為了避免人工牙根碰觸下頷骨的下齒槽神經，如何辨識下齒槽神經空腔位置對於牙醫師在植牙手術中相當重要。牙醫師在術前會先拍攝一張環口片來評估缺牙情形，而環口片的影像品質會影響牙醫師判斷下齒槽神經管的位置。本研究主要建立自動偵測下齒槽神經空腔位置之影像處理方法；為了簡化影像處理流程，此方法首先偵測下頷骨下緣邊跡位置，其次設定往下頷骨內之搜尋線，然後沿著搜尋線上之灰階變化剖面，應用小波濾波方法去除雜訊；再者從第一條搜尋線上所定義之下齒槽神經空腔之下緣點資訊，應用動態邊跡追蹤方法陸續描繪出下齒槽神經管下緣位置，最後使用二次曲線擬合下緣曲線使其平滑化，並垂直上移40個像素標定上邊緣，將環口片左右兩側的下齒槽神經空腔標定出來。系統驗證是利用牙醫師所描繪的下齒槽神經空腔位置為依據，計算本研究所研發系統演算法的正確率，使用南部某醫學中心十八個案例的環口片作為測試樣本，其中可行的結果有九個案例，正確率可達79%以上。由於頭顱結構相當複雜，環口片不易偵測，未來可以使用電腦斷層影像加以改進。

In order to avoid dental implant touching the inferior alveolar nerve in the mandible, how to identify the mandibular canal is extremely important to the dentist during dental implatation. Dentist usually use the panoramic radiograph to assess the situation of missing teeth before surgery, and the image quality of panoramic radiograph will affect the dentist to determine the location of the inferior alveolar nerve canal. In this study, the major purpose is to develop an image processing method for automatic detection of the inferior alveolar nerve canals. In this proposed method, the lower edge of mandibular is firstly detected, and then the searching lines along the interior of mandible are defined. Afterwards, the wavelet-based denoising method is applied to remove the noise along the gray level profile. All the lower positions of the inferior alveolar nerve canal are traced using dynamic edge tracing. The quadratic curve fitting is employed for these traced edges. Finally, 40 pixels up in vertical direction are considered as the canal region for both the left and right sides of the inferior alveolar nerve canals. In performance analysis, the regions of the inferior alveolar nerve canal drawn manually by an experienced dentist are used as the gold standard to determine the correction rate. 18 cases of panoramic radiographs from a southern medical center are tested. For the nine feasible cases, the correction rate is over 79%. Due to the complexity of craniofacial structure, it is not easy to detect the nerve canal. In the future, this may be improved using the images obtained from the cone beam CT for dental application.

[1]. http://kidshealth.org/parent/general/body_basics/mouth_teeth.html
[2]. 中華民國生物醫學工程學會, "生物醫學工程導論," 滄海圖書, 2008
[3]. S. T. Kim, et al., "Location of the Mandibular Canal and the Topography of Its Neurovascular Structures," Journal of Craniofacial Surgery, vol. 20, pp. 936-939, 2009.
[4]. http://www.saintjosephsgammaknife.org/book/export/html/50
[5]. E. N. Marieb, J. Mallat, P. B. Wilhelm, "Human Anatomy 5th edition," Pearson Benjamin Cummings, San Francisco, 2007.
[6]. C. Kilic, K. Kamburoglu, T. Ozen, et al, "The position of the mandibular canal and histologic feature of the inferior alveolar nerve, " Clin Anat, vol. 23,pp. 34–42, 2010.
[7]. M. Naitoh, K. Nakahara, Y. Suenaga, et al, "Comparison between cone-beam and multislice computed tomography depicting mandibular neurovascular canal structures, " Oral Surg Oral Med Oral Pathol Oral Radiol Endod, vol. 109, pp. 25–31, 2010.
[8]. H. Watanabe, M. A. Mohammad, T. Kurabayashi, et al, "Mandible size and morphology determined with CT on a premise of dental implant operation, "Surg Radiol Anat, vol.32, pp.343–349, 2010.
