Flexibility and Cutting Ability of Stainless Steel Endodontic Instruments

Flexibility and Cutting Ability of Stainless Steel Endodontic Instruments

J. WAN, J. GUZMAN, B.L. MUSIKANT, and A.S. DEUTSCH, Essential Dental Systems, South Hackensack, NJ

Objective: To examine the effect of pitch number and cross-sectional area on the flexibility and cutting ability of three stainless steel endodontic instruments used in reciprocation.

Methods: Three brands of size 40/.02 stainless steel instruments twisted from rectangular stainless steel wire were tested: Dentsply K-File, Dentsply Reamer, and SafeSiders. Flexibility was determined according to ISO standard 3630-1:2008. Each sample (12/gp) was bound 3mm from the tip in a torque measurement test stand, and flexibility was recorded as the torque required to deflect each sample through 45°. Cutting ability was determined by preparing anterior teeth to a size 30 and operating on them with each sample (12/gp) with a 4:1 reciprocating handpiece at 2500 rpm for 5 seconds. Loosened debris from cutting and subsequent water irrigation was caught in pre-weighed polystyrene dishes, stored at 37°C for 24 hours, and reweighed. Cutting ability was evaluated by the increase in dish weight from the collected debris. Data for both tests were analyzed using 1-way ANOVA and the SNK multiple comparisons testing at a significance level of P<0.05. The effect of pitch number was determined by comparing the Dentsply K-File to the Dentsply K-Reamer; the effect of cross-sectional area by the Dentsply Reamer to the SafeSiders.

Results:

Group	Flexibility (N*cm)			Cutting Ability (mg)
	Mean	SNK		Mean	SNK
SafeSiders	1.57 ± 0.23	A		1.67 ± 0.12	A
Dentsply K-File	1.93 ± 0.11	B		1.28 ± 0.34	B
Dentsply Reamer	1.97 ± 0.16	B		1.27 ± 0.29	B

 

Conclusions: No statistically significant difference was found between the Dentsply K-File and Reamer for either flexibility or cutting ability, while SafeSiders was found to be significantly more flexibility and cut significantly more than the Dentsply K-File and Reamer. Cross-sectional area was observed to have an effect on flexibility and cutting ability.