Restoration of the Endodontically Treated Tooth Flashcards
What does clinical assessment of a RCT tooth include?
Coronal seal
Amount of remaining tooth structure - ferrule
Swelling
Sinus
TTP
Is buccal sulcus tender to palpation
Mobility
Increased pocketing
What does radiographic assessment of a RCT tooth include?
Root filling - length, quality of obturation
Unfilled/missed root canals
Shape of canal
Patency - fracture instruments, posts, sclerosis
Bone support
Crown to root ratio (1:1.5)
Pathology
When should endodontics be carried out in relation to prosthodontics?
Before
What are the problems seen after RCT?
Lack or no ferrule
Wide post holes (re RCT)
Endodontic complications - fractured instruments, perforations, short/long root fillings
Are teeth brittle after RCT?
They do not become more brittle
Are root treated teeth more prone to fracture?
A root filled tooth with minimal loss of dentine is no more likely to fracture than a vital tooth
Are RCT teeth as hard as non-root treated teeth?
Dentine hardness is not altered after endodontic treatment
Does dehydration affect the hardness of a RCT tooth?
It doesn’t weaken dentine structure
What is coronal microleakage and when is it significant?
Ingress of oral micro-organisms into the root canal system
Important cause of RCT failure
Significant in multi-rooted teeth
Why is a coronal seal important?
The technical quality of the coronal restoration is significantly more important for apical periodontal health than the technical quality of the RCT
What are the different anterior restorative options?
Veneers
Crowns
Post crown
What is a post/core?
Core provides retention for crown
Post retains the core
Gains intraradicular support for a definitive restoration
Posts do not strengthen or reinforce teeth
Perp of the root canal for a post weakens the tooth
What are the components of a post and core?
Post is placed in the root canal
Core is what the prosthesis is cemented to eg - crown or bridge abutment
What teeth are suitable for a post placement?
Incisors and canines
Avoid in mandibular incisors
Premolars - only in widest root canal
Avoid in curved canals to avoid perforations
What is the root filling length for a post?
4-5mm root filling apically
What post width is needed?
No more than 1/3 of root width at narrowest point and 1mm of remaining circumferential coronal dentine
What else is needed for post placement?
Sufficient alveolar bone support, at least half of post length into the root
Minimum 1:1 post length/crown length ratio
Ferrule - at least 1.5mm height and width of remaining coronal dentine
What is a ferrule?
Dentine collar - encirclement of 1-2mm of vertical axial tooth structure within walls of a crown
Prevents tooth fracture
Orthodontic extrusion or crown lengthening may be necessary to achieve this
Describe the ideal post
Parallel sided
Non-threaded (passive)
Cement retained
How can posts be classified?
By manufacture - pre-formed/prefabricated or custom made
By material - cast metal, steel, zirconia, carbon/glass fibre
By shape - parallel sided or tapered
Describe prefabricated posts
Only 1 visit required
No imps or lab visits required
Chairside core build up
Post and core are different materials
Immediate prep of core
Large selection of designs and materials
Describe custom pots?
Cast from direct pattern fabricated in patients mouth
Indirect pattern can be fabricated in the lab
Unified post and core - one piece with the same material
2 visits needed - imps and fit
Risk of contamination of the root canal between visits
What metals can be used in posts?
Cast gold
Stainless steel
Brass
Titanium
What ceramics can be used in posts?
Alumina
Zirconia
What fibres can be used in posts?
Glass
Quartz
Carbon
What are the different post shapes?
Tapered
Parallel
What is a core build up?
Internal part of tooth is built up with restorative material to replace the lost tooth tissue
The core is prepared
It provides retention and resistance for permanent restorations
What materials can be used for cores and why?
Composite - most commonly used
Amalgam - avoid as retention is required
Glass ionomer - avoid as it absorbs water and core expands
What is a Nayyar core?
Root treatment is removed from the root canals
Amalgam is packed into the root canals and tooth is built up - this provides retention for amalgam
Cannot be prepared for 24 hours until amalgam sets
What are the problems with posts?
Perforation
Core fracture
Root fracture or crack
Post fracture
How is post perforation managed?
Repair - internal or external (periradicular surgery)
Extraction
What can be used for post removal?
Ultra-sonics
Masseran Kit
Eggler
Mskoti Forceps (screw retained)
What are the percentages and reasons for post failures?
60% due to restorative reasons
32% due to periodontal problems
8% due to endodontic reasons
What is important in core design?
Taper and length important
6º taper
Length to allow 2mm clearance for MCC
How is GP removed?
Dental dam
Soften with heat and solvent
Gates glidden to minimum size 3 (straight part of canal only)
Use working length and rubber stopper on gates glidden
Essential to leave 3-5mm GP in apical third
What should be written on a lab prescription for post and cores?
Please construct cast post and core
Para post (colour)
Core 6º taper
Please leave 2mm space in occlusion for crown
Enclosed registration, opposing impression, shade
What happens in try in of a post and core?
Check post space for temp bond
Irrigate with chlorhexidine 0.2%
Dry paper points
Ensure fits around prep
Check you have enough occlusal clearance
What is important when fitting a post and core?
Be careful not to fill post with cement
Firm apical pressure
Get rid of excess
No excess around when taking crown impression/fitting MCC
