restoration of the endodontically treated anterior tooth Flashcards
what needs to be considered when doing the clinical assessment
- coronal seal = restorations/crowns, leakage, caries?
- amount of remaining tooth structure = ferrule
- is tooth restorable?
- can tooth be isolated with rubber dam?
- need to look for signs of infection = swelling, sinus, TTP, buccal sulcus, mobility
- increased pocketing = perio disease and root fracture
- look at reflected and attached mucosa
what type of restorations are radiographs important for pre-treatment
- indirect
- but need for both
what is assessed from the radiograph
- root filling = length, quality, obturation
- unfilled/missed canals
- shape of canal
- patency = fracture instruments, posts
- bone support
- crown to root ratio
- pathology
why are voids and missed canals a problem
- voids allow transport of bacteria and substrate
what should the crown to root ratio be
- 1:1.5
- if teeth are 1:1 can cause problems with crown lengthening as root not long enough to support
what needs done before prosthodontics can begin
- inadequate root fillings should be re-treated
why is it important to know when RCT was done
- can determine if tooth is still healing or if treatment has failed
- if there is infection after 4 years it has failed
- but if it doesnt look right after only 6 months, then could still be healing
why should rubber dam and hypochlorite be used
- more likely to fail without
what are some other important considerations when assessing rCT
- fractured instruments
- cracks or fractures
- perforations
- periapical pathology
- repeated RCT’s, implants, alternativeS?
what is coronal micro leakage
- ingress of road micro-organisms into the root canal system
- significant in multi-rooted teeth
- important cause of RCT failure
what should be done to root treated teeth that have no been restored in 3 months
- should be re-root treated
- if GP has been exposed to the mouth for longer than 3 months, then it will be contaminated so need to redo it
how should RCT be sealed in
- trim GP to the ACJ and place RMGI over the pulp floor and root canal openings
why should lining not be too thick
- allowing remained of pulp chamber for retention and restoration
- liner should be over GP and over the base of pulp floor as often have a number of lateral canals in multi-rooted teeth
what is the importance of a coronal seal
- technical quality of coronal restoration is significantly more important for apical periodontal health than the technical quality of the RCT
- coronal restoration is more important than good RCT
how far should RCT go
- 1-2mm from radiographic apex of tooth
what can commonly give rise to infection of tooth
- leaking restorations
what can often cause leaking restorations
- salivary contamination
what are some problems to consider after RCT/re-RCT
- amount of tooth structure remaining
- restoration type
- lack of or no ferrule
- wide post holes
why is amount fo tooth structure left important
- need to have enough tooth to build a restoration on
- should consider this before starting
what are some endodontic complications
- fractured instruments, perforations, short/long root fillings
are teeth brittle after RCT
- teeth do not become more brittle after endodontic treatment
are root treated teeth more prone to fracture
- a root filled tooth with minima loss of dentine is no more likely to fracture than vital tooth
after RCT are teeth as hard as non-root treated teeth
- dentine hardness is not altered after endodontic treatment
- irrigants can sometimes make teeth softer = EDTA and citric acid can remove minerals
does dehydration affect the hardness of a RCT tooth
- does not appear to weaken dentine structure in terms of strength or toughness
what are the clinical choices for direct restoration
- composite = class III and IV restoration
- glass ionomer is rarely used now, more for cervical restorations (class V)
what are the clinical choice for indirect restoration
- crown or post crown
what is important about marginal ridges
- if these are intact, then don’t do crowns or post crowns
- once start to lose marginal ridges, need to replace with crowns
what are the restoration options for anterior teeth with intact marginal ridges
- direct composite restoration
what are the restoration options for anterior teeth with intact marginal ridges +/- discoloured crown
- direct restoration with composite
- bleaching tooth internally and externally and if it bleaches down enough could restore with composite
- if not then could veneer labially to mask discolouration
what are the restoration options for an anterior teeth with marginal ridges destroyed
- core build-up with crown
- post crown = last resort
how can age influence restorative option
- crowns only last 8-10 years so wouldn’t want to give to young patient as they will need to keep coming back for a new crown which means drilling more tooth structure away each time
what is a post/core
- used to gain intraradicular support for a definitive restoration
- core provides retention for crown
- post retains the core
- posts do not reinforce or strengthen teeth
- preparation for post weakens tooth as need to create space in root canal
are posts placed in incisors and canines
- post unnecessary if sufficient coronal dentine is present
- but excessive loss of coronal tooth tissue will need a post as pulp chamber and single root canal are not adequate enough to retain core
are posts placed in mandibular incisors
- avoid
- they have thin/tapering mesiodistal roots
- if you put posts in these, tooth will breakdown
are posts placed premolars
- small pulp chamber and tampering roots
- thin in mesiodistal cross-section and proximal invaginations
- place post in widest root canal if you have to place one
what should post width be
- no more than 1/3 of root width at narrowest point and 1mm of remaining circumferential coronal dentine
why do we need sufficient alveolar bone support for a post
- we can’t put a post in a mobile tooth as will just get a fracture as the root is not supported in the bone
what size does a ferrule need to be to do a post and core
- 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
- heigh and width should eb 1.5mm
- collar should go all the way around the tooth
what happens if a crown margin is not placed into solid tooth
- root fracture is much more likely to occur
what happens if there is no ferrule
