Conservative treatment of mandibular condylar fractures using a digital height-compensating occlusal splint: a 3D quantitative case series

Mandibular condylar fractures account for a substantial proportion of all mandibular fractures. Although conservative (closed functional) treatment is widely accepted—particularly for minimally to moderately displaced fractures—it currently lacks objective tools for quantifying and compensating for fracture-related condylar-height loss, which is a key determinant of functional outcome. We developed a quantitative workflow on the 3D Slicer platform that incorporates three-plane anatomical landmark analysis and a patient-specific height-compensating digital occlusal splint used in conjunction with orthodontic brackets for intermaxillary traction starting on the day of fracture. Here we report its clinical application in a consecutive case series. We retrospectively reviewed 8 consecutive patients (5 unilateral, 3 bilateral; 6 male, 2 female; mean age 24.9±17.8 years) with mandibular condylar fractures treated by conservative (closed functional) management at the Department of Orthodontics, Affiliated Stomatology Hospital of Kunming Medical University between December 2025 and July 2026. The treatment protocol comprised: (i) same-day bonding of orthodontic brackets on the maxillary and mandibular dental arches; (ii) CBCT acquisition followed by manual landmark placement (condylar apex, medial and lateral poles, gonion, sigmoid notch) on the 3D Slicer platform to measure the condylar-height difference ( \(Δ\) ) between the fractured and the contralateral healthy side; (iii) digital design and 3D printing of a patient-specific occlusal splint of uniform thickness equal to \(Δ\) , providing symmetric bilateral vertical elevation to compensate for the lost condylar height; and (iv) elastic intermaxillary traction guided by the splint and brackets. Pre- and post-treatment 3D quantitative parameters—angular (horizontal tilt, vertical tilt, anteroposterior tilt), positional (vertical, anteroposterior, mediolateral), and morphological (length, width, condylar height, \(Δ\) condylar height, volume)—were computed using the unfractured contralateral side mirrored across the mid-sagittal plane as the anatomical reference. Pre- versus post-treatment values were compared and visualized as color-coded deviation maps. Inter-observer reproducibility of the landmark-derived morphological measurements was assessed by the intraclass correlation coefficient (ICC). In the five patients with unilateral fractures (the primary quantitative cohort), \(Δ\) condylar height (healthy−fractured) decreased from 3.78±1.32 mm at presentation to 1.87±0.66 mm at the 3-month follow-up, representing a 50.5% mean closure of the initial height deficit. All three angular parameters moved toward the healthy-side reference: horizontal tilt from 11.18±4.07° to 10.03±3.12°, vertical tilt from 17.33±10.53° to 11.64±1.81°, and anteroposterior tilt from 61.52±9.46° to 71.08±7.70°. Positional and morphological parameters showed corresponding changes. Functional outcomes were recorded in all 8 patients. Maximum mouth opening reached 30.0±4.3 mm, and occlusion was stable, with no case of ankylosis, condylar resorption, or persistent malocclusion requiring re-intervention (follow-up range 3–6 months). Because of the uncontrolled, retrospective design, these observed pre–post changes cannot be attributed specifically to the splint; spontaneous remodelling and intermaxillary traction may have contributed to the changes observed. A quantitative workflow on the 3D Slicer platform, combining three-plane landmark-based angular and linear measurements with a height-compensating digital occlusal splint and bracket-guided intermaxillary traction, enabled objective, reproducible, and visually intuitive assessment and individualized conservative management of condylar fractures. In this preliminary case series, the workflow demonstrated technical and clinical feasibility as a proof-of-concept; its comparative effectiveness, long-term stability, and generalizability remain to be established in larger prospective controlled studies.