Performance Evaluation of a Miniaturized, Toothbrush-Shaped Ultrasound Transducer for Periodontal Imaging

A miniature, high-frequency ultrasound transducer could have major value in dentistry and periodontal care. Still, most current ultrasound transducers use large form factors, which limit access to molars and premolars. This paper reports a compact side-facing, toothbrush-shaped ultrasound transducer with a portable handle for real-time imaging of anatomical structures. The 128-element, high-frequency (40 MHz) response of the transducer was utilized to characterize the axial and lateral resolution at 2-16 mm depths, as well as the impact of angulation. The mean axial and lateral resolutions were 49 ± 15 μm and 149 ± 21 μm, respectively. The impact of angulation on imaging quality was evaluated. An acceptable angular window of -15° to +20° in the roll and pitch axes was found to produce correct anatomical information. Angulation in the yaw axis loses control over the reference plane. The transducer soft tissue-related measurements (gingival thickness and gingival height) correlated with the gold-standard clinical measurements. The correlation coefficients, <i>r</i> = 0.7243 (<i>p</i> = 0.0001) for gingival thickness and 0.7886 (<i>p</i> < 0.0001) for gingival height, show a strong correlation with the clinical method. The Bland-Altman plot compared ultrasound imaging and manual periodontal probe measurements indicated a bias of -0.002 mm and -0.0263 mm, respectively, for gingival thickness and height, with a 95% limit of agreement. The miniaturized high-frequency transducer offers optimal adaptation to the tooth surface with a wide range of working axes, providing high-resolution and detailed ultrasound images for real-time scans of the periodontium.