During rapid maxillary expansion, new bone forms at the opened midpalatal suture by which process?

The midpalatal suture is a site of intramembranous bone formation. When the suture is separated by expansion, osteoblasts deposit new bone directly within the fibrous tissue (intramembranous ossification) as it reorganizes and fills in.Other options: Endochondral ossification (a cartilage model) occurs at growth plates, synchondroses, and the condyle, not the palatal suture; new bone definitely forms during retention.Key exam takeaway: Sutural and most craniofacial flat-bone growth is intramembranous; retain the expansion to allow bony fill-in.