Evaluating the Impact of Oxidation Heat Treatment and Dual Opaquing Techniques on Enhancing Metal-Ceramic Bond Strength.

BACKGROUND: This research aims to assess the impact of oxidation heat treatment (OHT) and dual opaquing techniques on enhancing the bond strength between metal and ceramic. MATERIAL AND METHOD: Eighty rectangular patterns with dimensions of 0.5x3x25 mm (according to ISO 9693-2012) were fabricated in a custom-made silicon mold by using auto-polymerized pattern resin material. These rectangular patterns were cast using base metal alloys. The samples were split into two primary groups: group A, subjected to OHT, and group B, without oxidation treatment. Each primary group was then split up into subgroups according to the application of single layers (group A1, B1) or double layers (group A2, B2) of opaque porcelain. After pre-surface treatment and Ceramco 3 paste opaque application, dentin porcelain (Ceramco 3) was applied to the mid-region of the samples, followed by firing to achieve a standardized thickness. Flexural strength determination was conducted via a three-point bend test performed on the universal testing machine (UTM) (Instron Corp., Model 2519-107, USA), adhering to ISO standard 9693. Post-testing failure types were analyzed by morphological assessment of debonding surfaces via a scanning electron microscope (SEM). The statistical analysis was performed with SPSS version 16, incorporating ANOVA for intergroup analysis and independent t-tests for intragroup comparisons. RESULTS:  Group A2 exhibited the highest mean flexural bond strength (P<0.05) at 41.85 MPa when compared to group A1 at 37.60 MPa, group B2 at 35.47 MPa, and group B1 with the least mean flexural bond strength at 30.41 MPa. SEM observations revealed cohesive bond failure for groups A1, A2, and B2 and adhesive bond failure for groups B1. CONCLUSION:  It is evident that OHT and opaquing technique are important factors in determining the bond strength of ceramo-metal restorations. When combined, these techniques greatly increase the overall success and durability of metal-ceramic restorations, underscoring their significance in contemporary dental prostheses.

Repair of fractured metal-ceramic restoration using CAD/CAM technologies. Case report.

Fractures in esthetic ceramic veneering are one of the potential failure modes during prosthetic treatment. Depending on the type of chipping fracture, there are three possible outcomes: replacement, restoration repair, or polishing of the fractured area. Computer-aided design and manufacturing (CAD/CAM) technologies provide new methods to the maintenance and repair of fixed metal-ceramic restorations. Here, we report the case of a 68-year-old patient who came to the dentist with comcerns about his appearance due to spontaneous gingival bleeding and a fracture in the ceramic veneering of a metal-ceramic restoration. The patient reported occurrences of bruxism. The proposed treatment plan included consultation with a cardiologist, periodontal treatment, polishing of the chipped areas, repair of the fractured zone with an exposed metal core, and fabrication of a mouth guard. Once the ceramic veneering on the palatal and buccal sides of the retainers had been completely removed, a digital impression was obtained and sent to the dental lab so that milled zirconium veneer could be manufactured. The veneering was cemented the next day using the standard prosthetic field preparation process and resin-modified glass ionomer cement. In conclusion, fixed metal-ceramic restorations that have fractured can be successfully repaired using CAD/CAM methods and materials.

Clinical internal and marginal fit of metal-ceramic fixed dental prostheses fabricated with selective laser melting and 3D-printed pattern casting using cobalt-chromium metal alloy.