[9]. P. Felice, G. Cannizzaro, V. Checchi, et al," Vertical bone augmentation versus 7-mm-long implants in posterior atrophic mandibles. Results of a randomised controlled clinical trial of up to 4 months after loading, "Eur J Oral Implantol, vol.2, pp.7–20, 2009.
[10]. C. A. Babbush, "Dental Implants: The Art and Science," Elsevier Science Health Science div, Philadelphia, 2001.
[11]. A. Suomalainen, I. Venta, M. Mattila, et al, "Reliability of CBCT and other radiographic methods in preoperative evaluation of lower third molars, "Oral Surg Oral Med Oral Pathol Oral Radiol Endod, vol. 109, pp.276–284, 2010.
[12]. H. Watanabe, M. A. Mohammad, T. Kurabayashi, et al, "Mandible size and morphology determined with CT on a premise of dental implant operation, "Surg Radiol Anat, vol. 32, pp.343–349, 2010.
[13]. C. Frei, et al., "Study on the necessity for cross-section imaging of the posterior mandible for treatment planning of standard cases in implant dentistry," Clinical Oral Implants Research, vol. 15, pp. 490-497, 2004.
[14]. 台北市牙科植體學學會, "3D植牙新世界," 青田設計工作室, 2008
[15]. C. Angelopoulos, et al., "Comparison Between Digital Panoramic Radiography and Cone-Beam Computed Tomography for the Identification of the Mandibular Canal as Part of Presurgical Dental Implant Assessment," Journal of Oral and Maxillofacial Surgery, vol. 66, pp. 2130-2135, 2008.
[16]. R. J. Lazzara, "Criteria for implant selection: surgical and prosthetic considerations," Pract Periodontics Aesthet Dent, Lincoln, pp. 55-62, 1994.
[17]. 總代理科聞股份有限公司, "PRODUCT CATALOG, " Biolok International Inc
[18]. C. D. R. Kalpidis and R. M. Setayesh, "Hemorrhaging Associated With Endosseous Implant Placement in the Anterior Mandible: A Review of the Literature," Journal of Periodontology, vol. 75, pp. 631-645, 2004.
[19]. L. P. Joana, P. D. Miguel, M. B. Eva, P. D. Maria, "Intraoperative complications during oral implantology," Med Oral Patol Oral Cir Bucal, vol. 13, pp. 239-243, Aprl 2008.
[20]. http://issuu.com/luc.vrielinck/docs/peri-operative-complications-luc-vrielinck
[21]. W. K. Chiu, et al., "Three-dimensional accuracy of implant placement in a computer-assisted navigation system," International Journal of Oral & Maxillofacial Implants, vol. 21, pp. 465-470, 2006.
[22]. S. Kasemsarn, et al., "Morphology of Thai edentulous mandible using 3D reverse engineering: Relevance to immediate loading dental implant design," Jsme International Journal Series C-Mechanical Systems Machine Elements and Manufacturing, vol. 49, pp. 859-864, 2006.
[23]. Y. Uchida, et al., "Measurement of anterior loop length for the mandibular canal and diameter of the mandibular incisive canal to avoid nerve damage when installing Endosseous implants in the interforaminal region," Journal of Oral and Maxillofacial Surgery, vol. 65, pp. 1772-1779, Sep 2007.
[24]. O. Trost, et al., "A simple method to locate mandibular foramen: preliminary radiological study," Surgical and Radiologic Anatomy, vol. 32, pp. 927-931, 2010.
[25]. M. R. d. O. M. R. de Oliveira, et al., "Morphometrical analysis of the human mandibular canal: a CT investigation," Surgical and Radiologic Anatomy, vol. 33, pp. 345-352, 2011.
[26]. Y. Uchida, et al., "Measurement of Anterior Loop Length for the Mandibular Canal and Diameter of the Mandibular Incisive Canal to Avoid Nerve Damage When installing Endosseous Implants in the Interforaminal Region: A Second Attempt Introducing Cone Beam Computed Tomography," Journal of Oral and Maxillofacial Surgery, vol. 67, pp. 744-750, Apr 2009.
