Maxillary Bone Fracture Due to a Miniscrew-Assisted Rapid Maxillary Expansion: A Case Report.

Background/Objectives: Miniscrew-assisted rapid palatal expansion (MARPE) has been increasingly used as a nonsurgical alternative for maxillary expansion in adults. However, reports of complications remain limited. This case describes a rare instance of maxillary bone fracture following MARPE and its clinical implications. Methods: A 32-year-old patient underwent MARPE as part of presurgical orthodontic treatment for maxillary constriction. Five days after activation, severe pain developed, followed by sensory disturbances in the infraorbital region. CT imaging revealed a maxillary fracture extending from the infraorbital foramen to the alveolar process. Symptoms gradually improved over two years, but psychological distress led to the abandonment of orthognathic surgery. Results: This case suggests that MARPE-induced maxillary fractures may be associated with stress concentration at the zygomatico-maxillary suture, particularly in individuals with increased midpalatal suture interdigitation and thin cortical bone. Finite element analysis and stress distribution studies indicate that the zygomatic buttress serves as a major resistance point, which may have contributed to the fracture. Conclusions: These findings highlight the importance of careful patient selection, preoperative CT assessments of bone thickness, and individualized expansion protocols. In high-risk cases, alternative approaches, such as surgically assisted expansion, may be considered. Further research on MARPE's risk assessment and treatment protocols is needed to improve safety.