Abstract: Abstract: Objective To explore the relation between precision of intraoral scanning digitized model's evaluation on gingival parenchyma, and pocket depth, gingivitis inflammation degree, arch width, and anatomical position, thereby providing experimental reference for clinical application. Method 30 patients with chronic periodontitis having undergone supragingival scaling and periodontal probing examination were selected to obtain traditional plaster models. 3Shape Trios intraoral scanner was used for intraoral scanning to obtain digitized models. 3Shape D810 scanned plaster model and the scanning result was translated into STL-format file, which was imported into Geomagic Qualify 2012 software, to compare the 3D deviation value between two types of models for gingival of probed sites, incisor, premolar teeth, molar and gingival parenchyma of full dentition. The one-sample T-test, chi-square test, Pearson correlation coefficient were used to analyze the relation between 3D deviation magnitude of gingival and pocket depth (PD), gingivitis inflammation degree and arch width of each probed site. The variance analysis in method of randomized blocks design was adopted to analyze whether digitized models for anatomical position are different in gingival accuracy, and Tukey test was used to make a further pairwise analysis. Result The 3D deviation magnitude between intraoral scanning digitized model and traditional plaster model was not correlated to pocket depth, gingivitis inflammation degree or arch width (P>0.05), but was correlated to anatomical position of teeth. The precision for molar region was lower compared with incisor and premolar region (0.381±0.137). Conclusion The intraoral scanning digitized model can be an alternative to traditional plaster model in terms of gingival tissue and is clinically applicable.

Key words: Intraoral scan, Chronic periodontitis, Accuracy, Digital impression, 3Shape.