Comparison of the marginal fit of lithium disilicate crowns fabricated with CAD/CAM technology by using conventional impressions and two intraoral digital scanners
Available online 20 June 2015
Abstract
Statement of problem
Conventional
impression materials and techniques have been used successfully to
fabricate fixed restorations. Recently, digital pathways have been
developed, but insufficient data are available regarding their marginal
accuracy.
Purpose
The
purpose of this in vitro study was to compare the marginal gap
discrepancy of lithium disilicate single crowns fabricated with
computer-aided design and computer-aided manufacturing (CAD/CAM)
technology by using both conventional and 2 digital impression
techniques.
Material and methods
One
typodont maxillary right central incisor was prepared for a ceramic
crown. Ten impressions were made by using each method: conventional with
polyvinyl siloxane impression material, Lava COS (3M ESPE), and iTero
(Cadent) intraoral scanning devices. Lithium disilicate (e.max CAD)
crowns were fabricated with CAD/CAM technology, and the marginal gap was
measured for each specimen at 4 points under magnification with a
stereomicroscope. The mean measurement for each location and overall
mean gap size by group were calculated. Statistically significant
differences among the impression techniques were tested with F and t tests (α=.05).
Results
The
average (±SD) gap for the conventional impression group was 112.3
(±35.3) μm. The digital impression groups had similar average gap sizes;
the Lava group was 89.8 (±25.4) μm, and the iTero group was 89.6
(±30.1) μm. No statistically significant difference was found in the
effects among impression techniques (P=.185)
Conclusions
Within
the limitations of this study, digital and conventional impressions
were found to produce crowns with similar marginal accuracy.
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