A Wearable Cellulose Acetate-Coated Mouthguard Biosensor for In Vivo Salivary Glucose Measurement.

In this study, a cellulose acetate (CA) membrane is formed as an interference rejection membrane on a glucose sensor to measure glucose in saliva. Glucose in saliva is successfully measured in vivo without any pretreatment of human saliva. A mouthguard (MG) glucose sensor is developed to monitor salivary glucose, which is reported to be correlated with the blood glucose level. Salivary components of ascorbic acid (AA) and uric acid (UA) hinder the accurate measurement of the glucose concentration of human saliva. CA-coated electrodes are prepared to investigate the interference rejection membrane. To measure hydrogen peroxide, which is a reaction product of glucose oxidase, effects of AA and UA are examined. Characteristics of the fabricated biosensor are examined on the basis of artificial saliva. The as-developed MG sensor can quantify the glucose concentration in the range of 1.75-10 000 µmol/L, which includes a salivary sugar concentration of 20-200 µmol/L. For the measurement of saliva samples collected from healthy subjects, the output corresponding to the concentration is confirmed; this suggests the possibility of glucose measurement. This MG glucose sensor can provide a useful method for the unrestricted and noninvasive monitoring of saliva glucose for the management of diabetes patients.

Measuring system for an attitude angle of a denture using an Inertial Measurement Unit.

PURPOSE: The aim of this study was to assemble and verify a measuring system for 3-D movements (attitude angle) of the denture during function. METHODS: For the calibration test, the sensor was fixed at the center of the rotary table. Operation and stopping of the rotary table were repeated 8 times, and the direction of rotation was reversed in the middle. The amount of rotation was 1.2 and 2.4°. As a pilot clinical trial, the attitude angles of three upper complete dentures during tapping were measured by this system. RESULTS: The attitude angles calculated by this system reduced by 3-4%. Pitch and roll of Subject III were significantly larger than Subjects I and II (P<0.001), but yaw of Subject: III was significantly smaller than Subject: II (P<0.01) during tapping. Pitch and yaw of "good" was significantly smaller than "average" in the stability of the dentures (P<0.001). But roll of "average" was significantly smaller than "good" (P<0.05). Pitch and yaw of "B" was significantly smaller than "C" in the type of maxillary ridge (P<0.001). But roll of "C" was significantly smaller than "B" (P<0.05). CONCLUSIONS: The measurement accuracy of this system was equivalent to that of 3-D motion capture system by four infrared TV cameras. The measuring system using the IMU is reliable and easy to analyze the attitude angle of the denture during function. It may serve a diagnostic appliance to evaluate the quality of the denture.

Mouthguard biosensor with telemetry system for monitoring of saliva glucose: A novel cavitas sensor.

We develop detachable "Cavitas sensors" to apply to the human oral cavity for non-invasive monitoring of saliva glucose. A salivary biosensor incorporating Pt and Ag/AgCl electrodes on a mouthguard support with an enzyme membrane is developed and tested. Electrodes are formed on the polyethylene terephthalate glycol (PETG) surface of the mouthguard. The Pt working electrode is coated with a glucose oxidase (GOD) membrane. The biosensor seamlessly is integrated with a glucose sensor and a wireless measurement system. When investigating in-vitro performance, the biosensor exhibits a robust relationship between output current and glucose concentration. In artificial saliva composed of salts and proteins, the glucose sensor is capable of highly sensitive detection over a range of 5-1000µmol/L of glucose, which encompasses the range of glucose concentrations found in human saliva. We demonstrate the ability of the sensor and wireless communication module to monitor saliva glucose in a phantom jaw imitating the structure of the human oral cavity. Stable and long-term real-time monitoring (exceeding 5h) with the telemetry system is achieved. The mouthguard biosensor will be useful as a novel method for real-time non-invasive saliva glucose monitoring for better management of dental patients.

Adhesive Approach Using Internal Coping for Vertical Root Fractured Teeth with Flared Root Canals.

Vertical root fractures are often observed in teeth with endodontic treatment and post space preparation. Frequently, because such teeth have flared root canals with thin dentin walls, conventional treatments are disadvantageous in terms of adhesiveness, sealability and risk of refracture. Here we devised an intentional replantation method that uses internal resin coping, with a reinforcing effect on thin root canal dentin. In two patients treated with this method, satisfactory conditions have been maintained. This report suggests that an intentional replantation method in which an internal resin coping is employed may be a useful therapy for fractured teeth with flared root canals.

Effect of denture adhesive on stability of complete dentures and the masticatory function.

This study examines the effects of denture adhesive on the retention and stability of complete dentures and the masticatory function. The authors estimated the stability of complete dentures from 3-dimensional (3-D) denture movement and rotational denture movement and additionally the masticatory function from cycle time and chewing time. Six edentulous subjects who participated in this study had old and newly fabricated complete dentures. Upper denture movement was recorded using a 3-D motion capture system while chewing 3 kinds of food (peanuts, fish paste, raisins). Both the new and old dentures showed that using a denture adhesive contributes to reducing 3-D denture movement, rotational denture movement and chewing time during chewing the various foods. The cycle time in new and old dentures was statistically unaffected by applying denture adhesive. There was no statistically significant difference in improvement in 3-D denture movement or rotational denture movement between the new and old dentures, for any of the foods. This study observes the overall effect of denture adhesive during use for both dentures. The results of this study suggest that denture adhesive contributes to reducing denture movement and so improves chewing function.

[Fundamental study on the development of a measuring device using an accelerometer].

It is important to clarify stomatognathic functions. To diagnose them, some measuring devices, such as MKG and the Gnatho-hexagraph, were developed. Such equipment, however, is not widely diffused, due to cost. The purpose of this fundamental study was to obtain information on position using an accelerometer. This system consists of a micro dual-axis accelerometer and a peripheral interface controller. Two-dimensional acceleration, velocity, and movement can be calculated by a computer. We examined the accuracy of this system using a laser measuring device. The result was as follows: The accuracy of the system was 0.03 (p-p values) using acceleration of gravity and a frequency of 72.5 Hz. In the present study, mandibular movements during chewing raisins were analyzed using this system. The new system demonstrated its value for analyzing mandibular movements.