Objectives: Defects on of nickel–titanium endodontic file surface can play a role in instrument fracture. Aim of our study was to evaluate the effect of repeated dry heat sterilization on surface characteristics of NiTi rotary instruments by using scanning electrical microscopy (SEM), Energy dispersive x-ray spectroscopy (EDS) and Atomic Force Microscopy (AFM). Methods: ProTaper (Dentsply Maillefer, Switzerland) and AlphaKite (Komet, Italy) files were tested. The instruments were exposed to 1, 5 and 10 cycles of sterilization. Each groups included four Protaper and four AlphaKite. After sterilization the samples were observed by SEM (FEI, Netherlands), and surface analysis was performed on each instrument by EDS. Moreover, twenty areas of the surface the files were analyzed by AFM (Perception, Assing, Italy). Three-dimensional images were processed by Gwiddion software and the roughness average (Ra) and the root-mean-square value (Rms) of the scanned surface profiles were recorded. Data were statistically analyzed by Student t Test (p<0.05). Results: SEM observations showed the presence of debris, pitting and deep milling marks in both new and sterilized files. After 5 and 10 sterilization cycles, surface roughness increased significantly for ProTaper, while AlphaKite (TiN-coated) instruments showed no significant differences compared to the controls. EDS analysis showed the presence of Nickel and Titanium in both instruments, while Nitrogen (21.08%) was present only on AlphaKite surfaces. The percentages of metals changed after dry heat sterilization, with alterations of coating surfaces. AFM observations showed that Ra and Rms values of ProTaper instruments, after 5 and 10 cycles of sterilization were significantly higher compared to controls. In contrast, Ra and Rms values of AlphaKite instruments showed no significant differences with the controls. Conclusions: Our results suggested that dry heat sterilization might modify the surface morphology and chemical composition of NiTi instruments and that TiN coating might reduce these phenomena.
Ni-Ti rotary instruments surface alterations caused by heat sterilization
AMATO, Massimo;
2011-01-01
Abstract
Objectives: Defects on of nickel–titanium endodontic file surface can play a role in instrument fracture. Aim of our study was to evaluate the effect of repeated dry heat sterilization on surface characteristics of NiTi rotary instruments by using scanning electrical microscopy (SEM), Energy dispersive x-ray spectroscopy (EDS) and Atomic Force Microscopy (AFM). Methods: ProTaper (Dentsply Maillefer, Switzerland) and AlphaKite (Komet, Italy) files were tested. The instruments were exposed to 1, 5 and 10 cycles of sterilization. Each groups included four Protaper and four AlphaKite. After sterilization the samples were observed by SEM (FEI, Netherlands), and surface analysis was performed on each instrument by EDS. Moreover, twenty areas of the surface the files were analyzed by AFM (Perception, Assing, Italy). Three-dimensional images were processed by Gwiddion software and the roughness average (Ra) and the root-mean-square value (Rms) of the scanned surface profiles were recorded. Data were statistically analyzed by Student t Test (p<0.05). Results: SEM observations showed the presence of debris, pitting and deep milling marks in both new and sterilized files. After 5 and 10 sterilization cycles, surface roughness increased significantly for ProTaper, while AlphaKite (TiN-coated) instruments showed no significant differences compared to the controls. EDS analysis showed the presence of Nickel and Titanium in both instruments, while Nitrogen (21.08%) was present only on AlphaKite surfaces. The percentages of metals changed after dry heat sterilization, with alterations of coating surfaces. AFM observations showed that Ra and Rms values of ProTaper instruments, after 5 and 10 cycles of sterilization were significantly higher compared to controls. In contrast, Ra and Rms values of AlphaKite instruments showed no significant differences with the controls. Conclusions: Our results suggested that dry heat sterilization might modify the surface morphology and chemical composition of NiTi instruments and that TiN coating might reduce these phenomena.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
