Relationship between the efficacy of micro-implant-assisted rapid maxillary arch expansion and maturation of the midpalatal sutures

Objective: To investigate the relationship between the efficacy of micro-implant-assisted rapid palatal expansion (MARPE) and the degree of midpalatal suture (MBT) fusion. Methods: Forty patients with maxillary transverse hypoplasia from Hengshui People’s Hospital from January 2022 to August 2024 were recruited for MARPE treatment. These patients were divided into unfused (stages B and C, n = 18), initiation fusion (stage D, n = 10), and complete fusion groups (stage E, n = 12) according to the degree of MBT fusion based on the staging method for palatal sutures. Cone beam computed tomography (CT) and gypsum models were created before and on the day after arch expansion. The differences in maxilla, alveolar bone, tooth, and bony arch expansion efficiency between the three groups were measured and compared. Results: The success rates of arch expansion in the unfused, initial fusion, and complete fusion groups were 100%, 100%, and 83.3%, respectively. Expansion of the MBT in the first molar position was 4.11 ± 1.10 mm, 4.07 ± 0.42 mm, and 2.18 ± 0.66 mm in the unfused, initial fusion, and complete fusion groups, respectively (P < 0.05). The corresponding bony arch expansion efficiency was 58.82 ± 6.56%, 54.58 ± 8.65%, and 37.88 ± 4.36%, respectively, without statistical difference (P > 0.05). Conclusion: Patients with different degrees of MBT confluence and treated with MARPE had significant differences. Observation of the degree of MBT fusion before arch expansion predicts MARPE efficacy.