Aim: to compare NiTi hand instruments with Stainless- steel instruments according to separation, deformation and changing of working length during preparation of curved root canal in extracted teeth.
Materials and Methods: 24 of curved root canal we
re randomly divided into two groups. One group was prepared using stainless steel instruments and the other prepared by NiTi instruments. Separation and deformation of the two hand instrument systems were determined and the changing of working length during preparation were registered and compared. Data were collected and stastical analysis were conducted.
Results: Stainless steel system showed more separated and deformed instruments, but there were no significant differences between two systems. Also, change of working length was happened with stainless steel only but without significant differences with NiTi.
Conclusion: under the conditions of this study, it can be concluded that two hand instrumentation systems separated and deformed with no differences . However, working length was changed during use stainless steel but without differences between two system.
Aim: to compare the shaping ability of NiTi hand instruments with Stainless- steel instruments in preparation of curved root canal in extracted teeth.
Materials and Methods: a total of 24 of curved root canal were randomly divided into two groups. O
ne group was prepared using stainless steel instruments and the other prepared NiTi instruments. Curvatures pre-and post instrumentation were registered and compared. And straightening of the canals were determined by autocad analysis system.
Results: two systems were significantly changed the original canal curvature with no differences between both systems. However, the time required to finish preparation was significantly less with NiTi system.
Conclusion: under the conditions of this study, it can be concluded that two hand instrumentation system changed the original canal curvature, but the time consuming to finish the preparation was less with NiTi hand system.
Esthetic orthodontic archwires (fiber reinforced composite archwires) are
considered as the latest addition to orthodontic's world, and the load deflection rate is thought to be the
most important mechanical property of archwires which has strong e
ffect clinically, and this property is
affected by the cross section diameter and the material's type, for these reasons this study aims to
investigate the effect of the material's type and the cross section diameter of orthodontic archwires on the
load deflection rate of fiber reinforced composite(FRC) archwires with a diameter of 0.014 inch and
0.016 inch which are suitable for the leveling and alignment stage, and to compare these new materials
with Nickel titanium(NiTi) archwires .
