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

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