scholarly journals Susceptibility artifacts induced by crowns of different materials with prepared teeth and titanium implants in magnetic resonance imaging

2022 ◽  
Vol 12 (1) ◽  
Author(s):  
Xiaomeng Gao ◽  
Qianbing Wan ◽  
Qingping Gao
Keyword(s):  
Precious Metal ◽  
Titanium Implants ◽  
Zirconia Ceramic ◽  
Signal Loss ◽  
Susceptibility Artifacts ◽  
Metal Ceramic ◽  
Zirconia Crowns ◽  
Artifacts Reduction ◽  
Ceramic Crowns ◽  
Tooth Preparation

AbstractThis study aimed to investigate the artifacts induced by crowns composed of different materials with prepared teeth and titanium implants. Resin, metal-ceramic, ceramic and zirconia crowns were fabricated and placed onto the prepared teeth on a human cadaver head or titanium implants with prosthesis abutments on a dry human mandible. The samples were scanned on a 1.5 T MRI apparatus, and artifact areas were defined as the signal intensity and signal loss adjacent to the prosthesis and measured by a threshold tool with ImageJ2x. Data were analyzed using SPSS 22.0. Resin, ceramic, zirconia, and precious metal-ceramic crowns barely produced artifacts on the cadaver skull (p > 0.999). By contrast, pure Ti and nonprecious metal-ceramic crowns created significant artifacts (p < 0.001). The average artifacts reduction of double Au-Pt and Ag-Pd metal-ceramic crowns combined with titanium implants and abutments was 79.49 mm2 (p < 0.001) and 74.17 mm2 (p < 0.001) respectively, while artifact areas were increased in double Co-Cr and Ni–Cr metal-ceramic crowns by 150.10 mm2 (p < 0.001) and 175.50 mm2 (p < 0.001) respectively. Zirconia, ceramic and precious metal-ceramic crowns induce less MRI artifacts after tooth preparation while precious metal-ceramic crowns alleviate artifacts in combination with titanium implants.

scholarly journals Influence of Cervical Finish Line Type on the Marginal Adaptation of Zirconia Ceramic Crowns

2009 ◽  
Vol 34 (5) ◽  
pp. 586-592 ◽  
Author(s):  
M. Comlekoglu ◽  
M. Dundar ◽  
M. Özcan ◽  
M. Gungor ◽  
B. Gokce ◽  
...  
Keyword(s):  
Clinical Relevance ◽  
Clinical Applications ◽  
Zirconia Ceramic ◽  
Marginal Adaptation ◽  
Finish Line ◽  
Zirconia Crowns ◽  
Ceramic Crowns ◽  
Line Type

Clinical Relevance Cervical finish line type has an influence on the marginal adaptation of Y-TZP restorations. Both shoulder and mini-chamfer exhibited the least marginal opening values for zirconia crowns and can be recommended for clinical applications.

scholarly journals Fracture toughness of zirconia ceramic crowns made by feather-edge tooth preparation design

2012 ◽  
Vol 69 (7) ◽  
pp. 562-568 ◽  
Author(s):  
Nemanja Mirkovic ◽  
Aleksandra Spadijer-Gostovic ◽  
Zoran Lazic ◽  
Branka Trifkovic
Keyword(s):  
Fracture Toughness ◽  
Testing Machine ◽  
High Fracture Toughness ◽  
Zirconia Ceramic ◽  
Ceramic Samples ◽  
Edge Group ◽  
Group I ◽  
Ceramic Crowns ◽  
Tooth Preparation ◽  
Edge Preparation

Background/Aim. Fracture toughness determines functional crown strenght and prevents damages on ceramics during mastication. There is a lack of relevant literature data about fracture toughness of crowns made by feather-edge preparation. Mechanical testing of ceramic samples is supposed to show if feather-edge tooth preparation is a successful method for making ceramic crowns without any risk of reduction of their mechanical properties. This research was done to establish effects of feather-edge tooth preparation on fracture toughness of single zirconia ceramic crowns. Methods. The research was performed as an experimental study. Sixty (60) ceramic crowns were made on non-carious extracted human premolars. Thirty (30) crowns were made on the basis of feather-edge preparation (experimental group I). The group II included 30 crowns made on 1 mm rounded shoulder. Crowns fabrication was executed on a copy mill production system ?Zirkonzahn? (Zirkonzahn GMBH, Gais, Germany). The spherical compression test was used to determine fracture toughness, using 6 mm diameter ceramic ball. Fracture load for damaging ceramic crown was recorded on a universal testing machine - Zwick, type 1464, with the speed of 0.05 mm/min. Results. The results of this research introduced significant differences between fracture toughness of ceramic samples in every examined group. However, fracture toughness of crowns from both group was above 2 000 N, what was double beyond a recommended value. The mean value of fracture toughness in the feather-edge group was 2 090 N, and in shoulder group it was 2 214 N. Conclusion. This research showed a high fracture toughness of zirconia crowns made on feather-edge preparation. The examined crowns showed a fracture resistance at a sufficient distance in relation to the minimum values of functional loads. Further research of functional loads of these crown is necessary, as well as research of marginal adaptation of cemented crowns and gingival inflammatory response.

