scholarly journals Adaptability Evaluation of Metal-Ceramic Crowns Obtained by Additive and Subtractive Technologies

2020 ◽  
Vol 10 (16) ◽  
pp. 5563
Author(s):  
Cristina Elena Savencu ◽  
Costela Șerban ◽  
Liliana Porojan
Keyword(s):  
New Technologies ◽  
Selective Laser Sintering ◽  
Critical Factor ◽  
Cost Effective ◽  
Metal Ceramic ◽  
Before And After ◽  
Cad Cam ◽  
Ceramic Crowns ◽  
Internal Gap ◽  
Ceramic Restorations

(1) Background: Traditional metal-ceramic restorations are considered as a standard in the evaluation of new technologies. A critical factor in their longevity is represented by their adaptability; The purpose of this study was to evaluate the marginal and internal gap of ceramic-fused to metal crowns with frameworks obtained by additive manufacturing (AM) technologies and the influence of veneering process on their fit; (2) Methods: Metal-ceramic crowns have been produced by conventional lost-wax technology (T), digital milling (F), selective laser sintering (SLS) and selective laser melting (SLM). The adaptability was assessed using silicone replicas before and after ceramic veneering; (3) Results: The best values were obtained for the milled group followed closely by SLM and SLS, and a significantly higher gap for casted copings. The veneering process did not significantly influence the adaptability of the crowns, regardless of the manufacturing process used for frameworks. The present study promotes additive technologies (AT) as a fast, efficient, and cost-effective alternative to traditional technology. There are fewer steps in which errors can occur when digital technologies are used and the risk of distortion is diminished. (4) Conclusions: CAD/CAM technologies, both additive and subtractive, represent an excellent option to produce time-effective, precise metal-ceramic crowns with excellent adaptation.

scholarly journals Fit of metal-ceramic crowns

2021 ◽  
Vol 21 ◽  
pp. e225136
Author(s):  
Patrícia Valéria Manozzo Kunz ◽  
Gabriela Andrade Serpa ◽  
Leonardo Fernandes da Cunha ◽  
Gisele Maria Correr ◽  
Carla Castiglia Gonzaga
Keyword(s):  
Cobalt Chromium ◽  
Manufacturing Method ◽  
Significant Difference ◽  
Metal Ceramic ◽  
Before And After ◽  
Cad Cam ◽  
Marginal Discrepancy ◽  
Ceramic Crowns ◽  
Student’S T ◽  
Internal Fit

Aim: To evaluate the influence of cobalt-chromium (Co-Cr) coping fabrication methods and ceramic application on the marginal and internal fit of metal-ceramic crowns. Methods: Co-Cr copings for metal-ceramic crowns were prepared by lost wax casting or CAD-CAM machining of sintered blocks. The fit was analyzed using the silicone replica technique at four assessment points: marginal gap (MG), axial wall (AW), axio-occlusal (AO) angle, and central occlusal (CO) wall. After the initial analysis, the copings were ceramic-veneered with the layering technique, and the fit was again determined. Data were statistically analyzed by paired and unpaired Student’s-t test (α=0.05). Results: Marginal and internal fit before ceramic application according to the coping manufacturing method showed significant differences only at CO (p < 0.001), with milled copings (137.98±16.71 μm) showing higher gap values than cast copings (112.86±8.57 μm). For cast copings, there were significant differences at MG (before 109.13±8.79 μm; after 102.78±7.18 μm) and CO (before 112.86±8.57 μm; after 104.07±10.63 μm) when comparing the fit before and after ceramic firing. For milled copings, there was significant difference only at AO (before 116.39±9.64 μm; after 108.54±9.26 μm). Conclusion: This study demonstrated that the coping fabrication method influenced the internal fit. Ceramic firing maintained or improved the fit of the metal-ceramic crowns. The marginal discrepancy of all restorations, before and after ceramic firing, can be considered clinically acceptable.

scholarly journals 400 - Effects of Computerized Cognitive Training with an Elderly Community Sample

2020 ◽  
Vol 32 (S1) ◽  
pp. 116-116
Author(s):  
M Pires ◽  
A Antunes ◽  
C Gameiro ◽  
C Pombo
Keyword(s):  
Older Adults ◽  
Cognitive Training ◽  
New Technologies ◽  
Community Sample ◽  
Cost Effective ◽  
Well Being ◽  
Control Group ◽  
Depression Symptoms ◽  
Intensive Training ◽  
Before And After

