| Mr. Carl J. Berendt1 and Mr. Jianhua Yang2, 1Sportswire L.L.C., 39026 S. Hwy 82, Langley, OK 74350, 2Global Nitinol Technologies, 12851 Regan Lane, Saratoga, CA 95070
November 7, 2005
SMST – 2006 in Asilomar
Subject: Endodontic Instruments with Improved Fatigue Resistance A paper submitted by: Carl J. Berendt
ABSTRACT: Fatigue fracture is problematic in endodontic instruments. Improvements in fatigue resistance of Nitinol are desirable to provide increased fatigue life and fatigue life predictability.
Endondontic instruments made from Energetically Stable Martensitic stock meets and exceeds the industry specifications for these instruments and have an usable life up to 7 times longer than Austenitic files and reamers.
Material Composition: Nickel 55.8 +/- 1.5 wt.%. Titanium 44.2 +/- 1.5 wt.%
Trace Elements include: Fe, Cr, Cu, Co, 0, H, C, less than 1% wt total.
T.T.R. –5 to –15 Centigrade. Measured at Ingot.
Mechanical Properties: 1 mm diam. .0394 to .0400
Austenitic: UTS 191,950 , Strain 13 %, Upper Plt. 79,760,UTS/Up.Plt. relationship 2.41
Martensetic: UTS 224,660 , Strain 14.05%, Upper Plt. 78,870 , UTS/Up.Plt. Relationship 2.85
Efficacy: Cyclical Fatigue Testing NITI S/E Blanks vs NITI Martensite: Parts cycled @720 deflections per min. until destruction.
Group 1 AUSTENITE: 10 parts drawn from 60 pcs. 64.8 seconds Avg. Group 2 AUSTENITE: 10 parts drawn from 60 pcs. 102.2 seconds Avg. Group 1 MARTENSITE: 10 parts drawn from 60 pcs. 560.3 seconds Avg. Group 2 MARTENSITE: 10 parts drawn from 60 pcs. 564.4 seconds Avg. Finished Endodontic Instrument Cyclical Fatigue Testing: Parts Rotated and deflected around a 11.5 MM mandrel. Instrument rotated @ 300 rpm ran wet @ 37 C. Group 1 AUSTENITE: 10 parts tested from a group of 60 pcs. 86.6 seconds Avg. Group 2 AUSTENITE: 10 parts tested from a group of 60 pcs. 84.8 seconds Avg. Group 1 MARTENSITE: 10 parts tested from a group of 60 pcs. 260 seconds Avg. Group 2 MARTENSITE: 10 parts tested from a group of 60 pcs. 262 seconds Avg.
Credits:
Expert: Dr. Jianhua (Jay) Yang
Mentoring: John Dicello NDC
Dr. Allan Pelton NDC and SMST
Carl J. Berendt, General Manager SPORTSWIRE LLC.
P.O. 697, 39026 S. Hwy. 82, Langley, OK. 74350E – mail: cberendt@sportswirellc.com |