What type of bone growth is stimulated at the palatal suture of a 9-year-old during rapid palatal expansion?

The palatal suture (midpalatal suture) is a fibrous joint that ossifies through intramembranous ossification - the same process used for flat bones of the skull. When a rapid palatal expander (RPE) is activated, it separates the two halves of the maxilla at the midpalatal suture. The resulting traction stimulates osteoblast activity and new bone formation (intramembranous ossification) to fill the gap. This is distinct from endochondral ossification, which occurs at growth plates (cartilage-based bone formation). The suture remains open and expansive in children; it fuses by approximately 14-16 years in females and 15-18 years in males.