Community-focused programs that promote active and healthy aging can help preserve cognitive capacities, prevent or reverse cognitive deficits. Computer-based cognitive training (CCT) is a promising non-pharmacological, cost -effective and accessible intervention to face the effects of age-related cognitive decline. Previous studies proved CCT to have equal or better efficacy compared to traditional interventions. This comparative multifactorial study aims to test the efficacy of a CCT in a non-randomized community sample of 74 older adults: G1-CCT Experimental group (n=43) (Mean age M=72.21, SD=12.65) and G2- Paper-Pencil Control group (n=31; M=77.94, SD=10.51). Pensioners (97.3%), mostly women (83.8 %) with basic education (51.4%) and without dementia diagnosis, completed a cognitive training program of 17 or 34 group sessions (twice a week). G2 undertook a classic cognitive paper-pencil stimuli tasks. G1, performed, additionally, individual CCT with COGWEB® in a multimodal format (intensive training of attention, calculation, memory, gnosis, praxis, executive functions). Both groups completed Portuguese versions of Mini -Mental State Examination (MMSE),Montreal Cognitive Assessment (MOCA); Geriatric Depressive Scale (GDS); Mini Dependence Assessment (MDA); WHOOQL 5 and Social Support Satisfaction Scale (ESSS) before and after participating in the program. Both groups reported better post-test scores on basic cognitive functions (MMSE, MOCA), Depression symptoms (GDS-30), subjective well-being and quality of life (WHOOQL-5). G1 presented higher MOCA and lower GDS scores before and after CCT, although, group differences become less expressive when interaction effects are considered. Results are in line with findings from past studies, CCT supported by the new technologies, is as a relevant cost-effective therapeutic tool for health professionals working with older adults. Particularly for preventive purposes of neuro-cognitive disorders.

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.

Characterization of Dental Metal-Ceramic Interfaces of Heat Pressed Ceramics on Co-Cr Frameworks Obtained with Different Technologies

2018 ◽  
Vol 876 ◽  
pp. 25-30
Author(s):  
Liliana Porojan ◽  
Mihaela Bîrdeanu ◽  
Cristina Savencu ◽  
Sorin Porojan
Keyword(s):  
Cross Section ◽  
Selective Laser Sintering ◽  
Interface Strength ◽  
Noticeable Effect ◽  
Metal Ceramic ◽  
Dental Metal ◽  
Ceramic Restorations ◽  
Ceramic Interfaces

It is known that the quality of metal-ceramic restorations mainly depends on the interface strength. The aim of the study was to evaluate metal–ceramic interfaces of heat pressed ceramic on Co-Cr frameworks obtained with different technologies: melting-casting (CST), computerized milling (MIL), selective laser sintering (SLS) and selective laser melting (SLM). The microstructure of metal–ceramic interfaces and framework topography were characterized by scanning electron microscope (SEM). Sandblasted, polished surfaces and the cross section on the interfaces were observed. Sandblasted surfaces presented a uniform rough aspect and pronounced porous surface compared to that of polished surfaces and were better visible in SLS and SLM samples. The thickness of the veneer layer had a noticeable effect on the interface, because in the case of thicker veneers, cracks at the interfaces were visible for CST and MIL specimens. Considering the findings reported herein, some suggestions can be considered in practice, such as adaptation of the restorations morphology to the characteristics of the processed materials.

The Marginal Fit of CAD/CAM Monolithic Ceramic and Metal-Ceramic Crowns

2017 ◽  
Vol 28 (3) ◽  
pp. 299-304 ◽  
Author(s):  
Yolanda Freire ◽  
Esther Gonzalo ◽  
Carlos Lopez-Suarez ◽  
Maria J. Suarez
Keyword(s):  
Marginal Fit ◽  
Metal Ceramic ◽  
Cad Cam ◽  
Ceramic Crowns

Stress Distribution in Metal-Ceramic Crowns with a Facial Porcelain Margin

1987 ◽  
Vol 66 (9) ◽  
pp. 1493-1498 ◽  
Author(s):  
K.J. Anusavice ◽  
B. Hojjatie
Keyword(s):  
Stress Distribution ◽  
Tensile Stress ◽  
Maximum Tensile Stress ◽  
Butt Joint ◽  
Maxillary Central Incisor ◽  
Metal Thickness ◽  
Metal Ceramic ◽  
Pd Alloy ◽  
Ceramic Crowns ◽  
Ceramic Restorations

