High-frequency ultrasound (US-PD) and probing pocket depth (PPD) estimations were conducted in 539 teeth from 34 participants. The mean PPD was 1.83 ± 0.55 mm, and US-PD was 1.86 ± 0.64 mm. The mean absolute deviation was 0.54 ± 0.45 mm, mean difference based on Bland–Altman analysis was −0.03 mm, and ROC analysis showed that HFUS has a fair performance in identifying sites with ≥ 3 mm PPD, with an AUC of 0.718 (95% CI: 0.617–0.820). The prototype HFUS investigated can potentially be used for pocket assessment in buccal surfaces, with depth estimations similar to those obtained by probing. Periodontitis affects 19% of the global population and is a significant factor leading to tooth loss 1. Diagnosis includes determining clinical attachment loss (CAL), which is the sum of the probing pocket depth (PPD) and the gingival margin (GM) to cemento-enamel junction (CEJ) distance, using a periodontal probe. PPD is also relevant in periodontal follow-up, since ≥ 4 mm PPD with bleeding is associated with unstable periodontitis 2. However, these instruments are prone to error, leading to misclassification 3. Radiographic imaging is routinely used for disease diagnosis and monitoring, especially to assess interdental bone loss. However, it is hindered by limited visualization of the buccal plate, poor soft-tissue contrast, and the use of ionizing radiation. High-frequency ultrasound imaging (HFUS) enables visualization of both soft and hard periodontal tissues, positioning it as a tool with potential applications in periodontitis assessment 4-6. However, few studies have evaluated HFUS for assessing pocket depth. This study aims to compare HFUS imaging measurements of gingival pocket depth (US-PD) to PPD measurements. This case–control clinical study received ethics approval from the University of Alberta's Ethics Board (Pro00133128). Participants were recruited from the Periodontics clinic at the Myke Petryk School of Dentistry at the University of Alberta. An in-house-developed 20 MHz intraoral HFUS transducer was used for scanning, as shown in Figure 1. This prototype transducer has been validated in previous research and is described in the Appendix S1 7, 8. To compare HFUS measurements with clinical probing, three positions on the buccal surfaces of the upper and lower incisors, canines, and first premolars were selected for scanning per patient. A UNC-15 periodontal probe (Hu-Friedy Group, Chicago, IL, USA) was used to measure PPD. US-PD was measured from the GM to the base of the pocket, defined on images by contrast in echogenicity. US measurements were conducted blinded to clinical measurements. The agreement between PPD and US-PD was assessed using Bland–Altman analysis, with calculation of the 95% confidence interval and upper and lower limits of agreement (LoA). Additionally, the mean absolute deviation (MAD) and paired samples t-test were used. A receiver operating characteristic (ROC) and area under the curve (AUC) analysis were performed in the Statistical Package for the Social Sciences (SPSS, IBM, NY, USA). A minimum sample size of 34 for the paired-samples t-test was calculated using a power analysis with 80% power, an expected effect size of 0.5, and an α level of 0.05. A post hoc sample size calculated for the Bland–Altman analysis is described in the Appendix S1. A total of 539 teeth were scanned from 34 participants (18 females and 16 males, aged 23–77 years) who enrolled in this study. The mean overall measurement of PPD was 1.83 ± 0.55 mm, and US-PD was 1.86 ± 0.64 mm. The overall MAD was 0.54 ± 0.45 mm with no statistically significant difference between the two methods (p = 0.309), as described in Table 1. The mean difference was −0.03 mm, and the LoA ranged from 1.36 to −1.42 mm, indicating that 95% of the differences between the two methods lie within this range. The differences seemed evenly distributed with no proportional bias, and few values fell outside the LoA. ROC analysis showed that HFUS has a fair performance in identifying sites with ≥ 3 mm PPD, with an AUC of 0.718 (95% CI: 0.617–0.820). Given the importance of tracking subtle periodontal changes in the buccal periodontium, this project was designed to compare US-PD with PPD as an adjunctive diagnostic tool. Studies on the agreement of HFUS use in the periodontium have previously established HFUS as a reliable diagnostic tool 9, 10. In our results, Bland–Altman analyses showed that the mean bias between the two methods was less than 0.1 mm for most comparisons. The MAD between the two methods is less than 1 mm, and most differences between the measurements fell within the limits of agreement. ROC and AUC results showed fair performance of HFUS compared with PPD, suggesting clinical relevance for HFUS but indicating that the methods are not interchangeable. This study is subject to multiple limitations. Firstly, the use of a UNC-15 periodontal probe introduces measurement error, as probing depths are rounded to the nearest millimeter. Secondly, the positions of the periodontal probe and the ultrasound probe could not match precisely. Additionally, measurements were performed at multiple sites on the same individuals, resulting in clustered observations that may overestimate the precision of the tool. Finally, the current US probe is limited to imaging buccal surfaces. Therefore, these preliminary and site-specific findings should not be broadly applied to interproximal assessments or to diagnose full-mouth periodontitis. In summary, within the limitations, the results of this study support that there is no statistically significant difference between buccal US-PD and PPD measurements across most subgroups investigated, except for mandibular first premolars. The MAD between the two methods is < 1 mm, and most differences between the measurements fell within the limits of agreement. However, the authors note that HFUS and probing are not interchangeable; rather, HFUS serves as an adjunctive diagnostic aid for visualizing the buccal periodontium. Future research would benefit from the development of smaller, periodontium-specific HFUS probes that can reach more distal teeth and lingual and interproximal surfaces. C.A.F. was responsible for the study concept, participant recruitment, data gathering and management, data analysis, and drafting the manuscript. P.W.M. and F.T.A. were involved in the development of the study concept and research question, oversight of the study, provided guidance throughout the manuscript writing process, and reviewed the manuscript. M.G. provided her expertise in periodontics and reviewed the manuscript. H.L. provided his expertise in data analysis and statistics and reviewed the manuscript. All authors approved the final version of the manuscript to be submitted for publication. McIntyre Memorial Fund and the Gerald Stewart Radiology Endowment Fund, Mike Petryk School of Dentistry, University of Alberta. AI statement: This manuscript is based entirely on human-generated text, without the use of AI. University of Alberta's Ethics Board (Pro00133128). The authors declare no conflicts of interest. The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions. Appendix S1: Expanded methodological details regarding participant inclusion criteria, HFUS imaging procedures, ultrasound-derived pocket depth measurements, and statistical analyses. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.
Figueredo et al. (Wed,) studied this question.