Comparison of the accuracy of the image registration methods for the impressions of edentulous jaws.

OBJECTIVE

The aim of present study was to investigate the accuracy of two registration methods, best fit alignment and manual multi-point alignment followed by global registration, used in edentulous jaw impressions.

METHODS

Traditional complete denture impressions were taken via two methods: open-mouth and closed-mouth methods. The edentulous impression models, including maxilla:14 pairs and mandible:12 pairs, were scanned in the model scanner and saved in STL format. In the reverse engineering software Geomagic Control 2014, two registration methods, namely, best fit alignment and manual multi-point alignment combined with global registration, were used independently to align the open-mouth and closed-mouth impressions of the same patient, and the 3-dimensional (3D) deviation between the reference and test models was recorded. SPSS26.0, paired t test, significance criterion two-sided α = 0.05.

RESULTS

The nominal value threshold area was less in the best fit alignment group (maxilla 48.58%, mandible 44.16%) than in the manual + global registration group (maxilla 70.55%, mandible 66.27%), maxilla P = 0.000 < 0.05, mandible P = 0.014 < 0.05. The root mean square (RMS), average positive deviation and average negative deviation of the best fit alignment group were greater than those of the manual + global registration group, there were significant differences in the maxillary (P < 0.05), but not significant difference in the mandibular (P > 0.05).

CONCLUSION

The manual multi-point combined global registration method is more accurate than the best fit alignment used in the registration of edentulous jaw impressions and is more effective for the maxilla.