Marginal fit of lithium disilicate copings fabricated from direct optical scanning vs indirect laser scanning of stone dies from VPS impressions.

摘要

Statement of the problem. There are few quantitative investigations that contrast the marginal discrepancy of restorations fabricated with direct scanning technique (digital impression) and indirect scanning to digitize stone dies from VPS impressions.;Purpose. The purpose of this study was to compare the marginal discrepancy (MD) of CAD/CAM copings fabricated from Itero direct optical scanning system, and CAD/CAM lithium disilicate copings fabricated from indirect laser scans to digitize stone dies from VPS impressions poured in type 4 and 5 dental stones.;Materials and methods. Fourteen VPS impressions of an ivorine master die were made. Seven impressions were poured in type IV dental stone (Silky Rock) for group SSR; and the other seven with type V dental stone (Jade Stone) for group SJS. All fourteen stone dies were digitized with the Etkon scanner to design the copings. For group IS, seven digital impressions were made with an Itero scanner and the STL files were imported into Etkon scanner to design the copings with the same parameters as those used for the VPS impression groups. 21 CAD/CAM e.max copings were fabricated. Each restoration was stabilized on the master die with VPS and Micro CT scans were done to measure the MD. Eight measurements (&mgr;m) per specimen were made. ANOVA with Sidak multiple comparison tests were used to explore differences between groups and locations (&agr;< .05).;Results. There was no difference in the mean MD between groups SSR (99+/-67 &mgr;m), SJS (115+/-68 &mgr;m) and IS (118+/-66 &mgr;m), but there was a significant difference in MD depending on the location of the measurements (&agr; =0.05). Buccal and lingual margins showed the smallest MD, while mesial and distal margins presented the largest MD.;Conclusion. There was no difference on the marginal fit of lithium disilicate copings fabricated from direct scans (digital impression) and indirect scanning of stone dies made from conventional VPS impressions. &mgr;CT scans can be used as a non destructive measuring device for evaluation of marginal and internal fit of dental restorations.;Clinical implication. Digital impressions offer comparable accuracy to conventional VPS impressions. Indirect scanning through digitization of stone dies, as well as direct scanning of a preparation, provide enough accuracy to fabricate clinically acceptable e.max restorations.