Incidence of instrument separation using LightSpeed rotary instruments

By Knowles K, Hammond N, Biggs S, Ibarrola J.

Date: 01/2006
Journal: JOE


Purpose: to evaluate the incidence of nonretrievable instrument separation, when using the LightSpeed system by 3rd and 4th  year dental students 

•N= 3543 canals over a 24-month period


•Lightspeed was used according to the manufacturer instructions. Preflaring with G.G, instrumentation to WL to size 20. Lightspeed used at speed of 2000 rpm and torque of 1.42.

•Mater file was defined as the smallest size that required a minimum of 12 “pecks” to reach working length.

•If instrument separated, attempts were made to remove the instruments or bypass it, if not filled to the level of separated instrument.

•Tooth number, canal ,size of separated instrument, location of segment, and resolution.

Most highlighted Results:

•46 instruments were separated and non-retrievable  (1.30%).

•93.5% involved molars. Mandibular mesiobuccal was most commonly involved (48%).

•Size 40 was most commonly separated (26%),followed by 35 (17%).

•30% of the cases could be bypassed to WL.

•64% separation occurred in the mid range of instrument size, sizes 35, 37.5, 40, and 45.