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Endodontics 1 Flashcards

1
Q

What are the aims of the root canal preparation?

A
  • remove microbes and pulpal debris
  • create sufficient space for irrigation and medication
  • preserve integrity and location of apical canal anatomy
  • avoid iatrogenic damage to canal anatomy
  • facilitate canal filling
  • avoid further irritation or infection to periapical tissues
  • preserve sound root dentine to allow long term function of tooth
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2
Q

What are the stages of a root canal treatment?

A
  • pre operative diagnostic radiograph including estimated working length
  • preparation of tooth for RCT
  • access cavity and location of RC entrances
  • create straight line access
  • initial negotiation and coronal flaring
  • chemical preparation
  • corrected working length determination
  • apical preparation
  • obturation
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3
Q

What information can we get from a pre-operative (diagnostic) radiograph?

A
  • external morphology
  • number of canals
  • length, direction and degree of curvature
  • branching, lateral canals
  • position of pulp chanber in relation to external surface
  • estimated working length
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4
Q

What is the estimated working length?

A

length between the coronal referece point and the apical limit of the preparation

(apical limit of preparation should be 1mm short of the radiographic apex)

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5
Q

What is the anatomical apex?

A

it is the endpoint of the root

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6
Q

Why is the dentino-cemental junction considered the ideal end-point for the root canal preparation?

A

this is because it is considered to be the transition from endodontium to periodontium

this junction is strictly histological and impossible to locate clinically

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7
Q

Numerous studies have shown that the foramen is generally not in the centre but may be situated on the lateral side of the root. True or fasle

A

true

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8
Q

What is the apical constriction?

A

it is the narrowest part of the canal
(last few millimetres)

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9
Q

What is the use of the anatomical landmark of the apical constriction

A
  • assume periodontum starts here as we cannot clinically identify dentinocemental junction
  • consider preparing or filling beyond this point overfilling/overinstrumentation
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10
Q

The working length of a root canal preparation should be ____ from the radiographic apex. Why is this ?

A

2mm

accounts for foramen distance and radiographic image distortion

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11
Q

It was thought for a long time that the dentinocemental junction/apical constriction are located at an average of 1mm from the radiographic apex hence the preparation to 1mm of the radiographic apex. Why is this technique no longer reliable?

A
  • dentinocemental junction is rarely located at the apical constriction
  • thickness of cementum varies greatly from one tooth to another and between patients
  • thickness of cememtum changes with physiology; cementum thickness increases with ageing; and pathology (apical resorption related to the canal)
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12
Q

The apical constriction is not always located 0.5-1mm from the radiographic apex. True or false

A

true
can be 3mm away from the radiographic apex

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13
Q

How should you prep tooth for RCT?

A
  • remove all caries or defective restorations; must be done before opening the pulp chamber
  • place provisional restoration in broken down teeth for rubber dam application
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14
Q

What is the benefit of using rubber dam for RCT?

A
  • improve visibility
  • prevent microbial (saliva) contamination
  • soft tissue protection (lips and cheek)
  • confine excess irrigant
  • reduce risk of inhalation/ingestion of instruments/irrigants
  • improved patient comfort
  • reduce liability im medico-legal case
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15
Q

How should you create your access cavities?

A
  • remove the entire roof of the pulp chamber including pulp horns
  • shape of access cavity is determined by number of canals and the location of the canals
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16
Q

How many canals are present in the maxillar upper first molar? Name them

A

4
MB1
MB2
DB
palatal

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17
Q

How can you tell have penetrated the roof of the pulp chamber when preparing the access cavity?

A

a sudden drop is felt

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18
Q

What instrument is used to widen the access to create a smooth-walled preparation?

A

Endo Z bur

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19
Q

What is the benefit of a widened access cavity?

A
  • allows visualisation of the canal orifice
  • allows unimpeded straight line accesss
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20
Q

What is the benefit of using an endo-z bur to widen the access cavity?

A
  • prevents perforation of the pulp floor
  • damaging the pulp floor prevents access to the canals (debris blocking the canals
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21
Q

State the characteristics of an endodontic explorer

A
  • double ended
  • long, sharp tips
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22
Q

What is the purpose of the endodontic explorer?

