Editorial Type:
Article Category: Research Article
 | 
Online Publication Date: 01 Oct 2018

Fracture Strength and Precision of Fit of Implant-Retained Monolithic Zirconia Crowns

DDS,
DDS, PhD,
DDS, and
DDS, PhD
Page Range: 330 – 334
DOI: 10.1563/aaid-joi-D-17-00249
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New monolithic zirconia materials can be used to fabricate full-contour fixed dental prostheses with the computer-aided design/computer-aided manufacturing (CAD/CAM) method. The aim of this study was to examine the fracture strength and precision of fit of screw-retained monolithic zirconia crowns made directly on implants or by cementing on prefabricated titanium (Ti) bases. Monolithic screw-retained implant crowns (n = 6) were produced by CAD/CAM method using partially (PSZ) and fully stabilized (FSZ) zirconia. Industrially produced zirconia crowns were used as a reference. A lateral incisor study model was made onto an implant replica. Crowns were produced either directly on the implant or through cementing on a prefabricated titanium base (PSZ+Ti, FSZ+Ti). The crowns were tightened to implant replicas with a torque of 35 Ncm. The gap between the replica and the abutment or crown was measured from ×400 scanning electron microscope images for precision of fit. Mechanical testing until failure was completed with a universal testing machine with loading angle of 45°. Statistical analysis was performed (analysis of variance). Mean (±SD) failure loads were 259 ± 23 (PSZ), 140 ± 13 (FSZ), 453 ± 25 (PSZ+Ti), 439 ± 41 (FSZ+Ti), and 290 ± 39 (Procera). Mean (±SD) gap values were 2.2 ± 0.2 (PSZ), 2.5 ± 1.0 (FSZ), 7.0 ± 1.0 (PSZ+Ti), 7.7 ± 1.6 (FSZ+Ti), and 6.7 ± 1.7 (Procera). Monolithic zirconia crowns with a Ti base clearly show higher fracture strengths than the crowns fixed directly on the implant surface. Better marginal fit can be achieved with direct zirconia crowns than with crowns on a titanium base or industrially produced zirconia crowns.

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Figure 1

Lateral incisor study models on replicas: partially stabilized zirconia (PSZ) direct, PSZ + titanium (Ti) base, fully stabilized zirconia (FSZ) direct, FSZ + Ti base, Procera.


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Figure 2

Scanning electron microscope images (×400) of the gap between implant replica and different zirconia crowns. (a) Industrially produced Procera crown. (b) Fully stabilized zirconia direct. (c) Partially stabilized zirconia direct. (d) Titanium base.


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Figure 3

Illustration of marginal gaps (μm) of partially (PSZ) and fully stabilized zirconia (FSZ) crowns made directly on an implant replica or through cementing on a titanium base. Industrially produced zirconia crown (Procera, Nobel Biocare) is shown as a reference.


Contributor Notes

Corresponding author, e-mail: pahamo@utu.fi
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