Metal-ceramic Restorations Research Articles

Comparison of bond strength of two porcelains and two base metal alloys in metal-ceramic restorations

The purpose of this study was to evaluate the bond strength between two porcelains (VITA VMK Master and VITA VM13) and two types of base metal alloys (Ceramill Sintron and Verabond). In an experimental study, 20 rectangular strips (25 mm × 4 mm × 0.5 mm) of each base metal alloy (Ceramill Sintron and Verabond) were fabricated according to the manufacturer's instructions. After sandblasting and polishing, the samples were placed in an ultrasonic device to remove surface contaminants. A surface of 8 mm × 4 mm × 1 mm of samples was veneered with Vita VM13 and VITA VMK Master. The samples were divided into four groups (n = 10 each group; VM13/Ceramill, VMK Master/Ceramill, VM13/Verabond, and VMK Master/Verabond), and bond strength was evaluated by three-point bending test with a universal testing machine. Two-way ANOVA was used for comparison in each group, post hoc Scheffe's test was used for analyzing data between groups, and the Kolmogorov-Smirnov test was used for the normality (P < 0.05). The maximum bond strength was related to Verabond/VM13 (44.35 ± 7.9 MPa) and then the Ceramill Sintron/VM13 (39.33 ± 4.43 MPa), and the lowest was related to the Ceramill Sintron/VMK Master (29.75 ± 3.2 MPa). There was no significant difference between bond strength of VM13 with the two alloy groups (P > 0.05), and bond strength of VMK Master to Ceramill Sintron CAD/CAM alloy was less than the conventional Verabond alloy (P < 0.05); however, bond strength of all the groups was above the standard threshold (25 MPa). Based on the results of this study, the bond strength of the porcelain to Verabond was better, but the bond strength of the porcelain to Ceramill Sintron also was not less than the standard threshold; thus, this new CAD/CAM alloy can be an alternative to the conventional base metal alloys in the metal-ceramic restorations.

The Effect of Laboratory Procedures and Repeated-glazing on Color of Metal-ceramic Restoration.

Background:Routine laboratory procedures and repeated glazed effect the final color of metal-ceramic restorations (MCRs). Clinicians wonder if the color changes after routine laboratory procedures and repeated glazed is clinically acceptable or not.Aims:The aim of this study was to determine the color changes of MCRs after routine laboratory procedures and then glazed for 1, 2, and 3 times.Materials and Methods:Forty-five disc-shaped (10-mm diameter and 1-mm thickness) specimens were fabricated from Cr-Co metal-alloy. Bonding agent, first and second layer of shade A2 opaque porcelain (OP) were applied on the metal specimens. The color of specimens was measured with a spectrophotometer after each procedure and △E1, △E2, and △E3 values were calculated. Shade A2 feldspathic porcelain was applied (2-mm thickness) to all specimens. Glaze was applied on the porcelain for 1, 2, and 3 times and then, the color measured after each procedure and △E4, △E5, and △E6 values were calculated. Data were analyzed with one-way ANOVA and Duncan test (P < 0.05).Results:△E1 that was obtained between the first layer of OP and bonding agent showed the greatest value. △E2 that was obtained between the second and first layer of OP showed the lowest value. After repeated glazed procedures, the final color of the specimens was changed; but, these changes were clinically acceptable (△E < 5.5).Conclusions:The routine laboratory procedures and glazed for 1,2, and 3 times is effect the color of MCRs; but, the color changes were clinically acceptable (△E < 5.5).

Comparison of bond strength and fracture toughness of metal–ceramic restorations fabricated by conventional lost-wax technique and selective laser sintering

Introduction: Porcelain fused to metal is the most common restoration. The success of the prosthesis greatly depends on the mechanical bonding between the metal alloy and the ceramic. Newer techniques such as selective laser sintering (SLS) and computer-aided design are fast replacing the lost-wax technique due to ease of fabrication. This study was carried out to ascertain the best possible technique to ensure success. Materials and Methods: Forty strips of cobalt–chromium (Co–Cr) metal were fabricated and divided into two groups (lost-wax technique vs. SLS technology), which were then bonded with ceramic and compared for bond strength and fracture toughness. Results: SLS group showed higher bond strength than conventional lost-wax technique (CAST) group but lowered fracture toughness. This difference was also found to be statistically significant. Conclusion: The lost-wax technique is a time-tested method that needs not be abandoned until successful evolution of emerging technologies is firmly established.

