Restoration of Endodontically Treated tooth Flashcards
3 ways to assess the RCT tooth
clincal
radiographic
coronal seal and microleakage
clinical assessment of RCT tooth
- Coronal seal - restorations/crowns.
- Leakage? Caries? Extense?
- Amount of remaining tooth structure- ferrule
- Is the tooth restorable?
- Can you isolate it with rubber dam?
- Swelling
- Sinus (arrow has healed sinus)
- assess reflected and attached mucosa
- TTP
- any signs of infection at end of tooth?
- Buccal sulcus
- tender to palpation?
- Mobility – grade – note
- Increased pocketing
- periodontal disease and root fracture
when do you need a pre-treatment radiograph
indirect and direct to ensure no underlying infection or issue. Critique
8 parts radiogaphic assessment
- Root filling - length, quality of obturation e.g. voids
- Unfilled/missed root canals
- Shape of canal - post and cores
- need to assess: narrow, dentine abundance, curved?
- Patency
- fracture instruments, posts, sclerosis (access to canal)
- Bone support
- mild, moderate, severe (periodontal assess)
- Crown to root ratio (1:1.5) – ideal
- Pathology
- success tx? periapical radiolucency
- healing? resorption, perforations
voids
allow bacteria to penetrate and thrive,
why does GP appear beyond apex
through the apex – likely due to continued infection and external inflammatory resorption at apex
where should GP be sealed
GP shouldn’t be in clinical crown – trim back to ACJ (line)
issue of severe bone loss on radiograph
do not bother restoring
issue of smaller root
i.e. below ideal ration (1:1.5)
the smaller the root the less support – cannot do crown lengthening
filling deemed inadequate on clincal and radiographic assessment
Inadequate root fillings should be re-treated before prosthodontics commence
8 other consideration on assessing endo treated tooth
- When RCT done? Is it healing or has it failed?
- Was it done under rubber dam and was hypochlorite irrigant used? Gold standard for tx
- RF short or long? Weigh pros and cons of trying to extend
If:
- Cracks or fractures
- Fractured instruments
- Perforations
- Periapical pathology e.g. Cysts
- Repeated RCT’s. Implant? Alternative?
- Success rate decreases, is it sensible?
STOP - reassess - can you improve or need to replan
If in doubt refer for an opinion
Note observations /discussions in notes - legal
how long in general for RCT to heal
- generally peri apically pathology 4 years down the line – not healed.*
- Generally 2-5 years to fully heal
coronal microleakage
- Ingress of oral micro-organisms into the root canal system
- Important cause of RCT failure
- Significant in multi-rooted teeth as more canals
Root filled teeth unrestored for 3 months or longer should generally be re-root canal treated
- GP exposed for more than 3 months – contaminated by bacteria, working their way to apex – re treat
Trim GP to the ACJ and place RMGI over pulp floor and root canal openings vitrebond
- means if lining comes out GP is sealed so protecting Tx
Lining should not be too thick, allowing remainder of pulp chamber for retention and restoration GP at ACJ and pulp floor to block lateral canals
importance of coronal seal
Technical quality of the coronal restoration significantly more important for apical periodontal health than the technical quality of the root canal treatment
well seal more imp than superior RCT
issue here
swelling above lateral and central
heavily restored for 25 yo
- coronal microleakage lead to multiple problems
assess RCT in radiograph
- Within 1-2mm of radiographic apex
- Voids around master and accessory points
- “Kink” in the apical 1/3
- Radiolucency – cannot see extent
- More taken – spreading (GP of 12 removed)
- Interproximal fillings are leaking – source of infection and swelling
Coronal Microleakage?
restorations issue
spaces under mesial and distal restorations
what does this OPT show
see large infection of RCT
- cystic infection above RCT
- restorations not properly completed
- no dam likely - saliva contamination leading to infection
- discoloured, poor margins
Problems of Coronal Microleakage
5 potential problems after RCT/re-RCT
- Amount of remaining tooth structure – externally and internally
- Restoration type – will it be retained?
