2 - Restoration of endodontically treated teeth Flashcards
Describe the clinical assessment of a RCT tooth. (8)
- coronal seal (leakage or caries)
- ferrule present
- can the tooth be isolated with dam?
- swelling
- sinus
- TTP (including buccal sulcus)
- mobility
- increased pocketing
Describe the radiographic assessment of a RCT tooth. (7)
- root filling (length, quality)
- unfilled, missed canals
- shape of canal
- patency (fractured instruments, posts)
- bone support
- crown to root ratio
- pathology
Define ferrule.
Tooth tissue above gingiva level (like a collar of dentine usually)
What are problems that can be encountered when re-RCT teeth?
- amount of tooth structure remaining (internal and external)
- restoration type
- lack of ferrule
- wide post holes
- endodontic complications (eg fractured instrument)
What is coronal microleakage?
- ingress of oral microorganisms into root canal that has been RCT
- important cause of RCT failure (esp multi rooted teeth)
How do you prevent coronal microleakge?
Trim GP to ACJ and place RMGI over pulp floor and root canal openings (lining should be thin to allow retention for restoration)
How would you restore a RCT anterior tooth with intact marginal ridges?
- composite restoration
- veneer
How would you restore a RCT anterior tooth with intact marginal ridges but is discoloured?
- bleaching
- veneer
How would you restore a RCT anterior tooth with the marginal ridges destroyed?
- core buildup with crown
- post crown
What is a post/core?
- gains intraradicular support for definitive restoration of RCT teeth
- core provides retention for crown
- post provides retention for core
- posts do not strengthen or reinforce teeth (prep weakens tooth)
What is the guidance for post placement?
- incisors and canines (unnecessary if sufficient coronal dentine)
- avoid mandibular incisors, premolars with curved canals, molars
- 4-5mm root filing placed apically
- no more than 1/3 width of root and 1mm circumferential dentine
- sufficient bone support
- 1:1 post/crown length
- ferrule needs 1.5mm height and width remaining
What is the function of a ferrule?
- prevents tooth fracture
- prevents rotation of restoration
Describe the ideal post.
- parallel sides (avoids wedging and more retentive than tapered)
- non-threaded and passive (less tension and torque than threaded)
- cement retained (cement acts as buffer for masticatory forces)
What complication can occur with tapered posts?
Can split root when masticatory forces are applied
What different materials can be used in posts?
- cast metal
- steel
- ceramic
- carbon fibre
- fibreglass
What are the advantages of fibre posts?
- can bond composite directly
- pre-fabricated
- reduced chair time
Describe the features of metal posts.
- poor aesthetics
- root fracture
- corrosion
- nickel sensitivity
- radiopaque
Describe the features of ceramic posts.
- high flexural strength and fracture toughness
- favourable aesthetics
- difficult to retrieve
- root fracture common due to stress to root
Describe the features of fibre posts.
- flexible (similar properties to dentine)
- aesthetic
- easy to retrieve
- bonds to dentine with DBAs
- radiolucent on radiographs
- requires more support then metal post
What is a core buildup?
- internal part of tooth is built up with restorative material to replace lost tooth tissue
- core provides retention for definitive restoration ie crown/onlay
What materials are used for core buildups?
- composite (good aesthetics, bonds directly, used with fibre posts)
- amalgam (avoid as retention is poor, poor aesthetics)
- GI (not used, absorbs water and expands)
- cast gold
- smart dentine replacement (SDR)
- biodentine
What is a Nayyar core?
- RCT is removed from coronal portion of canals
- amalgam packed into canals and core is built up
- cannot be prepared for 24 hours whilst amalgam sets
Describe core design.
- 6 degree taper
- length depends on definitive restoration (2mm clearance for MCC)
What can be used as a provisional restoration for RCT teeth?
- temp bond provisional post core crown
- immediate denture
- dressing
- Essex retainer
How do you remove GP for post placement?
- soften with heat or solvent
- gates glidden to minimum size 3
- leave 4-5mm GP apical
How do you assess the GP plug for post placement?
- loupes
- PA
How you prepare the canal for post placement?
- para post XP drill
- can be used on slow speed or preferably reciproc at 1000rpm
- smallest size is equivalent to gates glidden 3
What problems can arise with post crowns?
- perforation of canals
- core fracture
- root fracture or crack
- post fracture
What is a sign of root fracture in RCT teeth?
- repeated de-bonding of restoration/post
- long single pocket is a sign of a vertical fracture
How do you manage a post perforation?
- repair by internal or external periradicular surgery (biodentine or MTA can remedy)
- XLA
How can you remove posts?
- ultrasonic
- masseran kit
- eggler
- moskito forceps (screw retained posts)
