Agar Overlay Test Research Articles

Paenibacillus larvae and their phages; a community science approach to discovery and initial testing of prophylactic phage cocktails against American Foulbrood in New Zealand.

Background: American foulbrood (AFB) is a devastating disease of the European honey bee (Apis mellifera) and is found throughout the world. AFB is caused by the bacterium Paenibacillus larvae (P. larvae). Treatment with antibiotics is strictly forbidden in many regions, including New Zealand. Safe and natural prophylactic solutions to protect honey bees from AFB are needed. Bacteriophages are a well-studied alternative to antibiotics and have been shown to be effective against P. larvae in other countries. Methods: We employed a community science approach to obtaining samples from around New Zealand to discover novel bacteriophages. Standard isolation approaches were employed for both bacteria and bacteriophages. Host range testing was performed by agar overlay spot tests, and cocktail formulation and in vitro testing were performed in 96-well plate assays, followed by sub-sampling and CFU visualization on agar plates. Results: Herein, we describe the discovery and isolation of eight P. larvae bacterial isolates and 26 P. larvae bacteriophages that are novel and native to New Zealand. The phage genomes were sequenced and annotated, and their genomes were compared to extant sequenced P. larvae phage genomes. We test the host ranges of the bacteriophages and formulate cocktails to undertake in vitro testing on a set of representative bacterial strains. These results form the basis of a promising solution for protecting honey bees in New Zealand from AFB.

Experimental study on the cytocompatibility of milling surface of poly-ether-ether-ketone (PEEK)

Poly-ether-ether-ketone (PEEK) is widely used in biomedical science because of its biocompatibility. However, the material is biologically inert. Many works have showed the potentiality of surface modification technique to enhance its biological performance, such as surface coating and impregnating bioactive materials into its substrate. Even so, these techniques are low efficiency or inapplicable in processing parts with complex structure. This thesis presents an experimental work of milling for the surface modification of PEEK, and its impact on the biological response is addressed. First, the influence of milling parameters on machined surface topography features is discussed based on the Taguchi method and end milling experiments. And then, the effect of the machined surface topography on the viability of fibroblasts is investigated by using cells from a mouse fibroblast L929 and the agar overlay test, MTT test. The experimental result indicated that there is a certain surface topography (characterized by Ssk = 0.011), which ensures the highest possible cells viability, but a significant decrease of L929 viability started with the surface roughness of Sa = 1.18 μm. The axial and radial depths of cut are the two most critical factors to affect surface topography parameters. It is concluded that the milling process significantly affects surface topography of PEEK, which in turn influences the L929 viability.

Cytotoxicity and Genotoxicity of Epoxy Resin-Based Root Canal Sealers before and after Setting Procedures.

Epoxy resin-based sealers are commonly used for successful endodontic treatment. This study aimed to evaluate the cytotoxicity and genotoxicity of epoxy resin-based sealers under unset and set conditions. Three epoxy resin-based sealers were used: Adseal, AH Plus, and Dia-Proseal. To test cytotoxicity, an agar overlay test and a 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) assay were performed using unset and set sealers on L929 mouse fibroblasts. The genotoxicity test of the comet assay was performed using the same cell line. Extract dilutions in the culture media were used as test materials for the MTT and comet assays. The comet tail produced by the damaged DNA was calculated by image analyses. Statistical analyses were performed using one-way analysis of variance and Tukey’s post hoc test. Unset sealers did not show defined decolorized areas. Hardened specimens of resin-based sealers showed circular discolored zones in the agar overlay test. Dia-Proseal was the least cytotoxic after hardening. These results were confirmed in the MTT assay. Cell viability was significantly higher in cells treated with hardened sealers in both groups than that in cells treated with freshly mixed sealers in the MTT assay. Unset AH Plus® and Dia-Proseal™ significantly increased cell viability with decreasing dilution. Adseal™ was the least cytotoxic. Freshly mixed Adseal™ was more genotoxic when freshly mixed than when set. Unset epoxy resin-based sealers were generally more cytotoxic and genotoxic than set materials. Cytotoxicity does not always match the genotoxicity results; therefore, various test tools are required to test toxicity. It is necessary to properly evaluate the toxic effects to establish a biocompatibility test that mimics clinical conditions.

