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BDS3 CDS > Endodontics > Flashcards

Endodontics Flashcards

1
Q

What are the three design objectives of root canal preparation?

A

Create a continuously tapering funnel shape
Maintain apical foramen in original position
Keep apical opening as small as possible

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2
Q

What is the access shape for upper central and lateral incisors?

A

Triangular, with the point towards the gingival margin

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3
Q

What is the access shape for upper canines?

A

Oval

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4
Q

What size of taper do all ISO stainless steel K files have?

A

02 taper or 2% taper

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5
Q

What are the different lengths of ISO instrument files?

A

21, 25 or 31mm

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6
Q

The handles of ISO instruments are colour coded. Which colours represent which file sizes?

A 
Pink - 06
Grey - 08
Purple - 10
White - 15,45
Yellow - 20,50
Red - 25,55
Blue - 30,60
Green - 35,70
Black - 40,80
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7
Q

What is the length of the cutting flutes on ISO instruments?

A

16mm

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8
Q

What are the drawbacks of conventional stainless steel preparation techniques?

A

mishaps (ledges, canal blockage, zipping of foramen)
debris extrusion with filing motion
time consuming
less predictable shapes in curved canals

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9
Q

Nickel-Titanium alloy allows files to have superelasticity. What is this and what are it’s benefits?

A

Superelasticity means alloy can be strained more than other alloys before permanent deformation occurs.
It allows NiTi files to be placed in curved canals with less lateral forces exerted - less transportation, zipping or ledging; more centrally placed preparation in harmony with the original canal shape

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10
Q

What are the advantages of NiTi vs SS?

A
  • increased flexibility in larger sizes and tapers
  • increased cutting efficiency
  • better safety in use
  • better user friendliness with less instruments and simple sequences
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11
Q

What are the disadvantages of NiTi preparation?

A
  • instrument fracture
  • expense
  • access can be difficult in posterior teeth
  • unsuitable for complex canal anatomy
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12
Q

ProTaper hand files come in sizes Sx, S1-S2 and F1-F4. What are the tip sizes of the Sx, S1 and S2 files?

A 
Sx = 19
S1 = 17
S2 = 20
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13
Q

How is working length calculated?

A

Working length is measured from a fixed reference point (which will remain unchanged throughout the treatment + is within clinicians field of view)
Determined after coronal flaring
WL should be as close as possible to CDJ - usually the apical constriction (narrowest part of canal)
Can be determined radiographically or by using an electronic apex locator

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14
Q

What is a glide path and how do you create one?

A

Glide path - space created within root canal where instruments can glide in relatively easy and bind/gauge apically

  • confirm straight line access, explore anatomy
  • introduce files 10-25 to resistance only (coronal only), coronal flare - S1
  • size 10 WW (watch winding) establish apex
  • irrigate + repeat using size 15 (WW) and size 20 (BF)
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15
Q

What is recapitulation and patency filing?

A

patency filing - use a small file eg size 08/10 through the apical constriction to minimise blockage

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16
Q

What is apical gauging?

A
  • decide which file to finish with apically by going 2 file sizes bigger than the first file to bind
  • check F files for debris apically when removing - if no debris then file is not engaging
  • use K file to check apical binding as K file will not bind coronally or middle 1/3 since taper in canal is larger
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17
Q

When obturating, GP points are coated with resin sealers. What are these and what are their properties?

A
  • epoxy resin, two paste mixing system
  • slow setting (8 hours)
  • good sealing ability
  • good flow
  • initial toxicity declining after 24 hours
  • water resistant (insoluble)
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18
Q

What are the contents of GP points?

A
  • gutta percha 20%
  • zinc oxide 65%
  • radiopacifiers 10%
  • plasticisers 5%
19
Q

Describe the cold lateral compaction technique used for obturation.

A
  • Master GP point fits apical collar, tweezers locked at WL
  • Master GP point forced to side of canal
  • Finger spreader inserted to 2mm from apical stop
  • Accessory points used in space created by finger spreader and added until canal is fully obturated
  • excess removal of GP done using heated instrument, aim to cut just below ACJ
  • use CaOH as a sealer and restore cavity with appropriate material
20
Q

What are the signs and symptoms of reversible pulpitis?

A
  • discomfort is experienced only lasting a few seconds when a stimulus is applied
  • exposed dentine (dentinal sensitivity), caries or deep restorations
  • no significant radiographic changes in periapical region
  • pain experienced is not spontaneous
21
Q

What are the signs and symptoms of irreversible pulpitis?