Selective laser melting and sintering technique of the cobalt-chromium dental alloy

Introduction/Objective. The objective of this paper is to describe the microstructure and mechanical properties of sintered Co-Cr alloy and to emphasize its advantages and disadvantages with respect to the microstructure and mechanical properties of cast Co-Cr alloy. Methods. Base Co-Cr alloy, EOSint M EOS Co-Cr SP2 (EOS GmbH, Munch, Germany), was used for the purpose of this research as the base material for sintering metal structures of metal-ceramic restorations. Metal sintering was conducted by using EOSint M 280 device of German origin in a stream of neutral gas ? argon. After that, the alloy was heated over a period of 20 minutes at the temperature of 800?C. The chemical composition of the alloy was determined by energy dispersive spectroscopy. Microstructure of the tested alloy samples was examined under an optical metallographic and scanning electron microscope. Physical and mechanical properties were measured in a universal testing machine. The samples were prepared according to the standard ISO 527-1:1993. Results. Chemical composition of the sintered Co-Cr alloy, determined by applying energy dispersive spectroscopy, indicated the same qualitative but different quantitative composition compared to cast Co-Cr alloys. The microstructure of the sintered Co-Cr alloy is lamellar in nature, with two dominant phases: ?-Co and/or ?-Cr (fcc ? face-centered cubic) and ?-Co (hcp ? hexagonal close-packed). Mechanical properties of the Co-Cr alloy obtained by applying selective laser melting technology compared to the cast Co-Cr alloy are superior or approximately the same. Conclusion. Selective laser melting of the Co-Cr alloy is a good example of new technologies based on digitization. Together with other digitized procedures, this technology is an introduction to a new era in dentistry popularly called Dentistry 4.0. The advantages of the selective laser melting technology with respect to the conventional technology of casting Co-Cr alloy metal structures are precise metal structure fitting and eco-friendly technology.

The ceramic fracture evaluation of metal-ceramic restorations fabricated by casting and laser sintering: a prospective clinical study

The ceramic fracture evaluation of metal-ceramic restorations fabricated by casting and laser sintering: a prospective clinical study

Preliminary Studies on the Biomechanical Behavior of Metal-ceramic Restorations

In order to increase the patient�s quality of life, interdisciplinary studies on dental materials are becoming more and more frequent in an attempt to assess as accurately as possible the resistance of dental restorations over time. One of the methods of analysis of resistance to the masticatory forces of dental restorations is the finite element method (FEM). We studied a 3-element dental bridge made of a metallic Co-Cr-Mo alloy and dental ceramics, designed for the prosthesis of a tooth 3.6. On each element of the dental bridge we applied a force of 250 N in the direction Z and a force of 100 N in the Y direction. The most vulnerable areas, where the highest stresses occur, are located predominantly in the neck regions and around the points of contact between the elements of the dental bridge. However, the experimentally determined values have low intensities that would not endanger the resistance of the restoration unless it is overloaded.

Application of zirconia surface coating to improve fracture resistance and stress distribution of zirconia ceramic restorations

Zirconia ceramic restoration (ZCR) has a higher fracture incidence rate than metal ceramic restoration. Different surface treatments were used to improve fracture performance of ZCR such as grit blasting (GB) by aluminium oxide powder. This type of surface treatment generate residual stresses on veneering ceramic causing crack initiation and ending with a fracture. In order to overcome the stress generated by GB, zirconia surface coating is used as a surface treatment to improve fracture resistance and to accommodate stresses along the ZCR layers. Fifty zirconia ceramic crowns were fabricated and divided according to the type of surface treatment into three groups; the first group is (ZG), involving 20 cores were coated with a mixture of partially-sintered zirconia powder (PZP) and glaze ceramic powder; the second group is (ZL), including of 20 cores were coated with PZP and liner ceramic paste. The third group is grit blasting (GB), preparing of 10 fully sintered cores at 1350 °C which then abraded by 50 µm aluminium oxide powder. The groups ZG and ZL were further subdivided into ZG26, ZG47, ZL26 and ZL47 based on two PZP sizes (47 and 26 µm). Each treated core was veneered with the veneering ceramic layer. Fracture resistance (FR) was measured by the universal testing machine. Finite element analysis (FEA) was used to simulate the stress distributions on the coated and non-coated zirconia crown models. The ZG47 group had higher FR (647.92 ± 97.33 N) and a significant difference (P < 0.00) compared to GB and other coated groups. The FEA exhibited lower and evenly distributed stresses of the zirconia glaze model than the zirconia liner and the non-coated models. The ZG47 coating considered as an alternative method to GB treatment which increases the FR which significantly improved the clinical performance of the ZCR.

