Endo Flashcards
How do you assess a RCT?
Clinically assess- coronal seal, ferrule, swelling/ sinus/ TTP/ mobility/ increased pocketing
Radiographically assess- length and quality of obturation (within 2mm apex, well condensed), bone support, radiolucency.
What is the ideal crown to root ratio?
1:1.5
List some problems post RCT?
Amount of remaining tooth structure
Wide post holes
Endo complications (fractured instruments, perforations, short/ long root fillings)
Coronal micro leakage
How long should an unrestored RCT be left until it needs to be re-root treated?
3 months
What is a post/ core?
Core provides retention for crown, post retains the core (does NOT strengthen/ reinforce the teeth)
What are some indications for post placement?
Incisors/ canines/ widest canal in premolar
4-5mm root filling apically to post
No more 1/3 of root width at narrowest point, 1mm coronal dentine
Sufficient alveolar bone support (half of post length)
Minimum 1:1 post length/ crown length ratio
1.5mm ferrule (height and width of coronal dentine)
What are contraindications of post placement?
Mandibular incisors (thin/ tapering/ narrow mesiodistal roots)
Posterior tooth
Curved canals (perforations)
Insufficient ferrule
What is ferrule?
Encirclement of 1-2mm dentine above gingival level
Describe the qualities of an ideal post design
Parallel sided post (avoids wedging, causing fracture)
Non-threaded (smooth, incorporates less stress to remaining tooth)
Cement retained - buffer between masticatory forces and post/tooth
What are the material options for a post?
Cast metal/ Stainless steel - poor aesthetics, root fracture, corrosion
Zirconia - high flexoras strength/ fracture toughness, difficult retrievability and root fracture common
Carbon/ glass fibre - flex the same as dentine, aesthetic, retrievable, bond to dentine with DBAs.
Describe the process of prefabricated post placement?
No impressions/ lab visit required - 1 appt
Chairside core build-up
Post and core in different materials
Describe the placement of custom posts?
Indirect pattern fabricated from impression of post hole and wax up of post and core in lab /
Casts from direct pattern fabricated in patients mouth (Duralay)
2 appts - impression and fit (temporise between- risk of root canal contamination)
Cast post made in Type IV heat hardened gold
Irrigate canal with chlorohexidine 0.2%, dry with paper points.
Place cement, use firm apical pressure, remove excess cement.
What is a core build up?
The internal part of the tooth built up with restorative material to replace lost tooth tissue (provides retention and resistance for definitive restorations).
What are the material options for core build up?
Composite (used with fibre post)
Amalgam (needs 24 hours to fully set, avoid as retention is required)
Glass ionomer (absorbs water and core expands in size-not used)
What is a Nayara core?
Root treatment is removed, amalgam packed into the canals and tooth is built up (provides retention).
Cannot be prepared until amalgam fully set (24 hours)
How is gusta percha removed?
Soften GP (heat/ solvent)
Gates glidden to minimum size 3 (straight part of canal) - use WL and rubber stopper on gates glidden
Leave 3-5mm GP in apical third
Check GP plug remains
What are some problems with post crowns?
Perforations
Core fracture
Root fracture/ crack
Post fracture
If repeated de-bonding of crown- suspect root fracture.
Long single pocket- suspect vertical fracture
How long does it take to assess healing of a RCT?
4 years
What are the requirements for post design (length etc)
Length should be 1:1 to crown height
4-5 mm GP should be left apically
Post should not pass beyond curvature of root
Width of post should not be more than q/3 root width at narrowest part
What is used as an inter appt medicament in Endodontic treatment?
Non-setting calcium hydroxide
Antimicrobial (high pH)
Hydrolyses LPS (anti-inflammatory)
Effective at removing tissue debris
Easy to remove
Alkaline pH encourages tertiary dentine formation
What is the purpose of obturation?
Produces an apical and lateral seal to prevent microorganism ingress, seals in any microorganisms and prevents reinfect ion
Creates an environment to allow healing
What is working length?
Estimated- measured from coronal reference point to apex (on radiograph) and subtract 1mm
Corrected- length irrigation and obturación should be completed to (measured using apex locator)
What is a patency file?
Small and flexible file used to clear the apical foramen (use size 10 K file)
What is the master apical file?
The largest file taken to working length (use this size of GP)
What material can be used as a pulp cap/ apical plug/ to plug perforations?
MTA - best for apical plug and perforations as requires moisture to set (pdl)
Bio dentine- sets more rapidly so can be used for director pulp cap, encourages bone formation due to high pH
What is GP made of?
Rubber
Zinc oxide
Resin
Barium sulphate (radiopaque)
What is the purpose of irrigation?
Dissolves organic debris
Disinfects canal
Lubricantes canal
Removes debris from prep
Which materials are used for irrigation?
Sodium hypochlorite 3% - used for 10 mins to dissolve organic debris, antimicrobiano action
EDTA (17%) - used for 1 min to remove smear layer (created during prep)
What is the purpose of cold lateral compression?
Seals gaps between GP points
Seals lateral canals
Seals gaps between dentine and core
What are Herb Schilder’s endo principles?
- clean and shape canal using mechanical and chemical irrigation
- smooth, tapered, continuously flaring canal
- maintain position of apical foramen