PURPOSE: To evaluate the fit of metal-ceramic three-unit fixed dental prostheses (FDPs) fabricated using selective laser melting (SLM) and 3D-printed casting pattern (CP) and to compare the effect of tooth type and ceramic veneering on marginal and internal gaps. MATERIALS AND METHODS: Patients requiring posterior three-unit FDPs were selected. For each subject, two FDPs were fabricated using SLM and CP. Silicon replica was used to measure the internal and marginal fit of frameworks before and after ceramic veneering. For each replica, 36 measurements were performed using a stereomicroscope: 4 marginal and 32 internal (4 deep chamfers, 12 axial, 4 axio-occlusal, and 12 occlusal). Statistical analysis was performed using two-way ANOVA and paired t-test. RESULTS: A total of 44 metal-ceramic FDPs were fabricated in 22 patients. The results showed that the fabrication method had no significant effect on the marginal, deep chamfer, or occlusal gaps. However, the method significantly affected the axial, axio-occlusal, and total internal fit, and the SLM had larger gaps than the CP. For the effect of ceramic veneering, measurements were significantly higher in the CP group at all gaps, except for the premolar axial and molar occlusal gaps. The SLM fit was less affected by ceramic veneering. Only premolar gaps significantly increased at the marginal, deep chamfer, and axial and axio-occlusal positions. CONCLUSION: Metal-ceramic FDPs fabricated using SLM and CP techniques provided a similar marginal fit. Premolars had smaller discrepancies compared to molars. The ceramic veneering process increased the gap of the prostheses, with SLM being less affected by ceramic veneering.

In Vitro Assessment of the Fracture Resistance of Different Prosthodontic Materials for Fixed Dental Prostheses.

Background: Fixed dental prostheses (FDPs) are commonly used in prosthodontics to restore missing teeth and improve oral function and esthetics. The selection of prosthodontic materials significantly impacts the fracture resistance of FDPs, thus influencing their clinical success. This study aimed to assess the fracture resistance of different prosthodontic materials commonly used in FDPs through in vitro testing. Materials and Methods: Thirty standardized FDP specimens were fabricated using three different materials: Monolithic zirconia, heat press lithium disilicate, and metal ceramic. Each group consisted of ten specimens. The specimens were subjected to standardized loading using a universal testing machine until fracture occurred. Fracture resistance values were recorded in Newtons (N) and statistically analyzed using one-way analysis of variance (ANOVA) followed by post-hoc Tukey tests. Results: The mean fracture resistance values for the three materials were as follows: zirconia, 1450 N; lithium disilicate, 1200 N; and metal ceramic, 950 N. Statistical analysis revealed a significant difference among the groups (P < 0.05). Post hoc Tukey tests indicated that zirconia exhibited significantly higher fracture resistance compared to lithium disilicate and metal ceramic (P < 0.05). However, there was no significant difference in fracture resistance between lithium disilicate and metal-ceramic groups (P > 0.05). Conclusion: Within the limitations of this in vitro study, zirconia demonstrated the highest fracture resistance among the tested materials for FDPs, followed by lithium disilicate and metal ceramic. The findings highlight the importance of material selection in achieving optimal clinical outcomes and longevity of fixed dental prostheses.

Specially Structured AgCuTi Foil Enables High-Strength and Defect-Free Brazing of Sapphire and Ti6Al4V Alloys: The Microstructure and Fracture Characteristics.

A novel AgCuTi brazing foil with a unique microstructure was developed, which could achieve strong vacuum brazing of Ti6Al4V (TC4) and sapphire. The brazing foil was composed of Ag solid solution (Ag(s,s)), Cu solid solution (Cu(s,s)), and layered Ti-rich phases, and had a low liquidus temperature of 790 °C and a narrow melting range of 16 °C, facilitating the defect-free joining of TC4 and sapphire. The sapphire/TC4 joint fabricated by using this novel AgCuTi brazing foil exhibited an outstanding average shear strength of up to 132.2 MPa, which was the highest value ever reported. The sapphire/TC4 joint had a characteristic structure, featuring a brazing seam reinforced by TiCu particles and a thin Ti3(Cu,Al)3O reaction layer of about 1.3 µm. The fracture mechanism of the sapphire/TC4 joint was revealed. The crack originated at the brazing seam with TiCu particles, then propagated through the Ti3(Cu,Al)3O reaction layer, detached the reaction layer from the sapphire, and finally penetrated into the sapphire. This study offers valuable insights into the design of active brazing alloys and reliable metal-ceramic bonding.

