title: Defects in GT rotary instruments after use: an SEM study.
abstract: Used rotary nickel-titanium instruments require frequent replacement. This laboratory study evaluated defects of GT Rotary instruments before and after usage. The instruments were fixed into custom-made holders and photographed in an SEM at x 260 to x 12,000 magnification at preset points. Instrument sizes 20 with 1.0, 0.8, and 0.6 taper and instrument sizes 35 with 1.2 taper were used in 12 canals. The used instruments were cleaned and then reexamined in an SEM as before. The presence of 11 types of conditions was scored from the pre- and postusage photographs. No instruments fracturing or plastic deformation was observed during the test. The presence of debris, pitting, and scraping changed significantly. Imperfections were found on used GT Rotary instruments and the presence of defects (pitting, scraping, and blunt-cutting edges) increased in all of the instruments. The behavior of GT Rotary instruments with usage seems to be different, compared with that found in other instruments.
authors.affiliation: Cattedra di Odontoiatria Conservatrice, Corso di Laurea in Odontoiatria e Protesi Dentaria, Università di Catania, Italy.
authors.forename: T R
authors.initials: TR
authors.lastname: Tripi
authors.forename: A
authors.initials: A
authors.lastname: Bonaccorso
authors.forename: V
authors.initials: V
authors.lastname: Tripi
authors.forename: G G
authors.initials: GG
authors.lastname: Condorelli
authors.forename: E
authors.initials: E
authors.lastname: Rapisarda
mesh_terms: D003755:Dental High-Speed Technique; D003762:Dental Instruments; D017743:Equipment Reuse; D006801:Humans; D008855:Microscopy, Electron, Scanning; D008963:Molar; D009532:Nickel; D018915:Root Canal Preparation / Q000295:instrumentation*; D013499:Surface Properties; D014025:Titanium
chemical_list: C040654:titanium nickelide; D009532:Nickel; D014025:Titanium