Investigation of Bioactive Compounds of Capsicum Frutescence and Annona Muricata by Chromatographic Techniques

Botanicals and herbal preparations for medicinal usage contain various types of bioactive compounds. The focus of this paper is on the analytical methodologies, which include the extraction, characterization of active ingredients in Capsicum frutescens fruits and Annona muricata L. leaves. Capsicum frutescens used for various problems with digestion including upset for conditions of the heart and blood vessels including poor circulation, excessive blood clotting, high cholesterol, and preventing heart disease. Whereas Annona muricata L. leaves are traditionally used to treat diabetes. People have been consuming raw leaves of Annona muricata L. to control blood glucose levels. The present investigation was designed to study the phytochemical profiling and bioactive component principles of Capsicum frutescens and Annona muricata by Thin layer Chromatography. Bio autography agar overlay test was done to detect the antimicrobial activity of the extracts. The results of this study confirmed the presence of various bioactive compounds in the acetone and methanol extracts of both the plants. The chromatographic analysis revealed that Capsicum frutescens fruit extract and Annona muricata leaf extract are composed of various Alkaloids, Terpenoids, Saponins, and Phenolics which are accountable for many biological activities. Bio autography assays shows that Capsicum frutescens shows growth inhibition against bacteria, but Annona muricata does not shown any significant activity. The findings of present study implies that both extracts are potent source for some medicinally important phytochemicals with antioxidant and antibacterial activities. Keywords: Phytochemicals; Thin Layer Chromatography; Bio autography.

혼합 직후 또는 경화된 근관용 실러의 한천중층시험

This study was performed to evaluate the cytotoxicity of root canal sealers before and after setting procedures by an agar overlay test. Six kinds of root canal sealers were used in this experiment: AH Plus, AH 26, ADSEAL, DIA-PROSEAL, Tubli-Seal, and Sealapex. Test materials were prepared as either freshly mixed type of provided components or hardened specimens after setting procedures in each Teflon ring-shaped holder. Agar overlay test was done with L929 mouse fibroblast cells and positive, negative and test materials were set on the solidified agar medium. After 24 hrs, decolorization index and lysis index were evaluated and its cell response was interpretated. Decolorization zones and lysis values by all root canal sealers used in this study showed index 5 when freshly mixed root canal sealers were placed. Decolorization zones by AH Plus and AH 26 were larger than those by other two kinds of resin sealers after setting procedures. Zinc oxide eugenol-based sealer, Tubli-Seal, showed decolorization index 3 and lysis index 5, otherwise, calcium hydroxide based-sealer, Sealapex, did decolorization index 2 and lysis index 4 after hardening procedures. Among test materials, DIA-PROSEAL had the least cytotoxicity after hardening, followed by ADSEAL and Tubli-Seal. In conclusion, all root canal sealers had the severe cytotoxic effects when freshly mixed materials were tested. However, cytotoxicity was reduced after sealer hardening, especially in case of DIA-PROSEAL.