- Lack or no ferrule
- Wide post holes e.g. reRCT
- Endodontic complications – fractured instruments, perforations, short/long root filling
are teeth brittle after RCT
Teeth do not become more brittle after endodontic treatment” Sedgley CM & Messer HH JOE 18:332 1992
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”
after RCT are teeth as hard as non-root treated teeth
“dentine hardness is not altered after endodontic treatment”
does dehydration affect the hardness of RCT teeth
“dehydration does not appear to weaken dentine structure in terms of strength or toughness”
2 clinical choices for endo tx teeth
- Direct restoration – composite (glass ionomer class V) – Class III and IV
- Indirect restoration – crown or post crown (veneer)
impact of marginal ridges
How intact? How many you have impacts restoration choice
- Intact ->* restoration
- Lost some ->* crowns
restoration for
anterior teeth with intact marginal ridges
Direct restoration – composite
- Over access cavity
- Or interproximal
restoration for
anterior teeth with intact marginal ridges +/- discoloured crown
Direct restoration – composite bleaching (internally and externally)
If pt not happy with colour veneer (crown) – to cover discolouration
Age – crowns 8-10 years survival so young likely need to replace (chip, leak, fall out) – cycle of crowns – destructive
restoration for
anterior teeth with marginal ridges destroyed
Core build-up with crown
(post crown – last resort as many issues)
what is a post/core
- Gains intraradicular support for a definitive restoration little tooth structure existing
- 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 removing tooth structure from inside of tooth
components of 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 categories
- tooth type
- root filling length
- 4-5mm root filling apically - so apex is sealed
- 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 hald of post length into the root
- Mobile teeth do not place – root fractures as root not supported in bone
- minimum 1:1 post length/crown length ration
- ferrule
tooth type consideration for post placement
Incisors and canines
- post unnecessary if sufficient coronal dentine is present
- BUT Extensive loss of coronal tooth tissue the tooth will need a post as the pulp chamber and single root canal are not adequate to retain a core [Anterior teeth are subject to lateral forces whereas posterior teeth are subject to vertical forces]
Avoid in mandibular incisors due to thin/tapering/ narrow mesiodistal roots – starting the demise of the tooth
Premolars - small pulp chambers and tapering roots. Thin in mesiodistal cross-section and proximal invaginations (canine eminence – concavity in mesial aspect of 4).
- If a post is to be placed then place in the widest root canal.
Avoid in curved canals to avoid perforations! Post straight; canal not
ferrule needed for post placement
- At least 1.5mm height and width of remaining coronal dentine
what is ferrule?
Dentine collar.
- Encirclement of 1- 2 mm of vertical axial tooth structure within walls of a crown (crown margins on dentine)
Prevents tooth fracture
- If crown margin is not placed onto solid tooth, root fracture significantly increased
Orthodontic extrusion or crown lengthening may be necessary to achieve this – move gingival margin apically, to move structure supra gingival – need to have long tooth, compliant pts, time
post or not?
- Upper right no – nice core
- Left – RCT and core before looks like – build core on tooth as enough ferrule for crown margins so restore with crown – avoid a post
3 aspects of ideal post
- Parallel sided
- Avoids ‘wedging’
- More retentive than tapered
- Non-threaded (Passive)
- Smooth surface incorporates less stress to remaining tooth than threaded (Active) sandblasted, smooth no grooves, no force transmission (causes stress root fracture)
- Cement Retained
- Less retentive than threaded posts but cement acts as buffer between masticatory forces and post/tooth
classification of posts by (3)
- Manufacture
- pre-formed/prefabricated or custom made
- Material
- cast metal, steel, zirconia, carbon/glass fibre
- Shape
- parallel sided or tapered
prefabricated posts
- Only 1 visit required
- No impressions and no fit visit required
- Chairside core build-up
- Immediate preparation of core
- Post and core are different materials
- Large selection of designs and materials
custom posts
Cast from direct pattern fabricated in patients mouth
- e.g. Duralay (acrylic based – not really used any more as monomer carcinogenic)
Indirect pattern can be fabricated in the lab
- e.g. impression of the post hole and wax-up of post and core in lab (most common method)
- Unified post and core e.g. made one piece, the same material – advantage – less corrosion, leakage
2 visits required
- impressions and fit.
- Temporisation between visits and lab stage required.
- Risk of contamination of the root canal between visits.Cast post made in Type IV heat hardened gold
3 possible post materials
metal - cast gold, stainless steel, brass, titanium
ceramics - alumina, zirconia
fibre - glass, quartz carbon
cons of metal posts
- Poor aesthetics – opaquer in crown can block out grey shine
- Root fracture,
- corrosion,
- nickel sensitivity.
pro of metal posts
radiopaque on radiographs
pros of ceramic posts
- High flexural strength and fracture toughness.
- Favourable aesthetics.
con of ceramic posts
- Difficult retrievability and root fracture common (post doesn’t give but root does)
pros of fibre posts
- Flexible, similar properties to dentine.
