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Azerbaycan Saytlari

 »  Home  »  Endodontic Articles 7  »  Shaping ability of GT Rotary Files in simulated resin root canals
Shaping ability of GT Rotary Files in simulated resin root canals
Results.



Because of the presence of two separated instruments (i.e. two 0.04/30 instruments, the one in a type II canal and the other in a type IV canal), the results are based on the analysis of 38 canals.

Width measurements and transportation.
Table 1 shows the mean total widths of the canals by shape. Tables 2 and 3 show, respectively, the mean right (outer) width and the mean left (inner) width of the canals by shape. There were statistically significant differences (P < 0.001) in the total width (Table 1) of the canals between the various canal shapes at the apex of the curve, the beginning of the curve and half-way to the orifice in the straight section. There were statistically significant differences (P = 0.001) for the amount of resin removed from the outer aspect of the curve (Table 2) at the apex of the curve, the beginning of the curve and half-way to the orifice in the straight section; and for the amount of resin removed from the inner aspect of the curve (Table 3) at all five measuring points (orifice, apex of the curve and endpoint (P < 0.05); halfway the orifice (P < 0.001); beginning of the curve (P = 0.001)).
Table 4 shows the direction of transportation at the specific positions along the canal length. Transportation was towards the inner aspect of the canal in canals with straight sections of 12 mm regardless the curve angle (types I and III); towards the outer aspect in canals with straight sections of 8 mm and 408 curves (type II) at all ¢five measuring points, and at the apex of the curve, the beginning of the curve and half-way to the orifice in the straight section when the curve was 608 (type IV). The occurrence of ‘outer widening’, i.e. an almost exclusive removal of resin on the outer aspect of the canal and associated with a narrower region situated more coronally was seen in three of the 10 type III canals and in three of the nine type IV canals.

Table 1. Mean total widths (mm) of canals by canal shape.

Mean total widths of canals by canal shape

Table 2. Mean outer width measurements (mm) of canals by canal shape.

Mean outer width measurements of canals by canal shape

Table 3. Mean inner width measurements (mm) of canals by canal shape.

Mean inner width measurements of canals by canal shape

Table 4. Number of canals transported towards the inner and outer aspect of the curve by canal shape.

Mean outer width measurements of canals by canal shape

Table 5. Incidence of canal aberrations and instrument failures by canal shape.

Incidence of canal aberrations and instrument failures by canal shape

Canal aberrations.
Table 5 shows the incidence of canal aberrations in relation to the canal type. A zip was encountered in eight canals (canal type I: 5; type III: 1; type IV: 2). There were no zips in type II canals. There was only one ledge in a type I canal. There were no perforations nor danger zones (i.e. excessive removal of resin on the inner curve).

Instrument evaluation.
Instrument failure is characterized either by fracture or by deformation. A total of nine instruments deformed during preparation (five in a type IV canal and four in a type III canal) and two fractured. The fracture of these two instruments, both 0.04/30, occurred at the tip of the instrument and beyond the apex of the curve (the one in a type II canal and the other in a type IV canal and in both canal types the beginning of the curve starts at 8 mm from the orifice).The deformations were see at the tip (5x) and at the mid-portion (4x) of the instruments with 0.04 tapers.