다공성 폴리(ε-카프로락톤)/실리카 복합체의 제조 및 특성평가

졸-젤법을 이용한 전기방사법과 캐스팅법으로 폴리(<TEX>${\varepsilon}$</TEX>-카프로락톤)(PCL) 나노섬유와 PCL/실리카 막을 각각 제조하였다. 용매에 N,N-dimethylformamide(DMF)를 혼합한 경우 부드럽고 연속적인 PCL 나노섬유가 제조되었다. PCL 기지상에 tetraethyl orthosilicate(TEOS) 농도가 0에서 40 vol%로 증가함에 따라 PCL/silica의 강도는 12에서 8MPa로 감소하였지만, 7주까지 phosphate buffered saline solution(PBS) 침지에 따른 강도값의 변화는 없었다. 실리카 첨가에 따른 인장강도의 감소는 기공도의 증가에 기인하였다. PCL/실리카 막의 결정구조는 사방정계로 실리카 농도가 0에서 40 vol%로 증가함에 따라 crystallite 크기는 57에서 18 nm로 감소하였다. 세포독성 실험결과, PCL/실리카는 시편의 수축 및 변형이 없고, 검체 주위에서 변색이나 L-929 세포의 이상이 관찰되지 않는 무독성이었다. Poly(<TEX>${\varepsilon}$</TEX>-caprolactone) (PCL) nanofibers and PCL/silica membranes were synthesized by sol-gel derived electrospinning and casting, respectively. Smooth PCL nanofibers were obtained from the precursor containing N,N-dimethylformamide (DMF). PCL/silica membranes were prepared by varying the tetraethyl orthosilicate (TEOS) contents from 0 to 40 vol% to investigate the effect of silica addition on mechanical properties and cytotoxicity of the membranes. Although the strength of the membranes decreased from 12 to 8 MPa with increasing the silica content, the strength remained almost constant 7 weeks after dipping in phosphate buffered saline solution (PBS). The strength reduction was attributed to the presence of a patterned surface pores and micro-pores present in the walls between pores. The crystal structure of the membranes was orthorhombic and the crystallite size decreased from 57 to 18 nm with increasing the silica content. From the agar overlay test, the PCL/silica membranes exhibited neither deformation and discoloration nor lysis of L-929 fibroblast cells.

İKİ SELF-ETCH BONDING SİSTEMİN BİYOUYUMLULUKLARININ VE BAĞLANMA DAYANIMLARININ DEĞERLENDİRİLMESİ

Objectives: The aim of this study was to evaluate the biocompatibility and dentin bond strengths of two different self-etch adhesive systems[Clearfil SE Bond (CSE) and G-Bond (GB)]. Materials and methods: Non-carious 8 extracted human third molar teeth were used in this study. The occlusal surfaces of all teeth were ground perpendicular to the long axis of each tooth to expose a flat dentin surface. The teeth were divided into two groups and adhesive systems were applied according to the manufacturer's instructions to the oclusal surfaces of the teeth and restored with Gradia Direct composite resin. The samples were sectioned perpendicular to the adhesive interface to produce sticks (adhesive area: 1 mm2) and fifteen sticks were obtained for each group. All sticks submitted to microtensile bond strength test (Microtensile tester, Bisco, Schaumburg, IL, ABD). Data were analyzed using one-way varyans analysis ANOVA. An agar overlay test was used for the cytotoxicity evaluation. Cytotoxicity was examined by measuring the zones of cell decolorization and evaluating cell lysis by an inverted microscope after 24 hours. Data were analyzed using Kruskal wallis and Mann withney U test. Results: CSE showed higher dentin bond strength mean (23.5 MPa) than GB (18.9 MPa) (p < 0.05). Both bonding systems showed lower lysis scores than positive control material (p<0.001). Conclusions: The bonding agent which is higer bond strength may be prefered for a long-lasting restoration since there is no a statistically significant difference between toxicity of used two bonding systems

Investigation of flexural strength and cytotoxicity of acrylic resin copolymers by using different polymerization methods.

