JVD 2015 #4 - Managing Endodontic Instrument Separation

Question 1

“Managing endodontic instrument separation” by McCoy,

what are the two most common causes of instrument separation?

Answer 1

instrument fatigue from overuse, applying excessive apical pressure (rotary motion);

separation from manufacturing defect is rare

Question 2

“Managing endodontic instrument separation” by McCoy,

where are NiTi files designed to break?

Answer 2

at the shaft-thank jnctn under extreme force/torque, but it can occur anywhere along the file

CP: Depends on type of NiTi rotary instruments:

• Gates-Glidden and Peeso: shaft-working tip junction
• LSX: Shaft-shank junction

but for all, it can occur anywhere along the file

Question 3

“Managing endodontic instrument separation” by McCoy,

what should you do if an instrument breaks?

Answer 3

(cry) CP: lol (it realy made me laugh!)

• take a radiograph (evaluate lenght and location of fragment)
• use loupes or surgical microscope for visualization
• strong attempts to remove (file braiding, magnetized instruments, ultrasonic endo tips, enlarge access)
• if can’t, owner informed, then consider switching to different option

N.B.:​

• Total obstruction of pulp canal by fragment ⇒ bypass impossible
• Fragment apical to curve in small canal ⇒ retrieval impossible

Question 4

“Managing endodontic instrument separation” by McCoy,

what if you can’t get the file out?

Answer 4

• Advise owner
• can obturate around it (?!) as long as cleaning, shaping and apical obturation is adequate; with regular radiographs monitored,
• can convert to an apico (if fragment is enough apical),
• can extract (root or tooth)

Question 5

“Managing endodontic instrument separation” by McCoy,

how often should NiTi files be changed? what about path finders?

Answer 5

3-6 uses;

pathfinder only use once!