Abstract: Objective: By comparing the failure rate of fixed restorations made by intraoral scanning and traditional impression in Stomatological Hospital of Xiamen Medical College over the past 5 years, the study provides a reference for wide clinical application of intraoral scanning. Materials and methods: Acquiring the laboratory orders for porcelain fused to metal (PFM) full crowns and all-ceramic crowns over the past 5 years, including failed orders that required re-production for various reasons. Dividing them into intraoral scanning and traditional impression groups, while each group was subdivided into PFM and all-ceramic crown groups. The failure rate was calculated separately, followed by statistical analysis (chi-square test). At the same time, the data of the past 5 years was divided into 5 groups in chronological order, and the laboratory orders and failure rates of intraoral scanning and traditional impression of each group were calculated. Results: A total of 50347 laboratory orders were collected, including 22619 orders for traditional impression group (14356 PFM and 8263 all-ceramic crown), and 27728 orders for intraoral scanning group (6303 PFM and 21425 all-ceramic crown). The total failure rate was 5.06%, of which the failure rate of the intraoral scanning group was 4.01%, while 6.35% for traditional one. The failure rate of the intraoral scanning group in the PFM group was 2.98%, and the traditional impression group was 5.58%. In the all-ceramic crown group, the failure rate of the intraoral scanning group was 4.32%, while 7.68% for traditional one. In the past five years, the traditional impression laboratory orders have been decreasing, while the failure rate showed a slight downward trend. The intraoral scanning laboratory orders have increased yearly, and the failure rate has shown a significant downward trend. Conclusions: Based on the limited data of our hospital over the past 5 years, the research shows that intraoral scanning has a higher success rate in fixed restoration than traditional impression, and could be widely used in clinical practice.

Key words: failure rate, intraoral scanning, traditional impression, all-ceramic crown, porcelain fused to metal