PURPOSEThe aim of this study was to appraise the some mechanical properties of polymethyl methacrylate based denture base resin polymerized by copolymerization mechanism, and to investigate the cytotoxic effect of these copolymer resins.MATERIALS AND METHODS2-hydroxyethyl methacrylate (HEMA) and isobutyl methacrylate (IBMA) were added to monomers of conventional heat polymerized and injection-molded poly methyl methacrylate (PMMA) resin contents of 2%, 3%, and 5% by volume and polymerization was carried out. Three-point bending test was performed to detect flexural strength and the elasticity modulus of the resins. To determine the statistical differences between the study groups, the Kruskall-Wallis test was performed. Then pairwise comparisons were performed between significant groups by Mann-Whitney U test. Agar-overlay test was performed to determine cytotoxic effect of copolymer resins. Chemical analysis was determined by FTIR spectrum.RESULTSSynthesis of the copolymer was approved by FTIR spectroscopy. Within the conventional heat-polymerized group maximum transverse strength had been seen in the HEMA 2% concentration; however, when the concentration ratio increased, the strength decreased. In the injection-molded group, maximum transverse strength had been seen in the IBMA 2% concentration; also as the concentration ratio increased, the strength decreased. Only IBMA showed no cytotoxic effect at low concentrations when both two polymerization methods applied while HEMA showed cytotoxic effect in the injection-molded resins.CONCLUSIONWithin the limitations of this study, it may be concluded that IBMA and HEMA may be used in low concentration and at high temperature to obtain non-cytotoxic and durable copolymer structure.

Cytotoxicity of alloying elements and experimental titanium alloys by WST-1 and agar overlay tests

ObjectiveThis study was performed to evaluate the biocompatibility of nine types of pure metals using 36 experimental prosthetic titanium-based alloys containing 5, 10, 15, and 20wt% of each substituted metal. MethodsThe cell viabilities for pure metals on Ti alloys that contain these elements were compared with that of commercially pure (CP) Ti using the WST-1 test and agar overlay test. ResultsThe ranking of pure metal cytotoxicity from most potent to least potent was: Co>Cu>In>Ag>Cr>Sn>Au>Pd>Pt>CP Ti. The cell viability ratios for pure Co, Cu, In, and Ag were 13.9±4.6%, 21.7±10.4%, 24.1±5.7%, and 24.8±6.0%, respectively, which were significantly lower than that for the control group (p<0.05). Pure Pd and Pt demonstrated good biocompatibility with cell viabilities of 93.8±9.6% and 97.2±7.1%, respectively. The Ti–5Pd alloy exhibited the highest cell viability (128.4±21.4%), which was greater than that of CP Ti. By alloying pure Co or Cu with Ti, the cell viabilities for the Ti–xCo and Ti–xCu alloys increased significantly up to 10wt% of the alloying element followed by a gradual decrease with a further increase in the concentration of the alloying element. Based on the agar overlay test, pure Ag, Co, Cr, Cu, and In were ranked as ‘moderately cytotoxic’, whereas all Ti alloys were ranked as ‘noncytotoxic’. SignificanceThe cytotoxicity of pure Ag, Co, Cr, Cu, and In suggests a need for attention in alloy design. The cytotoxicity of alloying elements became more biocompatible when they were alloyed with titanium. However, the cytotoxicity of titanium alloys was observed when the concentration of the alloying element exceeded its respective allowable limit. The results obtained in this study can serve as a guide for the development of new Ti-based alloy systems.

Cytocompatibility of pure metals and experimental binary titanium alloys for implant materials

ObjectiveThis study was performed to evaluate the biocompatibility of nine types of pure metal ingots (Ag, Al, Cr, Cu, Mn, Mo, Nb, V, Zr) and 36 experimental titanium (Ti) alloys containing 5, 10, 15, and 20wt% of each alloying element. MethodsThe cell viabilities for each test group were compared with that of CP-Ti using the WST-1 test and agar overlay test. ResultsThe ranking of pure metal cytotoxicity from most potent to least potent was as follows: Cu>Al>Ag>V>Mn>Cr>Zr>Nb>Mo>CP-Ti. The mean cell viabilities for pure Cu, Al, Ag, V, and Mn were 21.6%, 25.3%, 31.7%, 31.7%, and 32.7%, respectively, which were significantly lower than that for the control group (p<0.05). The mean cell viabilities for pure Zr and Cr were 74.1% and 60.6%, respectively (p<0.05). Pure Mo and Nb demonstrated good biocompatibility with mean cell viabilities of 93.3% and 93.0%, respectively. The mean cell viabilities for all the Ti-based alloy groups were higher than 80% except for Ti–20Nb (79.6%) and Ti–10V (66.9%). The Ti–10Nb alloy exhibited the highest cell viability (124.8%), which was higher than that of CP-Ti. Based on agar overlay test, pure Ag, Cr, Cu, Mn, and V were ranked as ‘moderately cytotoxic’, whereas the rest of the tested pure metals and all Ti alloys, except Ti–10V (mild cytotoxicity), were ranked as ‘noncytotoxic’. SignificanceThe results obtained in this study can serve as a guide for the development of new Ti-based alloy implant systems.