A

used to check:
* accessibility of the orifice
* location of orifice

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23
Q

What are the characteristics of a front surface mirror?

A
  • reflective surface at the front of the glass
  • does not produce double images as standard mirrors do
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24
Q

What is the benefit of straight line access?

A
  • reduces stress on instruments
  • reduces chances of procedural errors
  • simplified treatment by providing a clear path of insertion for instruments
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25
Q

List some ways in which straight line access can be reached

A
  • removal of overhanging dentine - remove pulp horns
  • remove any dentine lips
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26
Q

Gve examples of iatrogenic damage caused by root canal preparation

A
  • ledge
  • perforation
  • strip perforation
  • Zipping
    dentine mud
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27
Q

What does zipping refer to in endodontics?

A

refers to transportation (movement away) away from the apical preparation due to the file straigening

The elbow then becomes the narrowest part of the canal which is where obturation reaches

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28
Q

List the preparation techniques for a RCT

A
  • step back
  • crown down
  • double flare
  • modified double flare
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29
Q

What are the phases of the double flare technique ?

A
  • crown down- coronal 1/3 prepared
  • apical enlargment- apical 1/3 prepared
  • step back- apical preparation
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30
Q

What does the modified double flared technique entail?

A
  • initial negotiation and coronal flaring using handfiles or gates glidden
  • apical enlargment at WL until cutting clean dentine
  • step back
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31
Q

What is the benefit of the crown down technique (preparation of the coronal 1/3)?

A
  • removes infected pulpal tissue /debris
  • prevents microbes from being introduced to apical area
  • coronal obstructions removed
  • straigtening of coronal section
  • provides a resevoir for irrigant
  • reduces risk of apical blockages
  • working length maintained through subsequent preparation
  • allows for better apical tactile feedback
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32
Q

List characteristics of gates glidden drills

A
  • side cutting/non cutting tips
  • there are six size shown by the number of bands on the side
  • not flexible thus only used in straight part of cannal
  • long shanks- prone to fractures at the neck
  • aggressive- can easily remove dentine especially size 4s
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33
Q

What design features of the synrine prevents needle seperating during irrigation?

A

Luer-lock

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34
Q

What type of needles are used for irrigation?Why is this

A

27-30 G side vented needles

they prevent irrigant from being pushed through the apex

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35
Q

How far should you be able to insert your irrigant needle?

A

2-3mm of the working length

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36
Q

How does the irrigant reach the working length of the canal?

A

a small size 8/10 k-file can be used to agitate the irrigant to the working length

recaptulation essentially

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37
Q

List the characteristics of the ideal irrigant

A
  • antimicrobial
  • cheap
  • dissolves pulpal tissue
  • removes smear layer
  • easy to use
  • long shelf life
  • low surface tension
  • non staining
  • non- cytotoxic
  • compatible with dentine
  • substantive
  • tissue friendly
  • non-toxic
  • non- corrosive to instruments
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38
Q

Give characteteristic of NaOCl solution

A
  • effective antimicrobial
  • dissolves pulpal tissue and organic matter
  • toxic
  • not substantive
  • discolours
  • corrodes instrumets
  • unpleasant odour
  • ineffective in smear layer removal
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39
Q

What is a substantive antimicrobial agent?

A

this is one that is able to attach to hydroxyapatitite containing tissues and be released gradually

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40
Q

What gives the antimicrobial effect of NaOCl?

A

free chlorine iones break down bacterial proteins into amino acids

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41
Q

Why is regular replenishment and agitation of NaOCl required?

A

maintain Chlorine ions
agitation to maximise dissolution of organic debris

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42
Q

What is the concentration of NaOCl recommended?

A

0.5-3% usually recommended

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43
Q

Higher concentrations of NaOCl are effective against what microorganism?

A

E. faecalis

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44
Q

The volume of NaOCl uses is more critical than the concentration chosen. True or false

A

true

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45
Q

Whatare the symptoms of NaOCl accident?

