Authors: Walton RE.
Title: Histologic evaluation of different methods of enlarging the pulp canal space.
Journal: J Endod
Date: Oct 1976
Citation: 2(10):304-11
Category: Access and Canal Instrumentation
Evidence-based Ranking: 4
Purpose/Objectives: The objective was to histologically compare the effectiveness of enlarging the pulp space in all dimensions using filing, reaming and step-back filing. This was also compared in straight and curved canals. In addition, the relationships between the final canal shape and the completeness of planning of the walls, and whether smoothness of the walls indicated that all walls had been prepared with files.

Materials & Methods: 52 teeth - 91 canals, were prepared in teeth that were then extracted and radiographed. The teeth were divided into straight (less than 10o curvature) or curved (more than 10o ). The canals were randomly filed, reamed or stepped-back. After enlargement the teeth were temporized, extracted, radiographed, decalcified and embedded in paraffin, sectioned and examined under a light microscope. The degree of completeness of removal for each wall was recorded and statistically analyzed.

Results: While reaming and filing planed the walls similarly, step-back filing planed a greater percentage of walls in both straight and curved canals. Reaming resulted in fewer walls planed than filing or step-back filing. Reaming and filing produced more uniform preparations, but step-back produced a more thoroughly, though more irregular preparation.

AuthorÂ’s Conclusion: The advantage of the study was the filing was prepared in situ, on patients, under clinical conditions. Step-back filing more consistently planed the walls because the file sizes remained smaller and were not susceptible to the stiffness of larger files. Filing tended to be the least effective method. Straighter canals had more walls planed. Reaming and filing produced more round shapes, but the irregularities of step-back filing better cleaned more walls. Clean white dentin shaving is not an acceptable criteria for determining the amount of total debridement.

Validity of Conclusion: The results seem valid.

ReviewerÂ’s Comments: This article confirms the challenge of complete mechanical debridement. It is important to use irrigation solutions as an aid in thoroughly cleaning and shaping canals.