An invitro analysis of elemental release and cytotoxicity of recast nickel-chromium dental casting alloys

Transport Properties in Multicomponent Systems Containing Cyclodextrins and Nickel Ions

In this work, we propose a comprehensive experimental study of the diffusion of nickel ions in combination with different cyclodextrins as carrier molecules for enhanced solubility and facilitated transport. For this, ternary mutual diffusion coefficients measured by Taylor dispersion method are reported for aqueous solutions containing nickel salts and different cyclodextrins (that is, α-CD, β-CD, and γ-CD) at 298.15 K. A combination of Taylor dispersion and other methods, such as UV-vis spectroscopy, will be used to obtain complementary information on these systems. The determination of the physicochemical properties of these salts with CDs in aqueous solution provides information that allows us to understand solute-solvent interactions, and gives a significant contribution to understanding the mechanisms underlying diffusional transport in aqueous solutions, and, consequently, to mitigating the potential toxicity associated with these metal ions. For example, using mutual diffusion data, it is possible to estimate the number of moles of each ion transported per mole of the cyclodextrin driven by its own concentration gradient.

Comparative in-vitro microscopic evaluation of vertical marginal discrepancy, microhardness, and surface roughness of nickel-chromium in new and recast alloy

Reusing of alloy has become a need of time due to the increasing demand, depletion of resources, and substantial increase in their price. The alloys used require a long-term stay in the oral cavity exposed to a wet environment, so they must have good wear resistance, biocompatibility, and mechanically good strength. In this study, the vertical marginal discrepancy, surface roughness, and microhardness of the new and recast nickel-chromium (base metal) alloys were evaluated. 125 wax patterns were fabricated from a customized stainless steel master die with a heavy chamfer cervical margin divided into 5 groups. Each group had 25 samples. Group A: 25 wax patterns were cast using 100% by weight of new alloy, Group B: the casting was done by using 75% new alloy and 25% alloy by weight, Group C: wax patterns were cast using 50% new alloy and 50% alloy, Group D: 25% new alloy and 75% alloy and Group E: 100% recast alloy. The vertical marginal discrepancy was measured by an analytical scanning microscope, microhardness was tested on a universal testing machine, and surface roughness was on a tester of surface roughness. Castings produced using new alloys were better than those obtained with reused alloys. Alloys can be reused till 50% by weight along with the new alloy and accelerated casting technique can be used to save the lab time to fabricate castings with acceptable vertical marginal discrepancy, microhardness, and surface roughness. This indicated that 50% recasting of (Ni-Cr) can be used as a good alternative for the new alloy from an economical point of view.

Limitations of reuse for silver-palladium alloys -Evaluating post-recasting heat treatment impact on corrosion resistance

The aim of this study was to investigate the effect of repeated casting and heat treatment on the corrosion resistance of a commercial Ag-Pd-Cu-Au alloy as evaluated by electrochemical techniques. After repeated casting, the fifth cast of the Ag-Pd-Cu-Au alloy exhibited dramatic degradation of properties, although upon heat treatment, this corrosion resistance did improve. Despite the improvement by heat treatment, after five castings, this alloy may not have satisfactory hardness for clinical use. These results of this study demonstrate that, up to the fourth cast and heat treatment, the Ag-Pd-Cu-Au alloy has acceptable corrosion resistance and hardness.

In Vitro Measurement and Mathematical Modeling of Thermally-Induced Injury in Pancreatic Cancer Cells

Thermal therapies are under investigation as part of multi-modality strategies for the treatment of pancreatic cancer. In the present study, we determined the kinetics of thermal injury to pancreatic cancer cells in vitro and evaluated predictive models for thermal injury. Cell viability was measured in two murine pancreatic cancer cell lines (KPC, Pan02) and a normal fibroblast (STO) cell line following in vitro heating in the range 42.5-50 °C for 3-60 min. Based on measured viability data, the kinetic parameters of thermal injury were used to predict the extent of heat-induced damage. Of the three thermal injury models considered in this study, the Arrhenius model with time delay provided the most accurate prediction (root mean square error = 8.48%) for all cell lines. Pan02 and STO cells were the most resistant and susceptible to hyperthermia treatments, respectively. The presented data may contribute to studies investigating the use of thermal therapies as part of pancreatic cancer treatment strategies and inform the design of treatment planning strategies.