A
  • acute severe swelling and pain
  • profuse bleeding from canal
  • taste of chlorine and throat irritation
  • bruising or ecchymosis of skin or mucosa
  • longer term parasthesia or anaesthesia
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46
Q

How would you manage acute severe pain and swelling following a NaOCl accident?

A
  • inform patient
  • swelling may reduce
  • provide analgesics and antibiotics
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47
Q

How would you manage profuse bleeding from the canal following a NaOCl accident?

A
  • irrigate with saline
  • dry
  • apply temporary dressing
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48
Q

How would you manage taste of chlorine and throat irritation following a NaOCl accident?

A

patient to drink water and milk

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49
Q

How would you manage bruising or ecchymosis of skin or mucosa following a NaOCl accident?

A
  • apply cold compress
  • advise may take a week for bruising to subside
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50
Q

How would you manage longer term parasthesia or anaestheria following a NaOCl accident?

A

refer to hospital and inform patient

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51
Q

What should you do following a NaOCl accident in general?

A

recall 1- days and review symptoms
complete RCT when symptom free or refer to specialist

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52
Q

Taste of chlorine or throat irritation from NaOCl is an indication of …

A

presence of NaOCl in the maxillary sinus

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53
Q

What is the potential benefit of CHX over NaOCl as an endo irrigant?

A
  • extremely low level of tissue toxicity
  • substantive antibacterial activity (binds to hydroxyapatite containing tissue)- last up to 12 hours
  • more effective against G+ve such as E faecalis
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54
Q

What are the limitations of CHX as an irrigant?

A
  • inability to dissolve organic matter (necrotic pulps)
  • no action on the smear layer (minerals)
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55
Q

What does the smear layer contain?

A

Minerals
Organic matter (carbon containing compounds)

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56
Q

Why is EDTA able to remove the smear layer?

A

it reacts with the metal ions (minerals) contained in the smear layer e.g. calcium

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57
Q

What is the benefit of using EDTA as an irrigant?

A

it can help negotiate sclerotic canals
sclerotic canals - narrow due to deposition of tooth structure (hydroxyapaptite) so EDTA can bind

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58
Q

What are the limitations to using EDTA as an irrigant?

A
  • if remains too long on the tooth it weakens the tooth and increases leakage (binding to Ca2+)
  • it has no antibacterial effect
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59
Q

What is the benefit of a combination of EDTA and NaOCl?

A
  • synergistic effect
  • effective removal of the smear layer
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60
Q

Why is EDTA and NaOCl not used together?

A

this is because EDTA interacts with NaOC and this reduced the amount of chlorine ions available

this compromised the tissue dissolving and antibacterial abilities of NaOCl

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61
Q

How can EDTA and NaOCl be used?

A
  • alternate use of NaOCl and EDTA
  • copious amounts of NaOCl used to wash remnant of EDTA
    *
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62
Q

What is the benefit of using Iodine as an irrigant?

A

E facecalis
C albicans
antiviral

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63
Q

State an advantage and disadvantage of using citric acid as an irrigant

A
  • removes smear layer
  • reacts with NaOCl so reduces available chrlorine
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64
Q

Define the smear layer

A

surface film of debris retained on dentine or other surfaces of instrumentation

consists of dentine particles, remnants of vital or necrotic pulp tissue, bacterial components and retained irrigant

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65
Q

What is the benefit of smear layer removal?

A
  • ZOE (medicament) able to penetrate dentinal tubules
  • may improve the seal and reduce leakage (affects the bond of sealers)
  • may act as a barrier to irrigant penetration
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66
Q

State some advantages of leaving the smear layer

A
  • slow bacterial invasion
  • blocks dentinal tubules that are difficult to clean
  • inhibitory effect on bacterial growth
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67
Q

What does patency filing refer to?

A

the use of a small file through the apical foramen during canal preparation to prevent blockage of the apical part of the canal by debris

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68
Q

What are the standard lengths of K files?

A

21mm
25mm
31mm

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69
Q

What is the length of the cutting blades of the handfiles?

