2 - Restoration of endodontically treated teeth

Question 1

Describe the clinical assessment of a RCT tooth. (8)

Answer 1

• coronal seal (leakage or caries)
• ferrule present
• can the tooth be isolated with dam?
• swelling
• sinus
• TTP (including buccal sulcus)
• mobility
• increased pocketing

Question 2

Describe the radiographic assessment of a RCT tooth. (7)

Answer 2

• root filling (length, quality)
• unfilled, missed canals
• shape of canal
• patency (fractured instruments, posts)
• bone support
• crown to root ratio
• pathology

Question 3

Define ferrule.

Answer 3

Tooth tissue above gingiva level (like a collar of dentine usually)

Question 4

What are problems that can be encountered when re-RCT teeth?

Answer 4

• amount of tooth structure remaining (internal and external)
• restoration type
• lack of ferrule
• wide post holes
• endodontic complications (eg fractured instrument)

Question 5

What is coronal microleakage?

Answer 5

• ingress of oral microorganisms into root canal that has been RCT
• important cause of RCT failure (esp multi rooted teeth)

Question 6

How do you prevent coronal microleakge?

Answer 6

Trim GP to ACJ and place RMGI over pulp floor and root canal openings (lining should be thin to allow retention for restoration)

Question 7

How would you restore a RCT anterior tooth with intact marginal ridges?

Answer 7

• composite restoration
• veneer

Question 8

How would you restore a RCT anterior tooth with intact marginal ridges but is discoloured?

Answer 8

• bleaching
• veneer

Question 9

How would you restore a RCT anterior tooth with the marginal ridges destroyed?

Answer 9

• core buildup with crown
• post crown

Question 10

What is a post/core?

Answer 10

• 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)

Question 11

What is the guidance for post placement?

Answer 11

• 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

Question 12

What is the function of a ferrule?

Answer 12

• prevents tooth fracture
• prevents rotation of restoration

Question 13

Describe the ideal post.

Answer 13

• 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)

Question 14

What complication can occur with tapered posts?

Answer 14

Can split root when masticatory forces are applied

Question 15

What different materials can be used in posts?

Answer 15

• cast metal
• steel
• ceramic
• carbon fibre
• fibreglass

Question 16

What are the advantages of fibre posts?

Answer 16

• can bond composite directly
• pre-fabricated
• reduced chair time

Question 17

Describe the features of metal posts.

Answer 17

• poor aesthetics
• root fracture
• corrosion
• nickel sensitivity
• radiopaque

Question 18

Describe the features of ceramic posts.

Answer 18

• high flexural strength and fracture toughness
• favourable aesthetics
• difficult to retrieve
• root fracture common due to stress to root

Question 19

Describe the features of fibre posts.

Answer 19

• flexible (similar properties to dentine)
• aesthetic
• easy to retrieve
• bonds to dentine with DBAs
• radiolucent on radiographs
• requires more support then metal post

Question 20

What is a core buildup?

Answer 20

• internal part of tooth is built up with restorative material to replace lost tooth tissue
• core provides retention for definitive restoration ie crown/onlay

Question 21

What materials are used for core buildups?

Answer 21

• 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

Question 22

What is a Nayyar core?

Answer 22

• 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

Question 23

Describe core design.

Answer 23

• 6 degree taper
• length depends on definitive restoration (2mm clearance for MCC)

Question 24

What can be used as a provisional restoration for RCT teeth?

Answer 24

• temp bond provisional post core crown
• immediate denture
• dressing
• Essex retainer

Question 25

How do you remove GP for post placement?

Answer 25

• soften with heat or solvent
• gates glidden to minimum size 3
• leave 4-5mm GP apical

Question 26

How do you assess the GP plug for post placement?

Answer 26

• loupes
• PA

Question 27

How you prepare the canal for post placement?

Answer 27

• para post XP drill
• can be used on slow speed or preferably reciproc at 1000rpm
• smallest size is equivalent to gates glidden 3

Question 28

What problems can arise with post crowns?

Answer 28

• perforation of canals
• core fracture
• root fracture or crack
• post fracture

Question 29

What is a sign of root fracture in RCT teeth?

Answer 29

• repeated de-bonding of restoration/post
• long single pocket is a sign of a vertical fracture

Question 30

How do you manage a post perforation?

Answer 30

• repair by internal or external periradicular surgery (biodentine or MTA can remedy)
• XLA

Question 31

How can you remove posts?

Answer 31

• ultrasonic
• masseran kit
• eggler
• moskito forceps (screw retained posts)