Evaluating the sizes of Lightspeed® instruments

Abstract

The diameters of six different sized Lightspeed cutting heads were measured using a modified optical micrometer. Six specimens of instrument sizes 20, 22.5, 27.7, 30, 32.5 and 45 were examined. Except for one cutting head of size 30, all the recorded diameters were oversized compared to the expected diameter and the permitted tolerance (+/- 0.005 mm). Perfectly machined instruments would increase by 12.5%, 9.09% and 8.3% from instrument sizes 20-22.5, 27.5-30 and 30-32.5, respectively. Under the conditions of this study, the corresponding increases were 7.1%, 6.75% and 8.54%. Instrument size 20 had the widest range and is the smallest instrument in the Lightspeed set. The largest differences between the recorded and expected means were registered for the size 45 group. An earlier study using a different measuring method reported that Lightspeed instruments were mostly undersized.

The effect of instrument type and preflaring on apical file size determination

“…Hence, part of the difference is possibly related to LS tip configuration because the maximum diameter of LS instruments may be further away from the pilot tip of the instrument than is the case for K‐files. Conflicting reports (Marsicovetere et al . 1996, Schrader et al .…”

“…Hence, part of the di¡erence is possibly related to LS tip con¢guration because the maximum diameter of LS instruments may be further away from the pilot tip of the instrument than is the case for K-¢les. Con£icting reports (Marsicovetere et al 1996, Schrader et al 1998 suggest that LS instruments are undersized or oversized in relation to their nominal size.We measured the cutting heads of 26 LS instruments (from sizes 205 0, two instruments of each size) using a micrometer. On average, instruments were slightly smaller than the stated size by approximately 1 ISO unit (0.01 mm) and the di¡erence varied from þ0.5 to À3 ISO units.…”