Cytotoxicity of gutta-percha points and thermoplastic endodontic obturation materials

This study was purposed to evaluate the cytotoxicity of commercially available 3 types of prefabricated gutta-percha points and 8 types of thermoplastic endodontic obturation materials using MTT tests and agar overlay test. On MTT test, the Obtura ® showed significantly lower cell viability (16.3±0.8% vs. Control; p<0.05), which is over four times lower than those of other tested materials (p<0.05). The Diadent point ® , Sure-endo point ® , and Diadent Medium ® showed rather higher cell viability compared to that of Control (p<0.05). On agar overlay test, Sure-endo Soft ® and Sure-endo Hard ® showed a lower cytotoxicity (decolorization index = 2) compared to other tested materials (decolorization index = 3), while all the tested materials ranked as ‘moderate cytotoxic’ (response index = 2/2 or 3/2). From this study it is demonstrated that the endodontic obturation materials have various degrees of cytotoxicity, and further in vivo biocompatibility evaluation is needed.

Cytotoxic and antibacterial activity of the mixture of olive oil and lime cream in vitro conditions.

The mixture of olive oil and lime cream has been traditionally used to treat external burns in the region of Hatay/Antakya and middle Anatolia. Olive oil and lime cream have been employed by many physicians to treat many ailments in the past. A limited number of studies have shown the antibacterial effect of olive oil and that it does not have any toxic effect on the skin. But we did not find any reported studies on the mixture of olive oil and lime cream. The aim of this paper is to investigate the cytotoxic and antibacterial activity of olive oil and lime cream individually or/and in combination in vitro conditions, by using disk-diffusion method and in cell culture. The main purpose in using this mixture is usually to clear burns without a trace. Agar overlay, MTT (Cytotoxicity assay) and antibacterial susceptibility tests were used to investigate the cytotoxic and antibacterial activity of olive oil and lime cream. We found that lime cream has an antibacterial activity but also cytotoxic on the fibroblasts. On the other hand olive oil has limited or no antibacterial effect and it has little or no cytotoxic on the fibroblasts. When we combined lime cream and olive oil, olive oil reduced its cytotoxic impact. These results suggest that mixture of olive oil and lime cream is not cytotoxic and has antimicrobial activity.

Biodegradation and cytotoxic properties of pulse anodized Mg alloys

Magnesium has the potential to be used as an implant material owing to its non-toxicity. On the other hand, magnesium alloys corrode rapidly in subcutaneous gas bubbles. Consequently, the approach of using magnesium alloys as a biodegradable biomaterial is not well established. Therefore, the aim of this study was to provide corrosion protection by anodizing to surface for a biodegradable material. Micro-arc oxidation by pulsed DC was applied to AZ91D and AZ31B, and the cell bioactivity was defined. The anodic film was characterized by XRD and SEM. The specific mass loss variation from immersion test and potentiodynamic electrochemical test was performed for the quantification of corrosion resistance. Although the AZ91D had better corrosion resistance properties but the result of the in vitro tests showed low cell viability compared with the AZ31B. The results of the cell staining and agar overlay test revealed the AZ31B group had good biocompatibility and a low corrosion rate. In this study, the surfaces of AZ91D and AZ31B showed the formation of a uniform film by pulse power anodization improving corrosion resistance. Also, the cytotoxicity of the materials was examined by the aluminum content change of compound metal.