Cytokines profile in gingival crevicular fluid of subjects wearing fixed dental prostheses: a systematic review and meta-analysis.

BACKGROUND: Fixed dental prostheses (FDP) can affect the production of inflammatory cytokines causing damage to periodontal tissues. A systematic review and meta-analysis was carried out with the following two objectives: (1) to determine the prevalence and function of the different inflammatory cytokines present in gingival crevicular fluid (GCF) of teeth with metal-ceramic (M/C) and all-ceramic (A-Cs) prostheses, and (2) to analyze and compare the levels of inflammatory cytokines in GCF of teeth with M/C and A-Cs prostheses. METHODS: The protocol followed PRISMA and Cochrane guidelines and was registered in the OSF:10.17605/OSF.IO/RBHJU. A digital search was conducted in the databases PubMed/MEDLINE, Cochrane Library, Dentistry & Oral Sciences Source, Scopus, Web of Science, ScienceDirect, and Google Scholar, from July 15th, 2000 to March 1st, 2024. Study quality was assessed using the JBI tool for cross-sectional and longitudinal studies. A meta-analysis was performed using a random-effects model to evaluate the concentration of IL-1ß in GCF of teeth with FDP of M/C and A-Cs. RESULTS: The search strategy provided a total of 8,172 articles, of which 14 investigations met the inclusion criteria. The total number of patients studied was 468 of whom 53% were women and the rest (47%) were men. The ages of the patients ranged from 19 to 73 years, with a mean age ± standard deviation (SD) of 38,5 ± 12,8 years. A total of 843 fixed dental prostheses were studied, of which 407 (48,27%) were M/C prostheses and 410 (48,63%) were A-Cs prostheses. We found that the levels of IL-1ß, IL-1α, PGE2, NKA, CGRP, and CX3CL1 were increased in teeth with M/C prostheses compared to teeth with A-Cs prostheses. Meta-analysis revealed that there are no significant differences between IL-1ß levels in GCF in teeth with M/C prostheses compared to teeth with A-Cs prostheses (SMD = 13.89 pg/ml (CI = -14.29-42.08), p = > 0.05). CONCLUSIONS: A trend toward increased levels of inflammatory cytokines was found in GCF of teeth with M/C prostheses compared to teeth with A-Cs prostheses.

Dental human enamel wear caused by ceramic antagonists: A systematic review and network meta-analysis.

PURPOSE: Fixed restorations and dental enamel have different structures that produce different wear on opposing teeth, resulting in clinical problems. Therefore, it is necessary to determine the type of restoration that causes less wear on naturally opposing teeth to make recommendations. The objective of this study was to systematically analyze the evidence from observational studies and clinical trials on enamel wear in different ceramic restorations. STUDY SELECTION: The designs of the included studies were randomized clinical trials (RTCs), non-randomized clinical trials (non-RTCs), and observational studies (OS). The studies must answer the research question, be available in full text, be written in English or Spanish, and have had at least six months of follow-up. Protocol number: CRD42023397759. RESULTS: After screening 499 records, 20 RTCs were subjected to data extraction, 10 were excluded, 10 were included in the systematic review, and only 5 were included in the network meta-analysis. The risk of bias assessment reported moderate to high risk of bias, quality, and certainty of evidence was evaluated and rated as moderate. Network meta-analysis showed higher enamel wear was observed in natural dental enamel against metal-ceramic antagonists. CONCLUSIONS: Enamel wear occurs in all teeth, even when the antagonist is a natural tooth. The wear is larger on surfaces with the ceramic crown antagonists studied (metal-ceramic, glazed zirconia, and polished zirconia). It is necessary to conduct additional clinical trials with larger follow-up periods and sample sizes.

