Bone-anchored maxillary protraction (BAMP) is an emerging orthopedic treatment modality to address midface deficiency. It includes fixing surgical miniplates into the maxilla and mandible and running intermaxillary elastics between them. It is believed that the forces generated by BAMP therapy cause greater circummaxillary sutural separation, more bone growth and better protraction compared to traditional reverse pull headgear (RPHG) treatment. Despite the increasing popularity of BAMP, its effects at the tissue level still largely are unknown. This can be attributed partially to lack of an appropriate animal model to study BAMP. The purpose of this study was to evaluate the use of minipigs as an animal model for BAMP and measure deformation and growth of circummaxillary sutures during BAMP. Results presented are preliminary, based on three six-month-old mini-pigs. BAMP miniplates were placed surgically, similar to that in human subjects, and protraction forces were applied. Fluorescent bone labels were injected before and after protraction. During terminal surgery, displacement sensors were installed across the zygomatico-maxillary and naso-frontal sutures to measure their deformation during BAMP. After sacrifice, tissues were harvested and analyzed to determine effects of BAMP on mineral apposition and osteoblast differentiation. Our results indicate that minipigs can serve as a suitable animal model for BAMP. No post-operative complications were noticed. Preliminary findings suggest that the zygomatico-maxillary and naso-frontal sutures are tensed highly during BAMP. Opening and closing of the mouth introduced an oscillatory component to sutural loading. BAMP also resulted in increased mineral apposition and osteoblast differentiation at the sutures.
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