Endodontics Flashcards
What is the difference between:
- Step Back
- Serial Step Back
In canal preparation?
Which comes first?
Serial Step Back is first!
- Serial Step Back = Increase in size 10 patency file → MAF (usually size 25) - File thickness increases but length (WL) remains the same!
- Step Back = Incremental increase in file size and reduction in length to create 5% canal taper
What is meant by “Internal Resorption”?
What are 2 clinical signs?
Dentine resorption by dentinoclasts/odontoclasts stimulated by pulpal inflammation
- “Pink spot” on tooth
- Punched out lesion continous with pulp cavity
What area of RCT prep are SX files used for?
Outline some of their features (material, length, motion)?
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
Why are RCT teeth weaker? (4)
How is this issue addressed?
- Loss of tooth structure
- Loss of proprioception
- Loss of pulp roof → Cuspal flexure more prone to fracture
- Wider isthmus and Loss of marginal ridge
Add Core or Crown tooth (cuspal coverage)
What is the main cause of RCT failure?
How can this be avoided? (3)
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
What is pulp capping?
What are the two main types?
Pulp capping = Process of protecting pulp from injury or necrosis after being exposed or nearly exposed during cavity prep
- Direct - Exposed pulp directly covered
- Indirect - Pulp NOT exposed (thin layer of residually mineralised/sound dentine left)
What is meant by “Hyperplastic Pulp”?
What are the 2 treatment options?
“Pulp Polyp”
Form of irreversible pulpitis due to proliferation of chronically inflammed young pulp tissue
Treatment: RCT (Pulpotomy/Pulpectomy) or XLA
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?
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”
Is cracked tooth easy or hard to localise?
What tooth is most commonly affected?
HARD!
Mandibular 7s
What are 4 histopathological features of Acute Pulpitis?
- 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)
How do we treat RCT perforations?
Immediate repair with GIC or MTA
MTA only used when repair site enclosed in bone (no oral cavity contact with saliva)
Calcium Hydroxide has a high pH, what 2 things can it be mixed with when used as an intracanal medicament?
- Sterile water (often done)
- Barium Sulphate → Radiopacity for radiographs
What are the 3 treatment options for REVERSIBLE Pulpitis?
- Indirect Pulp Capping (Stepwise excavation)
- Direct Pulp Capping (Remove stimulus)
- Remove stimulus and Dress tooth
What are the 3 main aims of RCT?
- Remove and destroy microorganisms from complex root canal systems
- Seal root canal system - prevent bacterial re-entry
- Give body an opportunity to heal
After obturation, what is placed below the canal orifice and below the coronal restoration?
IRM (ZOE)
What are 3 indications for RCT?
- Irreversibly damaged/necrotic pulp
- Elective devitalisation (provide space for a post in crowns)
- Dubious pulp prognosis prior to tooth preparation
What are 4 possible sealers used in RCT?
- Calcium Hydroxide - Also used as intra-canal medicament between appointments
- Zinc Oxide Eugenol
- Glass Ionomer
- Resin Sealers
What might a NARROW periodontal pocket be indicative of? (2)
How can you differenciate between the two?
- Periodontal/Endodontic Sinus Tract
- 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
How can safe irrigation be achieved? (5)
- Use side venting needle
- Never bind irrigation needle (continuous movement)
- Irrigate slowly (avoid high pressure)
- Never inject solution
- 27 guage = 0.4mm diameter
Outline Canal Prep in RCT:
- Access cavity
- Irrigate (sodium hypochlorite)
- Explore canal orifices with DG16
- Find canals: Patency with size 10 K-Flex file
- Coronal prep (1/3rd - 2/3rd) with SX Rotary
- Explore apical 1/3rd and establish patency
- Determine WL (4)
- “Serial Step Back” - Increase file size to find Master Apical File (MAF) Usually Size 25! (The largest size file you can reach WL)
- “Step Back” - Create 5% Taper
- Circumferential smoothing of canal with size 20/25 file 1mm from WL
N.B. Between each stage, Irrigate and check patency
Name 3 histopathological features of CHRONIC Periapical Periodontitis
(HINT: 4 chronic inflammatory cells
- Chronic Inflammatory Cells
- Lymphocytes (B & T Cells)
- Plasma Cells
- Fibroblasts
- Macrophages
- (surrounded by) Granulomatous Tissue
- Epithelised OR Non-epithelised
Posts may be added for RETENTION. How is post retention increased?
- Greater post length
- Parallel sided post (vs. taper)
- Rough surface
- Threaded post (vs. self-threaded)
N.B. Posts do NOT improve fracture resistance!
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)
- Alveolar Abscess (Micro or Dento-Alveolar)
- 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)
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)
- Place in canal till “Zero” reading
- WL = 1mm from Zero reading
Contraindicated in Px with cardiac pacemakers
- Perforation
- Canal too moist
- Large lateral canal
- Contact with metal restoration