Recent update on potential cytotoxicity, biocompatibility and preventive measures of biomaterials used in dentistry

Dental treatment is provided for a wide variety of oral health problems like dental caries, periodontal diseases, periapical infections, replacement of missing teeth and orthodontic problems. Various biomaterials, like composite resins, amalgam, glass ionomer cement, acrylic resins, metal alloys, impression materials, bone grafts, membranes, local anaesthetics, etc., are used for dental applications. The physical and chemical characteristics of these materials influence the outcome of dental treatment. It also impacts on the biological, allergic and toxic potential of biomaterials. With innovations in science and their positive results, there is also a need for awareness about the biological risks of these biomaterials. The aim of dental treatment is to have effective, yet safe, and long-lasting results for the benefit of patients. For this, it is important to have a thorough understanding of biomaterials and their effects on local and systemic health. Materials used in dentistry undergo a series of analyses before their oral applications. To the best of our knowledge, this is the first and original review that discusses the reasons for and studies on the toxicity of commonly used biomaterials for applications in dentistry. It will help clinicians to formulate a methodical approach for the selection of dental biomaterials, thus providing an awareness for forecasting their risk of toxic reactions.

3D and 4D printing in dentistry and maxillofacial surgery: Printing techniques, materials, and applications

3D and 4D printing are cutting-edge technologies for precise and expedited manufacturing of objects ranging from plastic to metal. Recent advances in 3D and 4D printing technologies in dentistry and maxillofacial surgery enable dentists to custom design and print surgical drill guides, temporary and permanent crowns and bridges, orthodontic appliances and orthotics, implants, mouthguards for drug delivery. In the present review, different 3D printing technologies available for use in dentistry are highlighted together with a critique on the materials available for printing. Recent reports of the application of these printed platformed are highlighted to enable readers appreciate the progress in 3D/4D printing in dentistry.

Evaluation of cytotoxicity levels of poly vinyl ether silicone, polyether, and poly vinyl siloxane impression materials: An in vitro study

Aim:

To assess the cytotoxicity level of newly introduced poly vinyl ether silicone (PVES) compared to poly vinyl siloxane (PVS) and polyether (PE) elastomeric impression materials.

Settings and Design:

Comparative -Invitro study design.

Materials and Methods:

Mouse cell line NIH/3T3 was grown in Dulbecco's modified Eagle's medium. Samples of three elastomers were dissolved in dimethyl sulfoxide and were tested at various concentrations. Twenty-four well plates with NIH/3T3 cells with different concentrations of elastomeric solutions were incubated at 37°C. 3-(4,5-dimethylthiazol-2-yl)-2-5-diphenyltetrazolium bromide assay was performed on day 1, 3, and 7, with a time interval of 15 min, 30 min, 60 min, and 24^th h to estimate the cytotoxicity for all three elastomers.

Statistical Analysis Used:

Kruskal–Wallis ANOVA test and the period effect within the subjects, repeated-measure ANOVA was done using the Greenhouse–Geisser correction method.

Results:

The mean cell viability (survival rate) of NIH 3T3 cells at the concentrations tested was measured. A repeated-measure Kruskal–Wallis ANOVA determined the mean survival concentration on day 1, 3, and 7. PVES showed significant decrease in the survival rate on day 1 than PVS and PE, while PVS and PE had significant decrease in the survival rates of cells on day 3 and 7 which were statistically significant (P < 0.001).

