Periodontal Ultrasonic Measurement using a 20MHz High-Frequency Probe

Objectives: Ultrasonography has been extensively developed as a non-invasive diagnostic tool in a number of medical fields. In periodontology, several reports are now available for the ultrasonic measurement of tissue thickness, but a limitation for clinical use has been also indicated. That is, a size and sterility of ultrasound probe still remains to be resolved prior to the clinical application in patients. The aim of this study was to develop a small ultrasound probe including a single transducer that could be handle anywhere in the oral cavity, and to compute the gingival thickness from the echo pulse derived at the alveolar bone surface. Methods: The ultrasonic investigation was carried out in ten subjects diagnosed as chronic periodontitis (30-82 years old) after obtaining the informed consent. A newly developed probe assembly with a 2mm diameter of attached portion was driven with the pulsar receiver (Model 5077PR, Panametrics) connected with PC components. The detected sound waveform signal was automatically processed and calculated intensities and delays from the extracted echo spikes. High frequency, ultrasound source (20 MHz) via sterilized intermediate material was applied to the maxillary gingiva of subjects at the labial and palatal surface. Results: The average value of the intensity (V) and delay (µs) of the echo on the labial gingiva was 23.8±20.3V and 1.43±0.29 µs, respectively. The echo on the palatal papilla was significantly attenuated (5.4±2.3V, p<0.05) and delayed (3.99±0.66µs, p<0.001) as compared to that on labial (by one-way ANOVA). The clear echo spike from the interface between the gingival and bone was detected, and the intensity was affected by gingival thickness. Residual gingival inflammation influenced the thickness to emerge the delay and attenuation of the conducted echo. Conclusion: High-frequency ultrasonic detection could be applicable for the diagnosis of periodontal diseases. Supported by the Grant-in-aid from JSPS (No.19659456).