Reconstructing dentition defect model aims at assisting to remove, repair and make the partial dentures, which requests 3D model to support follow-up engineering redesign. Through processing dentition defect plaster casts of modification Kennedy Class II, we proposed a new method of 3D CAD modeling using ICT images. The method includes some key techniques: first, ICT image processing, accurately extract dentition edges from ICT images; Second, construct a full 3D dataset of Dentition Defect plaster cast; Finally, Generating 3D CAD dentition defect model. Our approach proposed contributes to the following removable partial denture CAD, finite element analysis and rapid prototyping (RP).