May 23, 2014


What is the most common cause of failure of root canal treatment?

  • Intracanal microrganisms
  • Missed canals
  • Inaccessible canals due to perforations
  • Ledges
  • Fractured files/silver points

Management of fractured instruments

  • Inform the patient
  • Take radiographs to document situation
  • If visible and in coronal canal it may be removable
  • If in middle bypass using small files
  • If at apex accept or bypass
  • Prognosis depends on when file fractured

Causes of fractured instruments

  • Cyclic fatigue is The file rotates freely but undergoes tension and compression until fatigue occurs
  • Torsional failure is when the file becomes locked in the canal but continues to rotate

How to avoid fracturing files

  • Always establish a good glide path-slide size 10
  • Lubricate canal with irrigants
  • Watch for loaded files
  • Attend rotary courses to get used to systems

Symptoms of hypochlorite accident

  • Pain whilst irrigating
  • Burning pain
  • Instantaneous swelling may spread
  • Bleeding from the canal
  • Patient may taste irrigant if in sinus
  • Anaesthesia or paresthesia

Treatment of hypochlorite accident

  • Irrigate with saline
  • Pain control via local anaesthesia and analgesics (NSAIDs preferable 600mg ibuprofen 4 times a day 1-2 days)
  • Cold compresses
  • After one day irrigation with warm water to encourage blood supply to increase
  • Recall 1 day, 3 days, 1 week (since incident)

Why are perforations a problem?

  • Removes further hard tissue which means the fracture resistance of the tooth is decreased
  • Creates a defect which bacteria in the gingival sulcus can colonise and cause periodontal disease
  • Creates another portal of exit for bacterial products
  • Creates a defect which allows the diffusion of fluid back into the canal to supply nutrients to bacteria
  • Creates a defect that means sodium hypochlorite can enter the tissues and potentially cause a hypochlorite accident

How to avoid perforation

  • Magnification 3X loupes minimum & light
  • Preop assessment- using bur next to PA
  • Use orifice openers with non cutting tips
  • Microdebriders size 10 06 taper or 04 taper (file on a stick)

Treatment of pulpally involved cracked teeth

  • Check for periodontal defects
  • Access of canals
  • Visualise fracture
  • Visualise extent
  • The crown margin must be able to be placed well below the fracture line
  • The lower second molars are the most commonly cracked teeth as this tooth is closest to TMJ and W shaped fissure pattern

Prevention of cracked tooth syndrome

  • Patients have teeth together for 10 mins a day in normal function!
  • Those that have cracked tooth syndrome usually have a parafunctional habit
  • Identify patients at risk
  • Assess quality and number of previous restorations
  • Provide education (stress and diet) cuspal coverage and or splint therapy

General Dental

Recent post

June 29, 2023

Pink Aesthetics...

Read more
canver icon1
General Dental,Periodontology

June 26, 2022

10 Key Points from EuroPerio10...

Read more
canver icon1
Periodontology,Reena's Notes

June 11, 2021

Working as a hygienist or therapist...

Read more
canver icon1
General Dental,Periodontology