A Potential Solution to Minimally Invasive Device for Oral Surgery: Evaluation of Surgical Outcomes in Rat

Hindawi Publishing Corporation Journal of Nanomaterials Volume 2015, Article ID 481854, 7 pages http://dx.doi.org/10.1155/2015/481854 Research Article A Potential Solution to Minimally Invasive Device for Oral Surgery: Evaluation of Surgical Outcomes in Rat Keng-Liang Ou,1,2,3,4 Li-Hsiang Lin,2,5 Hsi-Jen Chiang,1,2,5 Han-Yi Cheng,1,2,3 Shyuan-Yow Chen,6 and Chiung-Fang Huang2,7 1 Graduate Institute of Biomedical Materials and Tissue Engineering, Taipei Medical University, Taipei 110, Taiwan Research Center for Biomedical Devices and Prototyping Production, Taipei Medical University, Taipei 110, Taiwan 3 Research Center for Biomedical Implants and Microsurgery Devices, Taipei Medical University, Taipei 110, Taiwan 4 Department of Dentistry, Taipei Medical University-Shuang Ho Hospital, Taipei 235, Taiwan 5 School of Dentistry, College of Oral Medicine, Taipei Medical University, Taipei 110, Taiwan 6 Division of Periodontics, Department of Dentistry, Cathay General Hospital, Daan District, Taipei 106, Taiwan 7 School of Dental Technology, College of Oral Medicine, Taipei Medical University, Taipei 110, Taiwan 2 Correspondence should be addressed to Chiung-Fang Huang; Received 21 December 2014; Accepted 10 March 2015 Academic Editor: Abdelwahab Omri Copyright © 2015 Keng-Liang Ou et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The objective of the present research was to investigate the thermal injury in the brain after minimally invasive electrosurgery using instruments with copper-doped diamond-like carbon (DLC-Cu) surface coating. The surface morphologies of DLC-Cu thin films were characterized using scanning electron microscopy and atomic force microscopy. Three-dimensional brain models were reconstructed using magnetic resonance imaging to simulate the electrosurgical operation. In adult rats, a monopolar electrosurgical instrument coated with the DLC-Cu thin film was used to generate lesions in the brain. Animals were sacrificed for evaluations on postoperative days 0, 2, 7, and 28. Data indicated that the temperature decreased significantly when minimally invasive electrosurgical instruments with nanostructure DLC-Cu thin films were used and continued to decrease with increasing film thickness. On the other hand, the DLC-Cu-treated device created a relatively small thermal injury area and lateral thermal effect in the brain tissues. These results indicated that the DLC-Cu thin film minimized excessive thermal injury and uniformly distributed the temperature in the brain. Taken together, our study results suggest that the DLC-Cu film on copper electrode substrates is an effective means for improving the performance of electrosurgical instruments. 1. Introduction In recent years, there has been considerable concern over the application of electrosurgical instruments in dental surgery. Thermal damage to tissues surrounding the surgical sites is a critical challenge in clinical operations [1–3]. Various methods have been reported to reduce thermal damage caused by electrosurgical instruments, although other evidences indicate that minimally invasive electrosurgery can cause serious injuries to surrounding organs/tissues such as the blood vessels and nerves [4]. The interface between the minimally invasive electrosurgical needle and the tissue is an important factor for reducing thermal injury, but related experimental and mathematical studies are scarce. To investigate the thermal damage caused by minimally invasive electrosurgical instruments, the maximum temperatures and dimensions of the surgical region must be determined. Finite element method (FEM) is a useful tool for examining the temperature distributions in the tissues surrounding the surgery site including brain tissue [5, 6], and it has been previously used to study biomechanical operations in different medical fields using various boundary parameters [7– 10]. In addition, the three-dimensional (3D) FEM has been widely used for the thermal analysis of minimally invasive electrosurgical instruments [11], to investigate the thermal damage to tissues during clinical surgery. Therefore, this method was adopted to investigate and compare the thermal 2 diffusion and tissue injury by novel copper-doped diamondlike carbon (DLC-Cu) coated electrosurgical instruments. The aim of the present study was to investigate the thermal damage using finite element analysis (FEA) in a rat model of thermal injury. The surface of the electrosurgical instruments was coated with diamond-like carbon using nanostructure surface treatment (DLC-Cu). It was anticipated to reduce the thermal damage in the surrounding tissues during surgery. The nanostructured DLC-Cu surface treatment was applied to the electrosurgical instruments provided by BioEconeer Inc. because the DLC-Cu thin films provide superior physical properties, such as high thermal conductivity, low coefficient of friction, improved hardness, chemical inertness, antichemical corrosion, high impedance, and antibacterial properties [12]. Our animal model was developed to evaluate the decrease in thermal injury from the minimally invasive electrosurgical instruments coated with DLC-Cu film and further accelerate the wound healing process. 2. Materials and Methods Scanning electron microscopy (SEM; JEOL JSM-6500F, JEOL Ltd., Tokyo, Japan) and atomic force microscopy (AFM; Nanosurf-Mobile S, Nanosurf AG., Liestal, Switzerland) were employed to analyze the surface morphology and thickness of the DLC-Cu deposited instruments. The 3D finite element brain models were rebuilt using magnetic resonance images (MRI, Signa HDx 3.0T, USA). A number of images were obtained to describe the contour of the brain at different parallel surfaces. An edge detection program (AVIZO 7.2, Internet Securities, Inc.) was used to detect all the boundary components of the brain. The thermal properties of the brain tissue, DLC-Cu thin film, and AISI 304 stainless steel (the material used in making the electrosurgical instruments) have been described previously [13–16]. The thicknesses of the DLC-Cu thin films were 0 (SS), 100 (DLC-Cu-SS-1), 200 (DLC-Cu-SS-2), 300 (DLC-Cu-SS-3), 400 (DLC-Cu-SS-4), and 500 (DLC-Cu-SS-5) nanometers. The 3D reconstruction models were simulated using the ANSYS Workbench 12.1 (ANSYS, Inc., Canonsburg, PA, USA) program. The average number of nodes and number of elements in the brain models were approximately 77,000 and 42,000, respectively. The protocols for the present animal models were approved by the Institutional Animal Care and Use Committee of Taipei Medical University (LAC-101-0007). Twelve Sprague-Dawley (SD) rats (200–300 g, BioLASCO, Taiwan) were maintained according to the guidelines for the care and use of laboratory animals. Three rats each were sacrificed on day 0, day 2, day 7, and da (...truncated)