A Randomized Clinical Trial Comparing Zirconia and Metal-Ceramic Three-Unit Posterior Fixed Partial Dentures: A 5-Year Follow-Up.

To compare the survival, success rates, and biological/technical complications of posterior metal-ceramic (MC) and zirconia fixed partial dentures (FPDs). A total of 40 patients requiring 40 posterior FPDs were randomly assigned to receive 20 zirconia and 20 MC restorations. The restorations were examined 1 week (baseline) and 1, 3, and 5 years after the end of treatment. Technical and biological outcomes were compared. Data were statistically analyzed using the Wilcoxon signed-rank and Mann-Whitney U tests. The survival rates of both groups were 100%, and the success rates were 80% (zirconia) and 100% (MC). No biological complications were observed. Minor chipping was found in 20% of the zirconia restorations. No differences in periodontal parameters were observed between groups. Zirconia FPDs exhibited the same survival rate (100%) as MC FPDs after 5 years; however, the success rate was 80%, because an increased rate of chipping was observed in zirconia restorations.

The evaluation and comparison of marginal adaptation in metal ceramic and all ceramic restorations fabricated by two methods: CAD/CAM and conventional

Introduction: Marginal fit is a key factor for long term clinical success through any dental restorations. Poor marginal adaptation causes cement dissolution. This can lead to dental caries, gingival irritation, periodontal diseases, and finally treatment failure. The aim of this study was measurement and comparison of marginal gap quantities in metal ceramic and all ceramic dental restorations fabricated by various methods. Methods & Materials: A total of 60 complete crowns in 6 groups (n=10) were fabricated as. Follows: Group A: Conventional metal-ceramic collarless restorations. Group B: Metal-ceramic collarless restorations with CAD/CAM wax copings and porcelain layering. Group C: Metal-ceramic collarless restorations with Ceramill Sintron metal copings and porcelain layering. Group D: All ceramic e-max. Press (lithium disilicate) restorations. Group E: All ceramic restorations with CAD/CAM zirconia copings and porcelain layering. Group F: All ceramic CAD/CAM translucent zirconia (Zolid). Replica technique and optical microscope (60 x magnifications) used to gap measurement. Mann whitney and kruskal-wallis tests used to analyze the data. Results: The lowest mean marginal gap seen in group C (29.12) and the highest mean marginal gap seen in group E(78.19)The mean marginal adaptation was better in metal ceramic restorations than all ceramic restorations and the difference was significant (P˂0.001). Conclusion: According to our study, marginal gap of metal ceramic and all ceramic restorations was clinically acceptable (less than 120 microns).

Effect of two heat treatments on mechanical properties of selective-laser-melted Co-Cr metal-ceramic alloys for application in thin removable partial dentures

