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BDS3 > Endodontics > Flashcards

Endodontics Flashcards

1
Q

What are the 2 main types of Stainless Steel K-type instruments?

What is the helical angle & pitch of the type not in much use today?

A
  1. Reamers
  2. Files

REAMERS:

  • Helical angle = 10-30º → ROTATIONAL motion
  • Pitch = cutting flutes further apart (vs. files) → Better ability to collect debris
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2
Q

What is the difference between:

  1. Step Back
  2. Serial Step Back

In canal preparation?

Which comes first?

A

Serial Step Back is first!

  1. Serial Step Back = Increase in size 10 patency file → MAF (usually size 25) - File thickness increases but length (WL) remains the same!
  2. Step Back = Incremental increase in file size and reduction in length to create 5% canal taper
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3
Q

What is meant by “Internal Resorption”?

What are 2 clinical signs?

A

Dentine resorption by dentinoclasts/odontoclasts stimulated by pulpal inflammation

  1. “Pink spot” on tooth
  2. Punched out lesion continous with pulp cavity
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4
Q

What area of RCT prep are SX files used for?

Outline some of their features (material, length, motion)?

A

Prep of coronal 1/3rd - 2/3rd canal

  • Nickel Titanium (flexible)
  • 19mm (D0 = 0.19mm
  • 9 files, rapidly decreasing taper
  • In and Out motion used
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5
Q

Why are RCT teeth weaker? (4)

How is this issue addressed?

A
  1. Loss of tooth structure
  2. Loss of proprioception
  3. Loss of pulp roof → Cuspal flexure more prone to fracture
  4. Wider isthmus and Loss of marginal ridge

Add Core or Crown tooth (cuspal coverage)

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6
Q

What is the main cause of RCT failure?

How can this be avoided? (3)

A

Coronal leakage - therefore good seal (apical and coronal) is VITAL

Avoided by:

  • Caries removal
  • Rubber dam
  • Interim restoration (e.g. 2mm IRM/GIC) with sound restoration on top
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7
Q

What is pulp capping?
What are the two main types?

A

Pulp capping = Process of protecting pulp from injury or necrosis after being exposed or nearly exposed during cavity prep

  1. Direct - Exposed pulp directly covered
  2. Indirect - Pulp NOT exposed (thin layer of residually mineralised/sound dentine left)
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8
Q

What is meant by “Hyperplastic Pulp”?

What are the 2 treatment options?

A

“Pulp Polyp”

Form of irreversible pulpitis due to proliferation of chronically inflammed young pulp tissue

Treatment: RCT (Pulpotomy/Pulpectomy) or XLA

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9
Q

What is the difference between a Periapical “TRUE” and “POCKET” Cyst? (Define both)

Which therefore more likely to respond to RCT?

What pulpal condition usually leads to their formation?

A

Both are inflammatory apical cysts…

PERIAPICAL TRUE CYST = A distinct pathological cavity which is completely enclosed in epithelial cells and has NO communication with the root canals

PERIAPICAL POCKET CYST = A sac-like epithelial-lined cavity that is OPEN TO and communicates with the root canals - Therefore better responds to RCT

Usually proceeds “Chronic Periapical Periodontitis”/ “Chronic Granuloma”

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10
Q

Is cracked tooth easy or hard to localise?

What tooth is most commonly affected?

A

HARD!

Mandibular 7s

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11
Q

What are 4 histopathological features of Acute Pulpitis?

A
  • Hyperaemia (increased vascularity)
  • Vascular stasis - risk factor for blood clots
  • Oedema
  • Increased cellular infiltrate (T lymphocytes and Macrophages)
  • “WHEATSHEATHING” of Odontoblasts -Oedemous changes in Odontoblast layer (more commonly associated with non-carious causes)
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12
Q

How do we treat RCT perforations?

A

Immediate repair with GIC or MTA

MTA only used when repair site enclosed in bone (no oral cavity contact with saliva)

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13
Q

Calcium Hydroxide has a high pH, what 2 things can it be mixed with when used as an intracanal medicament?

A
  1. Sterile water (often done)
  2. Barium Sulphate → Radiopacity for radiographs
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14
Q

What are the 3 treatment options for REVERSIBLE Pulpitis?

A
  1. Indirect Pulp Capping (Stepwise excavation)
  2. Direct Pulp Capping (Remove stimulus)
  3. Remove stimulus and Dress tooth
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15
Q

What are the 3 main aims of RCT?

A
  1. Remove and destroy microorganisms from complex root canal systems
  2. Seal root canal system - prevent bacterial re-entry
  3. Give body an opportunity to heal
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16
Q

After obturation, what is placed below the canal orifice and below the coronal restoration?

A

IRM (ZOE)

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17
Q

What are 3 indications for RCT?

A
  1. Irreversibly damaged/necrotic pulp
  2. Elective devitalisation (provide space for a post in crowns)
  3. Dubious pulp prognosis prior to tooth preparation
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18
Q

What are 4 possible sealers used in RCT?

