Background and Aim: Metal CERAMIC restorations are widely used in crowns. The marginal fitness of these artificial crowns is prone to alteration during the firing cycle of porcelain. Gold electroformed metal-CERAMIC restorations have been introduced as alternatives to conventional metal-CERAMIC restorations. However little is known about the relationship between procelain firing procedures and marginal adaptation of this type of crown. The aim of the present study was to evaluate the influence of firing procedures on the marginal adaptation of electroformed metal-CERAMIC crown restoration.Materials & Methods: One steel die was prepared for maxillary molar crowns with deep chamfer finishing line design. Ten standardized gold electroformed copings were fabricated. Marginal discrepancy was measured at four sites along the circumferential margin of each coping (Midbuccal - Midpalatal - Midmesial - Middistal) using SEM (Mag: X400) prior to and after porcelain firing procedure. Data among the 2 different groups (before porcelain firing) were statistically analyzed using the paired t-test (a=0.05) analysis.Results: The marginal discrepancy of the postfiring procedures (21.45±2.27 mm) were significantly greater than those of the prefiring procedures (18.23±1.96 mm) (p<0.002).Conclusion: The porcelain-firing procedures influenced the marginal distortion of electroformed metal-CERAMIC crown restorations, but the marginal discrepancies for all copings and examined design are clinically acceptable (less than 100 mm).

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.

Background: Fixed prosthodontics is a routine DENTAL treatment and microleakage is a major cause of its failure.Objectives: The aim of this study was to assess the marginal microleakage of four cements in metal CERAMIC restorations with adapted and open margins.Materials and Methods: Sixty sound human premolars were selected for this experimental study performed in Tehran, Iran and prepared for full-crown restorations. Wax patterns were formed leaving a 300 μm gap on one of the proximal margins. The crowns were cast and the samples were randomly divided into four groups based on the cement used. Copings were cemented using zinc phosphate cement (Fleck), Fuji Plus resin-modified glass ionomer, Panavia F2.0 resin cement, or G-Cem resin cement, according to the manufacturers’ instructions. Samples were immersed in 2% methylene blue solution. After 24 hours, dye penetration was assessed under a stereomicroscope and analyzed using the respective software. Data were analyzed using ANOVA, paired t-tests, and Kruskal-Wallis, Wilcoxon, and Mann-Whitney tests.Results: The least microleakage occurred in the Panavia F2.0 group (closed margin, 0.18 mm; open margin, 0.64 mm) and the maximum was observed in the Fleck group (closed margin, 1.92 mm; open margin, 3.32 mm). The Fleck group displayed significantly more microleakage compared to the Fuji Plus and Panavia F2.0 groups (P<0.001) in both closed and open margins. In open margins, differences in microleakage between the Fuji Plus and G-Cem as well as between the G-Cem and Panavia F2.0 groups were significant (P<0.001). In closed margins, only the G-Cem group displayed significantly more microleakage as compared to the Panavia F2.0 group (P<0.05). Paired t-test results showed significantly more microleakage in open margins compared to closed margins, except in the Fuji Plus group (P=0.539).Conclusions: Fuji Plus cement exhibited better sealing ability in closed and open margins compared to G-Cem and Fleck cements. When using G-Cem and Fleck cements for full metal CERAMIC restorations, clinicians should try to minimize marginal gaps in order to reduce restoration failure. In situations where there are doubts about perfect marginal adaptation, the use of Fuji Plus cement may be helpful.

Background and aim: Mechanical fracture is a common cause for the failure of three-unit DENTAL bridges, particularly the all-CERAMIC ones.The goal of the present study was to evaluate the effects of convergent angles of the abutments on the peak and distribution of mechanical stresses within the prosthesis and at the restoration abutment interface of a three-unit all-CERAMIC bridge using finite element method.Materials and Methods: The cloud points of three-D geometrical data of the second premolar and first and second molar teeth were obtaind using ATOS Scanner system and utilized for the reconstruction of a surface model of the three-unit bridge in CATIA software. Data were than transferred to I-DEAS software for mesh generation and finite element analysis. Two EF models were developed with convergent angles corresponding to the up and low defined range including 171900 and 168700 tetraherdal solid four-node elements, respectively.The models were subjected to two different prosthesis materials and three different load cases.Results: The maximum tensile stresses occurred on the gingival surface of the second premolar retainer and at the tooth/restoration interface on the marginal distal surface of the second molar abutment. The peak tensile stress was relatively lower for the model with the higher convergent angle but the difference was not significant. Changing the prosthesis material from IE2 to Dicor decreased the stresses within the prosthesis.Conclusion: Higher safety factor was found for IE2 due to its higher mechanical strength. Moreover, it was proved that load condition played an important role on the mechanical stress observed.

DENTAL impression materials are fundamental to the production of accurate DENTAL prostheses and restorations. This study focused on the formulation and characterization of a novel, plasticizer-free condensation silicone paste, comparing its performance to a commercial benchmark, Speedex. A specific laboratory paste was developed using 39 vol% hydroxy-terminated polydimethylsiloxanes (PDMS-OH), a high concentration of inorganic fillers (60 vol% silica and calcite), and 1 vol% tetraethyl orthosilicate (TEOS). In contrast, characterization of Speedex revealed a lower inorganic filler content of approximately 40 wt% and the likely presence of plasticizers. A detailed comparative analysis of physicochemical, rheological, and mechanical properties was conducted. The high-filler laboratory formulation demonstrated significantly improved dimensional stability, exhibiting less shrinkage over 12 hours compared to Speedex. This enhancement, however, resulted in a predictable trade-off in mechanical properties. The formulated paste was substantially stiffer, with a higher elastic modulus (4.8 ± 0.2 MPa vs. 3.63 ± 0.12 MPa) and a slightly greater Shore A hardness (62 vs. 60), but it showed markedly reduced ductility, with a lower elongation at break (36.69% vs. 51.82%) than the more flexible commercial material. Rheological profiles also differed notably, reflecting their distinct compositions. These findings highlight that a high-filler, plasticizer-free formulation strategy can significantly improve dimensional accuracy, albeit at the cost of reduced flexibility, providing valuable insights into the structure–property relationships that govern the performance of condensation silicone impression materials.

Background and Aims: Marginal gap measurement in all CERAMIC restorations they are of fundamental important for the successful used. As some studies led to contradiction results, yhe aim of this study is to compare marginal gap restorations between 4 kinds of CERAMIC restorations Inceram, IPS-e. max Press, Zirconia (CAD/CAM) and PFM. Materials and Methods: In this In-vitro experimental research, one stainless steel die with deep chamfer finish line design (1 mm depth) was prepared on a maxillary premolar. 40 epoxy resin dies were made, dies were divided in to 4 groups (n=10), Zirconia, IPS e. max press, Inceram, Mental CERAMIC systems (MC). Then, the prepared crowns were put on the stainless steel die and observed their marginal mismatch under sterio microscope before cementation. Data were analyzed by One-way ANOVA, and one sample kolmogorosmirnov tests. Resultes: There was significant difference in the marginal gaps between (MC) (102. 92± 28. 7), Inceram (98. 41± 24. 91), IPS e. max press (128. 22± 25. 48), and Zirconia (69. 5± 10. 9) (P=0. 0001). Conclusion: The comparison of marginal gap for the four groups was significant test. Therefore, it can be concluded that marginal gap, the probability of leakage and recurrence of caries in Zirconia systems is the least and in the IPS e. max press systems is the most.