scholarly journals Effect of Finish Line on Marginal Fit of Sintered Gold Copings

2013 ◽  
Vol 24 (4) ◽  
pp. 322-325
Author(s):  
Fernanda Pelogia Gwinner ◽  
Marco Antonio Bottino ◽  
Lafayete Nogueira-Junior ◽  
Alvaro Della Bona
Keyword(s):  
Marginal Gap ◽  
Finish Line ◽  
Marginal Fit ◽  
Metal Ceramic ◽  
Ceramic Crowns ◽  
Master Model ◽  
Tooth Preparation ◽  
Student’S T ◽  
Equidistant Points ◽  
Student’S T Test

The aim of this study was to evaluate the vertical marginal gap of sintered gold copings and metal-ceramic crowns with different finish line preparations: a beveled round shoulder (BRS) and a beveled long chamfer (BLC), testing the null hypotheses that there are no differences in marginal gap regardless of finish line and phase of restoration (coping or crown). Stainless steel master models were fabricated to simulate tooth preparation for metal-ceramic crowns with different finish lines (BRS and BLC). Ten dies were obtained from each model. Preparations were coated with 2 layers of spacer to 1 mm from the margin. Sintercast gold copings were prepared, sintered and adjusted to the dies. The copings (n=10) were placed onto the master model and the marginal gap was measured in 24 equidistant points using optical microscopy (X230). An opaque and two body ceramic layers were subsequently applied to the copings and the same measuring procedure was performed for the crowns. The data were analyzed statistically using paired and unpaired Student's t-test (α=0.05). Mean marginal gap values (µm) for the copings and crowns were, respectively: 113.6 and 117.1 for the BRS; and 58.2 and 74.3 for the BLC preparation. Significantly greater marginal gaps (p=0.0307) were found for restorations with BRS than with BLC finish line, which also showed statistically significant differences in the gap size between coping and crown (p=0.001). In conclusion, marginal gap is influenced by ceramic application on copings fabricated on BLC preparation, and greater marginal gaps were found for restorations with BRS finish line, rejecting the experimental null hypotheses.

scholarly journals Color matching of full ceramic versus metal-ceramic crowns - a spectrophotometric study

2019 ◽  
Author(s):  
Delia Cristina Greța ◽  
Cristina Gasparik ◽  
Horațiu Alexandru Colosi ◽  
Diana Dudea
Keyword(s):  
Color Difference ◽  
Spectrophotometric Study ◽  
Zirconia Ceramic ◽  
Coding System ◽  
Color Match ◽  
Posterior Teeth ◽  
Metal Ceramic ◽  
Ceramic Crowns ◽  
Fair Poor ◽  
Instrumental Methods

Background and aims. To verify the color match of metal-ceramic and full ceramic crowns, using instrumental methods. Methods. A number of 153 teeth (anterior and posterior teeth), in 62 patients,  were restored with metal ceramic (MC, n=119), pressed-ceramic (PC, n=28), and zirconia-ceramic (ZC, n=6) full coverage crowns. The shade of a reference natural tooth was recorded instrumentally with a dental spectrophotometer (Vitaeasyshade Advance 4.0) in “single tooth measurement”, which provided  the base color in Vita Classic (VC) and Vita 3D Master shades (3D).  For verifying the outcome of the restoration “verify restoration” mode was used, and ΔE values were recorded for both VC and 3D Master shade guides. Moreover, matching symbols were also recorded (***=good, **=fair, *=poor). Descriptive statistics was performed and data were analyzed (One-sample z-Test, α=0.05) for comparison with visual thresholds in dentistry (Perceptibility Threshold – PT=1.2 and Acceptability Threshold – AT=2.7). Results. The data did not follow a normal distribution (Kolmogorov-Smirnov test, p<0.05). Recorded color difference was significantly higher than PT and AT, for all types of restorations, regardless of the  coding system (p<0.05). For MC crowns in 2.52% (4.20% for 3D) of the cases the color difference was smaller than PT, in 19.32% (the same for 3D) of cases was between PT and AT, and in 78.15% (76.47% for 3D) of cases was higher than the AT. For PC crowns in 3.57% (0% for 3D) of the cases the color difference was smaller than PT, in 25% (32.14% for 3D) of cases was between PT and AT, and in 71.42% (67.85% for 3D) of cases was higher than the AT. In the case of ZC crowns none of the restorations had color difference smaller than PT, but in 16.66% of cases was between PT and AT, and in 83.33% of cases was higher than the AT, for both VC and 3D. Conclusion. Within the limitations of the study, a better color match was achieved in the case of pressed ceramic crowns, made of lithium disilicate.  In most of the situations the color difference between the restoration and the reference tooth exceeded the perceptibility thresholds, but the matching was recorded as “fair” by the spectrophotometer.     