- Aesthetic
- Retrievable – special burs
- bond to dentine with DBA’s – can be hard to get etch and DBA down post hole - patchy
con of fibre posts
radioluncent on radiographs
2 possible post shapes
- Tapered (black background)
- Fibre
- Opaque/relatively clear
- Different widths
- Parallel
purpose of grooves in posts
give extra retention – help cement lock in
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
- May have some cusps/tooth – build up so have retention and resistance
3 possible core materials
composite
amalgam (posterior)
glass ionomer
composite as core material
- most commonly used core material.
- Tooth coloured so good aesthetics.
- Bonds to the tooth structure.
- Technique sensitive, so moisture control required.
- Used with fibre posts
amalgam as core material
- tend to avoid as retention is required.
- Poor aesthetics. E.g. All ceramic crown
- Core cannot be prepared straightaway – need 24hrs to set (unlike composite)
- Avoid pinned amalgams – fail often
posterior
glass ionomer as core materials
- not really used as it absorbs water and core expands in size
- take impression core at one side. If not restored with temporary or temporary falls out then the GI will absorb water and expand – cannot get definitive restoration cemented on
what type of material should be used for 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” Pilo et al. J Pros Dent 2002 88:302-6
- change if don’t have ferrule or not 2mm ferrule
Tx here
canine with composite core
Tx here
- mixture of dentine with composite core on tip
Tx here
- composite in centre and amalgam – potentially restored as MOD amalgam before – if filling in tooth is sound then can just prep down – no need to remove unless leaking, or unsure state underneath
Tx here
- composite into pulp chamber to build up core
Nayyer core
amalgam core in posterior tooth into RC
- Root treatment is removed from the root canals.
- Amalgam is packed into the root canals and tooth built-up.
- This provides retention for the amalgam
- Cannot be prepared for 24 hrs until amalgam sets
what are these
examples of core materials
- Amalgam – 24hrs set
- Other specific materials can be used for cores – ParaCore – resin based system – build up and prep straight away
- Biodentine – expensive and tricky to use, 10-12mins to set, cannot touch – inject and leave (hard to do in clinical practice
problems with post (4)
- post perforation
- core fracture
- root fracture/crack
- post fracture
*
post perforation
management
common
- Repair – internal or external (periradicular surgery)
- Extraction – longer time placed = lower success
how to avoud post perforation
Avoid curved, narrow root canals
- Common to post perforations – premolars – buccal canals
- Remember three dimensions
Off centre post – issue
- Lateral radiolucency and periapical radiolucency – don’t try to repair
AVOID POSTS AND CORES IN POSTERIOR TEETH – avoid for all if can
- Roots in different directions, furcation complications
possible cause of core fracture
1.5-2mm
No ferrule – core breaks in crown
possible cause of root fracture/crack
thinning the tooth from inside out when placing posts
All ceramic tooth coloured posts – strong so tooth fractures
Single deep pockets, pain = indicative of this
Lateral or premolar common
possible cause of post fracture
- too short, too narrow
- lateral forces – clenching, grinding
post fracture off in post hole – need to remove before restore
4 methods of post removal
- Ultra-sonics
- Masseran Kit
- Like apple corer
- Traphines go round (wider diameter than post)
- Go down the root canal, break cement and remove post
- No longer used in hospital – as hard to sterilised
- Like apple corer
- Eggler
- Moskito Forceps (screw retained)
- Only if post poking out of post hole as cannot enter post hole – limited
reasons for post crown failure
- 60% due to Restorative reasons e.g. caries around crown margins
- 32% due to Periodontal problems e.g. perio-exisitng issue, perio-endo
- 8% due to Endodontic reasons
unified post and core
preferred for non-vital teeth as it avoids material interfaces
RCT need crown and post?
- Not all root canal treated teeth that require a crown need a post and core.
- Avoid if at all possible
- not all cores need a post1
assessment and remedial treatment in endo restoration
- Proper assessment of tooth is required
- clinically and radiographically
- Carry out an remedial treatment before definitive restoration
taking an impression for a post
Parapost system in clinical techniques
- google – Dentsply
Metal post to make temporary post crown
2 other plastic
- One smooth and one ridged
- Smooth is used for impression
- Ridged used by technician to build up
Need to leave 4-5mm of GP
Pick right length and width post (trim ends) (width - colour coded)
- Wider post – central and canines
- Narrow post – lateral and premolars
Get corresponding coloured drill bit
Put rubber stop on – from pre-op radiograph – leaving 4-5mm
- Post end should always touch GP
Use impression post (smooth) – coat with adhesive, place in post hole
Get impression tray of right size
- Fill tray with silicone putty
- Place flow/ lightbodied over post and tooth with post
- And place impression tray on top
Leave to set and remove
- Should come out in one piece
Wax up post and core in lab
Avoid in posterior – extraction, RPD, implant instead
how to decide how to restore a tooth
Clinical judgement
* Could you build up core ?
