of the canal- apical constriction
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how do you use electronic apex locators?
- The EAL is connected by a wire to the lower lip and to a file which is placed in the root canal. Important that the access cavity has no excess irrigant in it but there is irrigant within the canal itself
The impedance between the lip and the pdl is a
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when finding out the WL from a radiograph, what is considered an acceptable measurement
- Acceptable to be within 1mm of radiographic apex
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why is glide path so important?
- Gives information about canal morphology: open, restricted or calcified canals + root canal anatomy

- creates or conforms a smooth reproducible path of adequate diameter before introducing rotary files
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what is an Endodontic glide path?
 a pre-existing part of the original anatomy- natural space once occupied by the dental pulp
 it may be irregular in many teeth especially in the apical 1/3 of the root
 care must be taken to follow the natural path of the canal
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what is the glide path preparation techniques?
1. locate the canal orifice
2. follow canal to apical constriction using a size 10 flexofile- this guarantees patency at the apical foramen which is a prerequisite for a successful glide path, record WL, confirm patency
3. use short push pull strokes un
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what do we use to enhance glide path? what torque do we use for it? and rpm?
Proglider- 1st rotary file we use
Use at 300 rpm
Torque 2
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Always instrument in wet canals using irrigant (sodium hypochlorite) as a lubricant when using rotary files. why?
• This will help prevent file breakage and avoid the accumulation of dentine dust that can potentially block the canal
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what are important guidelines for safe use of rotary instrumentation?
- Constant speed of rotation with torque control- use correct speed and torque for each file
- Irrigation before engaging file (canals must be very wet)
- Light pressure and progress slowly, withdraw when resistance is felt and clean any debris on its fl
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what are factors preventing passive movement of file
• Insufficient glide path- so file struggling to open up canal
• Build-up of debris within canal due to the dust and debris from the file as it cuts
• Build-up of debris on flutes of file
• Complicated root canal anatomy
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how do we shape to WL
- Start shaping with S1 (300 rpm, 4Ncm), brush on outward stroke. (Follow and brush 3-4 passes to get to WL)
- Irrigate, recapitulate, irrigate (size 10 flexofile)
- Shape with S2 (300rpm, 4Ncm) brush on outward stoke. Follow and brush
- Irrigate recapit
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Why is apical preparation carried out?what is the process called
out to determine the diameter of the canal at the AC and to finish the canal preparation to this size. (equal to or slightly larger)
 This is carried out using a process called apical gauging
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what happens at finishing stage?
use F1 (300rpm 4Ncm) to WL then place in RC. Once the file has gone to WL we withdraw it and not let it rotate as it can destroy the apical constriction. Irrigate canal then:gauge with size 20 flexofile (this is the equivalent ** file, we set it to WL and
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how do we check that a flexofile is snug at length?
• If size 20 flexofile is snug at length (by tapping the handle of the file if the handle stays in the same position and we know the tip of the file is equal to or slightly larger than diameter of apical constriction and that’s our shaping carried out. If
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how do you do final irrigation?
3 mL sodium hypochlorite
3mL citric acid
3mL sodium hypochlorite
dry canals with corresponding size of paper points and dress with non-setting, calcium hydroxide, cotton wool/sponge, coltosol, glass ionomer
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why do we do the 1st two steps: 3ml sodium hypochlorite and 3ml citric acid
to remove smear layer
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what do paper points do?
absorb residual irritant from canal.
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what do you have to make sure you recorded in patient notes?
- WL
- Reference point for each canal
- Apical size (F1-F5)
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what is the aim of inter appointment medicament
Reduce and prevent multiplication of microorganisms that remain following careful cleaning and shaping.
Prevent reinfection through coronal or apical leakage
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what are other medicament used in Endodontics treatment apart from calcium hydroxide
odontopaste, iodine
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what does odontopaste contain?
- Contains a corticosteroid, triamcinoclone
- Contains an antibiotic- clindamuycin hydrochloride
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when would you use odontopaste?
 Management of symptomatic irreversible pulpitis or as a pulpotomy agent in the emergency management of the above
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how long should odontopaste be left on to resolve inflammation
4-6 weeks
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when using odontopaste, why do we have to prevent paste contacting access cavity walls
as this can lead to discolouration of the tooth.
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what is the sequence of things needed to be done in an emergency pulpotomy?
method
LA
place rubber dam
completely open pulp chamber
wash gently with sodium hypochlorite
amputate coronal stump using high speed
wash and dry CW
Seal odontopaste/ ledermix into pulp chamber on a small piece of cw
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when is odontopaste contra-indicated
Not recommended during pregnancy or breast feeding (potential teratogenic effects)

Known hypersensitivity to corticoids and clindamycin, purulent pulpitis and endodontic treatment of deciduous teeth
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what can iodine do so that is used as a medicament
- Can penetrate into microorganisms and attacks cells molecules such as proteins , nucleotides and fatty acids resulting in cell death
- Is bactericidal, fungicidal and viricidal and sporicidal
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when is povidone iodine used? and also what are the contra-indications
Used when normal treatment didn’t work as it is very affective against Enterococci faecalis
contra indications: iodine hypersensitivity, pregnant and breast feeding woman
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Card 2

Front

how do we create an environment that will create bony healing?

Back

cleaning/ disinfection: removal of organic pulp debris, microorganisms and toxins
shaping: controlled removal dentine to produce a tapering shape that can be disinfected and sealed throughout its length with a root canal filling (gutta percha)

Card 3

Front

what is the biological objective of endodontics treatment:

Back

Preview of the front of card 3

Card 4

Front

what are the design objectives of Endodontics treatment

Back

Preview of the front of card 4

Card 5

Front

what are the instruments and materials needed

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Preview of the front of card 5
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