A
  • may include sharp pain upon thermal stimulus, lingering pain (often 30secs or longer after stimulus removed), spontaneity (unprovoked pain), referred pain
  • pain may be accentuated by postural changes such as lying down or bending over
  • OTC analgesics typically ineffective
  • deep caries, extensive restorations, fractures exposing pulpal tissues
  • hyperaemic pulp
22
Q

What are the signs and symptoms of pulp necrosis?

A
  • non-responsive to pulp testing, asymptomatic

- pain to percussion or radiographic evidence of osseous breakdown unless canal is infected

23
Q

What part of sodium hypochlorite is responsible for antibacterial activity?

A
  • NaOCl ionises in water into Na+ and hypochlorite OCl-
  • establishes equilibrium with hypochlorous acid (HOCl)
  • HOCl is responsible for antibacterial activity
24
Q

What are the properties of sodium hypochlorite?

A
  • potent antimicrobial activity
  • dissolves pulp remnants and collagen
  • only irrigant that dissolves necrotic and vital tissue
  • helps disrupt smear layer by acting on organic component
  • time essential for effectiveness: should irrigate for 10mins from when you have accessed the root apex with file
25
Q

What is an endodontic smear layer? How is removal of smear layer achieved?

A
  • organic pulpal material + inorganic dentinal debris, superficial 1-5um layer with packing into tubules
  • removed using 17% EDTA (chelating agent), or citric acid
  • 1min contact time necessary with EDTA
26
Q

What is a general rule of thumb for single visits or multi-visits regarding root canal treatments?

A
  • vital and asymptomatic -> single visit
  • all others -> multi-visit
  • must be decided on case by case basis
27
Q

K files have are made from a ________ shape therefore have __ points of contact.

A

Square, 4

28
Q

What are the objectives of root canal objectives?

A
  • to disinfect root canal
  • dissolve organic debris
  • flush out debris
  • lubricate root canal instruments
  • remove endodontic smear layer
29
Q

Root canal irrigants are delivered through which type of needle?

A
  • Luer lock syringe

- 27 gauge endodontic-tipped needle

30
Q

What are the objectives of cleaning and shaping the root canals?

A
  • remove infected soft and hard tissue
  • give disinfecting irrigants access to apical canal space
  • create space for the delivery of medicaments and subsequent obturation
  • retain the integrity of radicular structures
31
Q

What are the reasons for endodontic failure?

A

before: misdiagnosis, treatment planning/case selection problems
during: missed canals, ineffective clean, shape or fill; iatrogenic damage
after: recurrent caries; coronal leakage; post hole preparation problems

32
Q

How would you clinically assess a RCT tooth?

A

Check for:

  • coronal seal
  • swelling
  • sinus
  • TTP
  • buccal sulcus tender to palpation?
  • mobility
  • increased pocketing
33
Q

How would you radiographically assess a RCT tooth?

A

Check for:

  • root filling (length, quality of obturation)
  • unfilled/missed root canals
  • sclerosis
  • bone support
  • crown to root ratio 1:1.5
  • radiolucency
34
Q

What problems are associated after RCT/re-RCT?

A
  • amount of remaining tooth structure
  • lack of ferrule
  • wide post holes (eg re-RCT)
  • endodontic complications eg fractured instruments
35
Q

Are pulp less teeth more brittle than vital teeth?

A

Reduced structural integrity leads to weakening of tooth, NOT brittleness

36
Q

What is the purpose of a post/core?

A

To gain intraradicular support for a definitive restoration
Core provides retention for crown
Post retains core

37
Q

What are the guidelines for the width and length of a post?

A

No more than 1/3 of root width at narrowest point and 1mm of remaining circumferential coronal dentine
Minimum 1:1 post length/crown length ratio

38
Q

What are the guidelines for post placement regarding alveolar bone and ferrule?

A

Sufficient alveolar bone support must be present - at least half of post length into the root
At least 1.5mm of height and width of remaining coronal dentine

39
Q

What properties does the ideal post have?

A

Parallel sided
Non-threaded (passive)
Cement retained

40
Q

What is the adv of a parallel sided post than a tapered post?

A

Avoids wedging

More retentive

41
Q

What are the adv/disadv of a non-threaded cement retained post than a threaded post?

A

Incorporate less stress to remaining tooth tissue than threaded (active)
Cement acts as buffer between tooth and post during masticatory forces
Less retentive

42
Q

What materials can be used for a core?

A

Composite - most common
Amalgam
GI

43
Q

What problems are associated with posts?

A

Perforation, core fracture, root fracture or crack, post fracture.

44
Q

What methods can be used for post removal?

A

Ultra sonics
Masseran kit
Eggler
Moskito forceps (screw retained)

BDS3 CDS (4 decks)

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