Fabrication of Layered SiC/C/Si/MeSi2/Me Ceramic-Metal Composites via Liquid Silicon Infiltration of Metal-Carbon Matrices.

The growing demand for composite materials capable of enduring prolonged loads in high-temperature and aggressive environments presents pressing challenges for materials scientists. Ceramic materials composed of silicon carbide largely possess high mechanical strength at a relatively low density, even at elevated temperatures. However, they are inherently brittle in nature, leading to concerns about their ability to fracture. The primary objective of this study was to develop a novel technique for fabricating layered composite materials by incorporating SiC-based ceramics, refractory metals, and their silicides as integral constituents. These layered composites were produced through the liquid-phase siliconization method applied to metal-carbon blanks. Analysis of the microstructure of the resultant materials revealed that when a metal element interacts with molten silicon, it leads to the formation of a layer of metal silicide on the metal's surface. Furthermore, three-point bending tests exhibited an enhancement in the bending strength of the layered composite in comparison to the base silicon carbide ceramics. Additionally, the samples demonstrated a quasi-plastic nature during the process of destruction.

Impact of Prosthetic Material and Restoration Type on Peri-Implant Bone Resorption: A Retrospective Analysis in a Romanian Sample.

Background/Objectives: This research investigates the nuanced factors influencing peri-implant bone resorption in implant-supported fixed prostheses, with a focus on age, gender, implant location, time since prosthetic loading, and material characteristics. Methods: Records from a dental clinic in Oradea, Romania, between 1 January 2017 and 1 January 2023, were scrutinized and were selected by means of purposive sampling. All records were analyzed between 1 May 2023 and 15 June 2023. A total of 160 implants were included, and the prosthetic restorations were either metal-ceramic or zirconia. Implants from a single manufacturer were used, and a standardized loading protocol was followed. The study examined variables such as age, gender, implant location, prosthetic material, and time since prosthetic loading. Results: A total of 160 implants were included, with 78 applied to female patients (48.8%) and 82 to male patients (51.2%). The age range of the patients undergoing dental implant procedures was 30 to 79 years. Implants were distributed between the mandible (51.2%) and maxilla (48.8%), with 49.4% placed in the posterior dental arches and 50.6% in the anterior dental arches. The majority of patients received metal-ceramic prosthetic reconstructions (76.9%). Statistical analysis revealed significant differences in resorption patterns between zirconia and metal-ceramic restorations (p < 0.001), with zirconia restorations exhibiting higher resorption in the mesial-vertical and distal-vertical planes compared to metal-ceramic restorations. Age-related factors showed a significant association with distal-vertical resorption (p = 0.017), with patients aged 60-69 years exhibiting higher resorption values compared to those aged 40-49 years. Gender differences were observed in mesial-horizontal resorption (p = 0.036), with male patients displaying higher resorption values compared to female patients. Implant location and time elapsed since implant loading did not show significant associations with resorption patterns. Conclusions: The study provides insights into the multifactorial nature of peri-implant resorption. Age, gender, and material characteristics contribute to variations, informing personalized treatment approaches. The findings facilitate a comprehensive understanding for clinicians, enhancing treatment planning and post-operative care.

Dental ceramic damage associated with incorrect laboratory procedures.

Ceramic is a commonly used material in dentistry for reconstructing missing teeth or their tissues due to its biocompatibility, durability and excellent esthetic properties. Despite these advantages, the ceramic restoration damage remains a significant clinical problem. Its causes can be divided into clinical and laboratory factors. The most known include uneven occlusion, improper preparation, trauma, or parafunctions. This study focuses on characterizing less known laboratory causes of ceramic restoration damage. We reviewed the current literature available in the PubMed and Scopus databases. On the basis of 63 selected studies, 3 basic causes of damage were identified: excessive stresses between the framework and ceramic veneering, poor quality of the connection between the facing layer and the substructure, and defects resulting from the nature of the ceramic material such as defects in the ceramic layer, brittleness and lack of flexibility. The stages of the manufacturing process of various permanent ceramic restorations were presented. By controlling these procedures, we can eliminate the errors, resulting in long-term effective functioning of the ceramic restorations.

