Fractal dimension analysis of mandibular trabecular bone in severely infraoccluded primary molars: a retrospective case-control study

Background: Infraocclusion is a condition where the occlusal surface of a tooth lies below the occlusal plane or the level of adjacent teeth. Etiological factors, such as ankylosis and increased masticatory forces, can directly affect alveolar bone development and resorption processes, potentially leading to microstructural alterations in the region. These changes can affect the density and organisation of mandibular trabecular bone. Fractal dimension (FD) analysis is a promising method for evaluating such structural changes. This study aimed to investigate the effect of severe infraocclusion in mandibular primary molars on trabecular bone structure using FD analysis of panoramic radiographs. Methods: This retrospective study included 72 children aged 7–12 years: 36 with severe infraocclusion and 36 age- and gender-matched controls without infraocclusion. Panoramic radiographs obtained at the Faculty of Dentistry, Gazi University between January 2020 and December 2024 were evaluated. Infraocclusions were classified according to the Brearley and McKibben system. FD values were calculated using ImageJ software. Statistical analyses were performed using SPSS version 27. Due to non-normal data distribution, appropriate statistical tests were applied. Chi-square test was used for gender and germ comparisons; Mann-Whitney U test for age and germ-related FD values; and Independent Samples T-test for FD comparisons between groups and genders. A p-value < 0.05 was considered significant. Results: A significant difference in FD values between groups only in the mandibular angulus region (p < 0.05), with higher values found in the study group. No gender-releated differences were observed (p > 0.05). Within the study group, a significant difference in FD values was observed in the condylar region according to the presence of the permanent tooth germ, with higher values recorded when the germ was present (p < 0.05). Conclusions: Infraocclusion might be associated with localised changes in the mandibular trabecular bone. FD analysis can provide valuable insight into its etiology and assist in clinical treatment planning. Further studies using with larger samples and periapical radiographs are recommended.

Fractal dimension analysis; Infraocclusion; Mandible; Primary molar; Retrospective study

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