Periodontal Measurement Accuracy and Reliability Using Intraoral Ultrasound

Intraoral ultrasonography (iUS) has emerged as a noninvasive, radiation-free imaging modality capable of real-time visualization of both soft and hard tissues, yet its clinical accuracy and reliability remain incompletely characterized. This study aims to evaluate the accuracy and reliability of periodontal parameters measured on intraoral ultrasonograms. An in-house customized 20-MHz ultrasound imaging system with a rotational head was used to image the periodontium. Ex vivo accuracy was assessed in 58 teeth from 3 cadaver specimens with high-resolution micro-computed tomography (µCT) as the gold standard. Two raters independently performed repeated measurements of alveolar bone level (ABL) and alveolar bone thickness (ABT) on 50 iUS images using a standardized anatomy-guided protocol. Intermethod agreement was quantified using intraclass correlation coefficients (ICCs), mean absolute differences (MADs), paired t tests, and Bland-Altman analysis. In vivo clinical reliability was evaluated in 19 adolescents undergoing orthodontic treatment, with 3 raters measuring the ABL, ABT, attached gingival thickness, and free gingival thickness on 134 iUS images. Ex vivo analysis demonstrated excellent iUS accuracy and consistency for ABL (MAD 0.18-0.31 mm, ICCs 0.94-0.96) and excellent accuracy and good agreement for ABT (MAD 0.05 mm; ICCs 0.87). Paired t tests revealed no significant differences between iUS and µCT measurements for either parameter (all P > 0.05). Bland-Altman analysis demonstrated excellent agreement with near-zero bias for both ABL and ABT, with narrow 95% limits of agreement across raters. In vivo measurements exhibited outstanding intrarater reliability (ICCs ≥ 0.84; MAD ≤ 0.10 mm) and good-to-excellent interrater reliability (ICCs ≥ 0.82; MAD ≤ 0.18 mm) for all parameters. The standardized, anatomy-guided protocol minimized operator dependency, enabling reproducible assessments across raters. These results demonstrate that iUS provides highly reproducible and reliable periodontal measurements in cadavers and healthy adolescents. Further studies in patients with moderate-to-severe periodontal disease are required to fully validate iUS for longitudinal monitoring.