- Open Access
Comparison of cyclic fatigue resistance of original and counterfeit rotary instruments
© Ertas et al.; licensee BioMed Central Ltd. 2014
Received: 29 January 2014
Accepted: 19 May 2014
Published: 31 May 2014
In recent years, with the advances in counterfeiting methods, counterfeit products have reached the dental market. The purpose of this study was to compare the cyclic fatigue resistance of original and counterfeit rotary root canal instruments.
Materials and methods
The cyclic fatigue of original and counterfeit ProTaper F2 endodontic instruments was tested (n = 20) in 3 mm radius steel canals with a 60° angle of curvature. The number of cycles to fracture (NCF) was calculated, and the data were subjected to the Student’s t-test (α = 0.05).
The original instruments showed better cyclic fatigue resistance than the counterfeit ones (p < .001). The mean NCF was 483 ± 84 for the original files and 186 ± 86 for the counterfeit files.
The cyclic fatigue resistance of the counterfeit instruments was very low. As a result, clinicians should be careful not to purchase counterfeit products.
Nickel-titanium (Ni-Ti) rotary instruments were introduced to the dental profession in the early 1990s, and today these instruments are commonly used among dentists. Over the years, many different rotary Ni-Ti instruments have been marketed.
It is well-known that the separation of Ni-Ti rotary instruments is a risk to the success of dental treatments . In clinical practice, the fracture of Ni-Ti rotary instruments occurs via two different mechanisms: torsional fracture and flexural fatigue . Torsional fracture occurs when part of the instrument binds to the dentin, while the file continues to rotate . However, flexural fatigue fracture of the file occurs when the instrument rotates freely in a curvature, generating tension/compression cycles in the region of maximum flexure, until fracture occurs .
In recent years, with the advancement of counterfeiting methods, counterfeit products have reached the dental market. These imitation medical products present potential health risks for patients, because the quality and/or performance of these products are largely unknown. From 2001-2009, thirteen counterfeit medical devices were reported, and four of them were involved in surgical implants and dental filling material . However, the performance of any counterfeit endodontic products have not yet been investigated.
The purpose of this in-vitro study was to compare the cyclic fatigue resistance of counterfeit and original rotary files. The null hypothesis is that there is no significant difference between counterfeit and original rotary NiTi files with regard to cyclic fatigue resistance.
Materials and methods
Comparison of mean NCF values of original and counterfeit files
In the present study, original and counterfeit rotary Ni-Ti instruments were tested. The findings of our study revealed that cyclic fatigue in the instruments, although having similar shapes, is quite different, and the quality of the imitation/counterfeit products is poor. Thus, the null hypothesis was rejected. The differences between the original and counterfeit instruments in their manufacturing processes and their alloys could have influenced the fatigue resistance of the instruments . In addition, the cross-sections of counterfeit instruments were different from the original ones. Therefore, the results of this study could be influenced by the different cross-section [6–8]. The standard deviation of the counterfeit group was very high, and the NCF was very low for some samples, which could indicate unstandardized or substandard manufacturing processes.
The devices used in dentistry directly affect the health of the patients. These individuals rely on dentists to provide the best care possible, and dentists must be able to trust the dental materials that they use. In recent years, a number of events have indicated that unprincipled manufacturers bring either illegal or counterfeit dental materials to the medical instrument market . Additionally, there is a surprising lack of published information on this subject, possibly due to the difficulties in identifying counterfeit products.
Dentists should purchase safe, original dental products, either directly from the manufacturers or through their authorized distributors and dealers. There are several ways to identify possibly gray-market, imitation, or counterfeit dental supplies, including unusual low prices, unknown distributor names, and suspicious packaging .
Original rotary instruments showed superior cyclic fatigue resistance when compared to counterfeit instruments. Clinicians should be careful not to purchase imitation dental products.
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