Statement of problemHeat treatment has been used to reduce the residual stress of alloys fabricated by selective laser melting (SLM) to avoid deformation. Co-Cr metal-ceramic alloys are used to fabricate metal-ceramic restorations and removable partial dentures (RPDs) on the same substrate by SLM. A heat treatment that enables the fabrication of metal-ceramic restorations and RPDs with excellent mechanical properties should be evaluated. PurposeThe purpose of this in vitro study was to determine the effects of 2 heat treatments on the mechanical properties of SLM Co-Cr metal-ceramic alloys intended for the fabrication of thin RPDs. Material and methodsTensile bars were manufactured using cast metal-ceramics (C-MC group), RPD alloys (C-RPD group), and SLM Co-Cr metal-ceramic alloys. The SLM specimens were subjected to 2 different heat treatments, L1 at 880°C and L2 at 1100°C, and were further divided into subgroups (L1-MC, L1-RPD, L2-MC, and L2-RPD). Thirty-six tensile specimens were prepared in C-RPD, L1-RPD, and L2-RPD (simulated partial denture alloys for clinical use) and in C-MC, L1-MC, and L2-MC (simulated metal-ceramic alloys); 18 metal-ceramic bond strength specimens were prepared in C-MC, L1-MC, and L2-MC groups (n=6). The tensile test and 3-point bend test were conducted using a universal testing machine. The fracture surfaces of the L2-RPD tensile bar were examined using a scanning electron microscope. The Student t test (α=.05) was used for statistical analysis. ResultsNo significant differences were observed between the bond strengths of L1-MC and C-MC (P=.74) or between those of L2-MC and C-MC (P=.124). The 0.2% yield strength (σ0.2) and elongation of all SLM specimens exceeded the minimum requirements required for the fabrication of thin RPDs as prescribed in ISO 22674:2016. The σ0.2 value of L1-MC and L2-MC was significantly higher than that of C-MC. Significant differences in σ0.2 values were found among the 3 RPD groups, L1-RPD>L2-RPD>C-RPD. For the elongation, significant differences were found among the 3 groups, L2-RPD>C-RPD>L1-RPD. The fracture surface of L2-RPD showed clear submicroscale dimples with fusion defects. ConclusionsWhen Co-Cr metal copings and RPD frameworks were fabricated on the same substrate simultaneously using SLM, heat treatment at 1100°C was found more suitable than at 880°C to release residual stress, considering the toughness required for dental prostheses.

A Review on Translucent Zirconia.

Zirconia is suggested in many clinical situations due to acceptable biocompatibility, lower price compared with gold restorations, and better appearance than traditional metal ceramic restorations. New translucent monolithic zirconia has been developed to merge strength with improved tooth-colour matching. This work aims to review relevant articles on new translucent zirconia restorative materials. The published articles on translucent zirconia were searched through PubMed, Medline, Google scholar, and indexed journals using the following keywords: translucent zirconia, transparent zirconia, and tooth colored zirconia. The most relevant articles were selected and reviewed. Introduction of translucent zirconia, has brought the advantages such as less tooth preparation, biological compatibility, high strength, good mechanical properties, and less antagonist wear. However, the effects of altering material constituents to increase translucency on properties such as phase transformation and low temperature degradation may warrant further investigations. Translucent zirconia can be prescribed in many clinical situations and may provide less complicated procedures compared with the production of multilayer restorations of opaque zirconia cores and translucent feldspathic veneers. This may otherwise decrease fabrication time and defects, improve biological properties, reduce abutment tooth reduction, and result in less antagonist tooth attrition.

Color Aspect of Monolithic Zirconia Restorations: A Review of the Literature.

Monolithic zirconia restoration is an acceptable treatment option in restorative dentistry and a developing trend in esthetic dentistry. Digital dentistry has simplified fabrication of monolithic zirconia restorations. Zirconia ceramic has introduced an opportunity to achieve both esthetic and mechanical requirements for restorations. This is rarely found for a ceramic in dentistry. Monolithic zirconia restorations represent an acceptable durability, comparable to metal-ceramic restorations, while they are superior to metal-ceramic restorations esthetically; however, difficulties to gain an optimal shade reproduction and a color match with monolithic zirconia restorations still remain. The color of these restorations may be influenced by manufacturing processes, laboratory procedures, and clinical factors. Manufacturing processes determine basic optical properties of zirconia ceramics. Different laboratory procedures may create optical changes in zirconia ceramics. Also clinical factors such as dental background, cement, and zirconia restoration features may affect the resulting color. This literature review aimed to discuss potent factors in the color of monolithic zirconia restorations. An electronic search of the PubMed/Google Scholar database was performed to find related English-language articles published between January 1, 2000, and October 31, 2017. The key terms of background, cement, ceramic, color, esthetics, shade, spectrophotometry, thickness, translucency, and zirconia were used both individually and simultaneously. Also, a manual search was conducted, and five classic articles of color science were added. Thus 192 articles were included. In the last decade, shade reproduction of monolithic zirconia restorations has been highly regarded; however, further improvements are required in the manufacturing process to produce tooth-like zirconia ceramics. An esthetic guideline named background-cement-ceramic color harmony was suggested in this study; however, more clinical practice guidelines should be established for monolithic zirconia restorations on esthetics, and therefore, more studies are required.