A

16mm regardless of the legth of the file

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70
Q

Give examples of techniques used for instrument manipulation

A
  • watch winding technique
  • circumferential technique (push-pull)
  • balanced force technique
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71
Q

When would the split-dam technique be used in endodontics ?

A
  • when there is insufficient tooth structure
  • presence of porcelain crown or veneers
72
Q

How can you prevent leakages of irrigant when using the split dam technique?

A
  • accurate positioning of the high vacuum suction tip
73
Q

How can you estimate the depth of the pulp chamber?

A

using radiograph

74
Q

What is a 2% taper?

A

this is when the diameter of the file increases by 0.02mm at each millimetre

75
Q

What is the estimated height of the buccal cusp to the pulp chamber roof in mandibular and maxillary molars?

76
Q

What is the estimated pulp chamber height in mandibular molars?

77
Q

What is the estimated height of the pulp chambers in the maxillary molars?

78
Q

What is the depth of seperation between the pulpal floor and the furcation in maxillary and mandibular molars?

79
Q

Briefly describe the access of a maxillary anterior tooth

A

access starts at the cingulum and extends towards the incisal edge

Triangular shape to encompass the pulpal horns

80
Q

How does an endo access cavity for a canine differ from an incisor?

A

rounder cavity access
no need to flare access as only one pulp horn

81
Q

What should be removed when creating a canine access cavity?

A

the lingual shoulder

using SX or GG bur

82
Q

What should you be aware of when creating access cavitues of mandibular incisors?

A

labio-lingual inclination of the tooth

83
Q

What must you remove when creating an access cavity in a mandibular incisor?

A

lingual ledge

84
Q

Give a brief example of complex morphology in mandibular premolars

A

canals can divide deep within the root

85
Q

What are the 9 guidelines for the anatomy of the pulp chamber floor?

A
  • law of centrality
  • law of concentricity
  • law of CEJ
  • law of colour change
  • 1st law of orifice location
  • 2nd law of orifice location
  • 3rd law of orifice location
  • 1st law of symmetry
  • 2nd law of symmetry
86
Q

What is the law of centrality?

A

floor of the pulp champer is located in the centre of the tooth at CEJ level (unrelated to occclusal anatomy)

87
Q

What is the law of concentricity?

A

walls of the pulp champer are concentric to the outer surface at the CEJ

88
Q

What is the law of CEJ?

A

distance of the external surface to the wall chamber is the same throughtout the circumference of the tooth at the CEJ

89
Q

How can you locate canal orifices using the law of colour change?

A

pulpal floor is darker, transparent
pulpal walls are brighter and opaque

90
Q

The first law of orifice location refers to …

A

orifices located at the wall to floor junction

91
Q

The second law of orifices refers to …

A

orifices at angles in floor to wall junction

92
Q

The third law of orifice location refers to …

A

orifices at terminus of roots developmental fusion lines

93
Q

What do the 1st and 2nd law of symmetry state?

A

orifices are equidistant and perpendiculat to the M-D line drawn through the pulpal floor

if the canal is on the line then it is unlikely to find a 2nd canal in that root

94
Q

What are the disadvantages of conservative access cavities?

A
  • missed anatomy
  • incomplete disinfection
  • instrument fracture
  • increase complexity of your case
95
Q

What are the advantages of coronal flaring?

A
  • eliminates cervical bulging
  • reduces effect of canal curvature
  • prevents working length changes
  • better visualisation of canal
  • cleansing and disinfection of coronal third before entering apical third
  • early and increased irrigant volume
96
Q

What should the passage of the endo files be guided by?

A

root canal walls

NOT access cavity walls

97
Q

Where is the MB2 canal ususally located?

A

perpendicular from the DB canal

98
Q

How can you radiographicall identify the MB2 canal?

A

a distal angled radiograph with a file in the MB1
If it is off centre, there may be an MB2

If MB2 and MB1 are close they may join

soak with NaOC 5.25% and look for bubbling

99
Q

An endodontic explorer is also referred to as …

A

DG16 probe

100
Q

What is a micro-opener?

