Purpose: to compare pre and post-instrumentation WL in curved root canals prepared by (a) using early coronal flaring (flaring completed before WL determination) versus late coronal flaring (flaring completed after WL determination); and
(b) using either stainless steel or nickel-titanium instruments.
N= 30 extracted human maxillary and mandibular first and second molar teeth.
- Access cavities were prepared, working length determined using #10 k file by observing the tip of the file at apex under microscope.
- The teeth were then divided into two groups (G1: Stainless steel (SS) + gates glidden, G2: nickel titanium rotary files).
- Coronal flaring was accomplished for the SS group using Gates Glidden drills and for the Ni-Ti group using rotary Ni-Ti files.
- WL determined after preflaring & after complete canal preparation.
Most highlighted Results:
- WL decreased for all canals after complete canal preparation. The mean decrease in WL was significantly greater for the SS group ( 0.48mm )than for the Ni-Ti group ( 0.22 mm ).
- Less change in WL occurred in both groups when initial WL was determined after coronal flaring (SS: -0.36 mm , Ni-Ti: -0.07).
When the canals preflared using gates glidden , WL should be determined after preflaring.