ROOT-CANAL INSTRUMENTS ARE POORLY STANDARDIZED

In an earlier study we demonstrated that root canal instruments vary g reatly in their effectiveness in removing substrates. To further analy ze the reason for this variation of results, the dimensions of the ins truments used were considered of interest as their matching effectiven ess may be size dependent. Nine different brands of Hedstrom files, se ven brands of K files, and four brands of special files were examined. The measurements were done in a computerized measuring microscope and the data were compared with earlier reported data on machining. Altho ugh the dimensions of the instruments varied greatly, no correlation c ould be found between the machining and dimensions. Only one brand of files was completely within allowable size range.