STEALTHAUTHENTIFICATION USING RANGE OF RADIO FREQUENCY TRANSPONDER IN THE ENDODONTIC SPACE

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INTRODUCTION: In recent years, automatic identification procedure (Auto-ID) has become very popular in many service industry, merchandise and distribution logistic, finance, transport and medical system. Auto-ID exists to provide information about people, animal, goods and procedure in transit. One of the technically optimal solutions of Auto-ID, using a silicon chip, has been provided as a technology of radio frequency identification (RFID). The most common form of electronic data-carrying-device in everyday life is a smart card based upon a contact field (phone card, bank card) on the data communication between host system and chip in housing of the card. Now an integrated design of contactless data transfer between the device and its reader is more flexible. In the ideal case, the power required to operate the electronic microchip in the card would also be transferred from the reader using contactless technology. This contactless system used for the transfer of power and data is cal … More led RFID. METHODS: Ten extracted human third molar teeth free from dental caries were used to encapsulate RFID transponders. Fifteen cylindrical transponders (o. d. 3 mm, length 13 mm) using a medium wave frequency (125 kHz Emfreccia ONMETALTM, Mitsubishi Materials, JAPAN) were tested. The endodontic cavity, including the coronal chamber and root canal of each tooth, was prepared to fit the cylindrical core of the RFID from the coronal side of the tooth. Volume expansion of cavity in the tooth and decrease of the dentin thickness might result in significant reduction of facility as a radio frequency shield. Dentin thickness of 3mm was preserved to allow functioning as a barrier for radio frequency between the transponder and the reader. Three acrylic cylinders (ψ10×22 mm) were used as controls in which co-axial holes (diameter: 3mm, depth: 13mm) were drilled to fit for the transponders. A reader (EmfrecciaTM, Mitsubishi Materials) that communicated with the transponder enclosed in dentin was located on the extension line of the tooth axis, because these tags had sharp directionality for communication with the reader along the cylindrical shaft direction. The tooth was held with a plastic clamp attached to a carriage in longitudinal axis direction. The maximum communication range was measured with establishment of the data transfer by a utility program for IBM-PC compatible via RS-232-C serial interface. RESULTS: The mean communication distance of unencapsulated RFID transponders was 18.6±1.7mm (n=15), while the mean ranges in RFID transponders encapsulated with acrylic materials (control) or teeth were 18.1±1.6 mm (n=45) and 17.8±1.7mm (n=150), respectively. The percentages of the range compared with the unencapsulated were 97.3±1.6% and 94.6±1.9%, respectively. No statistical significant difference under these conditions could be observed. The actual decrease of communication distance under dentin encapsulated conditions was very small (5.4%). DISCUSION: The RFID tag, holding ID information attached to the wristband, has already been carried out for a swift identification of inpatients. But continuous wearing of a wristband may induce physical and mental stress in some patients. The method embedding the RFID in the tooth might disengage the patients from the stress by the wristband. However, the contrivance to exclude psychological pressure on recipient in using the embedded RFID, such as placing the detector close to the embedded position in the human body, should be elaborated. Embedded ID into oral cavity could be apply to a mobile phone in combination with a RFID reader. This engineering system is called 'stealth identification' that utilizes communication equipment such as a mobile phone. In most of the voice communications, the distance between the face and the handset is relatively small. When the handset equips RFID reader, the identification can be established by detecting the RFID during the phone usage. It would be difficult to detect existence of the RFID transponder in the oral cavity. Furthermore, it seems almost impossible to distinguish voice communication from the identification process using the RFID in a tooth by the third party. The invisible method is relatively safe to hide the existence of imbedded RFID from malicious purpose. This contributes to the protection of individual privacy. The patient has little physical and mental restrain. CONCLUTION: The insulation effect of the tooth had small enough to allow for the penetration of the signal of the medium frequency band. Less