Avaliação das alterações geométricas e dimensionais ... - Dentsply

Câmara AS. Evaluation of instruments structural changes from NiTi ProTaper System to NiTi
ProTaper Universal System and their effects over torsional resistance and flexibility [tese
doutorado]. Araraquara: Faculdade de Odontologia da UNESP; 2008.
ABSTRACT
The present study has proposed to evaluate the instruments
structural changes from NiTi ProTaper System to NiTi ProTaper Universal
System as well this effect over torsional resistance and flexibility. It was used a
total amount of 298 instruments. At the beginning, 12 instruments of each size
from both systems were analyzed dimensional and geometrically by optical
microscopy under parameters of angle, length and tip diameter, pitch’s length
along the blade and instrument’s diameter from tip until the end of the active
part. Besides, one sample of each size had its 3-mm from the tip’s cross
sectional area calculated under SEM images. After that, all the instruments
were randomly divided into 4 different groups: Group 1 having 60 ProTaper
instruments inside (S1, S2, F1, F2 and F3),12 samples from each size, to be
submitted to torsion test; Group 2 having 60 ProTaper instruments inside (S1,
S2, F1, F2 and F3),12 samples from each size, to be submitted to bending test;
Group 3 having 84 ProTaper Universal instruments inside (S1, S2, F1, F2, F3,
F4 and F5),12 samples from each size, to be submitted to torsion test; Group 4
having 84 ProTaper instruments inside (S1, S2, F1, F2, F3, F4 and F5),12
samples from each size, to be submitted to bending test. These torsion and
bending tests were performed using a bench test device connected with a
software to acquire and process data specially developed to this purpose,
according to ISO 3630-1. Maximum torque, angular deflection until fracture and
bending moment values were statistically analysed using Student’s t test. The
results have shown that ProTaper and ProTaper Universal system’s instruments
presented good geometric standardization and acceptable surface features,
however differences were detected among the systems. The maximum torque
and the bending moment at 45º. were higher for instruments with larger
diameters and cross sectional area at 3mm from the tip in both systems even
though angular deflection hasn’t shown this same relationship.
Key Words: Endodontics; Torque; Fracture