OBJECTIVETo develop a three-dimensional (3-D) comparison and measuring techniques to analyze changes in palatal forms of the serial maxillary alveolar cast and to evaluate the significance of the different reference change indexes.

METHODSFollowing digitizing the casts with a 3-D laser scanner and using reverse engineering software Geomagic Studio 7.0 for a pair of 3-D digital maxillary alveolar cast of an infant of UCLP before and after cheiloplasty, a pair of cast surfaces were reconstructed. The reference points and the character lines were extracted.

RESULTSThe model coordinate system and the datum planes were established on the basis of reference points extracted. The newly developed analysis technique completed 3-D comparison of palatal forms of UCLP infants before and after cheiloplasty. Distances and volumes changes between the surfaces were determined and expressed graphically.

CONCLUSIONSWith establishing the model coordinate system and the datum plane, it is possible to visualize the comparison outcome of the reference change indexes longitudinally. The various reference change indexes may reflect the trend of the infant maxillary growth.