A
  1. Calcium Hydroxide - Also used as intra-canal medicament between appointments
  2. Zinc Oxide Eugenol
  3. Glass Ionomer
  4. Resin Sealers
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19
Q

What might a NARROW periodontal pocket be indicative of? (2)

How can you differenciate between the two?

A
  1. Periodontal/Endodontic Sinus Tract
  2. Cracked tooth

Differentiating - Cracked tooth:

  • No draining pus
  • Pain related to biting/release of pressure
  • Non-vital = “Halo” and “J-shape” radiolucency
  • Improved with Ortho band placement
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20
Q

How can safe irrigation be achieved? (5)

A
  • Use side venting needle
  • Never bind irrigation needle (continuous movement)
  • Irrigate slowly (avoid high pressure)
  • Never inject solution
  • 27 guage = 0.4mm diameter
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21
Q

Outline Canal Prep in RCT:

A
  1. Access cavity
  2. Irrigate (sodium hypochlorite)
  3. Explore canal orifices with DG16
  4. Find canals: Patency with size 10 K-Flex file
  5. Coronal prep (1/3rd - 2/3rd) with SX Rotary
  6. Explore apical 1/3rd and establish patency
  7. Determine WL (4)
  8. “Serial Step Back” - Increase file size to find Master Apical File (MAF) Usually Size 25! (The largest size file you can reach WL)
  9. “Step Back” - Create 5% Taper
  10. Circumferential smoothing of canal with size 20/25 file 1mm from WL

N.B. Between each stage, Irrigate and check patency

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22
Q

Name 3 histopathological features of CHRONIC Periapical Periodontitis

(HINT: 4 chronic inflammatory cells

A
  1. Chronic Inflammatory Cells
  • Lymphocytes (B & T Cells)
  • Plasma Cells
  • Fibroblasts
  • Macrophages
  1. (surrounded by) Granulomatous Tissue
  2. Epithelised OR Non-epithelised
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23
Q

Posts may be added for RETENTION. How is post retention increased?

A
  • Greater post length
  • Parallel sided post (vs. taper)
  • Rough surface
  • Threaded post (vs. self-threaded)

N.B. Posts do NOT improve fracture resistance!

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24
Q

Majority of pulpal infection is INTRA-radicular, what are 2 instances when the infection becomes EXTRA-radicular?

How do they differ in Treatment outcomes? (2)

A
  1. Alveolar Abscess (Micro or Dento-Alveolar)
  2. Radicular Cyst (Periapical True or Pocket Cysts)

They may be

  • Responsive to intra-canal treatment (abscess with drainage or pocket cyst)
  • Persistant, requiring periradicular surgery or XLA (cysts, particularly true cyst)
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25
Q

How can an Electronic Apex Locator be used to determine the working length?

Name 1 contraindicaion for its use…

What might cause incorrect readings (“Short Circuits”)? (4)

A
  • Place in canal till “Zero” reading
  • WL = 1mm from Zero reading

Contraindicated in Px with cardiac pacemakers

  1. Perforation
  2. Canal too moist
  3. Large lateral canal
  4. Contact with metal restoration
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26
Q

Name 2 materials used in pulp capping?

What do they do? (3)

A
  1. Calcium Hydroxide (setting)
  2. Mineral Trioxide Aggregate (MTA)
  • Bacteriostatic (Calcium Hydroxide also initially Bactericidal)
  • “Dentine bridge” formation - soft affected dentine arrested (hardens)
  • High pH → Neutralise low acid pH
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27
Q

Name 2 antibacterial irrigants, where one DOES dissolve organic tissue remnantas and one does NOT.

A

DOES = Sodium Hypochlorite (0.5-5.25%)

DOESN’T = Chlorhexidine (0.2-2%)

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28
Q

What are the 5 advantages/features of Rubber Dam use?

A
  1. Prevents inhalation/ingestion
  2. Prevents infection with saliva
  3. Enhances access and retracts soft tissues
  4. Better Px comfort
  5. Medico-legal requirement

N.B. Only ONE tooth isolated in endo

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29
Q

What is the “Ferrule Effect”?

A

The need to have enough sound tooth structure above the alveolar bone to minimise risk of tooth fracture after RCT when placing a crown.

Ferrule = metal band totally encircling tooth (think crown margin prep)

  • 2mm dentine parallel axial wall
  • Does NOT impinge on biological width
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30
Q

What % of patients will experience flare ups (to various severities) post-RCT?

How is this treated? (3)

A

3-5%

  • Painkillers
  • Re-access tooth
  • Drainage & Antibiotics
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31
Q

What are the recognisable signs/symptoms in the diagnosis of:

  1. REVERSIBLE Pulpitis?
  2. IRREVERSIBLE Pulpitis

(Pain type, Time lasting, Onset)

A

REVERSIBLE PULPITIS

  • Short, sharp pain (lasting seconds)
  • Provoked by hot/cold stimuli
  • Following recent restoration or signs of TSL visible

IRREVERSIBLE PULPITIS

  • Dull, throbbing pain (longer lasting, days - weeks)
  • Spontaneous onset - May be provoked by hot/cold or made worse on lying down
  • Following recent restoration or history of reversible pulpitits
  • Often hard to localise to specific tooth and may radiate to other areas (e.g. jaw, face, ear)
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32
Q

What are the 4 main Irrigants used in RCT and their concentrations?