A

an explorer with the capability of a K-file

101
Q

Califications of the canal occur from ____ to______.

A

coronal to apical

102
Q

What are some tips for managing calcifications in canals?

A
  • magnification and good lighting
  • avoid damage to pulpal floor
  • working dry (blow air into cavity) then wet cavity
  • remove existing restorations if feasible
  • use larger SS files or C+ file (stiffer and can push through)
  • coronal flaring
  • stop, close and next appointment
103
Q

If you have reached the CEJ and you have not found your canals what should you do?

A

take a radiograph with a file/bur to check depth and angulation

104
Q

Give examples of clinical conditions which may require a radiograph

A
  • dental caries
  • traumatised teeth
  • tooth surface loss
  • cracker/fractured teeth
  • pulpitis
  • periapical periodontitis
  • root resorption
105
Q

What are the aims of endodontic treatment?

A
  • disinfection of teeth- caries removal, disinfection of root canal system
  • sealing of teeth after root canal preparation to prevent reinfection
106
Q

In order to seperate the MB1 and MB canals in maxillary molars, what technique would you use to take your radiographs?

A

mesial cone angulation

107
Q

In order to achieve maximum seperation of the MB and ML canals in mandibular molars, what technique would you use to take your radiograph?

A

distal cone shift

108
Q

What instrument is used to ensure GP points/obturation material is sufficiently packed into the canal orifices?

A

endodontic pluggers
Machtou pluggers

109
Q

List the general principles for the crown down/ coronal -apical root canal preparation

A
  1. access
  2. coronal flaring
  3. scouting
  4. working length
  5. glide path
  6. apical preparation and finishing
110
Q

What is coronal flaring?

A

opening the canal orifice and enlargening the coronal aspect of the root canal

111
Q

What is scouting?

A

introducing the first small file to explore the coronal 2/3 of the canal

112
Q

How is working length determined ?

A

apex locator
radiograph

113
Q

What is a glide path?

A

this involves creating pilot channel/pathway to working length

114
Q

Briefly describe the watch-winding technique

A

continuous clock-wise and anti-clockwise rotation with slight apical pressure, rapidly advances a fine file down root canal

115
Q

What kind of hand file manipulation can Hedstom files be used for?

A

circumferential filing (push pull)

116
Q

Hedstrom files should not be used for what hand filing technique?

A

watch winding

117
Q

What are the main benefits of the NiTi files over the conventional stainless steel files?

A

super-elasticity
shape memory

118
Q

What are the main rules of instrumentation for rotary instruments?

A

never exceed 10 seconds in a cana
limit to 3 insertions/pecks (brush don’t peck?)
each peck should be 1-2mm

119
Q

What is the protaper gold sequence for hand and rotary use?

A
  • SX
  • S1
  • S2
  • F1
  • F2
  • F3
120
Q

What are functions of the scouting file?

A
  • confirms straight line access
  • verifies diameter of the canal
  • reveals anatomy
121
Q

What is the function of the optional SX file?

A
  • allows flaring more coronally
122
Q

What is the characteristic of the SX file?

A

shorter than other pro-taper files
19mm

123
Q

What is the function of the S1 file

A

prepares the coronal 1/3 of the canal

124
Q

What is the function of the S2 file?

A

enlarges and prepares the middle one-third

125
Q

What is the function of the S1 and S2 shaping files ?

A

brushing (creates lateral space) allowing each instrument to passively feed deeper into the canal

126
Q

What is the protaper gold filing sequence?

A
  • scout
  • glidepath
  • shaping (shaping files)
  • finishing (Finishing files)
127
Q

What are the ideal properties of obturation materials?

A
  • easily manipulated
  • dimensionally stable (no shrinkage)
  • seals apically and laterally
  • non irritating to PA tissues
  • impervious to moisture, non porous
  • unaffected by tissue fluids (no corrosion/oxidation)
  • inhibits bacterial growth
  • radiopaque
  • does not discolour the tooth
  • sterile
  • easily removed for retreatment
128
Q

What technique is used for obturation following hand filing?

