Ultrasound detection of submerged dental implants through soft tissue in a porcine model.

STATEMENT OF PROBLEM Current methods of measuring soft tissue thickness over potential dental implant sites and locating submerged implants may be imprecise or invasive. PURPOSE The purpose of this study was to develop and demonstrate proof of the concept of a customized ultrasound imaging system in locating and measuring the depth of implants submerged beneath soft tissue. MATERIAL AND METHODS A complete ultrasound system, including a customized soft tissue-matched transducer, transceiver, and digital signal processing algorithms, was created for the specific application of detecting dental implants anchored in bone beneath soft tissue. The system was used to locate implants placed in cancellous bone and measure overlying soft tissue depth in a porcine model. Ten measurements were made on each porcine model by manually moving the transducer laterally over the soft tissue surface. Data were analyzed with descriptive statistics. RESULTS The mean signal-to-noise ratio, SNR (standard deviation), from the bone surfaces, was 19.1 (4.6) dB, and the mean SNR from the implant surfaces was 36.6 (2.2) dB, resulting in a mean difference of 17.5 dB, or x56.2, in average signal power between the bone and implant surfaces. Consequently, implants were easily and accurately (+/-0.2 mm) located beneath at least 5 mm of soft tissue. Likewise, soft tissue depths over bone and implants were accurately measured and were within the corresponding caliper tissue measurement error (+/-0.5 mm). CONCLUSIONS The specialized ultrasound imaging system located and measured the depth of implants placed in bone submerged beneath soft tissue in a porcine model.