OBJECTIVETo test a new cast-making method based on computer aided design (CAD) and rapid prototyping (RP) technology for defected maxilla.

METHODSHead CT data of 12 patients with defected maxilla were transmitted into a computer. Three-dimensional digital image of the patient's defected maxilla was then obtained based on Mimics 8.11 and Geomagic 7.0 and the plastic cast of the defected region was manufactured by prototyping. The obturator was made on this plastic cast that duplicated the undercut tissue of defected area. The prominent part of the obturator was made of elastic heat-curing resin and it was helpful to gain the retention through the engagement between the obturator and the tissue undercut. After the obturator was finished, the upper removable partial denture was fabricated in conventional method. The combination of these two parts was achieved using magnetic attachment. Clinical effects of obturator and removable partial denture were evaluated and the nasalance value of 5 patients before and after insertion of the obturator was measured using nanometer.

RESULTSThe obturator and removable partial denture could be seated into place separately. They all had good retention and stability. After the obturator was seated in place, the nasalance of non-nasal and vowel text decreased from (46.53 +/- 13.86)% to (22.60 +/- 8.52)% (P < 0.001).

CONCLUSIONSThe cast-making method based on CAD and RP technology for cast-making of defected maxilla is feasible and practical.