Conclusion:

PVES shows early cytotoxic signs as compared to PVS and PE, and cell viability for PVS was the highest among all. When making impression with PVES and PE, it is always better to evaluate the impression and gingival sulcus carefully with magnification to prevent adverse reaction, if any material is left inadvertently for longer period of time.

Antibacterial activity of fig leaf (Ficus carica Linn.) extract against Enterococcus faecalis and its cytotoxicity effects on fibroblast cells

Background:

Enterococcus faecalis is one of the bacteria that commonly found in root canal and pulp infection after root canal treatment. Sodium hypochlorite is the most widely used root canal irrigation, but it has toxic properties if exposed to periradicular tissues. It is necessary to develop an alternative for root canal irrigation. Fig leaf (Ficus carica Linn.) extract contains active substances such as flavonoid, tannin, and terpenoid which have been known for their antibacterial potency.

Aim:

This study aimed to determine the minimum bactericidal concentration (MBC) of fig leaf (F. carica Linn.) extract against E. faecalis and its cytotoxicity on fibroblast cells in vitro.

Materials and Methods:

A serial dilution method was used to determine the MBC of fig leaf extract on E. faecalis which grown on nutrient agar media. Inoculation was carried out at concentrations that suspected minimum inhibitory concentration (MIC), MBC, concentration between MIC and MBC, and control groups on different nutrient agar. MIC and MBC of fig leaf extract against E. faecalis were known by counting the growth of bacteria colonies on nutrient agar media in CFU/ml. The cytotoxicity of MIC and MBC of the extract acquired were tested using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, and the results were read using an ELISA reader. Data of E. faecalis colonies were analyzed using Kruskal–Wallis and Mann–Whitney test.

Results:

The result showed a significant difference among the groups (p<0.05). fig leaf extract at a concentration of 50% showed no bacterial growth, and cell viability at this concentration was 77.7%.

Conclusion:

Fig leaf extract has antibacterial effect on E. faecalis with MBC at 50% and not cytotoxic to fibroblast cells.

Technological features of metal-ceramic prosthesis frameworks manufactured from domestic alloys of precious and base metals

The aim of the study was to examine changes in physical and mechanical properties of dental alloys depending of the initial composition at re-casting. Russianc precious alloys: Plagodent (AuPtPd) and Palladent (PdAu) and base alloys: Vitiriy-N (NiCrMo) and Vitiriy-C (CoCrMo) were used as study samples, which were divided in three groups: a primary casting from the granules; 50% of re-casting; 100% of re-casting. We investigated the yield strength in bending, coefficient of thermal expansion and hardness. Changing in the composition of the alloys has led to changes of all physical and mechanical properties.

Evaluation of Surface Roughness and Tensile Strength of Base Metal Alloys Used for Crown and Bridge on Recasting (Recycling)

BACKGROUND

Dental casting alloys play a prominent role in the restoration of the partial dentition. Casting alloys have to survive long term in the mouth and also have the combination of structure, molecules, wear resistance and biologic compatibility. According to ADA system casting alloys were divided into three groups (wt%); high noble, Noble and predominantly base metal alloys.

AIM

To evaluate the mechanical properties such as tensile strength and surface roughness of the new and recast base metal (nickel-chromium) alloys.

MATERIALS AND METHODS

Recasting of the base metal alloys derived from sprue and button, to make it reusable has been done. A total of 200 test specimens were fabricated using specially fabricated jig of metal and divided into two groups- 100 specimens of new alloy and 100 specimens of recast alloys, which were tested for tensile strength on universal testing machine and surface roughness on surface roughness tester.

RESULTS

Tensile strength of new alloy showed no statistically significant difference (p-value>0.05) from recast alloy whereas new alloy had statistically significant surface roughness (Maximum and Average surface roughness) difference (p-value<0.01) as compared to recast alloy.

CONCLUSION

Within the limitations of the study it is concluded that the tensile strength will not be affected by recasting of nickel-chromium alloy whereas surface roughness increases markedly.