THE EFFECT OF USING FILES WITH ALTERED TIPS IN A SONIC HANDPIECE - ANIN-VITRO STUDY

The objective of this study was to establish the effect of altering th e non-cutting tips on Shaper files during canal preparation with the M M1500 Sonic Air handpiece. A total of 90 simulated canals in clear res in blocks of various angles and positions of curvature were prepared u sing Shaper files activated by an MM 1 500 Sonic Air handpiece. Thirty canals were prepared with unmodified files having non-cutting tips, 3 0 canals were prepared with files which had their tips removed complet ely and a further 30 canals were prepared with files which had tips re duced by half. All canals were prepared using an identical preparation procedure which involved a linear filing motion and an anticurvature technique in curved canals. The parameters investigated included loss of canal length, weight loss from the blocks, smoothness of canal wall s, transportation and overall shape of the prepared canals. The effect of altering the file tips was to increase significantly the loss of w orking distance and the prevalence of canal aberrations such as zips a nd danger zones. Altering the tips also had a detrimental effect on th e pattern and extent of transportation as well as widening canals exce ssively in their apical third. Overall, under the conditions of this s tudy, alterations to the non-cutting tips of Shaper files was counter- productive and resulted in canals displaying many adverse features. Co nversely, retention of the non-cutting tips allowed canal preparation to proceed rapidly and effectively producing canal shapes which displa yed many desirable features.