Summary:
Purpose: To evaluate the elemental composition, micro-structure and hardness of Ni-Ti endodontic instruments and to assess the relevance of shape memory and superelastic properties.
N= 5 instruments per brand (Table 1).
•After embedding the Ni-Ti instrument along their longitudinal axis in resin and metallographic preparation the elemental composition, structure and hardness were evaluated.
•SEM/energy-dispersive X-ray spectrometer (EDX), X-ray diffraction (XRD) and microhardness measurements were used to test the above parameters.
Most highlighted Results:
- The instruments comprised of Ni (52.1– 56.2%wt) and Ti (43.8 to 47.9%wt) .
- XRD analysis revealed the presence of the austenitic structure in all instruments.
- Vickers hardness values ranged from 312 (K3) to 376 VHN (Endosequence). – K3 -> Lowest microhardness – Profile -> Intermediate microhardness – Protaper -> High microhardness.
- No correlation was found between Ni content and hardness among the instruments tested.
- Microstructural and hardness data confirm that the Ni-Ti instruments were manufactured by cold worked Ni-Ti and do not posses shape memory or superelastic properties.
Clinical significance:
The endodontic instruments tested were manufactured from cold worked Ni-Ti wires and thus have neither shape memory nor superelastic properties.
