Restoration of Endodontically treated tooth Flashcards
What should be considered when assessing endodontically treated tooth clinically?
Coronal seal - restoration type
-> Leakage/Caries?
Amount of remaining tooth structure- ferrule
Is the tooth restorable?
Can you isolate it with rubber dam?
Swelling
Sinus
TTP- indicates if inflammation in PDL
Buccal sulcus - tender to palpation
Mobility
Increased pocketing – periodontal disease and root fractures
What is the sign of vertical root fracture?
Long/narrow pocket not reflected in other areas of mouth
What are we looking for on radiographic assessment of endodontically treated tooth?
Root filling - length, quality of obturation (voids)
Unfilled/missed root canals
Shape of canal
Patency - fracture instruments, posts, sclerosis
Bone support – mild, moderate, severe
Crown to root ratio (1:1.5)
Pathology - periapical radiolucency (healing?), resorption, perforations
How doe external root resorption appear in endodontically treated teeth?
Lack of conical apex
Moth eaten appearance
What are some of the issues when doing reRCT?
Lack of remaining tooth structure- ext/int
Lack of/no ferrule
Wide post holes
Endodontic complications - fractured instruments, perforations, short/long root fillings
How much do certain cavities weaken tooth by?
MOD cavity- weakens tooth by 66 %
MO cavity- weaken by 33%
If you cut an access cavity- it takes away large proportion of structural integrity
What is coronal microleakage?
Ingress of oral micro-organisms into the root canal system
-> one of main causes of RCT failure
What can be done to prevent coronal microleakage?
Root filled teeth unrestored for 3 months or longer should generally be re-root canal treated
Trim GP to the AC and place RMGI over pulp floor and root canal openings
Why is cusp coverage required for endodontically treated teeth in posterior region?
- Prevent coronal microleakage
- Prevent catastrophic fracture (tooth splits though furcation or breaks underneath alveolar crest)
** RCT must be adequate- disinfected with NaOCl and obturated accurately
What are some of the myths regarding the properties of endodontically treated teeth?
More brittle
Prone to fracture
Not as hard
Dehydration affects hardness
-> evidence against all of these claims
What are the treatment options for endodontically treated anterior tooth with intact marginal ridges?
Composite restoration- if small B/L access cavity
Veneer (not protective)
What are the treatment options for endodontically treated anterior tooth with intact marginal ridges but discoloured crown?
Bleaching
Veneer
Crown
What are the treatment options for endodontically treated anterior tooth with destroyed marginal ridges?
Core build up with crown
Post crown
What is required for direct posts?
Ferrule
What is the post option if there is no ferrule?
Cast post and cores (not fibre)
-> avoid if possible and build up core with composite
What is the purpose of a post core?
Gains intraradicular support for a definitive restoration
-> Core provides retention for crown
-> Post retains the core (placed in root canal)
What are the issues with post core crowns?
Posts do not strengthen or reinforce teeth
Preparation of the root canal for a post, weakens the tooth
Why may a diaphragm be added to a post?
To provide bulk in root that has fractured
In what teeth should posts be avoided?
Mandibular incisors- too narrow/tapering roots
Premolar- in maxillary 4s, 75% have 2 canals
-> tapering roots
-> small pulp chambers
-> proximal invaginations
Curved canals- perforation risk
If a post must be put in a molar tooth, where is it best placed?
Put in longest, straightest canal
Lower molar- distal root
Upper- palatal root
What are the guidelines for post placement?
4-5mm root filling apically- maintains apical seal
Post width
-> No more than 1/3 of root width at narrowest point and 1 mm of remaining circumferential coronal dentine
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?
Encirclement of 1- 2 mm of vertical axial tooth structure within walls of a crown
What is the function of a ferrule?
Braces crown at neck of tooth- helps prevent fracture, rotational movement and leakage
What can be done if no ferrule is present?
Orthodontic extrusion or CLS can be considered (if no other options and meticulous OH)
What are the options for a tooth with ferrule that is hollowed out significantly?
- Fibre post
- Composite
- Cast post (is this conservative?)
How is a post cemented?
Using GI or resin
Where should a crown prep finish ideally?
Ideally crown prep finishes on tooth tissue (not always possible)
What are the ADV/DIS of DT light posts?
ADV
- Are meant to change colour when contact moisture- easier visualisation
- Flexes the same as dentine
DIS
- need enough tooth structure and ferrule
- Difficult to take out as they are bonded in with composite
- Moisture and technique sensitive
What are the features of the ideal post?
Parallel sided
- Avoids ‘wedging’
- More retentive than tapered
Non-threaded (Passive)
-> Smooth surface incorporates less stress to remaining tooth than threaded (Active)
Cement Retained
-> Less retentive than threaded posts but cement acts as buffer between masticatory forces and post/tooth
What are the different types of prefabricated post?
Tapered Smooth
Tapered Serrated
Tapered Threaded
Parallel Smooth
Parallel Serrated
Parallel Threaded
What are the ADV/DIS of prefabricated posts?
ADV
Only 1 visit required
No impressions and laboratory visit required
Chairside core build-up- immediate preparation of core
Large selection of designs and materials
DIS
Post and core are different materials
What is the main issue with tapered post?
Wedges on tooth and flexes on biting
What are the different types of metal post?
cast gold, stainless steel, brass, titanium
What are the ADV/DIS of metal post?
ADV:
Radiopaque
DIS:
Poor aesthetics
Root fracture
Corrosion
Nickel sensitivity
What are the different types of ceramic post?
Alumina
Zirconia
What are the ADV/DIS of ceramic posts?
