Avoiding the Alveolar Nerve Via a Real-Time Impedance Analysis: A Novel Method to Improve Implant Surgery Safety

Journal of Medical Devices, vol. 14

Abstract

Abstract Safe lower jaw implantations require precautions to avoid damaging the alveolar nerve. The prevailing methods are preoperative. In this study, we propose a novel approach to measure the distance between a pilot-drill and the alveolar nerve by employing high-frequency impedance measurements. The objective is to provide in vivo real-time information as an early warning of the proximity of the alveolar nerve. The method is examined and tested on animal samples. The impedance measurements were performed using a high-frequency network analyzer. Overall 40 pilot drillings were distributed over five sheep mandibles, with four on each side. Drillings were performed in three steps: inside the cortical layer, inside the spongiosa, and well inside the nerve canal. The inductance measurements were performed with a connected pilot drill, followed by an immediate 3D cone-beam computed tomography (CT) to measure the distance between the tip of the drill and the nerve canal. The measurements show that impedance information is a reliable indicator for proximity of the drill to the nerve. We observe a general trend of decreasing inductance as the drill approaches the nerve and find that at very high frequencies one can detect the closeness to the nerve from characteristic ratios of impedance at nearby frequencies. We report also that using phase information increases the reliability of this method. The findings provide a solid proof of concept for the proposed method. While the results are promising at this stage, the applicability for in vivo conditions requires further studies.

Authors 5

1. Georg Schiffers Aachen Department of Oral and Maxillofacial Surgery

   RWTH Aachen University

   Affiliation as printed

   Department of Oral and Maxillofacial Surgery, RWTH Aachen University, Pauwelsstrasse 3, Aachen, Nordrhein-Westfalen DE 52074, Germany

2. Julian Arnold Aachen Institute for Networked Systems (INETS)

   RWTH Aachen University

   Affiliation as printed

   Institute for Networked Systems, RWTH Aachen University, Aachen, Nordrhein-Westfalen 52072, Germany

3. Alexander Karl-Heinz Bartella

   University Hospital Leipzig

   Affiliation as printed

   Department for Cranio-Maxillofacial and Plastic Facial Surgery, University Hospital Leipzig, Leipzig, Sachsen 04103, Germany

4. Petri Mähönen Aachen Faculty of Electrical Engineering and Information Technology Institute for Networked Systems (INETS)

   RWTH Aachen University

   Affiliation as printed

   Faculty of Electrical Engineering and Information Technology, Institute for Networked Systems, RWTH Aachen University, Aachen, Nordrhein-Westfalen 52072, Germany

5. Bernd Lethaus Aachen Department of Oral and Maxillofacial Surgery

   RWTH Aachen University · University Hospital Leipzig

   Affiliation as printed

   Department of Oral and Maxillofacial Surgery, RWTH Aachen University, Pauwelsstrasse 3, Aachen, Nordrhein-Westfalen DE 52074, Germany; Department for Cranio-Maxillofacial and Plastic Facial Surgery, University Hospital Leipzig, Liebigstraße 12, Haus 1, Leipzig, Sachsen 04103, Germany