A

cold lateral condensation

129
Q

What techniques are available for obturation when the canal has been prepared using the rotary file system?

A
  • single cone (match GP cone with finishing rotary file)
  • warm vertical condensation
  • carrier-based system
130
Q

What are the advantage of the single cone filling technique?

A
  • easy
  • quick
  • good control of WL
  • easily revised if necessary
  • inexpensive
131
Q

What are the disadvantages of the single cone technique?

A
  • reliance on sealer
  • inadequate fill
132
Q

What is the chloro-percha technique ?

A
  • GP placed in chloroform solvent for 30 seconds
  • solvent adapted GP which may fill canal better
133
Q

What is the risk of the chloro-percha technique?

A

shrinkage!

134
Q

What are the advantages of the cold lateral compaction technique?

A
  • gold standard
  • long term success
  • good control of WL
  • easily revised if necessary
  • easy to master
  • inexpensive
135
Q

What are the disadvantages of the cold lateral compaction technique?

A
  • time consuming
  • does not produce homogenous mass of GP
  • not suitable for irregularly shaped canals
  • too many accesory points; difficult to locate finger spreader and subsequent GP points
  • wedging forceds
136
Q

Briefly describe the cold lateral compaction technique

A
  • coat root surface with sealer cement
  • dip master GP point into sealer and insert it into canal to WL
  • add accesory GP points by first creating a space with the finger spreader then quickly inserting the accessory GP point into the space created
  • if there are any points (identified by finger spreader) add more GP
  • sear off coronal part and pack down with machtou plugger
137
Q

What is the initial apical file?

A

the first file which binds apically

138
Q

What is the master apical file?

A

largest file which reaches WL

139
Q

Ideally, the master apical file should be a number …

140
Q

What are the advantages of warm vertical compaction?

A
  • homogenous mass of GP
  • fills lateral and accessory anatomy
  • quick
  • can be revised if necessary
141
Q

What are the disadvantages of warm vertical compaction?

A
  • initial cost of equipment
  • more skill to control WL
  • sealer extrusion
142
Q

What are the advantages of the carrier based system?

A
  • fills lateral and accessory anatomy
  • quick
  • filling can be revised
143
Q

What are the disadvantages of the carrier based system?

A
  • initial cost of equipment
  • more skill to control WL
  • sealer extrusion
  • failure to heat GP adequately may result in GP not sitting properly
  • under-prepared root canals or incorrect angle of insertion can strip GP from its carrier
  • difficult removal and post preparation
144
Q

What is the purpose of the funnel shaped canal preparation created in a RCT?

A
  • faciliates intracanal medicament e.g. CaOH between visits (antibacterial between visits)
  • facilitates irrigation for disinfection
  • disruption of the biofilm mechanically
145
Q

What does a taper refer to?

A

it is an increase in file diameter at each millimetre along the working surface towards the file handle

146
Q

Compare and contrast stainless steel files to rotary systems

A

Stainless steel files
* larger in diameter and thus more rigid
* this often presents a problem if the canal is not straight

Rotary Systems
* made of titanium
* more flexible so follows the anatomy of the canal
* allows the designer to go to a larger diameter while still maintaining the flexibility of the file
* more conservative

147
Q

Describe the taper observed in protaper/rotary systems

A

they have a variable taper
at different levels, the taper changes (how much the diameter increases at each mm changes)

148
Q

What are the advantages of using GOLD nickel titanium taper files?

A

there is an additional heat treatment done (which gives the gold colour) that increases the flexibility of the files

these files have resistance to cyclic fatigue

149
Q

What is the benefit of creating a smooth glide path?

A
  • enables a transition to larger files
  • maintains the original anatomy whilst also reducing stress on larger shaping files
150
Q

Why is pre-flaring the canal necessary?

A

to minimise the chance of permanently blocking the canal with a broken rotary instrument

151
Q

What instruments can you use to create a glide path?

A
  • hand files
  • path files
  • pro-glider
152
Q

When using handfiles to secure a glidepath, they can be secured using up to a size __ file

153
Q

When checking the patency of the canal you can go _____ beyond the apical foramen

154
Q

In between files, what must you do ?

