J Korean Acad Prosthodont.  2016 Jul;54(3):210-217. 10.4047/jkap.2016.54.3.210.

Evaluation of marginal and internal gap under model-free monolithic zirconia restoration fabricated by digital intraoral scanner

• Lee JW
• Park JM

• KMID: 2344858
• DOI: http://doi.org/10.4047/jkap.2016.54.3.210

Abstract

PURPOSE
The aim of this study was to evaluate the marginal and internal adaptation of monolithic zirconia restoration made without physical model by digital intraoral scanner.
MATERIALS AND METHODS
A prospective clinical trial was performed on 11 restorations as a pilot study. The monolithic zirconia restorations were fabricated after digital intraoral impression taking by intraoral scanner (TRIOS, 3shape, Copenhagen, Denmark), computer-aided designing, and milling manufacturing process. Completed zirconia crowns were tried in the patients' mouth and a replica technique was used to acquire the crown-abutment replica. The absolute marginal discrepancy, marginal gap, and internal gap of axial, line angle, and occlusal part were measured after sectioning the replica in the mesiodistal and buccolingual direction. Statistical analysis was performed using Kruskal-Wallis and Mann-Whitney U test (α=.05).
RESULTS
From the adaptation analysis by replica, the statistically significant difference was not found between mesiodistal and buccolingual sections (P>.05), but there was significant difference among the measurement location (P<.01). The amount of absolute marginal discrepancy was larger than those of marginal gap and internal gap (P<.01).
CONCLUSION
Within the limitations of this study, the adaptation accuracy of model-free monolithic zirconia restoration fabricated by intraoral scanner exhibited clinically acceptable result. However, the margin of zirconia crown showed tendency of overcontour and cautious clinical application and follow up is necessary.

Keyword

Intra-oral scanner; Computer aided design-computer aided manufacturing (CAD-CAM); Model-free prosthesis; Replica technique

MeSH Terms

Computer-Aided Design
Crowns
Follow-Up Studies
Mouth
Pilot Projects
Prospective Studies
Replica Techniques

Figure

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  Fig. 1. Clinical case of model-free monolithic zirconia crown produced by intraoral scanner. (A) Intraoral scan data, (B) Intaglio surface of completed crown, (C) Occlusal view of monolithic zirconia crown, (D) Lateral view of restoration.

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  Fig. 2. Replica technique procedure to measure the internal fit of monolithic zirconia crown. (A) Internal gap was taken with silicone registration material, (B) Replica was fabricated with silicone stabilizing registration material of different color.

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  Fig. 3. Intersections of the replica preparation for microscopic measurement.

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  Fig. 4. Cross-section of replica specimens. (A) Buccolingual section, ×30, (B) Schematic diagram, ×30, (C) Magnified diagram of B, ×100. AMD: absolute marginal discrepancy, MG: marginal gap, AI: axial internal gap, LI: line angle internal gap, OI: occlusal internal gap.

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  Fig. 5. Box plot of mean marginal and internal fit of monolithic zirconia restorations made from intraoral scan data without physical model.

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