Which is the main one used?

Which is often used as a final irrigant (smear layer removal) or to clear obturated (re-RCT) or sclerosed roots?

Which is used in therapy resistant cases?

A
  1. Sodium Hypochlorite (0.5-5.25% - Usually 2.5% & 3.5% used in clinics) - MAIN
  2. Chlorhexidine (0.2 - 2%)
  3. EDTA (Ethylenediaminetetraacetic Acid) (17%) - FINAL IRRIGANT (useful in smear layer removal or for sclerosed canals)
  4. Aq Iodine-based Compound (10%) - Used in therapy resistant cases as broad-spec antibacterial
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33
Q

How does the quantity and quality (type) of bacteria differ coronally and apically?

A

Coronal

  • MORE bacteria
  • Facultative anaerobes (these are also 1st microbes present)

Apical

  • Less bacteria
  • Obligate anaerobes (as O2 decreases)

Most bacterium present in Coronal 1/3rd, therefore “Crown Down” approach used

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34
Q

How does the smear layer influence dentine permeability?

Why is its presence good and bad?

How do we get rid of it?

A

Smear layer blocks dentine tubules → Reduced permeability

GOOD: Less pulpal communication → Inflammation (e.g. restorative material leakage)

BAD: Encourages microorganism activity

Removed via Acid-Etch

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35
Q

What are the 2 regulating bodies for Stainless Steel hand files?

To what measurements are their:

  • Cutting length
  • Full length
  • Instrument taper

regulated?

A
  1. ISO (International Organisation for Standardisation)
  2. ANSI (American National Standards Institute)
  • Cutting Length = 16mm
  • Full Length = 21, 25 or 31mm
  • FIXED Taper = 2% (0.02mm increase in diamter per 1mm increase length)
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36
Q

What are the 2 main types of abscess that can arise from Acute Periapical Periodontitis?

How do they differ?

A
  1. Micro Abscess = PMNs restricted to small area
  2. Dento-Alveolar Abscess = PMNs spread to engulf whole periapical region

The latter infection may then spread to local (Sinusitis) or distant (Cellulitis) regions of the body

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37
Q

What is the helical angle of SS Flexofile?

How does this differ to SS Reamers?

A

45°

Larger than reamers (10-30°)

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38
Q

In what circumstances should a Px be refered to maxfax?

A

Suspected Ludwig’s Angina

  • Pyrexia
  • Limited opening
  • Difficulty swallowing
  • Large swelling (around eye or midline under chin)
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39
Q

What is an alternative rotary file to SX?

What are its widths? How do these relate to widths of SX files?

A

Gates Glidden (also used to prep coronal 1/3rd - 2/3rd)

GG1 (50) = 1.5mm - same as SX D6

GG2 (70) = 1.3 - SX D7

GG3 (50) = 1.1 - SX D8

GG4 (110) = 0.9 - SX D9

GG5 (130) = 0.7

GG6 (150) = 0.5

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40
Q

What are 5 contra-indications for RCT?

A
  • Tooth cannot be restored/made functional
  • Insufficient periodontal support
  • Complex anatomy (e.g. dens in dente)
  • Uncooperative patient
  • Poor oral hygiene which cannot be improved
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41
Q

How do

  1. Pain symptoms
  2. Treatment

differ between a VITAL and NON-VITAL Cracked Tooth?

A

PAIN SYMPTOMS:

VITAL = Sharp pain on biting and release

NON-VITAL = Dull ache on biting

TREATMENT:

VITAL = Ortho/Cu band applied and Cuspal coverage restoration (e.g. crown)

NON-VITAL = XLA or consider hemi-section

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42
Q

What is the success rate of:

  1. Primary RCT?
  2. Secondary RCT?
A
  1. 85-95%
  2. 77-80%
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43
Q

What are the 4 requirements of post placement after RCT?

A
  1. No space between GP and Post
  2. Minimum 4-5mm GP
  3. Post length: 2/3rd root (or no less than crown height)
  4. Equal amount of post above and below alveolar crest
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44
Q

What are the main components (and their %) in MTA?

A

75% Portland Cement

20% Bismuth Oxide

5% Calcium Sulphate

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45
Q

What is the difference between rotary and hand files? (3)

A
  • Rotary files = Less tactile sensation
  • Hand files = FIXED taper (Stainless Steel = 2%)
  • Hand files = Stainless Steel (vs. SX Rotary = Nickel Titanium alloy)
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46
Q

Which type of hand file is used in size 10 for “Patency” ?

