Association between fixed orthodontic treatment and pulp stone development: a retrospective study

This retrospective longitudinal cohort study aimed to evaluate changes in pulp stone prevalence between pretreatment and post-retention panoramic radiographs and to assess potentially associated factors, including sex and active multibracket treatment duration. Additional objectives were to characterize pulp stone distribution by tooth type, jaw, and side and to quantify changes in the radiographic density and pixel-based size of pre-existing pulp stones.

This study included 199 patients (117 females and 82 males; mean age at T₀, 12.5 years) who underwent fixed multibracket orthodontic treatment. Panoramic radiographs obtained before orthodontic treatment (T₀) and after completion of the retention phase (T₁) were evaluated for radiographically detectable pulp stones in permanent first and second molars. The interval between appliance removal and T₁ imaging varied among patients and was not recorded separately. Patient- and tooth-level prevalence analyses were performed in the full cohort, whereas changes in radiographic density, expressed as the mean grey value, and pixel-based size of pre-existing pulp stones were quantified using ImageJ in the baseline-positive subgroup (n = 38). Statistical analyses included paired and between-group comparisons, correlation analyses, and regression models to evaluate longitudinal changes and potential associations with sex and active multibracket treatment duration.

Patient-level pulp stone prevalence increased significantly from 19.6% at T₀​​ to 28.6% at T₁ (p < 0.001). The increase was greater in males than in females (17.1 versus 3.4 percentage points; p = 0.001). At the tooth level, descriptive increases were observed in all evaluated first and second molars. Maxillary molars showed higher prevalence at both time points, whereas the descriptive magnitude of change was broadly comparable between the jaws. Active multibracket treatment duration (mean, 16.6 months) was not significantly associated with an increase in the number of pulp stone-positive molars per patient (p = 0.90). Exploratory quantitative analyses showed positive pooled mean changes in radiographic density and pixel-based size, with substantial variability among measurements. No sex-related differences were identified for either quantitative outcome, while analyses of the association between active multibracket treatment duration and pixel-based size yielded inconsistent results.

Patient-level pulp stone prevalence increased between the pretreatment and post-retention radiographs, with a greater increase observed in males. Maxillary molars showed higher prevalence at both time points. Exploratory quantitative analyses showed positive pooled mean changes in radiographic density and pixel-based size; neither outcome showed sex-related differences, and findings regarding the association between active multibracket treatment duration and pixel-based size were inconsistent. In the absence of an untreated comparison group, these findings describe longitudinal changes within an orthodontically treated cohort but do not establish a causal effect of fixed orthodontic treatment.

Patient-level prevalence of radiographically detectable pulp stones was higher at the post-retention assessment than at pretreatment. Because pulp stones may complicate access to the root canal system, their recognition and documentation on clinically indicated radiographs may be relevant if endodontic treatment is required later. The present findings do not justify additional radiographic examinations solely for pulp stone detection.