Zirconia-ceramic versus metal-ceramic implant-supported multiunit fixed dental prostheses: A systematic review and meta-analysis.

Implant-supported prostheses could serve as a reliable restorative option for partial edentulism. Various restorative materials have been utilized in fabricating these prostheses, impacting both esthetics and peri-implant health. The present systematic review aimed to assess the survival rate and mechanical complications of zirconia ceramic compared to metal-ceramic implant-supported multiunit fixed dental prostheses (FDPs). We conducted searches in online databases such as MEDLINE (PubMed), Scopus, and Cochrane up until December 2022. A risk-of-bias assessment was done for all the included studies. Data extraction was performed based on the following parameters: author, year, study design, number of implants, abutment material, age range, observation period, incidence of mechanical complications, and survival rate. This systematic review included six studies (four randomized controlled trials and two retrospective studies). The meta-analysis significantly favored metal-ceramic restorations regarding mechanical complications with a risk ratio (RR) value of 1.64 and P = 0.001. Meta-analysis showed no difference in metal-ceramic FDPs in prostheses survival rate (P = 0.63; RR: 1.27, 95% confidence interval: 0.52-3.37; heterogeneity: P = 0.65; I2: 0%). While metal-ceramic multiunit implant-supported prostheses exhibited fewer mechanical complications compared to zirconia-ceramic prostheses, there was no significant difference in terms of prosthesis survival rate between the two. Hence, both treatments appear to be viable options for long-term implant-supported prostheses.

Effect of different production techniques on the color of porcelain-fused-to-titanium restorations.

In dentistry, the shade selection of the restoration affects the success of the restoration. For this reason, it may be decisive for clinicians to determine whether the difference in framework production influences color in metal-ceramic restorations. The study examined the effects of different framework production techniques used in porcelain-fused-to-titanium restorations on color changes. 45 square-shaped samples were manufactured using cast, milling, and laser-sintering techniques. Opaque and dentin porcelain were performed, and all samples were glazed. A spectrophotometer was used for color measurements. Before opaque application, after opaque application, and after porcelain + glaze application, it was obtained L*, a*, and b* values. Color differences (ΔE00) were calculated with the CIEDE2000 formula. ANOVA (Post Hoc: Bonferroni) and Shapiro Wilks (Normality) tests were used for statistical analysis (p < 0.05). At the different laboratory steps, the difference between cast&laser-sintered groups and between milled&laser-sintered groups was statistically significant (p < 0.05). Before and after opaque application, the differences in L*, a*, and b* values between cast, milled, and laser-sintered groups were statistically significant (p < 0.05). Different framework production methods influenced the color of porcelain-fused-to-titanium restorations.

A Retrospective Evaluation of 5 Years of Clinical Results of Metal-Ceramic vs. Monolithic Zirconia Superstructures in Maxillary All-on-4TM Concept.

The aim of the current study was to present the clinical and radiological outcomes of monolithic zirconia superstructures compared to the metal-ceramic ones in the All-on-4 concept for the prosthetic rehabilitation of the maxillae. A total of 30 patients were subdivided into groups according to their superstructure type (metal-ceramic (n = 15) or monolithic zirconia (n = 15)). All implants were functionally loaded within 24 h after insertion with provisional acrylic superstructures. Prosthetic complications, marginal bone loss, plaque accumulation, probing pocket depth, bleeding on probing, and bite force were documented over a period of 5 years. Marginal bone loss around the implants of the ceramic group remained well over the five years (1.21 ± 0.23 mm). However, marginal bone loss was significantly lower around the implants in the monolithic zirconia group (0.22 ± 0.14 mm) (p < 0.001). Bleeding on probing, plaque accumulation, and probing pocket depth values were correlated with marginal bone loss. Among all evaluated parameters, no differences could be detected in terms of the angulation of the implants. Detachment or chipping was observed in seven cases in the metal-ceramic superstructure group. In all cases, dentures were removed and repaired in the laboratory. In the monolithic zirconia group, chipping was detected after one year in two cases, after two years in four cases, and after five years in one case and could be managed by polishing in situ. Monolithic zirconia superstructures presented superior results regarding the parameters evaluated.

