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Azerbaycan Saytlari

 »  Home  »  Endodontic Articles 11  »  Surface analysis of ProFile instruments by scanning electron microscopy and X-ray energy-dispersive spectroscopy: a preliminary study
Surface analysis of ProFile instruments by scanning electron microscopy and X-ray energy-dispersive spectroscopy: a preliminary study
Discussion - References.



Discussion.
The morphometric variations of ProFile instruments, as well as the presence of debris, metal strips, flattened surfaces and defects had the same characteristics as those reported by Marsicovetere et al. (1996) in new Lightspeed instruments. The consequences of these imperfections in terms of durability and performance of the files during clinical use have not yet been adequately evaluated. According to Eggert et al. (1999), the effects of these irregularities on the cleaning and shaping performance of the instruments is difficult to assess and probably not clinically relevant. On the other hand, Thompson (2000) states that the presence of surface irregularities on the cutting edges of the instruments may compromise their cutting ability and potentially cause problems with corrosion.
The presence of adherent material on the tips and along the concavities and radial lands of new ProFile instruments is also in agreement with the observations of Marsicovetere et al. (1996) and Eggert et al. (1999) in new Lightspeed instruments. The fact that the adherent material was analyzed in this work and exhibited high concentrations of C and S and a small amount of O constitutes an important contribution to the understanding of its origin. As discussed in a recent review by Thompson (2000), the manufacture of NiTi endodontic files requires complex machining operations, involving careful selection of cutting speeds and feed rates, together with the appropriate choice of tools and cutting oils. Adjusting the process parameters of this operation is a difficult task and if the cutting speed and/or feed rate employed for machining the ProFile instruments were too high, overheating of the cutting tool and of the instrument surface could have occurred. Overheating generally causes decomposition and oxidation of the lubricating oil. The results obtained here suggest that such a process may have occurred and that a sulphurized cooling and lubricating agent was employed during the machining of the instruments, which is a common practice to increase cutting speeds, feed rates and depths of cut in this type of operation (El Baradie 1996). The heat and the surface irregularities would certainly increase the adhesion of the reaction products, rendering their removal during the subsequent cleaning operation much more difficult.
The presence of these deposits on the surface of new instruments, the fact that they are difficult to remove together with the observation that dentine adheres to these deposits after root-canal instrumentation requires attention. Before manufacturers can suitably adjust their processing parameters to prevent the accumulation of these substances, a review of the cleaning methods is necessary, because the adherence of dentine to the deposits may prevent appropriate file sterilization and enhance the risk of cross infection between patients.
The cleaning procedure employed in this work followed the favourable results reported by Tanomaru Filho et al. (2001), regarding ultrasonic cleaning of endodontic instruments. The use of ethyl alcohol in the ultrasonic bath is a traditional practice for cleaning metallic parts from oil contamination. The fact that the deposits on new instruments could not be completely removed by these cleaning procedures is an important contribution to the task of reviewing the cleaning methods.

References.

Eggert C, Peters O, Barbakow F (1999) Wear of nickel-titanium Lightspeed instruments evaluated by scanning electron microscopy. Journal of Endodontics 25, 494-7.
El Baradie MA (1996) Cutting fluids. Part I. Characterisation. Journal of Materials ProcessingTechnology 56, 786-97.
Hurtt CA, Rossman LE (1996) The sterilization of endodontic hand files. Journal of Endodontics 22, 321-2.
Marending M, Lutz F, Barbakow F (1998) Scanning electron microscope appearances of Lightspeed instruments used clinically: a pilot study. International Endodontic Journal 31, 57-62.
Marsicovetere ES, Clement DJ, del Rio CE (1996) Morphometric video analysis of the rotary nickel-titanium Lightspeed instrument system. Journal of Endodontics 22, 231-5.
Murgel CAF, Walton RE, Rittman B, Pecora JD (1990) A comparison of techniques for cleaning endodontic files after usage: a quantitative scanning electron microscopy study. Journal of Endodontics 16, 214-7.
Reams GJ, Baumgartner JC, Kulild JC (1995) Practical application of infection control in endodontics. Journal of Endodontics 21, 281-4.
Serene TP, Adams JD, Saxena A (1995) Nickel-titanium instruments: applications in endodontics. St. Louis, MO,USA: Ishiyaku EuroAmerica, Inc.
Tanomaru Filho M, Leonardo MR, Bonifacio KC, Dametto FR, Silva IAB (2001) The use of ultrasound for cleaning the surface of stainless steel and nickel-titanium endodontic instruments. International Endodontic Journal 34, 581-5.
Thompson SA (2000) An overview of nickel-titanium alloys used in dentistry. International Endodontic Journal 33, 297-310.