Influence of repeated firings on marginal, axial, axio-occlusal, and occlusal fit of metal-ceramic restorations fabricated with different techniques

Statement of problemIll-fitting restorations can jeopardize dental, periodontal, and systemic health. Repeated ceramic firing may influence the fitting accuracy of restorations, but scientific information regarding this issue is lacking. PurposeThe purpose of this in vitro study was to assess and compare the influence of repeated firings on the marginal, axial, axio-occlusal, and occlusal fit of metal-ceramic 3-unit fixed partial dentures (FPDs) manufactured with different framework methods, including casting, fully sintered hard alloy milling (FHAM), presintered soft alloy milling (PSAM), and selective laser sintering (SLS). Material and methodsA total of 60 Co-Cr metal frameworks for 3-unit FPDs were fabricated with 3 different computer-aided design and computer-aided manufacturing (CAD-CAM) techniques and conventional casting for a typodont model. The discrepancy values for premolar and molar abutments were measured by using the silicone replica technique after fabrication of the framework, second firing, fourth firing, and seventh firing. The replicas were separated into mesiodistal and buccolingual cross-sections, and digital images of the cross-sections were obtained with a stereomicroscope at ×80 magnification. The measurement points were examined to record the discrepancy values (μm) with in-built measuring software. The recorded data were subjected to repeated-measures 4-way ANOVA and the Bonferroni post hoc test (α=.05). ResultsFor all measurement periods, the marginal, axial, axio-occlusal, and occlusal discrepancy values differed significantly among the manufacturing groups (P<.001). Moreover, the repeated firings had a statistically significant influence on the discrepancy values of PSAM, FHAM, and SLS groups (P<.05). The cast group was not significantly affected by repeated firings (P>.05). The PSAM group revealed the lowest discrepancy values at all measurement periods (P<.05), except after the second firing in the marginal and axial locations. ConclusionsThe PSAM-fabricated restorations demonstrated superior fitting accuracy. All manufacturing groups were influenced by repeated firings, except the cast group. The marginal discrepancy values of all manufacturing groups were within the range of clinical acceptability (<120 μm).

Evaluation of the shear bond strengths between two alternative metal alloys and porcelain

The success of metal-ceramic restorations is influenced by the compatibilitybetween base metal alloys and porcelains. Although porcelain manufacturersrecommend their own metal systems as the most compatible for fabricating metalceramicprostheses, a number of alloys have been used. The purpose of this study wasto evaluate the bond strength of CoCr alloy (Wironbond C) and NiCr alloy (Wiron 99)using shear forces at the metal-ceramic interface. A stainless steel cylindrical matrixwas used for preparation of the metal dies, application of ceramic and to perform theshear tests. Ten metal dies of each alloy were made for each alloy, and the metallicportion was obtained with the lost wax casting technique with standardized waxing of6.5mm of height and of 6mm of diameter. The ceramic was applied according to themanufacturer’s recommendations with the aid of a Teflon matrix that allowed itsdimension to be standardized in the same size as the metallic portion, and shear testswere performed in a universal testing machine at a cross-head speed of 0.5mm/min.The mean shear bond strength values were 53.06MPa for Wirobond C alloy, withstandard deviation of 10.67, and 45.38MPa for Wiron 99, with standard deviation of9.01. No statistically significant difference was observed between the shear strengthof the two metal-ceramic alloys.

Research progress in CoCr metal-ceramic alloy fabricated by selective laser melting

Cobalt-chromium alloys have been applied to dental porcelain fused to metal (PFM) restorations over the past decades owing to their excellent corrosion resistance, good biocompatibility and low price. The production of CoCr metal-ceramic restorations has always been based on traditional lost-wax casting techniques. However, in recent years, selective laser melting (SLM) is becoming more and more highly valued by dental laboratories and dental practitioners due to its individuation, precision and efficiency. This paper mainly reviews the recent researches on the production process of copings, microstructure, mechanical property, metal-ceramic bond strength, fit of copings, corrosion resistance and biocompatibility of SLM CoCr metal-ceramic alloy.

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

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.

Comparative evaluation of three noninvasive gingival displacement systems: An in vivo study.