Digital workflow for monolithic and veneered zirconia and metal-ceramic posterior fixed partial dentures: A five-year prospective randomized clinical trial.

Purpose To evaluate and compare the survival, success rates, and biological and technical complications of three-unit posterior monolithic and veneered zirconia and metal-ceramic (MC) posterior fixed partial dentures (FPDs) fabricated using a digital workflow and computer-aided design and computer-aided manufacturing (CAD/CAM) over a 5-year follow-up.Methods Ninety patients in need of three-unit posterior FPDs were randomized to receive monolithic zirconia (MZ), veneered zirconia (VZ), and MC restorations (n = 30 each). Teeth preparations were scanned using an intraoral scanner, and restorations were milled and cemented with resin cement. Clinical performance and periodontal parameters were assessed at baseline and yearly up to 5 years after insertion. Data analysis was performed using the Kaplan-Meier method, Friedman test, and Wilcoxon signed-rank test with Bonferroni correction and Mann-Whitney U test.Results The 5-year survival rates of the MZ, VZ, and MC FPDs were 87%, 97%, and 100%, respectively (P = 0.04). Most complications were biological in nature. Only one MZ FPD fractured 58 months after placement. All the restorations were assessed as satisfactory at each recall. Differences were found in the gingival index score over time in the VZ and MC groups. The margin index remained stable throughout the follow-up period in both zirconia groups.Conclusions The results of this study suggest that using a digital workflow to fabricate posterior FPDs is an adequate treatment option and that monolithic zirconia could be a viable alternative to metal-ceramic or veneered zirconia. However, further long-term studies are necessary to provide stronger evidence in patients with bruxism.

Influence of stress-relieving heat treatments on the efficacy of Co-Cr-Mo-W alloy copings fabricated using selective laser melting.

Purpose This study aimed to evaluate the influence of stress-relieving heat treatments on the metal-ceramic bond strength and fitness accuracy of selective laser melting (SLM)-fabricated Co-Cr alloy copings.Methods SLM-manufactured Co-Cr samples were stress-relieved at 750 (Ht-750) and 1150 °C (Ht-1150). The microstructure, surface roughness, metal-ceramic bond strength, marginal and internal fit, Vickers hardness, and residual stress were then compared with those of the non-heat-treated group (As-built). The results were analyzed using one-way ANOVA and post-hoc tests (Tukey's or Student's t test) (P = 0.05).Results The microstructure of the Ht-1150 samples had a brittle oxide layer and lower surface roughness, resulting in significantly lower bond strength values than those of the other groups. The As-built group exhibited significantly lower marginal gap values than the Ht-750 and Ht-1150 groups. Therefore, the post-heat treatments degraded the marginal fitness. The surface residual stress in all sample groups were compressive because of the sandblasting effect. The compressive stresses were larger in Ht-1150 than in As-built and Ht-750 owing to their low hardness values.Conclusions Stress-relief annealing porcelain-fused-to-metal single crowns does not improve bond strength and degrades fitness accuracy because additional post-heat treatments induce thermal distortion. These findings are expected to facilitate the direct application of As-built SLM single crowns in dentistry to minimize post-manufacturing costs and time.

Comparison of the fracture strengths of single-unit metal-ceramic and monolithic zirconium restorations in the molar region: a systematic review and meta-analysis.