- root fracture
what can you do to get a ferrule
- orthodontic extrusion or crown lengthening may be necessary
- can put a wire in the post hole and add chain in it to try and extrude structure supragingivally = very few cases amenable to this however
what is the ideal post
- parallel sided = avoid wedging, more retentive
- non-threaded = passive
- cement retained = less retentive but cement acts as a buffer between masticatory forces and post/tooth
what are the different manufactured ways of a post
- pre-formed
- prefabricated
- custom made
what are the different materials for a post
- cast metal
- zirconia
- carbon/glass fibre
what are the different shapes of posts
- parallel sided or tapered
what are the different kinds of prefabricated posts
- tapered smooth
- tapered serated
- tapered threaded
- parallel smooth
- parallel serated
- parallel threaded
what is good about prefabricated posts
- only 1 visit needed
- no impressions and no fit visit required
- chair-side build-up of core
- large selection of designs and materials = some have notches and grooves (notches)
what is bad about prefabricated posts
- post and core are different materials = causes problems such as leakage and corrosion
what are the ways in which custom made posts are made
- cast from direct pattern fabricated in patient mouth = Duralay - old technique, not used as much now as monomer is carcinogenic
- indirect pattern can be fabricated in the lab = most common method
- impression of post hole taken and wax-up of pot and core in lab, sculpt the material into a post and core which is then invested in requested material
what is good about indirect method of making custom made posts
- post and core are made from same material
what are some problems about indirect methods of making custom made posts
- 2 visits required
- impressions and fit
- temporisation between visits and lab stage required
- risk of contamination of the root canal between visits
what is the common material for custom posts to be cast in
- type IV heat hardened gold
what are some metal post material
- cast gold
- stainless steel
- brass
- titanium
what are some problems with metal post material
- poor aesthetics = this isn’t as much a problem anymore as new things have been made to block out metal shine
- root fracture
- corrosion
- nickel sensitivity
what is good about metal post materials
- radiopaque on radiographs
what are some ceramic post materials
- alumina
- zirconia
what is good about ceramic post materials
- high flexural strength and fracture toughness
- favourable aesthetics
what is a problem about ceramic post materials
- difficult to remove and root fracture common
- the tooth around them often fractures
what are some fibre post materials
- glass
- quartz
- carbon
what is good about fibre post materials
- flexible = similar properties to dentine
- aesthetics, removable, bone to dentine with DBA’s
what is a problem about fibre post materials
- radiolucent
- can’t really see difference between this and overlying composite
why are grooves placed on posts
- there to give extra retention and help block the cement into them
what are the advantages and disadvantages of tapered prefabricated post
- +ve
- conservative
- high strength
- high stiffness
- -ve
- less retentive than parallel or threaded
what are the uses and precautions for tapered prefabricated posts
- use = small circular canals
- cautions = avoid excessively flared canals
what are the advantages and disadvantages of parallel prefabricated posts
- +ve
- high strength
- good retention
- comprehensive system
- -ve
- precious metal
- expensive
- corrosion of stainless steel
- less conservative
what are the uses and cautions of parallel prefabricated posts
- use = small circular canals
- cautions = care duding prep
what are the advantages and disadvantages of threaded posts
- +ve
- high retention
- -ve
- stresses generated can cause fracture
what are the uses and cautions fo threaded posts
- use = only when max retention essential
- caution = care to avoid fracture during seating
what are the advantages and disadvantages of custom cast post and core
- +ve
- high strength
- better than prefab
- -ve
- less stuff than wrought
- “multiple appointments
- complex
what are the uses and cautions of custom made posts and core
- use = elliptical or flared canals
- caution = care to 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 permanent restorations
what are some core materials
- composite = most common
- amalgam
- glass ionomer
- biodentine
what is god about composite as a core material
- tooth coloured
- bond to tooth structure
what is a problem about composite as a core material
- moisture sensitive
what posts are composite cores often used wit
- fibre posts
what are problems with amalgam as core material
- tend to avoid as retention required as can’t bond to tooth
- poor aesthetics = shine through
- needs 24 hours to set
- need to avoid pinned amalgams as often fail
why are glass ionomer cores not really used
- absorbs water
- core will increase in size so then can’t get crown on
why is biodentine quite difficult to use
- takes about 10-12 minutes to set and if it is touched in that time the setting time begins from the start again
what is a Nayyar core
- amalgam is packed into the root canals and tooth is built-up
- use all the little spaces under the pulp horns to retain amalgam
how can you manage a perforation
- repair = internal or external
- peri-radicular surgery
- extraction
how can a core fracture
- if don’t have enough of a ferrule then core can break off from root
- get fractures without a ferrules
what can be indicative of a root fracture
- if you find a single deep pocket
- common with ceramics
how can a post fracture occur
- post could be tooth short or narrow
- if there are lots of lateral forces applied, it can fracture
how can posts be removed
- ultrasonics
- masseran kit
- eggler
- moskito forceps
how does a masseran kit work
- like an apple corer
- work way down root canal and break cement down and get post out
- don’t away with mostly as it is difficult to sterilise
how does a moskito forceps work
- screw retained
- applied to post and pushed against root surface
- can only be used if there is something sticking up to grasp onto
what are the reasons for post crown failure
- 60% due to restorative reasons
- 32% due to periodontal reasons
- 8% due to endodontic reasons