[27]. S. Lofthag-Hansen, et al., "Cone-Beam CT for Preoperative Implant Planning in the Posterior Mandible: Visibility of Anatomic Landmarks," Clinical Implant Dentistry and Related Research, vol. 11, pp. 246-255, 2009.
[28]. Y. Uchida, et al., "Measurement of Anterior Loop Length for the Mandibular Canal and Diameter of the Mandibular Incisive Canal to Avoid Nerve Damage When installing Endosseous Implants in the Interforaminal Region: A Second Attempt Introducing Cone Beam Computed Tomography," Journal of Oral and Maxillofacial Surgery, vol. 67, pp. 744-750, 2009.
[29]. M. Naitoh, et al., "Comparison between cone-beam and multislice computed tomography depicting mandibular neurovascular canal structures," Oral Surgery Oral Medicine Oral Pathology Oral Radiology and Endodontology, vol. 109, pp. E19-E25, 2010.
[30]. N. L. Frederiksen, "Diagnostic imaging in dental implantology," Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology, vol. 80, pp. 540-554, 1995.
[31]. V. E. Rushton and K. Horner, "The use of panoramic radiology in dental practice," Journal of Dentistry, vol. 24, pp. 185-201, 1996.
[32]. P. D. Allen, et al., "Detecting Reduced Bone Mineral Density From Dental Radiographs Using Statistical Shape Models," Information Technology in Biomedicine, IEEE Transactions on, vol. 11, pp. 601-610, 2007.
[33]. K. Shinjo, et al., "Improvement of the detection method for carotid artery calcification in dental panoramic radiographs," in Intelligent Signal Processing and Communication Systems, 2009. ISPACS 2009. International Symposium on, 2009, pp. 119-122.
[34]. Neng-Yuh Zhou, Using active contour model to detect the path of teeth root tube in panoramic X-ray Film, Master thesis, Institute of Biomedical Engineering, National Cheng Kung University, 2004.
[35]. T. Kondo, et al., "Computer-based extraction of the inferior alveolar nerve canal in 3-D space," Computer Methods and Programs in Biomedicine, vol. 76, pp. 181-191, 2004.
[36]. S. Sotthivirat and W. Narkbuakaew, "Automatic detection of inferior alveolar nerve canals on CT images," in Biomedical Circuits and Systems Conference, 2006. BioCAS 2006. IEEE, 2006, pp. 142-145.
[37]. N. L. Gerlach, et al., "Reproducibility of 3 Different Tracing Methods Based on Cone Beam Computed Tomography in Determining the Anatomical Position of the Mandibular Canal," Journal of Oral and Maxillofacial Surgery, vol. 68, pp. 811-817, 2010.
[38]. K. Gyehyun, et al., "Automatic Extraction of Inferior Alveolar Nerve Canal Using Feature-Enhancing Panoramic Volume Rendering," Biomedical Engineering, IEEE Transactions on, vol. 58, pp. 253-264, 2011.
[39]. M. Nixon, A. Aguado, Feature Extraction & Image Processing, Elsevier Ltd., 2008.
[40]. S. Mallat, "A Theory for Multiresolution Signal Decomposition: The Wavelet Representation, " IEEE Transactions on Pattern Analysis and Machine Intelligence, vol. 11, no. 7, July 1989.
[41]. D. J. Withey, et al., "Dynamic edge tracing: Boundary identification in medical images," Computer Vision and Image Understanding, vol. 113, pp. 1039-1052, 2009.
[42]. Y. Yuan, C. Zhong, X. Qin, "Application of wavelet transform in 3D medical images segmentation, " Mini-Microsystems, vol.24, pp.1081-1083, June 2003.
[43]. Y. Wang, J. Zheng, H. Zhou, L. Shen, "Medical image processing by denoising and contour extraction, " International Conference, pp.618-623, June 2008.