Diagnostic Fidelity of Low-Dose Cone-beam Computed Tomography for Alveolar Bone Assessment in Severe Periodontitis: Retrospective Study

Introduction and aims To evaluate whether a radiation-optimised low-dose cone-beam computed tomography (CBCT) protocol provides diagnostic information comparable to a standard-dose reference for assessing alveolar bone in patients with Stage III or IV periodontitis. Methods Following the ALADAIP principle, this retrospective study identified 47 Stage III/IV periodontitis patients who had undergone both standard-dose and low-dose CBCT scans within a 7-day window. The low-dose protocol (70 kV, 3 mA, 180° rotation) had previously been established using an ex vivo dose titration approach. Morphological fidelity (relative alveolar bone loss, buccal thickness, furcation involvement) and densitometric consistency (cortical and trabecular voxel grey values) were quantified at nonoperated reference sites. Inter-protocol agreement for staging and measurements was analysed using weighted kappa statistics and intraclass correlation coefficients. Results The optimised low-dose protocol reduced radiation exposure by 74.1%. Inter-protocol agreement was perfect for relative bone loss staging (kappa = 1.00) and excellent for all linear measurements (alveolar bone height, buccal bone thickness, tooth-alveolar angulation; intraclass correlation coefficients >0.98). Furcation involvement assessment also showed high consistency (kappa = 0.811). In contrast, cortical voxel grey values showed poor reliability (intraclass correlation coefficient = 0.296). These densitometric inaccuracies were significantly worse in the subgroup with body mass index ≥25 kg/m² ( P < .05). Conclusions This optimised low-dose CBCT approach offers a viable path for dose reduction without compromising critical morphological diagnostic outcomes in complex Stage III/IV periodontitis. Although robust for morphological assessment, the protocol’s densitometric limitations in patients with higher body mass index warrant caution when interpreting bone quality. Clinical significance For Stage III/IV periodontitis requiring complex intervention and long-term surveillance, when 3-dimensional evaluation is required, this radiation-optimised protocol enables high-fidelity monitoring of bone destruction while minimising cumulative radiation risks. Its excellent performance in 3-dimensional morphological assessment is pivotal for precise surgical planning and for evaluating therapeutic outcomes. However, the body-mass-index-dependent densitometric inaccuracies suggest that clinicians should prioritise morphological analysis over voxel-based bone density interpretation, particularly in overweight patients.