ETT 2 Flashcards
Principles of Post-Core Systems?
- Conservation of tooth structure
- Anatomic considerations
- Retention form
What happens if you remove too much tooth structure during post-space preparation?
Weaken root which may fracture during cementation of post or subsequent function
Difficulty in conserving tooth structure?
- Hard to enlarge root canal uniformly
- Hard to judge how much tooth structure has been removed
- Most roots are narrower mesiodistally than buccolingual
- Many roots have proximal concavities that cannot be seen in standard PA radiographs
Anatomic Considerations in **Maxillary **Roots of CENTRAL/LATERAL INCISORS?
- Sufficient volume and length
- Root tapers to apex
Anatomic Considerations in Maxillary Roots of CANINES?
- Oval canal bucco-lingually
- Flattened mesio-distally
Anatomic Considerations in Maxillary Roots of FIRST PREMOLARS?
Thin and tapering towards apex
1 root: 43%
33% Apical bifurcation
2 roots: 22%
3 roots: 2%
Anatomic Considerations in Maxillary Roots of SECOND PREMOLARS?
Less intricate compared to 1st premoalrs
1 root: 90%
8% Apical bifurcation
2 roots: 2%
Anatomic Considerations in Maxillary Roots of MOLARS?
Palatal root is the most suitable
85% palatal roots curved in buccal direction
Anatomic Considerations in Mandibular Roots of CENTRAL/LATERAL INCISORS?
Small diameter
Anatomic Considerations in Mandibular Roots of CANINES?
Proximal root invaginations (Same as maxillary)
Anatomic Considerations in Mandibular Roots of PREMOLARS?
Have sufficient bulk for standard-sized posts
Anatomic Considerations in Mandibular Roots of MOLARS?
Distal root straight and wide buccolingually
Mesial concavity 0.5mm in depth
Retention Form in Anterior Teeth?
Long posts with circular cross section
Retention Form in Posterior Teeth?
NO Long posts due to curved roots and elliptical canals
Two or more short posts in divergent canals
Sometimes Nayyar’s technique
Describe Nayyar’s Technique
A coronal-radicular dowel and core technique for endodontically-treated posterior teeth whereby amalgam is condensed 2-4mm into each canal, pulp chamber and coronal portion of tooth.
Natural divergence of canals and undercuts in pulp chamber provide excellent retention.
Amalgam offers resistance to horizontal and vertical forces.
Criteria for Nayyar’s Technique?
- Size of remaining pulp chamber must be sufficient width and depth to provide adequate bulk of amalgam and retention
- Adequate dentine thickness in area of pulp chamber required for rigidity and strength
Steps to Nayyar’s Technique?
- GP removed by heated instrument 2-4mm into each canal
- Gates Glidden burs increase diameter of canals
- Remove unsupported enamel
- Check that cavity preparation has resistance and outline form
- Place matrix band
- Condense amalgam into preparation
- Remove matrix band then carve anatomic form of tooth
- Crown delivery
Post-space Preparation
- Apical 2-3mm of post space allow for snug fit of selected final post
- Coronal seal and fit of core material
What should you do if you do not have past records of the reference point and working length?
- Past PA radiographs
- Clinical crown height
What happens after Post-space Preparation?
- Trial seating and adjustment of post
- Refinement of coronal tooth structure
- Place core material
- Definitive cementation of metal post
Lentulo-spirals are used for?
Inserting glass ionomer cement into canal
NOT for resin cements
What cements are used for provisional cementation?
Zinc polycarboxylate and ZOE cement
RMGIC is contraindicated in?
- Non-vital teeth because expansion due to water sorption may induce root fracture
- All-ceramic feldspathic type restorations
What cements are used for definitive cementation of posts?
- Zn phosphate
- GIC
- Resin cemenet
How to do core build-up?
- Matrix band
- Composite resin or Amalgam
- Adhere to OD principles
What drills to use for fibre post?
DT Light drills
What drills to use for metal post?
Parapost drills