What are the 4 main aims of Patency?

A

K-Flex

  1. Prevents blockage
  2. Check if exudate present
  3. Helps maintain and follow anatomy
  4. Delivers irrigant apically
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47
Q

What are the 3 main types of Stainless Steel files?

What is the cross section of each?

Which is the most flexible?

Which is mainly used for RE-RCT (GP removal)?

Which is non-twisted?

Which has a non-cutting tip?

Which should be used with a Push-Pull motion ONLY?

A
  1. Flexofile - Square, Triangle, Square (see later Q)
  2. K-Flex - 2 cutting edges (parallelogram/diamond)
  3. Hedstrom - Speech bubble

Most flexible = Flexofile (duhh)

RE-RCT = Hedstrom

Non-twisted = Hedstrom (grounded)

Non-cutting tip = Flexofile

Push-Pull motion only = Hedstrom

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48
Q

How does the cross section of Flexofiles differ depending on file sizes?

A

Size 6-10 = SQUARE (Flexible)

15-40 = TRIANGLE

45-140 = SQUARE (Rigid)

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49
Q

What 2 irrigants should not be used together?

Which 2 irrigants should be used together? Why?

A

Chlorhexidine should NOT be used with Sodium Hypochrlorite

Aqueous Iodine-based Compound should be flushed with Sodium Hypochlorite after use to avoid brown discolouration

50
Q

What are the 3 main functions of Irrigants in RCT?

When should they be used?

A
  1. Remove debis
  2. Improve vision
  3. Lubricate the canal

2-3ml irrigation should be used following EVERY INSTRUMENT USE

51
Q

At what anatomical point should GP be seared off?

What 2 instruments can be used?

A

1mm below canal orifice

Heated instruments: Heat carrier then plugger OR System B

52
Q

What are the 4 main types of Apical Constriction?

A
  1. Single constriction
  2. Tapering constriction
  3. Multi-Construction
  4. Parallel constriction
53
Q

What should be done before each instrumental stage in RCT? (2)

A
  1. Irrigation
  2. Patency (Size 10 K-Flex file)
54
Q

When is patency established?

A

AFTER Prep of coronal 1/3rd - 2/3rd (using SX Rotary)

55
Q

What height of suprabony tooth structure is needed to deem a tooth restorable for endo?

What are 2 alternatives if this minimum height isnt met?

A

4mm (2mm Ferrule effect, 2mm Biological width)

  • Crown lengthening
  • Extract tooth
56
Q

In Mandibular 1st molars, what would you see that indicates there may be 2 distal canals?

A

Distal canal off centre (not in line with the mesial root/canal)

57
Q

What are 6 different types of Obturation techniques?

A
  1. Lateral Condensation (Cold or Warm)
  2. Vertical Condensation
  3. Thermo-Mechanical Compaction
  4. Thermo-Plasticized Gutta Percha (using Injection guns)
  5. Carrier-Based
  6. Barrier

“Single Cone” Technique = NOT recommended

58
Q

What are 4 ways the working length can be determined?

A
  1. Electronic Apex Locator
  2. WL Radiograph
  3. Paper Points
  4. Tactile Sensation
59
Q

Outline steps in Cold Lateral Condensation…

A
  • Select Finger Spreader A or B (loose in canal to WL, usually A)
  • Fit Master GP (Largest size GP that fits to working length)
  • Dry canal with paper points
  • Coat MGP tip with sealer and add to WL
  • Place Finger Spreader in canal - 1mm AWAY from WL
  • Add corresponding accessory points (A or B) at 1mm from WL
  • Mid-fill radiograph after 2/3 accessory points
  • Add additional accessory points till canal filled
  • Sear off GP to 1mm below canal orifices using: Heated carrier then plugger OR System B
60
Q

What are 7 indications for Pulp capping?

(Hint: Think clinically)

A
  • No recurring or spontaneous pain
  • No swelling
  • Tooth not TTP
  • Sensibility and Vitality Test +ive
  • Radiographs: No evidence of periradicular pathology and obvious pulp chamber/RC’s present
  • Pink pulp - bleeding on touch (but not excessive)
  • Younger Px
61
Q

Why is sodium hypochlorite a good RCT irrigant? (2)

A
  • Anti-bacterial
  • Dissolves organic tissue remnants
62
Q

What is meant by “Exudate”?

A

The bacterial nutrient supply

63
Q

Are microorganisms present within the root canal or the periapical lesion?

A

In the root canal

Periapical lesion = Apical Inflammatory lesion acting as 1st line of defence against invading microorganisms

64
Q

What is meant by “Serial Step Back”?

A

Increase in file size from 10 (patency) → MAF (usually 25)

Master Apical File (MAF) = Largest file size that reaches WL with tugback (usualy size 25)

65
Q

How can a radiograph be used to determine the WL?

What is the minimum file size for WL radiographs?