* Does tooth need a post now?
* Restorative cycle
Do it right the first time
* Quality of root tx
* Disinfection
* Last resort
Post issues – beyond the last resort
how to decide how to restore a tooth
Clinical judgement
* Could you build up core ?
* Does tooth need a post now?
* Restorative cycle
Do it right the first time
* Quality of root tx
* Disinfection
* Last resort
Post issues – beyond the last resort
key consideration in restoring a RCT molar or premolar
Molars and premolars have narrow roots
Post preparation may lead to a strip or lateral perforation in these teeth
* Disadvantages of posts in molars outweigh advantages
Core retention can be obtained from physical undercuts and dentine pins or preferable bonding agents
what to do if no coronal tissue in posterior RCTx tooth
If no coronal tissue – posts may be inserted for short distance into the largest straightest root canal e.g.
* Upper 6 – palatal
* Lower 6/7 – distal
In most cases sufficient natural retention for a core
* Use natural undercuts from pulp chamber or prep into orifices, or dentine pins or bonding agents
At least 1mm ferrule of definitive coronal restoration required unless all-porcelain restoration
what to do if no coronal tissue in posterior RCTx tooth
If no coronal tissue – posts may be inserted for short distance into the largest straightest root canal e.g.
* Upper 6 – palatal
* Lower 6/7 – distal
In most cases sufficient natural retention for a core
* Use natural undercuts from pulp chamber or prep into orifices, or dentine pins or bonding agents
At least 1mm ferrule of definitive coronal restoration required unless all-porcelain restoration
minimal restoration required for posterior RCTx tooth
Minimum tx required for RCTx molar or premolar is a cast restoration with occlusal coverage e.g. MOD onlay
94% of RCTx molars receiving coronal coverage were successful compared with 56% occlusally unprotected teeth
Always consider reducing cusp heigh of posterior teeth by 1.5-2mm prior to RCT if restorations involve greater than 1surface
post failure why?
3
60% due to Restorative reasons
32% due to Periodontal problems
8% due to Endodontic reasons
1st choice restoration for RCTx premolar
cuspal coverage
why do posterior teeth need cuspal coverage restorations
3
- prevent catastrophic fracture (render unrestorable)
- maintain coronal seal
- prevents microbial ingress
GP remaining below post
3-5mm
purpose of core
retention of crwon
factor in space for it so can get a funcational and aesthetic crown
ferrule prep should be on
crown margins on solid tooth tissue rather than restorative material, 1.5-2mm circumferential collar of dentine extending supragingivally
ferrule effect
when place crown on, get some bracing on coronal portion of tooth where crown meets the ferrule prep and cement retains the crown in place, gives some resistance to rotational force and microleakage
core design
2
Core – taper and length important
* 6 degree taper
* Length required - to allow 2 mm clearance for MCC
designing a new restoration considerations
how long will post be
have you got a ferrule
is the canal straight
how much space do you need for core
provisional restorations
when to decide
prior to starting any prep
options for provisional restorations
4
- Provisional post core crown (Temp bond) – using putty matrix or from kit; rather easily dislodge – microleakage risk
- Immediate denture to sit over root face ? – possible gingival issues later on
- Dressing ? Not aesthetic but might prevent leakage
- Essex retainer
how to remove GP for post space
Dental dam (pros and cons)
* Obscure long axis of tooth
* Need to remove for definitive impression
Soften (heat / solvent)
Gates gliddens to minimum size 3 (straight part of canal only)
* Use working length and rubber stopper on gates Glidden
Essential to leave 3 – 5 mm GP in apical third
Check GP plug remains
* Loupes
* Microscope
* Peri apical
when to do post prep
Leave tooth for at least 24hrs after GP removal to allow AH plus to set inside tooth – risk disrupting it if do post prep at same time
para post XP components
4
narrowest is the same as GG3 0.9mm)
- Provisional post – titanium
- Burn out post (not important)
- Para post drill
- Impression post – use as part of definitive impression
anti-rotation notch/grove
If sufficient coronal structure is present rotation is prevented by a vertical coronal wall
If coronal dentine is absent then a small vertical groove in the canal serves as an anti-rotational element; located on the bulkiest area of the root (usually lingual)
lab prescription for post and core
- 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)
try in stage of post and core
- Check post space for temp bond (ultrasonic to clean)
- Irrigate chlorhexidine 0.2%
- Dry paper points
- Ensure fits around prep
- Do you have enough occlusal clearance?
fit of post and core
Be careful not to fill post pace 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
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