The use of metal-ceramic restorations with porcelain butt-joint facial margins has increased in the past several years. Although these crowns exhibit improved esthetics compared with metal-ceramic crowns which display a metal gingival collar or metal knife-edge margin, the effectiveness of this design in resisting intra-oral forces is not known. The objective of this study was to analyze the stress distribution induced by simulated intra-oral loads on crowns with variable coping configurations. The copings, with a thickness of either 0. 1 or 0.3 mm, were modeled with a facial termination of metal at three locations: at the gingival floor, 0.9 mm above the gingival floor, and 4.2 mm above the gingival floor. The coping and crown dimensions were based on a prepared maxillary central incisor with a facial shoulder and a lingual chamfer. Both Ni-Cr and Au-Pd alloy copings were employed in the crown models. Finite element stress analyses were performed on crowns which were subjected to several loading conditions. A cement film thickness of 0.030 mm was assumed. For all cases, the stresses which developed in porcelain and cement near the facial and lingual margins due to a vertical load of 200 N were predominately compressive in nature. For the crowns with Ni-Cr copings, the tensile stress in porcelain ranged from 11.0 MPa (for crowns with a facial metal thickness of 0.3 mm) to 12.5 MPa (for a metal thickness of 0.1 mm). The corresponding stresses for crowns with Au-Pd alloy copings were 8.3 MPa and 8.6 MPa, respectively. Maximum compressive stresses in cement near the lingual margin were 22.3 MPa for the Ni-Cr crowns and 30.0 MPa for the Au-Pd crowns. The maximum tensile stress in porcelain was 29.0 MPa and occurred near the area of loading for the Au-Pd case. The maximum tensile stress in the facial porcelain region (8.3 MPa) developed within the incisal third of the facial surface. Under the conditions assumed in this study, the alloy type, coping thickness, and coping termination point have a negligibly small effect on the stresses induced in porcelain or cement near the facial margin.

scholarly journals Implant-supported fixed hybrid acrylic complete dentures opposing fully restored mandibular metal ceramic restorations

2020 ◽  
Vol 13 (2) ◽  
pp. e233913
Author(s):  
Mohammed A Alfarsi ◽  
Sharaz Shaik
Keyword(s):  
Effective Treatment ◽  
Treatment Plan ◽  
Cost Effective ◽  
Vertical Dimension ◽  
Complete Dentures ◽  
Cost Effective Treatment ◽  
Hygiene Measures ◽  
Metal Ceramic ◽  
Full Mouth Rehabilitation ◽  
Ceramic Restorations

This report presents a full-mouth rehabilitation case. A patient came with a failing dentition in maxilla, and after the treatment, the patient had a shortened full-arch, implant-supported, screw-retained hybrid acrylic complete denture in the maxilla and full-arch metal ceramic restorations in the mandible. The report describes the steps involved in the prosthodontic rehabilitation; a cost-effective treatment plan, the restoration of vertical dimension, an immediate denture, an implant-level impression, a verified-master cast, the fabrication of definitive prosthesis, the occlusal scheme and multiple follow-ups in 6 months. We discussed the merits/demerits of screw-retained prosthesis, impression techniques and various types of fixed complete dentures. We learnt the difficulty in hygiene measures and dissatisfaction of the patient with the hygienic gaps under the acrylic fixed dentures.

scholarly journals A base-line study of the wear of burs used for chairside milling of ceramic crowns of different hardness: effect on internal fit and surface roughness

2020 ◽  
Author(s):  
Ayman Abd Alla Ahmed
Keyword(s):  
Surface Roughness ◽  
Tungsten Carbide ◽  
Diamond Particle ◽  
Base Line ◽  
Replica Technique ◽  
Before And After ◽  
Cad Cam ◽  
Ceramic Crowns ◽  
Internal Fit ◽  
And Tungsten

Abstract Background: In the CAD/CAM environment, wear of the milling burs may affect the accuracy of the milled crown. However, no studies have related bur wear to both the resultant internal fit of the crown or to the surface roughness. The aim of this study was to study this, using diamond burs and a feldspathic ceramic (Sirona Blocs C, Dentsply Sirona, Germany) and tungsten carbide burs and Zirconia (inCoris TZI puck, Dentsply Sirona, Germany).Methods: Thirty of each of the two materials were milled from the same standard preparation. One set of diamond burs was used for the feldspathic ceramic and one set of tungsten-carbide burs for the Zirconia. Before and after the 10th, 20th and 30th milling times, diamond particle loss was counted and cutting blade changes of the tungsten-carbide burs measured. Internal fit was measured using a silicone replica technique and surface roughness with a 3D measuring laser microscope.Results: Increasing wear of the diamond burs as measured by an average 26% loss of diamond particles after 30 crowns, which resulted in a 6% decrease in internal luting space and a 16% increase in surface roughness. Increasing wear of the tungsten-carbide burs resulted in a 13% decrease in the luting space, but there was an overall 16% increase in surface roughness. Conclusions: This is the first study to compare the wear of diamond and tungsten-carbide milling burs with the internal fit and surface roughness of the crown. The wear of milling burs affects the luting space, reducing it as the burs wear, and therefore the milling parameters must be adjusted to compensate for this.

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