A
  • Pre-op radiograph: Estimated WL 1mm from apex OR use EAL
  • Size 15 file placed at Estimated WL and WL radiograph taken
  • WL adjusted as necessary, if OVER 3mm from radiographical apex, another radiograph is needed

Minimum file for WL radigraph = 15 !!!

66
Q

What are the 2 main states bacteria survive in?

Which is the most resistant to RCT?

A
  1. Planktonic State - Free floating microorganisms (single cell or clumped) which are unattached to the surface
  2. Biofilm - Bacteria cells in layers, attached to surfaces via extracellular polymer

BIOFILM = Most resistant to RCT

67
Q

What are the 4 main ways pulpitis can be classified?

A
  1. Reversible Vs. Irreversible
  2. Acute Vs. Chronic
  3. Partial Vs. Total
  4. Open Vs. Closed
68
Q

What are the access cavity shapes for all upper and lower teeth?

A

MAXILLARY:

Incisors = Triangular

Canines = Ovoid

Pre-molars = Ovoid (bucco-palatally)

Molars = Triangle (base bucally and apex palatally, covering mesial 2/3rd occlusal surface and avoiding oblique ridge)

MANDIBULAR:

Incisors = Triangular

Canines = Ovoid

Pre-molars = Ovoid (bucco-palatally)

1st Molars = Trapezoid (mesial 2/3rd occlusal surface)

2nd Molars = Trapezoid/Triangular (mesial 2/3rd occlusal surface)

69
Q

What are the 2 main type of hand file motions?

Which files require which type of motion?

A
  1. Rotational - “Watch Winding” or “Balanced Force”
  2. Push-Pull

Flexofiles and K-flex use BOTH. Hedstrom use push-pull only

Push-Pull

  • Mainly used in refining rather than preparation (use in prep with Flexofile/K-Flex → Zip or Elbow formation)
  • Short amplitude (1-2mm)
  • Risk of apical debris blockaging
70
Q

What differing results would you see between a Peridontal Pocket and ENDODONTIC Sinus Tract for the following special investigations:

  1. Sensibility Testing?
  2. Periodontal Probing?
  3. Caries present?
  4. Periodontal condition?
A
71
Q

What are some non-odontogenic causes of pain which mimic acute odontogenic pain?

A
  • TMJD
  • Bruxism
  • Cluster Headache
  • Trigeminal Neuralgia
  • Glossopharyngeal Neuralgia
  • Allergic or Bacterial Sinusitis
  • Herpes Zoster
  • Temporal arthritis
  • Atypical odontalgia
  • Idopathic facial pain
  • Burning mouth syndrome
72
Q

What 2 microorganisms exist in both primary and secondary necrotic pulp (e.g. after failed RCT)?

A
  • Yeasts (Candida albicans)
  • Extra-oral Enterococcus faecalis
73
Q

What is meant by “STEP BACK”?

How is it achieved? (explain file sizes)

A

Process of creating a 5% canal taper (to follow canal anatomy and shape). This is carried out after MAF is chosen (usually size 25).

Incremental increase in file size each 1mm up the canal (beginning at WL)

Size increase 25-60 = 0.5mm diameter each 1mm

(25,30,35,40,45…)

After 60, size file increased per 2mm up canal

(60,70,80…) due to 1mm diameter increas e between sizes

74
Q

What 2 main hard tissue changes would you expect to see in tooth with infected pulp?

A
  1. Pulp calcification - Reactionary dentine (mild stimuli) and Reparative dentine (noxious stimuli)
  2. Internal (dentine) resorption → Pink spot and Punched out lesion
75
Q

Name A-F:

A

A = Apex

B = Apical Constriction (0-2mm from Anatomical Apex)

C = Root Canal

D = Cementum

E = Dentine

F = Apical Foramen (Diameter = 0.3-0.6nm)

76
Q

In maxillary 1st molar, which root is most likely to have TWO canals?

What is the % likelihood of this?

A

Mesiobuccal root (“MB2”) - Usually indicated by a groove in the MB pulp chamber horns

71-93% chance!

77
Q

What may happen in the incident of Sodium Hypochlorite “accident” during irrigation? (4)

How can this be avoided?

What is the treatment?

A

Severe pain, Tissue swelling, Tissue blanching and Bloody exudate from the tooth (BECAUSE SODIUM HYPOCHLORITE DISSOLVES ORGANIC TISSUE REMNANTS)

Avoided by safe irrigation and rubber dam isolation (Sodium hypochlorite dissolves organic tissue remnants)

Treatment: Irrigate with sterile water, reassure patient and immediate MaxFax referal

78
Q

What is the difference between Direct Pulp Capping and Cvek’s Partial Pulpotomy?

(HINT: Process and Materials used)

A

Direct Pulp Capping = Only SMALL amount of vital pulp exposed on symptom-free tooth. Direct cap with Calcium Hydroxide (setting) or MTA

Partial Pulpotomy = PARTIAL removal of pulp: Only Coronal pulp removed (1-3mm), preserving vitality of remaining radicular pulp. 15.5% Ferric Sulphate applied to pulp to achieve pulp haemostasis and lined with GIC or IRM/ZOE

79
Q

At what distance from the pulp must bacterium penetrate to induce IRREVERSABLE pulpal damage?

