Purpose: to investigate the incidence of hand and rotary instrument separation in an endodontic graduate program between 2000 to 2004 and to determine if any co mon denominators exist – to identify variables that affect instrument separation.
Materials and Methods:
•N = 4865 cases (2828 Molars, 1014 premolars, 1023 anteriors)
•Data recorded included: tooth number, canal, the level at which instrument separated, instrument type, size, and brand, use of torque or nontorque controlled motorm student’s year of residency.
•Clinical records and radiographs of all the cases with separated instruments were retrieved to ensure accuracy of data. Glide-path was don to size 20, minimum apical preparation was #35, instrument used 8 times in general.
Most highlighted Results:
•Total of 81 separated instruments (12 hand SS [0.25%], 69 rotary NiTi [1.68%])
•Mandibular molars 55.5% Vs. Maxillary molars 33.3%
•Molar significantly higher than premolars
•82% in apical third VS. 14.8% in middle third Vs. 2.5% coronal third
•No significant difference between torque and non-torque. users
•Highest percentage of instrument separation MB root of Max and Mand Molars
•Care should be taken when instrumenting severely curved canals especially MB canals