A

Irrigate
Recapitulate
Irrigate
(IRI)

155
Q

You should never irrigate to working length. True or false

A

True

Hence why you measure your syringe
(recapitulation allows you to agitate you irrigant further into the canal)

156
Q

What must you do to your files (rotary and hand) before they enter the canal?

A
  • inspect them before and after they come out of the canal
  • (additionally you can measure then before and after to ensure they have not broken)
  • you should also clean your files
  • check that there is no flattening or unwinding of files
157
Q

How can you clean rotary files?

A
  • wet gauze
  • alcohol wipe
  • sponge

File can be inserted into the sponge to clean superficial debris and then cleaned with wet gauze or alcohol wipe

158
Q

Why are endodontic files single use?

A
  • prions- cannot be removed after autoclaving
  • to prevent fractures
159
Q

What are the types of fatigues that a file can experience?

A

Metal/cyclic fatigue
Torque fatigue

160
Q

What are the factors that contribute to cyclic fatigue?

A
  • radius of curvature
  • diameter
  • taper
  • number of cycles
  • curvature
161
Q

What factors contribute to torque failures?

A
  • pressure
  • suface area
  • RPM
  • lubrication
  • curvature
162
Q

The sequence for protaper hand and protaper gold files are the same. Outline the file sequence

A
  1. Scouting
  2. Glidepath
  3. Shaping
  4. Finishing
163
Q

What are the uses of a scouting file?

A
  • confirms straight line access
  • verifies the diameter of the canal
  • reveals the anatomy of the canal
  • initiates the glide path
164
Q

What is the function of the SX file?

A
  • used to achieve a coronal flare so the canal can now happily contain more irrigation
165
Q

What is the main characteristic of the SX file?

A
  • 19mm file length
    *
166
Q

What are the functions of the S1 and S2 protaper files?

A
  • S1 file prepared the coronal 1/3 of the canal
  • S2 file enlarges and prepares the middle 1/3 of the canal
167
Q

What is the benefit of using the brushing technique with rotary systems?

A

it is used to create lateral space allowing each instrument to passively feed deeper into the canal

168
Q

When using an apex locator, when is a zero reading detected?

A

this is detected when the file exits the canal

169
Q

How does a zero reading on an apex locator appear?

A

appears as a single red line

170
Q

What is the size equivalent of an F1 finishing file?

171
Q

What is the size equivalent of an F2 finishing file?

172
Q

What is the size equivalent of an F3 finishing file ?

173
Q

What is apical gauging?

A

this is a technique used to determine the size of the apical constriction and the taper of the apical portion closest to the foramen

174
Q

Outline the full process of a RCT using rotary system

A
  • pre-op radiograph for EWL, canal anatomy
  • rubberdam/clamp after LA (caries free)
  • scout using #10/ #8 files at (<2/3 of EWL) for straightline access
  • SX for coronal flare
  • Glidepath with #10, #15, #20 at 2/3rd of EWL then full EWL
  • comfirm WL with apex locator, then WL radiograph, if withing 2mm of apex no need to repeat
  • S1/S2 to WL, IRI, patency with #8/10 file
  • F1 to complete apical prep, IRI, F1 GP cone
  • Master cone F1 radiograph (with good tugback to confirm this is the master cone)
  • IRI, penultimate flush with EDTA (flush as follows NaOCl, EDTA, NaOCl)- remember EDTA can weaken the root surface/enamel
  • dry canals
  • obturation of DRY canals; coat with sealer on paperpoint, then coat GP, use heater plugger to sear off GP at orifice level, compact with machtou plugger then sear off 1mm below orifice level
  • post op radiograph
  • review in 6 months to a year
175
Q

When should you apically gauge?

A

only when there is no tugback with the mastercone

176
Q

What types of sealers are used during obturation?

A
  • ZOE
  • CaOH
  • Epoxy
  • Silicone
  • Resin
  • GI
  • RMGI

Clinical Knowledge 2 (40 decks)

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