Despite the success of monolithic zirconia restorations (MZ), metal-ceramic restorations (MC) are still considered the gold standard for fixed prosthetics in the posterior region. This systematic review and meta-analysis aimed to compare the fracture strengths of single-unit MC and MZ in the molar region. This review was based on the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA, 2020) statement. All articles were searched from the PubMed and Web of Science databases until November 18, 2022. All in vitro studies evaluating the fracture strengths of MC and MZ were also included. Statistical analysis was performed with the Comprehensive Meta-Analysis program, with a significance level of 0.05. Out of 753 studies, five were selected. The fracture strengths of MZ and MC did not show any statistically significant difference for both tooth (95% CI - 1.589: 2.118, p = 0.779, z = 0.280) and implant (95% CI - 2.215: 2.191, p = 0.992 z = - 0.010) supported restorations. However, different abutment materials (p < 0.001) and aging treatments (p < 0.001) in tooth-supported restorations displayed a significant statistical difference. Additionally, a significant difference was also observed in subgroup analysis considering different cements (p = 0.001) and load speeds (p = 0.001) in implant-supported restorations. Fracture strengths of MZ and MC did not show a significant statistical difference in implant or tooth-supported single-unit posterior restorations. MZ may be a suitable alternative to MC in single-unit posterior restorations. The results should be interpreted with caution, as the included studies were in vitro.

Comparative Analysis of the Structural Weights of Fixed Prostheses of Zirconium Dioxide, Metal Ceramic, PMMA and 3DPP Printing Resin-Mechanical Implications.

The aim of this study was to determine the mechanical implications of four-unit fixed dental prostheses (FDPs) made of (1) monolithic zirconium dioxide (ZR O2), (2) polymethylmethacrylate (PMMA), (3) metal ceramic (PFM) and (4) impression resin (3DPP). METHODS: Four groups were studied with eight samples for each material (n: 32). Each structure was weighed, subjected to compressive tests and analyzed using 3D FEA. RESULTS: PMMA presented the lowest structural weight (1.33 g), followed by 3DPP (1.98 g), ZR O2 (6.34 g) and PFM (6.44 g). In fracture tests, PMMA presented a compressive strength of 2104.73 N and a tension of 351.752 MPa; followed by PFM, with a strength of 1361.48 N and a tension of 227.521 MPa; ZR O2, with a strength of 1107.63 N and a tension of 185.098 MPa; and 3DPP, with a strength of 1000.88 N and a tension of 143.916 MPa. According to 3D FEA, 3DPP presented the lowest degree of deformation (0.001 mm), followed by PFM (0.011 mm), ZR O2 (0.168 mm) and PMMA (1.035 mm). CONCLUSIONS: The weights of the materials did not have a direct influence on the mean values obtained for strength, stress or strain. Since the performance was related to the tension and forces supported by the structures in critical zones, the importance of considering design factors is clear. In vitro and 3D FEA assays allowed us to simulate different scenarios for the mechanical properties of certain materials before evaluating them clinically. Thus, they can generate predictions that would allow for the design of a better research methodology in future clinical trials.

[A prospective single-cohort study of implant-supported full-arch metal-ceramic prosthesis with gold-platinum alloy framework for treatment edentulous mandible in elderly patients: 15-year report]. / Implantatsionnoe protezirovanie protyazhennymi metallokeramicheskimi konstruktsiyami s karkasom iz zolotoplatinovogo splava u pozhilykh patsientov: rezul'taty 15-letnego perspektivnogo odnogruppovogo kogortnogo issledovaniya.

