Wavelet Transforms of TM Joint Vibrations: A Feature Extraction Tool for Detecting Reducing Displaced Disks

ABSTRACT

The objective of this study was to determine if wavelet transforms (WTs) of vibrations recorded from temporomandibular joints (TMJs) with reducing displaced disks could be visually separated from WTs of vibrations recorded from normal TM joints by blinded observers. From a continuous series of 124 diagnosed TMD patients, 28 were confirmed with at least one reducing displaced disk. Vibrations were recorded from each affected joint, together with incisal point movements, using BioPAK (BioResearch, Inc., Milwaukee, Wl) during opening, closing, and lateral excursions. Identical recordings were taken from 28 patients who were determined to have normal “nondisplacing, nondisplaced” joints. A 3x7 Biorthogonal Spline Wavelet Transform was used to create three-dimensional time-frequency graphs of the vibration events for each subject. Printed copies of the graphs were then shown sequentially to seven blinded observers who were asked to separate them into two groups without any knowledge of their significance. Each observer was independently able to separate the two groups without committing more than one error. We conclude that the vibrations generated by reducing displaced disks are sufficiently different from the vibrations of normal joints to be separable by visual inspection of their respective wavelet transforms.

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Notes on contributors

John Radke

Mr. John C. Radke received his B.M. from Cornish College in Seattle, Washington and an M.B.A. from the Keller Graduate School of Management, Chicago, Illinois. From 1972 to 1983, he developed the Kinesiograph and other devices as Senior Vice President at Myo-Tronics Research, Inc. working under Dr. Bernard Jankelson. Currently, Mr. Radke is president of BioResearch Associates, Inc. in Milwaukee, Wisconsin, where he has guided their research and development efforts for the past seventeen years. He has coauthored and published numerous clinical studies utilizing jaw tracking, electromyography, and TM joint vibration analysis. Mr. Radke is considered an expert in the application of artificial intelligence to dental diagnosis.

Ralph Garcia

Dr. Ralph Garcia, Jr. received his D.D.S. degree from Emory University in 1962 and subsequently served in the U.S. Air Force, finishing as Chief of Prosthodontics at Lockbourne AFB in Ohio. He is a respected lecturer, both nationally and internationally, most notably in the areas of TMD and occlusion. In addition he regularly conducts in-house seminars in his full-time private practice in Tampa, Florida. He has published several scientific articles related to the diagnosis and treatment of specific disorders of the temporomandibular joint. Dr. Garcia is a member of the American Equilibration Society, the International College of Craniomandibular Orthopedics, and the American Academy of Craniofacial Pain. He serves as the dental consultant for temporomandibular imaging to the University of South Florida, College of Medicine.

Robert Ketcham

Dr. Robert Ketcham received his D.D.S. degree from Indiana University in 1968. In 1970 he received an M.S.D. (majoring in fixed and removable partial prosthodontics) from the same institution. He is a former assistant professor of fixed and removable prosthodontics at Indiana University and consultant in prosthodontics and TMD to the Veterans Administration Hospital in Ft. Wayne, Indiana. He has maintained a private practice limited to TMD diagnosis and treatment in Ft. Wayne since 1972. He is a member of several professional societies including the American College of Prosthodontists, the American Equilibration Society, and the International College of Dentists. Dr. Ketcham is certified by the Indiana State Board of Dental Examiners as a provider of continuing education programs. He has given numerous presentations over the past 12 years on topics related to the diagnosis and treatment of temporomandibular disorders and orofacial pain.