Agreement Between Cone Beam Computed Tomography, Bone Sounding, Pulse-Echo Ultrasound, and Caliper Measurements for Gingival Thickness Assessment: A Method-Comparison Study.

Background/Objectives: Accurate assessment of gingival thickness (GT) is important for periodontal and implant treatment planning. Methods: In this method-comparison study based on prospectively collected clinical data from 2012, GT was assessed at standardized buccal sites using cone beam computed tomography (CBCT), bone sounding (BS), an earlier-generation pulse-echo ultrasound (US) device, and direct digital caliper (CA) measurement. Of 53 acquired CBCT scans, 12 (23%) were non-evaluable because the buccal soft tissues could not be reliably delineated, leaving 41 sites from 41 patients for analysis. A ±0.30 mm clinical comparison margin, based on the difference used in the original sample-size calculation, was applied to interpret agreement. Results: Mean comparator-minus-CBCT biases were -0.19 mm for BS (95% limits of agreement [LoA], -0.98 to 0.61 mm), -0.16 mm for US (95% LoA, -0.83 to 0.51 mm), and -0.71 mm for CA (95% LoA, -1.99 to 0.56 mm). Although BS and the tested US device showed smaller average differences from CBCT than CA, the LoA for all comparisons exceeded this margin. Phenotype classification was exploratory because only four sites were classified as thin by CBCT. Conclusions: BS and the tested pulse-echo US device showed smaller average differences from CBCT than CA; however, the limits of agreement for all comparisons exceeded this margin, so none of the comparator methods can be considered interchangeable with CBCT. The 23% non-evaluable CBCT rate and the device- and protocol-specific nature of the findings limit their generalizability to current-generation systems.