Bone-Morphology (BM) classification: a novel staging system for mandibular conventional ameloblastoma, a multicenter retrospective study.

BACKGROUND: Ameloblastoma is the most common odontogenic epithelial tumor, characterized by local aggressiveness and high recurrence rates. Current management lacks a practical staging system to guide surgical decisions, making it challenging to balance radical resection with functional preservation. METHODS: This retrospective cohort study developed and validated a novel bone destruction and radological Morphology (BM) staging system for mandibular conventional ameloblastoma. We analyzed 649 patients from three tertiary centers (2005–2024), categorizing them into BM stages I-III. Recurrence-free survival (RFS) was analyzed using Kaplan–Meier methods and log-rank tests. RESULTS: The BM staging system effectively stratified recurrence risk and guided surgical choices. The 5-year RFS rates decreased significantly with advancing stage: stage I (71.9%), stage II (46.4%), and stage III (24.5%) (P < 0.0001). In stage I, both curative resection surgery (CRS) and curettage and fenestration decompression (CFD) achieved 100% 5-year RFS. For stage II patients, CRS was marginally superior to CFD. For stage III, CRS led to significantly better outcomes (88.2%) than other approaches (P < 0.0001). In stages I and II, patients treated with fenestration decompression or local curettage had significantly worse prognosis than those receiving CRS or CFD. CONCLUSIONS: The BM staging system provides effective prognostic stratification and guides surgical decisions. Modified conservative surgery (CFD) is appropriate for stage I, while curative resection is recommended for stage III to minimize recurrence risk. For stage II patients, the choice between CRS and CFD should weigh the benefit of lower recurrence against the risk of jaw discontinuity and functional impairment.