Fit of metal ceramic crowns cast in Au-1.6wt% Ti alloy for different abutment finish line curvature

2006 ◽  
Vol 22 (5) ◽  
pp. 397-404 ◽  
Author(s):  
Jianxiang Tao ◽  
Masanobu Yoda ◽  
Kohei Kimura ◽  
Osamu Okuno
Keyword(s):  
Ti Alloy ◽  
Finish Line ◽  
Metal Ceramic ◽  
Ceramic Crowns

PROSPECTS FOR MANUFACTURING FRAMES OF METAL CERAMIC STRUCTURES OF DENTAL PROSTHESES BY THE METHOD OF SELECTIVE LASER SINTERING

2021 ◽  
pp. 232-239
Author(s):  
Stepanov V.A. ◽  
Shemonaev V.I. ◽  
Buyanov E.A. ◽  
Grachev D.V. ◽  
Parchomenko A.N. ◽  
...  
Keyword(s):  
Objective Assessment ◽  
Selective Laser Sintering ◽  
Clinical Effectiveness ◽  
Study Groups ◽  
Laser Sintering ◽  
Dental Prostheses ◽  
Metal Ceramic ◽  
Abutment Teeth ◽  
Ceramic Crowns ◽  
Solid Tissues

The article presents the results of evaluating the prototyping of metal-ceramic structures made by casting and selective laser sintering. To achieve this goal, 27 patients with fabricated metal-ceramic crowns and bridgeworks were examined. Two study groups were created. The first group included 14 patients for whom dental prosthesis frameworks were made by casting. The second group consisted of 13 people, for whom the frames of dentures were made by the method of selective laser sintering. The analysis of clinical effectiveness was carried out according to the following criteria: 1- precision of the felling of prosthesis frame to solid tissues of abutment teeth; 2- the condition of the marginal periodontium; 3- the integrity of the ceramic cladding. The results of the study showed that the precision to solid tooth tissues of metal-ceramic dental prostheses made by laser selective sintering is higher than of frames made by casting. In accordance to the second criteria the best results were also shown by the participants of the second group. No chipping of the ceramic veneer from the metal-ceramic denture frameworks made by laser selective sintering was found. Thus, dentures which frameworks are made by the method of selective laser sintering are characterized by a higher objective assessment of their precision to the solid tissues of the abutment teeth. Lesions of the marginal periodontium both inflammatory and dystrophic were less in the participants of the second group. The frequency of defects in the coating of metal-ceramic dentures was significantly lower in the case of fabrication frameworks by laser selective sintering.

scholarly journals Carbon fiber–reinforced PEEK versus titanium implants: an in vitro comparison of susceptibility artifacts in CT and MR imaging

2020 ◽  
Author(s):  
Theresa Krätzig ◽  
Klaus C. Mende ◽  
Malte Mohme ◽  
Helge Kniep ◽  
Marc Dreimann ◽  
...  
Keyword(s):  
Carbon Fiber ◽  
Vertebral Body ◽  
Titanium Implants ◽  
Fiber Reinforced ◽  
Dose Delivery ◽  
Susceptibility Artifacts ◽  
Carbon Fiber Reinforced ◽  
Radiation Planning

Abstract Artifacts in computed tomography (CT) and magnetic resonance imaging (MRI) due to titanium implants in spine surgery are known to cause difficulties in follow-up imaging, radiation planning, and precise dose delivery in patients with spinal tumors. Carbon fiber–reinforced polyetheretherketon (CFRP) implants aim to reduce these artifacts. Our aim was to analyze susceptibility artifacts of these implants using a standardized in vitro model. Titanium and CFRP screw-rod phantoms were embedded in 3% agarose gel. Phantoms were scanned with Siemens Somatom AS Open and 3.0-T Siemens Skyra scanners. Regions of interest (ROIs) were plotted and analyzed for CT and MRI at clinically relevant localizations. CT voxel–based imaging analysis showed a significant difference of artifact intensity and central overlay between titanium and CFRP phantoms. For the virtual regions of the spinal canal, titanium implants (ti) presented − 30.7 HU vs. 33.4 HU mean for CFRP (p < 0.001), at the posterior margin of the vertebral body 68.9 HU (ti) vs. 59.8 HU (CFRP) (p < 0.001) and at the anterior part of the vertebral body 201.2 HU (ti) vs. 70.4 HU (CFRP) (p < 0.001), respectively. MRI data was only visually interpreted due to the low sample size and lack of an objective measuring system as Hounsfield units in CT. CT imaging of the phantom with typical implant configuration for thoracic stabilization could demonstrate a significant artifact reduction in CFRP implants compared with titanium implants for evaluation of index structures. Radiolucency with less artifacts provides a better interpretation of follow-up imaging, radiation planning, and more precise dose delivery.

Precision of fit of two margin designs for metal-ceramic crowns

2008 ◽  
Vol os15 (1) ◽  
pp. 32-32
Author(s):  
P Limkangwalmongkol ◽  
GJ Chiche ◽  
MB Blatz
Keyword(s):  
Metal Ceramic ◽  
Ceramic Crowns
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