Abstract: Objective: To compare the registration accuracy of two methods used in edentulous jaw impressions, and to explore the suitable registration method. Methods: The impressions were taken by two methods, which were open-mouth and close-mouth. Twelve maxillary and 10 mandibular impressions were obtained and scanned by laboratory scanner, then saved in the format of STL. Open-mouth and close-mouth impressions were superimposed in reverse engineering software with two methods, respectively, i.e. Best Fit Alignment and Manual n points+Global Registration. Then the 3D deviation was showed. Results: The deviation nominal value range area percentage of Best Fit Alignment group (maxilla 48.58%, mandible 44.16%) < Manual+Global Registration group (maxilla 70.55%, mandible 66.27%). There was significant difference among maxilla and mandible (P<0.05). RMS (root mean square), mean positive, and negative deviation of Best Fit Alignment group were higher than those of Manual+Global Registration group, in which the differences of maxilla were statistically significant. Conclusion: Manual multi-point + Global Registration is better than the Best Fit Alignment for the impressions of edentulous jaw, especially in the maxilla.

Key words: registration, three dimension, edentulous jaw