What is the treatment?

A

Penetration within 0.5mm to pulp → Pulpal necrosis and periradicular radiolucency

TREATMENT = RCT or XLA

80
Q

What are 5 advantages of Calcium Hydroxide as material in pulp capping?

A
  1. Cheap and Easy to use
  2. Promotes healing and repair
  3. Initially Bactericidal, then Bacteriostatic
  4. High pH → Stimulates fibroblasts and neutralises low pH of acids
  5. Stops internal resorption
81
Q

What are the 2 main criteria of Master GP?

Is it always the same as Master Apical File?

A
  1. Largest GP
  2. That fits to WL (with tug back)

NO, so try the size above MAF first and reduce if it doesn’t reach WL…

Less accuracy might mean u have to try different files (of same size) or cut off tip

82
Q

Why is Straight Line Access important? (3)

A
  • Less file curvature
  • Improved tactile sensation
  • Deliver greater volume of irrigant
83
Q

What is the 1 biological aim of RCT?

What are the 4 mechanical aims of RCT?

A

BIOLOGICAL:

Elminate all pulpal tissues, bacteria and related irrigants from the root canal system

MECHANICAL:

  1. Produce a continuously tapered preparation
  2. Maintain original anatomy and position
  3. Seal root canal to prevent bacterial re-entry coronally
  4. Keep apical foramen as small as possible and avoid its movement
84
Q

What different investigations can be carried out to diagnose endodontic pain?

A

MECHANICAL

  • Palpation
  • TTP?
  • Periodontal probing (Wide pocket = Perio problem, Narrow pocket = Sinus or Cracked tooth)

THERMAL (SENSIBILITY)

  • EndoFrost (-50ºC)
  • Heated Gutta Percha

ELECTRIC (VITALITY)

  • Electric pulp tester → A-delta fibres

RADIOGRAPHS

  • PA’s
85
Q

What is the “Crown-Down” Approach?

Why do we do this? (2)

A

Idea of coronal preparation first in RCT

Why?

  1. More necrotic bacteria found coronally
  2. Helps achieve Straight Line Access

SLA important to:

  • Reduce curvature
  • Improve tactile sensation
  • Deliver greater volume of irrigant
86
Q

What are the 4 main aims of obturation?

A
  1. Prevent microorganisms and their toxins penetrating peri-radicular tissues
  2. Seak remaining bacterial in canal environment thay CANNOT thrive
  3. Prevent penetration of peri-radicular exudate (bacterial nutrient supply) into the root canal space
  4. Prevent re-infection of root canal system from coronal aspect (more bacteria)
87
Q

What are the 3 main aetiologies (causes) of Acute Periapical Periodontitis?

A
  1. Infection → Pulp necrosis
  2. Acute exacerbation of Chronic Periapical Periodontitis
  3. Inflammatory response to Irritants (e.g. acid/alkali irritants or irritiants from incomplete cured restorative material) in HEALTHY periapical tissues
88
Q

What should we assess in:

  1. Immediate Post-operative radiograph? (3)
  2. Later Post-operative radiograph (RCT outcome)? (1 + extra)
A

IMMEDIATE

  • Obturation (canal filled) to WL
  • No voids
  • Adequate taper (5%)

LATER

  • Normal OR healing peri-radicular tissue (if previous lesion present)
  • Should also assess Px symptoms and any signs of swelling or sinus’*
89
Q

What is the favourable method of cleaning:

  1. Main canals?
  2. Lateral canals or fins?
A
  1. Mechanical (files)
  2. Chemical (irrigants)
90
Q

If bacterial penetration is between 1.1-0.5mm from the pulp, what does this result in? How is this treated?

A

Reversible damage to pulp

TREATMENT = Removal of dental caries, pulp capping (Calcium hydroxide or MTA) and appropriate restoration placement

91
Q

When do we use:

  1. NON-SETTING CaOH? (2)
  2. SETTING CaOH? (2)
A
  1. Apexification (Immature teeth) or Intracanal Medicament (between appts)
  2. Direct Pulp capping or Canal Liner
92
Q

You see a Halo and J-shaped radiolucent lesion surrounding root - What is this?

A

NON-VITAL Cracked Tooth

93
Q

What are the ideal properties of a RCT Sealer?

A
  • Good adhesion to canal walls
  • Adequate working time
  • Expand on setting
  • Same as filling material: Bicompatible, Removable, Radiopaque, Bacteriostatic, Impervious to moisture & Non-staining
94
Q

What are 3 advantages of exposing pulp (e.g. in direct pulp capping or Cvek’s partial pulpotomy) over INDIRECT pulp capping?

A
  1. Reduced potentiaal of dentine chips entering pulp → Inflammation
  2. Superficially contaminated pulp tissue removed
  3. Good contact between pulp and capping agent
95
Q

What is the “Biological Width”?

