An in vitro comparative study of working length changes in curved canals after coronal flaring by using rotary and hand instrumentation

The aim of this study is to investigate the effect of early coronal flaring on changing the working length of curved canals by using NiTi rotary instruments and SS manual instruments. Forty five MB curved canals of upper/lower first and second extracted molars were used.

Comparison Study of separation and deformation of stainless steel and Nickel-Titanium hand instruments and changing of working length during preparation of curved root canals of extracted teeth

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 were 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.