Evaluation of deformation and fracture rates for nickel-titanium rotary instruments according to the frequency of clinical use

Year 2018, Volume: 52 Issue: 2, 89 - 93, 01.05.2018

Ayça Yılmaz Sıtkı Selçuk Gökyay Rüştü Dağlaroğlu İşıl Karagöz Küçükay

Abstract

DOI: 10.26650/eor.2018.461

Purpose

To evaluate the deformation and fracture
rates for ProTaper Universal (PTU) nickel-titanium rotary instruments according
to the frequency of clinical use.

Materials and Methods

A total of 619 PTU instruments (S1, S2, F1,
F2, and F3) that have been used in the clinic by a single endodontist were
collected over a period of 4 years. These instruments were grouped on the basis
of one to three (Group A), four to six (Group B) and seven to nine (Group C)
clinical uses (one canal = one use). All instruments were evaluated by a
blinded investigator under a stereomicroscope at 15×–45× magnification for the
presence of deformation and fracture.

Results

The overall rates of deformation and
fracture were 10% and 1.2%, respectively. The deformation and fracture rates
for the S2, F1, and F2 instruments showed no significant differences among
groups. However, fracture rate for S1 instruments in Group A was significantly
higher than for those in Group B (p=0.025) and Group C (p=0.004). In Group C,
the S1 instruments showed a significantly higher deformation rate compared with
the S2 (p=0.04), F1 (p=0.008) and F2 (p=0.049) instruments; there were no other
significant differences within groups.

Conclusion

Under the conditions of the current study,
frequency of use seemed to influence the deformation rates of PTU rotary
instruments. Except S1, these instruments could be used without any fracture or
deformation in up to 9 clinical cases by an experienced endodontist.

Keywords

NiTi rotary system; ProTaper Universal; dental instruments; deformation; fracture

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