Evaluation of alveolar bone density around abutments in fixed prostheses designed according to prosthetic principles using CBCT: a retrospective study

Abstract

Aims: The aim of this retrospective study was to evaluate temporal changes in the alveolar bone density surrounding abutment teeth in fixed prosthetic restorations designed according to prosthetic principles, using normalized gray values obtained from cone-beam computed tomography (CBCT). Methods: Among 211 patients who had undergone at least two CBCT scans within the last decade (2016-2025), 15 patients who met the inclusion criteria were selected. A total of 22 fixed dental bridges and 55 abutment teeth were evaluated, with a mean actual follow-up duration of 15.9\pm 6.3 months (range: 8.3-31.5 months). For each abutment, a 2-mm circumferential peri-radicular bone zone was segmented using 3D Slicer software. To minimize variability arising from different imaging parameters, gray values were normalized based on the theoretical -1000 HU reference of the maxillary sinus air cavity. To account for intra-subject clustering, data were analyzed using a linear mixed-effects model (LMM) and Pearson correlation analysis. A significance level of p<0.05 was adopted. Results: No statistically significant difference was detected between the normalized bone density values at T1 and T2 according to the LMM (F=0.217, p=0.642). Examination of the measurements from both time points revealed a strong positive correlation, indicating that baseline and follow-up normalized gray values remained statistically unchanged throughout the observation period (p<0.001). Conclusion: In fixed prosthetic restorations planned in accordance with established prosthetic principles, the alveolar bone density surrounding abutment teeth did not exhibit a significant change over the follow-up period. Normalization-based CBCT analysis enhances comparability among scans taken with differing imaging parameters and provides a useful method for detecting longitudinal variations in peri-abutment bone density.