Clinical Evaluation of the Lava COS Intraoral Scanning System

Objectives: The aim of the present study was to compare the fit of all-ceramic crowns fabricated from Lava COS impressions with the fit of all-ceramic crowns fabricated from silicone impressions.

Methods: Twenty patients agreed to take part in the study to receive two Lava crowns each for the same preparation. One crown was fabricated from intraoral scans, and the other crown from a two-step silicone impression. Prior to cementation the marginal, occlusal and interproximal fit of both crowns was clinically evaluated by two calibrated and blinded examiners; the marginal fit was also scored from replicas. Data from the replica scores were analysed by Anderson-Darling test, Levene's test and Mann-Whitney test. All tests were performed with α-level of 0.05.

Results: Mean marginal gap in the conventional impression group was 78 µm ± 8.9, median 70.5 µm; in the digital impression group 53 µm ± 4.9, median 49.0 µm. Mann-Whitney test revealed a significant difference between the groups (p<0.05). With regards to tooth surfaces the mean marginal gaps in the conventional group were: mesial 69 µm ± 9, distal 102 µm ± 30, buccal 78 µm ± 12 and lingual 62 µm ± 12. The corresponding gaps for the digital group were: mesial 52 µm ± 8, distal 64 µm ± 12, buccal 43 µm ± 8 and lingual 53 µm ± 10. No differences were found regarding the occlusion. There was a trend for better interproximal fit for the digitally fabricated crowns.

Conclusions:

1.      Crowns from Lava COS impressions revealed significantly better marginal fit than crowns from silicone impressions.

2.      Marginal discrepancies in both groups were clinically accepatable.

3.      Crowns from intraoral scans tended to show better interproximal contact area quality.

4.      Crowns from both groups performed equally well as regards occlusion.

Supported by 3M ESPE