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J Prosthet Dent. 2014 Sep;112(3):555-60. doi: 10.1016/j.prosdent.2013.12.002. Epub 2014 Mar 11.

A comparison of the marginal fit of crowns fabricated with digital and conventional methods.

Author information

1
Student, Graduate Prosthodontics Program, Faculty of Dentistry, The University of British Columbia, Vancouver, British Columbia, Canada.
2
Professor, Division of Biomaterials, Faculty of Dentistry, The University of British Columbia, Vancouver, British Columbia, Canada.
3
Professor, Division of Prosthodontics and Dental Geriatrics, Faculty of Dentistry, The University of British Columbia, Vancouver, British Columbia, Canada. Electronic address: cwyatt@dentistry.ubc.ca.

Abstract

STATEMENT OF PROBLEM:

Little evidence is available with regard to the marginal fit of crowns fabricated with digital impressions and computer-aided design/computer-aided manufacturing technology in comparison with crowns fabricated from conventional techniques.

PURPOSE:

The purpose of this study was to determine and compare the marginal fit of crowns fabricated with digital and conventional methods.

MATERIAL AND METHODS:

The maxillary right second premolar was prepared for a ceramic crown in a typodont. The typodont was then digitized with a laboratory scanner, and the digital file was used to mill a replica of the maxillary arch from a monolithic block of yttria-stabilized zirconia to serve as the master model. Digital impressions of the prepared maxillary right second premolar were recorded with a scanning unit. Scan files were exported as .STL files and sent by e-mail to a dental laboratory. The files were input into a digital design workflow for digital articulation, digital waxing, and design of the definitive crown. Fifteen crowns were produced by milling computer-aided designed lithium disilicate glass ceramic blocks with a 5-axis milling. Fifteen lithium disilicate glass ceramic crowns were produced with a conventional impression and a laboratory fabrication method. The original zirconia die was removed from the zirconia master model to evaluate the crown margins. Circumferential marginal gap measurements were made at 8 measurement locations: mescal, distal, buccal, palatal and associated line angles (mesiobuccal, mesiolingual, distobuccal, and distolingual). Measurements were made to determine the vertical component of the marginal gap according to the definition of marginal fit.

RESULTS:

A total of 240 images (2 groups, 15 crowns per group, 8 sites per crown) were recorded and measured. The overall mean ±SD vertical gap measurement for the digitally made crowns was 48 ±25 μm, which was significantly smaller than that for the conventionally made crowns (74 ±47 μm).

CONCLUSION:

The fully digital fabrication method provided better margin fit than the conventional method.

PMID:
24630399
DOI:
10.1016/j.prosdent.2013.12.002
[Indexed for MEDLINE]

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