High-precision and non-invasive measurement of crestal bone level by optical coherence tomography

Identifying crestal bone level (CBL) on the buccal and lingual aspects poses challenges in conventional dental radiographs. Given that optical coherence tomography (OCT) has the capability to non-invasively provide in-depth information about the periodontium, this in vitro study aimed to assess whether OCT can effectively identify periodontal landmarks and measure CBL in the presence of gingiva.

An in-house handheld scanning probe connected to a 1310-nm swept-source OCT (SS-OCT) system, along with self-developed algorithms were employed to measure the CBL in dental models with artificial gingiva. Markers were positioned 0.5 mm above the artificial gingival margin (SG) and the crestal bone (SC) on both the mid-buccal and mid-lingual sides of 28 plastic teeth. The distances between the paired SG and SC were measured in the OCT images after correcting for the optical path through the covering artificial gingiva. These measurements were subsequently compared to the ground truth values obtained using a 2.5D inspection system.

The mean difference in CBL measured by SS-OCT and 2.5D was 0.008 mm (95 % CI: -0.092 to 0.108 mm). Statistical analysis using a three-way ANOVA indicated that the measurement differences were not significant across maxillary/mandible, anterior/posterior, and buccal/lingual dimensions. Furthermore, these differences were not associated with gingival thickness (α = 0.05).

The proposed SS-OCT system demonstrated its capability to accurately and non-invasively assess CBL through artificial gingiva. Moreover, it facilitated the semi-automatic delineation of critical periodontal landmarks on OCT en face images, highlighting its potential for clinical applications.