Accuracy of single-tooth restorations based on intraoral digital and conventional impressions in patients

The purpose of this clinical study was to compare the marginal fit of dental crowns based on three different intraoral digital and one conventional impression methods.

Forty-nine teeth of altogether 24 patients were prepared to be treated with full-coverage restorations. Digital impressions were made using three intraoral scanners: Sirona CEREC AC Omnicam (OCam), Heraeus Cara TRIOS and 3M Lava True Definition (TDef). Furthermore, a gypsum model based on a conventional impression (EXA'lence, GC, Tokyo, Japan) was scanned with a standard laboratory scanner (3Shape D700). Based on the dataset obtained, four zirconia copings per tooth were produced. The marginal fit of the copings in the patient's mouth was assessed employing a replica technique.

Overall, seven measurement copings did not fit and, therefore, could not be assessed. The marginal gap was 88 μm (68-136 μm) [median/interquartile range] for the TDef, 112 μm (94-149 μm) for the Cara TRIOS, 113 μm (81-157 μm) for the laboratory scanner and 149 μm (114-218 μm) for the OCam. There was a statistically significant difference between the OCam and the other groups (p < 0.05).

Within the limitations of this study, it can be concluded that zirconia copings based on intraoral scans and a laboratory scans of a conventional model are comparable to one another with regard to their marginal fit.

Regarding the results of this study, the digital intraoral impression can be considered as an alternative to a conventional impression with a consecutive digital workflow when the finish line is clearly visible and it is possible to keep it dry.