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Impact of digital impression techniques on the adaption of ceramic partial crowns in vitro. J Dent 2014 Jun;42(6):677-83

Date

02/11/2014

Pubmed ID

24508541

DOI

10.1016/j.jdent.2014.01.016

Scopus ID

2-s2.0-84901203384 (requires institutional sign-in at Scopus site)   71 Citations

Abstract

OBJECTIVES: To investigate the effects, digital impression procedures can have on the three-dimensional fit of ceramic partial crowns in vitro.

METHODS: An acrylic model of a mandibular first molar was prepared to receive a partial coverage all-ceramic crown (mesio-occlusal-distal inlay preparation with reduction of all cusps and rounded shoulder finish line of buccal wall). Digital impressions were taken using iTero (ITE), cara TRIOS (TRI), CEREC AC with Bluecam (CBC), and Lava COS (COS) systems, before restorations were designed and machined from lithium disilicate blanks. Both the preparation and the restorations were digitised using an optical reference-scanner. Data were entered into quality inspection software, which superimposed the records (best-fit-algorithm), calculated fit-discrepancies for every pixel, and colour-coded the results to aid visualisation. Furthermore, mean quadratic deviations (RMS) were computed and analysed statistically with a one-way ANOVA. Scheffé's procedure was applied for multiple comparisons (n=5, α=0.05).

RESULTS: Mean marginal (internal) discrepancies were: ITE 90 (92) μm, TRI 128 (106) μm, CBC 146 (84) μm, and COS 109 (93) μm. Differences among impression systems were statistically significant at p<0.001 (p=0.039). Qualitatively, partial crowns were undersized especially around cusp tips or the occluso-approximal isthmus. By contrast, potential high-spots could be detected along the preparation finishline and at central occlusal boxes.

CONCLUSIONS: Marginal and internal fit of milled lithium disilicate partial crowns depended on the employed digital impression technique.

CLINICAL SIGNIFICANCE: The investigated digital impression procedures demonstrated significant fit discrepancies. However, all fabricated restorations showed acceptable marginal and internal gap sizes, when considering clinically relevant thresholds reported in the literature.

Author List

Schaefer O, Decker M, Wittstock F, Kuepper H, Guentsch A

Author

Arndt Geuntsch in the CTSI department at Medical College of Wisconsin - CTSI

MESH terms used to index this publication - Major topics in bold

Ceramics
Computer-Aided Design
Crowns
Dental Impression Materials
Dental Impression Technique
Dental Marginal Adaptation
Dental Materials
Dental Porcelain
Dental Prosthesis Design
Humans
Image Processing, Computer-Assisted
Molar
Polyvinyls
Siloxanes
Surface Properties
Tooth Preparation, Prosthodontic
User-Computer Interface