Restoration of the endodontically restored tooth Flashcards
Clinical Assessment:
Evaluate coronal seal for leakage, caries, existing restorations/crowns.
Assess remaining tooth structure (ferrule presence).
Check restorability (can it be isolated with rubber dam?).
Look for swelling, sinus tract, TTP, tenderness in buccal sulcus, mobility, periodontal pocketing.
Radiographic Assessment:
Root filling: Assess length, quality, presence of voids.
Identify missed/unfilled canals, canal shape, patency issues (fractured instruments, posts, sclerosis).
Evaluate bone support (mild, moderate, severe) and crown-to-root ratio (ideal 1:1.5).
Detect pathology (periapical radiolucencies, resorption, perforations).
Inadequate root fillings should be re-treated before restoration.
Challenges After RCT/Re-RCT:
Limited remaining tooth structure (internally and externally).
Wide post holes from previous treatment.
Endodontic complications (fractured instruments, perforations, poor obturation).
Properties of RCT Teeth:
Are RCT teeth brittle? No! Dentine hardness remains unchanged.
Are they more prone to fracture? No, unless excessive dentine loss occurs.
Does dehydration weaken them? No, it does not affect dentine strength/toughness.
Microleakage Issues:
Oral microorganisms can invade the root canal system.
Major cause of RCT failure, especially in multi-rooted teeth.
If left unrestored for >3 months, retreatment is needed.
Preventative measures: Trim GP to AC, place RMGI lining over pulp floor/root canal openings.
Key conclusion: Coronal restoration quality is more important for periapical health than RCT quality.
Anterior Tooth Restoration Options
Intact marginal ridges:
Composite restoration (or veneer if discoloured).
Anterior Tooth Restoration Options
Marginal ridges destroyed:
Requires post-core and crown.
Post consideration: for anterior
Ferrule presence is crucial.
If no ferrule, cast post-core is not ideal.
Posts do not strengthen teeth but provide retention for core.
What is a post/core?
- Core provides retention for crown
- Post retains the core
- Posts do not strengthen or reinforce teeth
- Preparation of the root canal for a post, weakens the tooth
Components of a post and core
Post - placed in the root canal
Core - is what the prosthesis is cemented to e.g. crown or bridge abutment
Guidelines for Post Placement
Incisors/canines: Post unnecessary if coronal dentine is sufficient.
Premolars: Small pulp chambers, thin mesiodistal roots → place post in the widest root canal only.
Avoid posts in curved canals (risk of perforation).
Root filling length: Minimum 4-5mm of apical GP.
Post width: No more than 1/3 of root width at narrowest point.
Post length: At least 1:1 crown-to-post ratio.
Ferrule requirement: Minimum 1.5mm height & width of coronal dentine.
What is a ferrule?
A 1-2mm dentine collar around the axial walls of a crown.
Prevents root fracture!
Without a ferrule, root fracture risk is significantly higher.
May require crown lengthening or orthodontic extrusion to achieve.
Ideal Post Characteristics:
Parallel-sided (more retentive, avoids wedging).
Non-threaded (passive) to reduce stress on root.
Cement-retained, as cement buffers occlusal forces.
Qualities of Prefabricated Posts:
1 visit required (no lab work or impressions).
Post & core are separate materials.
Immediate preparation possible.
Post Materials:
Metal (gold, stainless steel, titanium): Strong but poor aesthetics, risk of corrosion, root fracture.
Ceramic (alumina, zirconia): Aesthetic but brittle, hard to retrieve.
Fibre (glass, quartz, carbon): Aesthetic, bonds to dentine, flexible but radiolucent.
How should posterior teeth be restored?
Usually extensive coronal loss → requires cuspal coverage (onlay/crown).
Core Build-Up:
Provides retention & resistance for final restoration.
Can be done using composite, amalgam, or glass ionomer.
Composite is preferred due to bonding ability.
Examples of cores
nayyar core
onlay
endocrown
Posts in Posterior Teeth:
Generally not recommended unless canal is long and straight.
Risk of fracture increases if post is placed incorrectly.
What type of material for a core build- up?
No significant difference in fracture and failure characteristics of composite, amalgam and cast gold as core material under a crown provided a 2mm ferrule exists on the margin of healthy tooth”
Post Removal Methods:
Ultrasonic vibration
Trephan burs (Masseran Kit)
Eggler device
Moskito forceps (for screw-retained posts)
Sliding hammer
Anthogyr (Safe Relax)
Complications of post removal
Root fractures (immediate or delayed)
Unrestorable tooth after post removal
Post perforation → Extraction may be needed
Fractured post → Risk of incomplete removal.
Causes of Post Failure
Restorative reasons (60%) → Poor post adaptation, lack of ferrule, incorrect post material.
Periodontal reasons (32%) → Bone loss, mobility, root fractures.
Endodontic reasons (8%) → Persistent infection, reinfection, poor obturation.
Key Takeaways:
Assess RCT teeth carefully before restoration.
Not all root-treated teeth need posts.
A ferrule is crucial for survival.
Unified post-core is preferred to avoid multiple interfaces.