Strength and cytotoxicity in glass‐fiber‐reinforced denture base resin with changes in the monomer

AbstractGlass fibers (GFs) are often used to strengthen denture base resins. An increase in the GF content can result in severe viscosity, bunching of the GFs, and difficulty in the handling and packing of the poly(methyl methacrylate) (PMMA) resin. To ensure better impregnation of the GFs and improvements in the workability, more methyl methacrylate is needed as the percentage of GFs is increased. The purpose of this study was to determine adequate powder/liquid ratios according to the GF ratios to reinforce with GFs and to evaluate the effect of probable residual monomer on the cytotoxicity and mechanical properties of PMMA denture base resin reinforced with different ratios of GFs. Five specimens were made according to the defined powder/liquid ratios. Ten specimens for each group were prepared with a stainless steel mold. The flexural strength (FS) and elastic modulus were measured with a three‐point bending test in a universal testing machine. To examine changes in toxicity with time, three types of specimens for each group were fabricated and immersed for 0, 24, and 72 h in distilled water after polymerization. The cytotoxicity was evaluated with an agar overlay test. The workability was improved, and the FS and elastic modulus of the denture base resin reinforced with GFs were made significantly higher with increases in the amount of monomer. There was no difference between the control group and the GF‐reinforced groups with regard to the cytotoxicity, despite the increasing monomer concentration. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Study of Effect on Cell proliferation and Hemolysis of HAP and TCP Nanometer Particles

Hydroxyapatite (HAP) and tricalcium phosphate (TCP) nanoparticles (NPs) are in current use covering a wide range of medical applications, hence, it is indispensable to study the potential side effect acting on living organism, and to figure out the biocompatibility evaluation model of nanoparticles for standardization and methodology. In the present study, HAP and TCP NPs were selected and their diameters were within 30-80nm. Cytotoxicity in vitro was analyzed by agar overlay and direct contact exposure test was conducted to evaluate potential toxicity to SD rat macrophages, and hemolysis test of NPs was performed in compliance with ISO 10993-12 guidelines. The results showed that both HAP and TCP NPs could inhibit proliferation of macrophages when their concentration was reached to 20 µg/ml, and the extent of haemolysis would be increased more than 5% while 1000µg/ml NPs were contacted with rabbit blood cells. Furthermore, TCP NPs could induce obvious hemolysis reaction and inhibit proliferation of macrophages compared with group of HAP NPs at the same concentration.

Evaluation of the cytotoxicity of ventilation tube, nasal packing, and spongostan used in ear-nose-throat surgeries

Purpose: The aim of this study was to determine biocompatibility of spongostan, merocell, and ventilation tube using agar diffusion and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide tests in cell culture and to evaluate the results in terms of clinical practices. Materials and Methods: The experimental procedures involved in this study were approved by the Animal Ethics Committee of Cumhuriyet University (B.30.2.CUM.0.01.00-50/4), and the study was conducted following accepted guidelines for the care and use of laboratory animals for research. The present study was supported by Cumhuriyet University Scientific Research Projects (CÜBAP) Project no T-408. L929 mouse fibroblast cell culture was used in the present study. In this study, indirect toxic effects of the leakage products from the materials were tested with the agar overlay test, and also direct toxic effects of leakage materials occurring at different time and leakage products from the materials were tested with the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide test. Results: As a result of evaluating the 21 days' leakage material of the ventilation tube a moderate (+2), 24 and 48 h of leakage material of the merocell low degree and 24-hour leakage material of the spongostan limited cytotoxicity were found. Conclusion: Many biomaterials cytotoxicity study were found in the literature as well as in our study shown by MTT and agar diffusion tests they were not toxic.

