Seminar 7: RCT FAILURE Flashcards
In apical lesions the cells are organised into what zones?
Zones of FISH
What are the zones of fish starting from closest to furthest from the root apex?
Zone of infection
Zone of contamination
Zone of irritation
Zone of stimulation
What cells are found in FISH zone of infection?
Microorganisms
PMN cells
What cells are found in FISH zone of contamination?
Leukocytes
Dead bone cells
Bacterial toxins seeping from infection zone
What cells are found in FISH zone of irritation?
Macrophages
Osteoclasts
What cells are found in FISH zone of stimulation?
Fibroblasts and Osteoblasts
Collagen is secreted by these cells and they are stimulated as toxins are mild enough in this area but not too strong to cause destruction
What happens to zones of FISH during acute exacerbation episodes?
They become disrupted
Describe model of periapical disease
Bacterial invasion in root canal
Non specific acute inflam
Phagocytosis of bacteria
Delayed immune response
When does condensing osteitis arise?
Aka periapical osteosclerosis
Occurs when long standing mild chronic irritation
What is the pathophysiology behind condensing osteitis?
Eg if the coronal pulp is necrotic and radicular pulp is vital this can dampen the noxious effect so immune system responds by laying down bone rather than resorbing
What is the average number of species per root canal?
10^5 CFU/ml
Which species are more dominant in acute exacerbations?
Fusobacteria
As time goes on the bacterial species in apical lesions become more what?
Gram negative
Anaerobic
How do facultative anaerobes make ATP?
Oxygen as well as fermentation when oxygen is low
What is special about e faecalis?
- Has a proton pump inhibitor acting against calcium by deactivating it from CaOH
- Can survive as a mono species
According to ESE when should RCTs be reviewed ?
One year
Or until lesion healed
At least 4 years following trauma
What are the causes of RCT failure ?
Infection
Foreign body reaction
Cyst
What are the two types of infections to cause failure ?
Intraradicular
Extraradicular
What is the success rate for conventional retreatment ?
75-85%
What are some common causes of RCT failure?
Cracks Leaking restorations Untreated canals Inadequately cleaned canal Operative errors
What are the options after RCT failure ?
Re endo
Surgery
Xla
What are the types of endo surgery ?
Periradiular surgery
Corrective surgery
Fistulatative
What is an example of periradicular surgery
Apicectomy
Periradicular curettage
What is an example of corrective surgery ?
Hemisection
What is an example of fistulatative surgery?
Decompression
What is a class 1 instrument fracture ?
An instrument that protrudes into the chamber
What is a class 2 instrument fracture ?
A fracture file within the straight part of canal
What technique can be used to remove broken instrument ?
Braiding technique
What is a class 3 fracture instrument?
Beyond the curvature
What is special about E feacalis
- Live and persist in poor nutrient environment-Survive in extreme environments with low pH, high salinity and high temperatures
Endure prolonged periods of starvation and utilize tissue fluid that flows from the periodontal ligament
- Survive in the presence of several medications (e.g., calcium hydroxide) and irrigants (e.g., sodium hypochlorite)
- Form biofilms in medicated canals
Invade and metabolize fluids within the dentinal tubules and adhere to collagen - Acquire antibiotic resistance