ADV
High flexural strength
High fracture toughness
Favourable aesthetics
DIS
Difficult retrievability
Root fracture is common
What are the different types of fibre post?
glass, quartz, carbon
What are the ADV/DIS of fibre posts?
ADV
Flexible- similar properties to dentine
Aesthetic
Retrievable
Bond to dentine with DBA’s
DIS
Radiolucent on radiographs
What are the ADV/DIS/recommended uses/precautions for tapered pre-fab posts?
ADV:
Conservative
High stiffness
High Strength
DIS:
Less retentive
RU:
Small circular canals
Precautions:
Avoid excessively flared canals
What are the ADV/DIS/recommended uses/precautions for parallel prefab posts?
ADV:
High strength
Good retention
DIS:
Expensive
Corrosion if SS
Less conservative
RU:
Smaller circular canals
Precautions:
Exercise care during prep
What are the ADV/DIS/recommended uses/precautions for threaded posts?
ADV:
High retention
DIS:
Stresses created can cause fracture
RU:
When max retention is essential
P:
Avoid fracture during seating
What are the ADV/DIS/recommended uses/precautions for Custom cast post and core?
ADV:
Higher strength than prefab
DIS:
Less stiff
Multiple appointments
Technically complex
RU:
Elliptical or flared canals
P:
Remove nodules before insertion
What is a core build up?
Internal part of tooth is built-up with restorative material to replace the lost tooth tissue
-> core is prepared- provides retention and resistance for definitive restorations
What are the ADV/DIS of composite cores?
ADV:
* Tooth coloured- better aesthetics
* Bonds to tooth
* Immediate prep
* On demand set
DIS
* Technique sensitive- moisture control required
What posts is a composite core used with?
FIBRE
What are the drawbacks of Amalgam cores?
- Retention required
- Poor aesthetics
- Must wait a day until you prepare it
- Avoid pinned amalgams
What is the issue with GIC core?
Absorbs water and core expands in size
What is the aim of a core build up?
Make it look like ideal crown prep of unrestored tooth
-> 6 degree taper
-> 2mm occlusal clearance
What is a nayaar core?
Traditionally uses amalgam
Utilises pulp space and some of the root canal system for more retention
Difficult to retreat
Composite can be used- difficult as no colour contrast
What is the main advantage or restoring eddo-treated tooth with onlay?
more conservative, removes less tooth structure
How is cusp fracture avoided when placing onlay?
Want it to go over cusps
-> ensure cusp has been reduced by 2mm as it will fracture if not
What are the materials for onlays?
Bell glass- pressed composite
Zirconia
Gold
What is an endo crown?
Indirect version of Nayyar core
Increases surface area for bonding and part in pulp space will give mechanical retention
Difficult to keep dry
Mostly zirconia
What is paracore?
Core material which is similar to bulk fill flowable composite
What are the features of Smart Dentine Replacement?
- Self-settling properties
- Shade is not great
- Etch tooth, bond and inject
- Stronger than traditional flowable
What are some principles to keep in mind when restoring/retreating endodontically treated teeth?
Do not rush obturation- will take longer to fix it
Spend time on disinfection too (especially if you are putting post in it)
If you are concerned about quality of current RCT, then re-do
Posts are last resort- structural integrity is really poor
What are the steps in restorative cycle?
Small filling
Large filling
RCT
Crown
Post crown
ReRCT / re post crown
Extraction
-> Aim to stop advancing
What can be used to ascertain whether GP plug is still present when placing a post?
- Loupes
- Microscope
- Radiographs- to check seal
What can be used to remove posts?
Ultrasonic
Trephan- Masseran
Eggler device
Moskito Forceps (screw retained)
Sliding hammer
Anthogyr (Safe relax)
What are the features of ultrasonic tips for post removal?
Can be made of SS with diamond/Titanium
-> Remove very small bits of dentine
What are the features of the masseran trephan?
Cores around post
Can be destructive
Can be combined with ultrasonic
What are the problems with post removal?
You can’t remove it
Root fracture (immediate or delayed)
Render tooth unrestorable
Post space too wide
You break post
What are the issues that can occur when carrying out treatment involving posts?
Perforation
Core fracture
Root fracture or crack
Post fracture
What can be done to mitigate perforation?
Use Reciproc motor (electric motor) with post drill- 1000rpm at torque 4 gives more control
What are the treatment options for post perforation?
Repair
-> Internal
-> External- periradicular surgery, restore with MTA
Extraction
What are the reasons for post failure?
60% due to Restorative reasons (secondary caries, unrestorable tooth etc)
32% due to Periodontal problems
8% due to Endodontic reasons
What can be used as a provisional for a post crown?
Provisional post core crown ( Temp bond)
Immediate denture
Dressing- Not aesthetic but might prevent leakage
Essex retainer
What are the components of the para post system?
Provisional post
Burn out post (not important)
Para post drill
Impression post
What is written in the lab prescription for parapost?
Please construct cast post and core.
Para post (colour)
Core 6 degree taper
Please leave 2mm space in occlusion for Crown
Enclosed registration / opposing impression
Shade
What are the steps in the try-in of a parapost?
Check post space for temp bond
Irrigate chlorhexidine 0.2%
Dry paper points
Ensure fits around prep
Do you have enough occlusal clearance
What are the steps in the fit of a post?
Be careful not to fill post space with cement
-> You may prevent it seating
Use firm apical pressure
Get rid of excess
Can ask lab for provisional acrylic crown
Make sure no excess around when taking crown impression / fitting MCC
Practice fit sequence