A

Dimention of soft tissue extending from site attaching to tooth → Crest of alveolar bone (usually 2mm)

96
Q

“PEPPSEY”

Name the microorganisms commonly found in necrotic pulp

A

Prevotella

Eubacterium

Porphyromonus

Peptostreptococcus

Streptococcus

Enterococcus faecalis (Extraoral)

Yeasts (Candida albicans)

97
Q

What files are made from Nickel Titanium alloy and which are made from Stainless Steel?

Name 4 differences…

A

NiTi

  • SX Rotary file

Stainless Steel

  • Flexofile
  • K-Flex
  • Hedstrom

NiTi…

  1. More flexible (so use in curved canals)
  2. Built in taper (SX) - vs. 2% fixed on SS
  3. Dont stay sharp for as long as SS
  4. Not applicable in all cases, SS hand file still needs to be used at beginning of prep
98
Q

Outline some endodontic armamentarium…

A
  • Access burs (including safe ended diamond)
  • Mirrors, Light & Magnification
  • Escavator (any caries removal)
  • DG16 Explorer (16mm straight probe to identify canal orificies)
  • Goose Neck bur
  • LN burs
  • Ultrasonics
  • Protaper Rotary Files (SX or Gates Glidden)
  • Stainless Steel Hand Files (Flexofile, K-Flex or Hedstrom
99
Q

Explain the process of Step-Wise Excavation procedure in relation to Indirect Pulp capping?

A
  • Remove caries BUT leave thin layer of residual (affected) dentine (in which we aim to arrest)
  • Apply capping material: Calcium Hydroxide or Mineral Trioxide Aggregate (MTA)
  • Add Temporary restoration (e.g. GIC or IRM/ZOE)
  • Leave 6-8 weeks
  • Re-open cavity (remove temp filling) and assess residual dentine has been arrested. If happy (clinically & radiographically) apply more capping agent if needed and seal with definative restoration
100
Q

Bacterial infection is the main cause of Pulpitis - What are 6 possible routes of infection?

What are 2 alternatives to a bacterial aetiology?

A
  1. Dental caries (+/- restorative procedure - microleakage)
  2. TSL: Attrition, Erosion, Abrasion or Abfraction
  3. Chronic Periodontal disease (via Lateral canals)
  4. Trauma → Cracks
  5. Anachoresis (RARE, blood-borne microbes)
  6. Root Resorption

ALTERNATIVES:

  1. Chemical (e.g. Acid/Alkali irritants, Filling materials or Acrylics)
  2. Thermal (e.g. During Cavity prep or Large metallic restorations)
101
Q

Regarding endo files, what is meant by:

  1. Helical Angle?
  2. Pitch?
A
  1. HELICAL ANGLE = The angle of cutting flutes to the long axis of the instrument
  2. PITCH = The number of cutting flutes per mm
102
Q

How can

  1. Ledges
  2. Dentine/Debris blockages

be removed/avoided?

A
  1. Pre-curve Size 10 K-flex file (engage ledge) or Good Coronal flare
  2. Copious irrigation or Light picking with small file
103
Q

What are the 2 types of “Rotational” hand file movement?

How do they differ? Which is best?

A

“Watch Winding” = BEST

Back & forth clockwise/anti-clockwise movement with light apical pressure.
“An arc of 30-60° whilst advancing into the root canal with light apical pressure”

“Balanced Forces”

Instrument centrally placed → Inserted into canal till binds → Clockwise rotation 60-90° → Anticlockwise 120-180° with apical pressure (crushes off dentine threads and enlarges canal) →Clockwise rotation 60-90° (loads flutes with debris for removal)

104
Q

What should be placed inside the tooth between RCT appointments? (3)

A

(Paper points used 1st to dry canal)

  • Non-setting Calcium Hydroxide
  • Cotton Pleget or Grey cavit G (prevents temp restoration going down canal)
  • Temp restoration coronally: IRM or GIC
105
Q

MGP should have tug-back when placed, is this achieved in a dry or wet canal?

A

Wet

BUT Obturation should only take place in DRY CANAL!

106
Q

Where does the rich neural/vascular supply enter the pulp and terminate?

What type of neural fibres are present? (which is main)

A

Enter via: Apical foramen and Lateral canals

Terminate: Between odontoblasts

Nerve fibres present: (Myelinated and Unmyelinated) A (beta and delta) & C fibres

MAIN = A (beta and delta) fibres

107
Q

What are 5 advantages of Mineral Trioxide Aggregate (MTA) in pulp capping?

A
  1. High pH → Neutralises low acid pH
  2. Bacteriostatic
  3. Forms HA/Carbonated apatite on MTA surface → Effective seal
  4. High compressive strength (40 MPa)
  5. Modulates cytokine production
108
Q

When are K-Flex files used in a push-pull motion?

Why are they NOT always used in this motion? What motion should we use?

