Periodontal files‹a comparative study
The purposes of this study were (1) to examine, evaluate, and compare several periodontal files in three different conditions: new, used, and used/sharpened; and (2) to evaluate the efficacy of five sharpening devices. The main characteristics observed included the number, shape, and interval of blades; the active, rake, and lip angles; changes induced by wear; the influence of sharpening; and the type of metal surfaces constituting the blades. There was a wide range of active angles on each individual file, from a high of 75o to a low of 51o. The range of active angles for all blades on all new files was even greater, from a high of 87o to a low of 30o. Wear, observed on some but not all blades, was not extensive and appeared either as abrasion or, occasionally, as fracture of the blade edge. Sharpness scores (5 = sharpest and 1 = dullest) for new file blades were also extremely variable and spanned the full range of values, with a majority of blades scoring 3.5 and below. Attempts to sharpen files with several devices produced inconsistent results. All five sharpening devices had significant shortcomings. It was concluded that the extreme ranges both in active angles and in sharpness scores probably have a significant influence on effectiveness of root instrumentation. [R.W.]
Pasquini, R., S. Clark, S. Baradaran, and D.Adams, J Periodont, 66:1040,1995