Corrosion in stainless-steel and nickel-titanium files.
This study evaluated and compared the corrosion susceptibility of stainless-steel and nickel-titanium (NiTi) endodontic files immersed in sodium hypochlorite. For each of the stainless-steel files (Kerr K-Flex, Caulk Flex-O, and Union Broach Flex-R) plus the NiTi files (Union Broach NiTi and Tulsa NiTi), the cutting flutes of 24 ISO size 20 files were immersed into 5.25% sodium hypochlorite. Their open circuit potential (OCP) was recorded for 1 h on a strip chart with high impedance. The strip chart recording for each file was classified into a stability score: (i) stable, (ii) unstable, or (iii) erratic. The OCP was measured by a potentiostat and a standard calomel electrode reference. The OCP classification of unstable and erratic for the files evaluated were as follows: K-Flex (16%), Flex-R (12%), Flex-O (75%), Union Broach NiTi (62%), and Tulsa NiTi (0%). After OCP testing, each of the 120 files was inspected by light microscopy at x 25. The frequencies of visually observed corrosion were detected as follows: K-Flex (2/24), Flex-R (1/24), Flex-O (6/24), Union Broach NiTi (2/24), and Tulsa NiTi (0/24). There was a significant difference in corrosion frequency between brands when evaluated by OCP and light microscopy; however, there was no significant difference between stainless steel and NiTi.
Stokes
O W
OW
Department of Endodontics, Northwestern University Dental School, Chicago, IL 60611, USA.
Fiore
P M
PM
Barss
J T
JT
Koerber
A
A
Gilbert
J L
JL
Lautenschlager
E P
EP
D000704:Analysis of Variance; D003343:Corrosion; D003762:Dental Instruments; D004563:Electrochemistry; D005069:Evaluation Studies as Topic; D008855:Microscopy, Electron, Scanning; D009532:Nickel / Q000737:chemistry*; D011897:Random Allocation; D018915:Root Canal Preparation / Q000295:instrumentation*; D012973:Sodium Hypochlorite / Q000737:chemistry; D012997:Solvents / Q000737:chemistry; D013057:Spectrum Analysis / Q000379:methods; D013193:Stainless Steel / Q000737:chemistry*; D018709:Statistics, Nonparametric; D014025:Titanium / Q000737:chemistry*
D012997:Solvents; C040654:titanium nickelide; D013193:Stainless Steel; D009532:Nickel; D014025:Titanium; D012973:Sodium Hypochlorite