ETT

Question 1

causes of root fracture in restored endodontically treated teeth

Answer 1

primry causes of root fracture
- tooth structural loss
- loss of free unbound water from root canal lumen and dentinal tubules
- age induced changes in dentine
- restorations and restorative procedures

secondary causes of fracture
- effects of endodontic irrigants and medicaments on dentine
- effects of bacterial interaction with dentien substrate
- biocorrosion of metallic post core

Question 2

exceptions where ETT would not need cuspal coverage

Answer 2

according to KT, all need EXCEPT THE FOLLOWING (even if the access is very minimal in case of dens e)

• opposing arch is denture
• lower 4s because it only has prominent buccal cusp, not much lingual cusp so no wedging effect

Question 3

in the past, they would put posts routinely before crowning, what are the disadvantages of such?

Answer 3

• remove additional tooth structure
• complicates future tx if endo retreatment is needed
• additional ooperative procedure, chance for iatrogenic error

Question 4

what are the hypotheses for ETT fracture

Answer 4

1) loss of tooth structure is the key reason for increased fractures of ETTs

2) loss of proprioception: reduced protective response to loading

3) elevated pain threshold bc now the tooth can no longer feel pain: reduced protective response to loading

4) microbial: bacteria dentine interactions lead to a release of by products

5) chemical:
- endo irrigants and medicaments may weaken dentine eg caoh increases dentine brittleness

6) age of tooth
- age related dentinal changes:

Question 5

defn of ferrule

Answer 5

GPT 9th ed
a band/ring used to encompass crown/root of a tooth

• need 1.5-2mm of dentine protruding from root above gingival level
• 360 degree collar of crown surrounding, parallel to walls of dentine, extending coronal to the shoulder of the prep

ferrule effect is when the small cone of dentine braces and protects root from splitting

Question 6

function of foundation restorations

Answer 6

anchorage:
- securing of restoration by supporting abutment
- may be achieved by mechanical/ adhesive means

the core serves to:
- restore sufficient coronal anatomy
- needed if there isnt 3-4mm tooth structure interproximally

the post serves to retain core. and when combned with core, it provides retention and resistance for the crown