SHAPING ABILITY OF PROFILE.04 TAPER SERIES-29 ROTARY NICKEL-TITANIUM INSTRUMENTS IN SIMULATED ROOT CANALS .2.

The aim of this study was to determine the shaping ability of ProFile, 04 Taper Series 29 rotary nickel-titanium instruments in simulated can als, A total of 40 simulated root canals made up of four different sha pes in terms of angle and position of curvature were prepared by Profi le instruments using a step-down approach, Part 2 of this two-part rep ort describes the efficacy of the instruments in terms of prevalence o f canal aberrations, the amount and direction of canal transportation and the overall postoperative shape, No zips, perforations or danger z ones were created although 24 specimens (60%) had ledges on the outer wall of the canal, The incidence of ledges differed significantly (P < 0.001) between the canal shapes, At specific points along the canal l ength there were highly significant differences (P < 0.001) in total c anal width and in the amount of material removed fi om the inner and o uter aspects of the curve between the various canal shapes. Overall, 4 0 degrees canals were wider than 20 degrees canals and canals with cur ves which began 8 mm fi om the orifice were wider than 12 mm canals, T he direction of canal transportation at the end-point of preparation w as balanced between inner and outer in the 8 mm canals, but more often towards the outer in the 12 mm canals, At the apex of the curve, tran sportation was invariably towards the outer aspect of the curvature, A t the beginning of the curve, transportation was more balanced between inner and outer, Mean absolute transportation, ignoring direction, wa s generally greater in 40 degrees canals and in those with the curve b eginning 8 mm from the orifice. Of particular importance was the findi ng that excessive resin was removed from the outer aspect of the canal at the apex of the curve which was often associated with irregular wi dened areas or ledges, This is in contrast to the pattern of tissue re moval found with stainless steel hand instruments where more resin is removed fi om the inner aspect of the canal at the apex, to create a d anger zone.