IADR Abstract Archives
Phase Transformations in Trushape® 3D-Conforming NiTi Rotary Files after Simulated Clinical Use
Objectives: A new generation of nickel-titanium (NiTi) rotary instruments with unique S-shape is designed to improve cleaning of tissue debris in root canals while preserving the dentin and natural anatomy of the root. The objective of this investigation was to employ differential scanning calorimetry (DSC) to investigate the structural transformations in Trushape® 3D-conforming NiTi (DENTSPLY Tulsa Dental) rotary files in the as-received condition, and after 1 and 3-simulated clinical uses.
Methods: Thirty simulated root canal preparation (30-degree curvature) in clear resin-blocks (DENTSPLY Maillefer) were completed. Files with 25 mm working length files and 6% taper in sizes 20, 25 and 30 were tested (n=10 per group). The files were cut with a diamond saw into 3 segments: tip region, intermediate segment, and shank region, having 3 – 4 mm in length. Each specimen for DSC analysis (Mettler Toledo, USA) consisted of three segments, and was cooled from room temperature to -80°C, heated to 120°C, and cooled back to -80°C at 10°C per minute; the DSC cell was purged with nitrogen. The DSC data were analyzed using ANOVA and the Tukey post hoc test (p<0.05).
Results: For all three instrument sizes, the DSC plots were similar for the control (as-received) specimens. Two peaks were observed on the heating plots, corresponding to the austenite-martensite transformation with the intermediate R-phase, and one peak was observed on the cooling plots. The austenite-finish temperature (heating) was less than about 30°C. For specimens from instruments with 1 and 3 simulated clinical uses, the heating and cooling DSC plots were also similar, although the enthalpy change was largely reduced. Small shifts in the onset temperatures for the transformations were observed.
Conclusions: The Trushape® 3D-Conforming instruments exhibited consistent DSC plots for specimens from both as-received and used instruments, indicative of well controlled fabrication process and enduring clinical performance.
Methods: Thirty simulated root canal preparation (30-degree curvature) in clear resin-blocks (DENTSPLY Maillefer) were completed. Files with 25 mm working length files and 6% taper in sizes 20, 25 and 30 were tested (n=10 per group). The files were cut with a diamond saw into 3 segments: tip region, intermediate segment, and shank region, having 3 – 4 mm in length. Each specimen for DSC analysis (Mettler Toledo, USA) consisted of three segments, and was cooled from room temperature to -80°C, heated to 120°C, and cooled back to -80°C at 10°C per minute; the DSC cell was purged with nitrogen. The DSC data were analyzed using ANOVA and the Tukey post hoc test (p<0.05).
Results: For all three instrument sizes, the DSC plots were similar for the control (as-received) specimens. Two peaks were observed on the heating plots, corresponding to the austenite-martensite transformation with the intermediate R-phase, and one peak was observed on the cooling plots. The austenite-finish temperature (heating) was less than about 30°C. For specimens from instruments with 1 and 3 simulated clinical uses, the heating and cooling DSC plots were also similar, although the enthalpy change was largely reduced. Small shifts in the onset temperatures for the transformations were observed.
Conclusions: The Trushape® 3D-Conforming instruments exhibited consistent DSC plots for specimens from both as-received and used instruments, indicative of well controlled fabrication process and enduring clinical performance.