The System for Root Canal Length Measurement Based on Multifrequency Impedance Method

Authors: Zheng Zhang, Xin Chen, Guoqing Ding

Abstract:

Electronic apex locators (EAL) has been widely used clinically for measuring root canal working length with high accuracy, which is crucial for successful endodontic treatment. In order to maintain high accuracy in different measurement environments, this study presented a system for root canal length measurement based on multifrequency impedance method. This measuring system can generate a sweep current with frequencies from 100 Hz to 1 MHz through a direct digital synthesizer. Multiple impedance ratios with different combinations of frequencies were obtained and transmitted by an analog-to-digital converter and several of them with representatives will be selected after data process. The system analyzed the functional relationship between these impedance ratios and the distance between the file and the apex with statistics by measuring plenty of teeth. The position of the apical foramen can be determined by the statistical model using these impedance ratios. The experimental results revealed that the accuracy of the system based on multifrequency impedance ratios method to determine the position of the apical foramen was higher than the dual-frequency impedance ratio method. Besides that, for more complex measurement environments, the performance of the system was more stable.

Keywords: Root canal length, apex locator, multifrequency impedance, sweep frequency.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.2021947

References:

[1] M. H. Nekoofar, M. M. Ghandi, S. J. Hayes, and P. M. Dummer, “The fundamental operating principles of electronic root canal length measurement devices,” Int Endod J, vol. 39, no. 8, pp. 595–609, 2006.
[2] M. Gordon and N. Chandler, “Electronic apex locators,” International endodontic journal, vol. 37, no. 7, pp. 425–437, 2004.
[3] A. Katz, A. Tamse, and A. Y. Kaufman, “Tooth length determination: a review,” Oral surgery, oral medicine, oral pathology, vol. 72, no. 2, pp. 238–242, 1991.
[4] N. McDonald and E. J. Hovland, “An evaluation of the apex locator endocater,” Journal of endodontics, vol. 16, no. 1, pp. 5–8, 1990.
[5] V. S. Cox, C. E. Brown, S. L. Bricker, and C. W. Newton, “Radiographic interpretation of endodontic file length,” Oral Surgery, Oral Medicine, Oral Pathology, vol. 72, no. 3, pp. 340–344, 1991.
[6] A. F. Fouad and L. C. Reid, “Effect of using electronic apex locators on selected endodontic treatment parameters,” J Endod, vol. 26, no. 6, pp. 364–7, 2000.
[7] I. Sunada, “New method for measuring the length of the root canal,” Journal of Dental Research, vol. 41, no. 2, pp. 375–387, 1962.
[8] M. Kosaka, M. Nemoto, Y. Kawaguchi, and H. Horiuchi, “Electrical characteristics of apparatus to determine the working length of the root canal, japan,” J. Conserv. Dent, vol. 22, no. 3, pp. 599–607, 1979.
[9] J. Ushiyama, “New principle and method for measuring the root canal length,” Journal of Endodontics, vol. 9, no. 3, pp. 97–104, 1983.
[10] C. Kobayashi, “Electronic canal length measurement,” Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology and Endodontics, vol. 79, no. 2, pp. 226–231, 1995.
[11] C. Kobayashi and H. Suda, “New electronic canal measuring device based on the ratio method,” Journal of endodontics, vol. 20, no. 3, pp. 111–114, 1994.
[12] H. Ounsi and A. Naaman, “In vitro evaluation of the reliability of the root zx electronic apex locator,” International endodontic journal, vol. 32, no. 2, pp. 120–123, 1999.
[13] P. White, B. Austin, H. Walia, and V. Dhuru, “Comparison of accuracy of four apex locators,” J Endod, vol. 22, p. 216, 1996.
[14] R. J. Czerw, M. S. Fulkerson, J. C. Donnelly, and J. O. Walmann, “In vitro evaluation of the accuracy of several electronic apex locators,” Journal of endodontics, vol. 21, no. 11, pp. 572–575, 1995.
[15] R. Ali, N. C. Okechukwu, P. Brunton, and B. Nattress, “An overview of electronic apex locators: part 2,” Br Dent J, vol. 214, no. 5, pp. 227–31, 2013.
[16] E. K. Stober, F. Duran-Sindreu, M. Mercade, J. Vera, R. Bueno, and M. Roig, “An evaluation of root zx and ipex apex locators: an in vivo study,” J Endod, vol. 37, no. 5, pp. 608–10, 2011.
[Online]. Available: https://www.ncbi.nlm.nih.gov/pubmed/21496657
[17] A. R. Welk, J. C. Baumgartner, and J. G. Marshall, “An in vivo comparison of two frequency-based electronic apex locators,” Journal of Endodontics, vol. 29, no. 8, pp. 497–500, 2003.
[18] I. Guyon and A. Elisseeff, “An introduction to variable and feature selection,” Journal of machine learning research, vol. 3, no. Mar, pp. 1157–1182, 2003.
[19] J. N. Martins, D. Marques, A. Mata, and J. Carames, “Clinical efficacy of electronic apex locators: systematic review,” J Endod, vol. 40, no. 6, pp. 759–77, 2014.
[20] B. C. Vasconcelos, M. Bueno Mde, S. M. Luna-Cruz, M. A. Duarte, and C. A. Fernandes, “Accuracy of five electronic foramen locators with different operating systems: an ex vivo study,” J Appl Oral Sci, vol. 21, no. 2, pp. 132–7, 2013.
[21] S. Nawab, M. J. A. RANA, and A. YAR, “Comparative evaluation of working length with digital radiography and third generation electronic apex locator,” Pakistan Oral & Dental Journal, vol. 36, no. 2, 2016.