Purpose: To compare by histologic examination the effectiveness of filing, reaming, and step-back filing for enlarging the pulp space in all dimensions.
N= 52 teeth with a total of 91 canals.
Filed: Filing motions were repeated with successively larger instruments to at least 2 sizes which resulted in clean dentin shavings and the walls felt “smooth.”
Reamed: Files were manipulated at working length until they could be rotated freely.
Step-back: Small files were inserted to the working length and rotated; this repeated with larger files up to sizes 25 to 30. Then, successively larger files were inserted to about 0.5 to 1 mm shorter lengths. This progressive decrease in length was continued until at least size 60 file was reached
Canals were enlarged by one of the three ways, then sections were stained and examined under the light microscope.
Most highlighted Results:
1.By combining curved and straight canals within each group, there was no significant difference between reaming and filing.
2.However, step- back filing resulted in significantly more walls planed compared to reaming and filing
3.In all three methods, significantly more walls were planed in the straight than in the curved canals.
Step-back filing seemed to produce a more thoroughly planed, prepared canal walls.
Filing tended to be the least effective method of dentin removal