A

Only for refining

Because they have cutting edges → Formation of Zips & Elbows

Best to use = Rotational (Watch winding)

109
Q

What are the ideal properties of a RCT filling material?

What do we use?

A
  • Complete canal seal
  • Dimentionally stable
  • Impervious to moisture
  • Bicompatible - Non-irritant to peri-radicular tissues
  • Non-staining
  • Bacteriostatic
  • Radiopaque
  • Removable!
  • Long shelf life

We use Gutta Percha (trans-polyisoprene isomer of Natural Rubber, so allergy tests needed on Px with Latex allergies)

110
Q

What are the 5 main principles behind coronal access cavities (using SX rotary file)?

A
  1. Remove entire pulp chamber roof → Visualisation
  2. Allow inspection of entire pulp chamber and remove entire pulp chamber contents
  3. Gain straight line access to 1st curve of root canals
  4. Covergent walls apically (retains temp dressing)
  5. Minimally invasive
111
Q

What are 5 disadvantages of MTA in pulp capping?

A
  1. EXPENSIVE!
  2. Long setting time (4 hours)
  3. Difficult handling
  4. Toxicity potential
  5. Discolouration potential (not good in anterior teeth)
112
Q

What radiograph should be used to assess Endodontic pathology?

What are 6 things we can see on this?

A

Periapical radiograph

  • Bone levels
  • Caries
  • Existing restorations and deficiencies
  • Root morphology (e.g. narrow or curved)
  • Sclerosed root canals
  • Apical or peri-radicular radiolucencies - Including “J-shaped” radiolucency characteristic of non-vital cracked tooth
113
Q

What are 4 disadvantages of Calcium Hydroxide use in pulp capping?

A
  1. Doesnt adhere to dentine or resin restoration
  2. Low compressive strength (20 MPa, vs. 40 on MTA)
  3. May degrade on acid-etch or tooth flexure (“cavosurface dissolution”)
  4. Does NOT exclusively stimulate dentinogenesis and reparative dentine formation
114
Q

What is meant by:

  1. PULPOTOMY?
  2. PULPECTOMY?
A

PULPTOMY (“PULP AMPUTATION”)

Part of inflammed pulp removed → Arrest bleeding → Cover with CaOH → Restore and monitor (remaining pulp preserved)

PULPECTOMY

Total pulp removal followed by RCT

115
Q

What motion (2) should be used for all Stainless Steel hand files?

Which file is the exception and what motion is used with it?

A
  • Rotational
  • Push-Pull

HEDSTROM = Exception, Push-Pull only

116
Q

What is the difference between:

  1. REACTIONARY
  2. REPARATIVE

Dentinogenesis?

A
  1. REACTIONARY DENTINOGENESIS = Odontoblast response to MILD Injury. Tertiary dentine formed at Dentine-Pulp interface → Reduced pulpal volume
  2. REPARATIVE DENTINOGENESIS = Odontoblast-LIKE cell response to EXTENSIVE Injury. Odontoblast death (leaving empty tracts), replaced with Odontoblast-like pulpal progenitor cells → Eburnoid (thin layer of hyaline calcified tissue)
117
Q

How do you assess a tooth for restorability prior to endodontic treatment? (2)

A
  1. Ferrule Effect (2mm dentine parallel axial wall NOT impinging on biological width)
  2. Biological Width (soft tissue extending from site attached to tooth → alveolar bone crest, usually 2mm)

Enough height needed above bone (Biological width + Ferrule effect)

May need to consider Crown Lengthening

118
Q

What tissue/cells are present within the pulp? (5)

A
  1. Neural & Vascular supply
  2. Loose CT (Type I,III and IV Collagen)
  3. Odontoblasts
  4. Progenitor cells → Reparative Eburnoid layer
  5. Inflammatory cells (T lymphocytes, Macrophages and Dendritic Antigen-presenting cells)
119
Q

What type of CaOH (setting/non-setting) is used for:

  1. Direct pulp capping?
  2. Indirect pulp capping?
  3. Cvek’s (partial) Pulpotomy?
  4. Conventional Pulpotomy?
  5. Pulpectomy?
  6. Apexogenesis?
  7. Apexification?

What are 2 other uses of CaOH in endo?

A
  1. Setting
  2. Setting
  3. BOTH (Non-setting first → then Setting CaOH and GIC → Then Composite restoration)
  4. None (15.5% Ferric sulphate)
  5. Non-setting
  6. TRICK Q (Apexogenesis = Pulp therapy on a immature permanent tooth and can include all of 1-4)
  7. Non-setting

Sealer or Intra-canal Medicament

120
Q

What are 4 Intra-canal Medicaments?

A
  1. Non-setting CaOH
  2. Ledermix
  3. Antibiotics
  4. Iodine Potassium Iodide
121
Q

What is the function of an intra-canal medicament?

A

To remove all remaining bacteria after canal instrumentation and irrigation

Ideally: Anti-bacterial and Anti-inflammatory

BDS3 (7 decks)

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