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Azerbaycan Saytlari

 »  Home  »  Endodontic Articles 4  »  A comparison of the shaping characteristics of two nickel–titanium endodontic hand instruments
A comparison of the shaping characteristics of two nickel–titanium endodontic hand instruments
Results.



Procedural accidents.
No perforations occurred in the canals of any groups.
Coronal movement of the apical stop was not dependent on the instrument type but it was more frequently observed in curved canals. In canals prepared with Ni–Ti S-files two straight, four J-form and four C-form canals were affected. In the Ni–Ti K-file group two straight, four J-form and two C-form canals had reduced working length following instrumentation. The mean distance between the apical stop and apex was 0.34 mm in the Ni–Ti K-file group and 0.32 mm in the Ni–Ti S-file group; this difference was not significant.

Zips and elbows.
The prevalence of zips and elbows was 26.6% in both groups. The mean width of the elbow was 0.36 mm. The mean elbow to root apex distance was 1.68 mm. In the Ni–Ti K-file group an elbow occurred in one of the straight canals, two of the J-forms and five of the C-form canals. In the Ni–Ti S-file group elbows were detected in two of the straight canals, five of the J-form and one of the C-form canals.

Preparation time.
There was no statistically significant difference in preparation times between the instruments (Table 1)..

Table 1. Mean preparation time (min) and area change (mm2) at the most coronal level grouped by file and canal form.

Mean preparation time (min) and area change at the most coronal level grouped by file and canal form
I, straight root canal;
J, apically curved canal;
C, continuously curved canal.

Area change at the orifice.
The results of area change measurements at the most coronal level are presented in Table 1. Statistical analysis revealed that Ni–Ti S-files removed significantly greater amounts of dentine compared to Ni–Ti K-files ( P < 0.05). The analysis of covariance did not show any statistically significant relationships between the amount of removed dentine at the most coronal level and the preparation time.

Canal transportation at the apical level.
Mean transportation values at the apical level are outlined in Figure 1. In the case of straight and C-form canals there were no significant difference between the two instruments. Significantly less transportation was obtained from the Ni–Ti K-file in J-form canals compared to Ni–Ti S-file in the same anatomical group ( P < 0.05). Ni– Ti S-file produced less transportation on the C-form canals compared to the J-form canals, however, this difference was statistically significant only in the proximal view ( P < 0.05). The Ni–Ti K-files were not significantly different in the J-form and C-form groups.

Figure 1. Mean preparation asymmetry values at the apical level representing both clinical and proximal views parameters.

Mean preparation asymmetry values at the apical level representing both clinical and proximal views parameters
*Means significance at P <0.05; bars represent standard deviation.


Canal transportation at the middle third level.
Results of transportation at the middle third level (danger zone) are presented in Figure 2. More transportation was found on J-form canals prepared by the Ni–Ti S-files in both views. Statistically significant differences ( P < 0.05) were found between the Ni–Ti K-files and Ni–Ti S-files only in the proximal view of this form of canal. The least transportation was associated with the C-form canals instrumented by Ni–Ti S-files. This parameter was found to be significant ( P < 0.05) between the J-form and C-form groups both in the clinical and proximal views when the preparation was made by Ni–Ti S-files.

Figure 2. Mean asymmetry values at the "danger" zone representing both clinical and proximal parameters.

Mean asymmetry values at the danger zone representing both clinical and proximal parameters
*Means significance at P <0.05; bars represent standard deviation.