3D image constructions of the IC in dentulous maxilla and edentulous maxilla. After imaging by micro-CT, the slice data was used for 3D construction, with the IC shown in red. IC morphology as observed from the front view was classified into Y-morphology and cylindrical . (A) Y-morphology of dentulous maxilla. (B) Y-morphology of edentulous maxilla. (C) Cylindrical of dentulous maxilla. (D) Cylindrical of edentulous maxilla.