Aim:An attempt is made to investigate clinical efficacy of cord, paste system, and a strip gingival retractile materials. This study aims to evaluate and compare the gingival retraction efficacy of retraction strip along with conventional retraction cord and paste system.Material and Methods:This in vivo experimental study was carried out on 30 patients. Three different gingival retraction systems were used to evaluate the amount of vertical and lateral displacement.Based on selection criteria, 30 individuals requiring fixed dental prosthesis with respect to mandibular first molar were selected. Tooth preparation for metal ceramic restoration with subgingival finish line was performed. Gingival displacement was accomplished with ultrapak cord, merocel strip, and magic foam cord immediately, 7 and 14 days after the tooth preparation, respectively. The amount of gingival displacement in vertical and lateral directions was measured at mesiobuccal, midbuccal, and distobuccal regions of the prepared tooth. The vertical retraction was measured intraorally by using digital vernier caliper, and postgingival displacement impression was used to measure lateral gingival retraction. Stereomicroscopic images of impression under ×10 resolution were transferred to image analyzer to measure the lateral displacement. The obtained data analyzed in one-way ANOVA and Bonferroni test were used to determine the significant difference at P < 0.05 level.Results:ANOVA test showed the significant difference between the materials tested with respect to the mean vertical and lateral gingival retraction (P = 0.001). Multiple comparisons by Bonferroni test revealed a significant difference in vertical and lateral displacement among the materials tested.Conclusions:Merocel strip provided the maximum amount of vertical and lateral tissue displacement, followed by ultrapak cord and least with magic foam cord which was statistically significant.

Metal-free materials for fixed prosthodontic restorations.

Metal-free materials for fixed prosthodontic restorations.

Mechanical behavior of anterior fixed partial dentures made of different materials subjected to static and dynamic loads

Introduction:&nbsp; the purpose of this study was to assess the mechanical behavior of lithium disilicate, alumina, and zirconia-based ceramic restorations, as well as metal-ceramic restorations, under static and dynamic load, in an upper anterior fixed site. Methods: four models of fixed partial dentures (FPD) were designed, representing alumina, zirconia, and metal-ceramic two-layered systems and a lithium disilicate monolithic system, with a 9 mm2 connector. The variables included were elastic modulus, Poisson’s ratio, and ultimate tensile strength. A static load of 100 N was applied up to 800 N, as well as a dynamic load of 100 and 200 N, calculating von Mises stress and maximum and minimum principal stresses. Results: all models showed a greater concentration of stress under static and dynamic load on the connector region, without exceeding the maximum tensile stress of metal and ceramic structures. The two-layered models showed greater stress concentration on the veneering ceramic compared with the structure. Conclusions: all stresses concentrated on the connector region, producing failure risk at this point of the structures. The veneering ceramic has a greater probability of failure in all two-layered models. The disilicate model can be considered as an alternative for clinical use. The metal-ceramic dentures showed the best distribution on the connector compared to all other models, confirming that they are the gold standard.

CAD/CAM cobalt-chromium alloy single crowns in posterior regions: 4-year prospective clinical study

Aim To evaluate the 4-year clinical outcomes of ceramic veneered CAD/CAM Co-Cr single crowns supported by natural teeth in posterior regions. Material and methods Eighty-nine patients were provided with 120 ceramic veneered CAD/CAM Co-Cr single crowns replacing either premolars and molars. Specific inclusion criteria were set and tooth preparations were standardized and performed by undergraduate students under the supervision of 2 expert prosthodontists. CAD/CAM Co-Cr frameworks were fabricated and veneered with ceramics. The restorations were cemented using a self-etching, dual-cure resin luting agent. The patients were recalled at follow-up every 6 months after baseline evaluation, for a total observational period of 4 years. The survival and success rates of the restorations were evaluated. The technical and esthetic outcomes were examined using the United States Public Health Service criteria. The biologic outcomes were analyzed at abutments and contralateral teeth and descriptive statistics were performed. Results None of the SCs was lost at follow-up, resulting in 100% cumulative survival rate and 99.2% cumulative success rates. No losses of retention were recorded. One hundred and eighteen restorations were rated alpha in all the measured parameters. A minor chipping of the veneering porcelain was detected in 1 restoration. No significant differences between the periodontal parameters of test and control teeth were observed. Conclusions CAD/CAM Co-Cr single crowns proved to be a valid treatment option and a viable alternative to noble metal-ceramic restorations in posterior regions after 4 years of clinical function.