OBJECTIVE: To study the effectiveness of implant-supported full-arch metal-ceramic prosthesis with gold-platinum alloy framework in elderly patients. MATERIALS AND METHODS: The study included patients with complete and/or partial loss of teeth and terminal dentition. In 2007-2008, 354 implants were inserted in 27 patients. The age of the patients was 61.31±5.08 years. Mombelli index criteria (mBI [modified Sulcus Bleeding Index]) were used. The plaque index was determined using a modified Löe & Silness method. The state of the peri-implant bone (ΔMBL) was determined by a series of OPG. The Geriatric Oral Health Index (GOHAI) was used to assess oral health in the elderly. RESULTS: Metal-ceramic full-arch implant prostheses with a gold-platinum alloy framework, based on a sufficient and optimal number of implants (6-8), showed high survival rate (100%) after 15 years. Marginal bone loss (ΔMBL) after 15 years was -1.44±1.27 mm. The survival rate of implants was 99.4%. Scores on the GOHAI scale were higher in patients after orthopedic rehabilitation (from 52.7±7.1 to 54.1±8.4, p<0.001). CONCLUSION: After 15 years, all prostheses had mechanical defects, which at the same time allowed them to be used without restrictions. Screw fixation of full-arch implant prostheses, although it was associated with mechanical complications, nevertheless made it possible to perform surgical interventions in a timely manner and stop the development of inflammatory complications. Thus, we do not see any grounds for removing metal-ceramic prostheses and replacing them with new implant prostheses even after a 15-year period of operation. At the same time, it is necessary to take into account the reduction in the possibility of individual oral hygiene in elderly patients, as well as possible restrictions on self-visiting a dentist or dental hygienist.

Technical assessment of shear bond strength at ceramo-alloy interface after various surface treatment combinations and application of metal bonding agent.

BACKGROUND: Bonding between metal and ceramic is one of the most important aspects of a successful prosthesis. Various methods have been recommended for preparing the metal surface to enhance the bond between metal and ceramic including the use of a metal bonding agent. OBJECTIVE: This study aims to evaluate and compare the shear bond strength of the metal-ceramic (M-C) interface after combinations of various surface treatments including the application of a metal bonding agent. METHOD: 40 Ni-Cr alloy specimens were made and divided into 4 groups of 10 each based on the combination of surface treatments. Sandblasting, surface grinding, and Oxidation heat treatment (OHT) were performed on specimens from Group 1 (Control). In addition, Group 2 specimens received ultrasonic cleaning, Group 3 steam cleaning, and Group 4 metal bonding agent application. Following surface treatments on all specimens, porcelain build-up was performed, and shear bond strength was tested in a Digital Universal testing machine. The statistical tests used were independent t-test and ANOVA. RESULTS: Results revealed that Group 4 specimens had the highest mean value of shear bond strength of 39.087 MPa while Group 3 specimens showed the least mean shear bond strength of 18.154 MPa with highly statistically significant results (p< 0.001). CONCLUSION: The surface treatments and application of bonding agent to metal prior to porcelain application resulted in increased shear bond strength of the metal-ceramic interface.

Metal-Ceramic Compatibility in Dental Restorations According to the Metallic Component Manufacturing Procedure.

In terms of production technology, metal-ceramic systems for dental restorations comply with a concrete algorithm, the efficiency of which is always dependent on the applications for which they are intended. The first stage involves obtaining metal support, followed by firing the ceramic on the surface of the metal to meet the list of functional and aesthetic requirements of a future restoration. The compatibility of the two materials-the metal component and the ceramic component-must be ensured in several respects: chemical compatibility, thermo-chemical compatibility, and mechanical compatibility. Thus, there is a need to simulate the thermal behavior of the metal-ceramic couple in its processing to achieve appropriate dental prostheses. In this study, three types of Co-Cr metal frames were manufactured using three different production technologies: conventional casting, milling (CAM), and selective laser melting (SLM). Composition analyses, scanning electron microscopy (SEM), and microstructural analyses of the metal-ceramic interface for each type of production technology, as well as the determination of the hardness and the thermal expansion coefficients of experimental materials and three-point bending tests, were carried out in this study. Considering all these aspects, we demonstrated the influence of the technology of producing the metallic part of the metal-ceramic bonding process in dental prostheses.