Comparative morphometric characteristics of the working surface of endodontic rotary nickel-titanium instruments after maximum cyclic loading

Aim. Is the morphometric analysis of the working surfaces of endodontic rotating nickel-titanium instruments.

Materials and methods. The chemical composition and physical properties of the three types of endodontic rotating nickel-titanium F2 instruments have been analyzed: proptaper Universal (PTu, Dentsply, Maillefer, Ballaigues, Switzeland), Ultrataper (Eurofile, China) and Superfile (Eurofile, China) protapers. The evaluation of endodontic treatment of 75 endoblocks was also carried out.

Results. The research work shows that endodontic rotary instruments have both different chemical composition and heterogeneity of the alloy. The average comparable percentage of titanium and nickel in the studied alloy samples has been revealed. The quality of endodontic treatment of the endoblocks’ channels with various rotating nickel-titanium instruments is also comparable and meets the specified criteria.

Conclusion. The morphometric analysis has revealed a difference in the structure of the metal alloy of the F2 protapers, with a comparable content of nickel (46-52%) and titanium (38-41%). The content of pure nickel-titanium alloy along the periphery of the endodontic instrument in Universal protapers ensures high cutting ability of the faces. The obtained data on different resistance to cyclic loads should be taken into account in the endodontic treatment of multi-root teeth. The analysis of the structure of the nickel-titanium alloy indicates the predetermination of the development of the tool’s fracture with prolonged use and the need to take into account the cycles of the endodontic rotary tool.

1. A. Skriabina. Comparative characteristics of resistance to cyclic loads. Protaper universal, superfile and ultrataper Mechnikov Readings 2020. Materials of the 93rd All-Russian Scientific and Practical Student Conference with international participation, St. Petersburg, April 29-30, 2020 / Ministry of Health of the Russian Federation, Federal State Budgetary Educational Institution of Higher Education, Northwestern State Medical University named after I.I. Mechnikov. St. Petersburg: I.I. Mechnikov Northwestern State Medical University; 2020: 489.

2. T.N. Manak, V.G. Devyatnikova. Experimental study of physical and mechanical properties of nickel-titanium rotary endodontic instruments. Topical issues of prevention, diagnosis and treatment of dental diseases. Collection of scientific papers of the Republican Scientific and Practical conference with international participation dedicated to the 20th anniversary of the 2nd Department of Therapeutic Dentistry of the Belarussian State Medical University and Professor Peter A. Leus’s anniversary. Under the general editorship of T.N. Manak, L.G. Borisenko. 2018. P. 91-95.

3. A.V. Mitronin, Yu.A. Ostanina, Yu.A. Mitronin. Morphometric analysis of the working surface of the group instruments after dissection of the root canal of Endodontija Today, 2019;17(2):9-16.

4. K.A. Nevstruyev. Assessment of the "fatigue" of nickel-titanium tools during operation. Derzhavinsky Forum, 2019; 3(12):187-197.

5. Nickel-titanium instrument of the 5th Generation – an innovative approach to the mechanical treatment of root canals, clinical capabilities, work protocol and comparative characteristics of the instrument (clinical review). B.R. Shumilovich, V.V. Rostovtsev, L.M. Adunts, R.V. Selin. Success of modern science. 2017;1(6):67-74.

6. N.A. Sobkina. Analysis of the quality of preparation of root canals of teeth with endodontic instruments of the ProTaper system Russian dentistry. 2018;3:49-52.

7. A.S. Topunova. The experience of using rotating tools [Text] / A.S. Topunova // Bulletin of the Council of Young scientists and Specialists of the Chelyabinsk region. 2017;3(18):183-187.

8. V.E. Statkevich. Comparative characteristics of methods of instrumental treatment of the root canal. Trends of the development of science and education. 2018;45(7):56-57.

9. Analysis of structural features of ni-ti instruments after their fracturing. T.O. Paderina. Book: Mechnikov Readings-2020. Materials of the 93rd All-Russian Scientific and Practical Student Conference with international participation. Ministry of Health of the Russian Federation, Federal State Budgetary Educational Institution of Higher Education, the Northwestern State Medical University named after I.I. Mechnikov. 2020:470.

10. Zafar MS. Impact of Endodontic Instrumentation on Surface Roughness of Various Nickel-Titanium Rotary Files. Eur J Dent. 2021 May;15(2):273-280.

11. Barbara Müller. The advent of the nickel-titanium alloy in endodontics has significantly expanded the possibilities of machining the canal with a flexible instrument with shape memory. Dental Tribune. May 24, 2016.

12. Ni-Ti Rotary instrument fracture analysis after clinical use. Structure changes in used instruments , T Stefanescu , April 2016, Environmental Engineering and Management Journal 15(5):981-988. Various heat-treated nickel–titanium rotary instruments evaluated in S-shaped simulated resin canals

13. Gu Y, Kum KY, Perinpanayagam H, Kim C, Kum DJ, Lim SM, Chang SW, Baek SH, Zhu Q, Yoo YJ. Various heat-treated nickel-titanium rotary instruments evaluated in S-shaped simulated resin canals. J Dent Sci. 2017 Mar;12(1):14-20. doi: 10.1016/j.jds.2016.04.006

14. Gutmann JL, Gao Y. Alteration in the inherent metallic and surface properties of nickel-titanium root canal instruments to enhance performance, durability and safety: a focused review. Int Endod J. 2012 Feb;45(2):113-28. doi: 10.1111/j.1365-2591.2011.01957.x.

15. Zupanc J, Vahdat-Pajouh N, Schäfer E. New thermomechanically treated NiTi alloys – a review. Int Endod J. 2018 Oct;51(10):1088-1103. doi: 10.1111/iej.12924.