Antimicrobial Activity of 23 Endemic Plants in Madagascar

Purpose: To screen the crude methanol extracts obtained from 23 endemic plants in Madagascar for antimicrobial activity.Methods: In order to assess the antimicrobial properties of the extracts, their minimum inhibitory concentrations (MICs) were obtained using the broth microdilution method. The six test pathogenic species used were Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Salmonella typhi, Pseudomonas aeruginosa and Candida albicans. Bioautography agar overlay test and phytochemical screening were also performed on the most active extracts. Results: From the 23 plants tested, 16 of which are used in traditional medicine, Poivrea phaneropetala (Combretaceae), Koehneria madagascariensis (Lythraceae) and Rhopalopilia perrieri (Opiliaceae) exhibited the broad spectrum of activity, being active against all the test organisms, while Monoporus clusiifolius (Myrsinaceae) showed the strongest antifungal activity against Candida albicans with a minimal inhibitory concentration of 0.250 mg/ml. Bioautography and phytochemical analysis of the five active extracts against bacterial strains and of oneactive extract against C. albicans indicate that the active compounds responsible for antimicrobial activity may be mainly flavonoids and/or terpenes.Conclusion: These preliminary results are the first antimicrobial studies on these plants and lend support for the use of some of them in traditional medicine.Keywords: Antimicrobial properties, Traditional medicine, Microdilution assay, Bioautography, Madagascar.

Fabrication of a hydroxyapatite scaffold for bone tissue regeneration using microstereolithography and molding technology

Recently, many groups have researched the reconstruction of bone tissue and the development of bone scaffolds using solid freeform fabrication technology. However, the capacity to produce three-dimensional hydroxyapatite (HA) scaffolds with a very accurate architecture is limited by difficulties in the manufacturing process. In this study, a HA scaffold with an accurate pore size of 300 ± 10 μm was fabricated using a microstereolithography (MSTL) system and molding technology. In addition, an agar-overlay test was performed to investigate the cytotoxicity of the fabricated scaffold.

Properties of experimental titanium‐silver‐copper alloys for dental applications

The aim of this study was to develop Ti-Ag-Cu alloys with a higher corrosion resistance, better biocompatibility, and better mechanical properties than commercially pure titanium and its alloys. The microstructure, corrosion resistance, mechanical property and cytotoxicity of the Ti-Ag-Cu alloys were investigated. The corrosion resistance was evaluated by open circuit potential measurements and potentiodynamic polarization tests in artificial saliva at 37 degrees C. The mechanical properties were evaluated using tensile and microhardness tests. The biocompatibility was tested by evaluating the cytotoxicity of the alloys using an agar-overlay test and MTT assay. It was found that the open circuit potentials of the Ti-Ag-Cu alloys were higher than that of pure Ti. However, the passive current densities of the Ti-Ag-Cu alloys were similar to that of pure titanium. The mechanical properties improved with increasing Ag and Cu content. All the Ti-Ag-Cu alloys examined were found to be noncytotoxic similar to pure Ti. Therefore, Ti-Ag-Cu alloys can be used as biomaterials in the dental field.

Cytotoxicity of intraoral orthodontic elastics

Aim: The present study compared in vitro four types of latex intraoral elastics (5/16 = 7.9 mm, mean load) regarding their possible cytotoxic effects. Material and Methods: The sample was allocated to four groups of 24 elastics: Group A (American Orthodontics), Group M (Morelli), Group T (TP Orthodontics), and Group U (Uniden). Cytotoxicity assays were performed using cell culture medium containing epithelioid-type cells (Hep-2 line) derived from human laryngeal carcinoma. Two methods for evaluating the cytotoxicity, the agar overlay test and “dye-uptake” test, were employed at two different moments (0 and 24 h). Data were compared by analysis of variance (ANOVA) and Tukey’s test (p<0.05). Results: The results showed statistically significant difference (p<0.05) between Groups T and M, T and U, A and M, and A and U, for dye-uptake test at 0 and 24 h. No cell lysis was found in Groups T and A for the agar overlay test, whereas 80% cell lysis was found in Groups M and U after 24 h according to the Stanford’s response index (RI). Conclusion: Both TP Orthodontics and American Orthodontics elastics evoked less cell lysis than Morelli and Uniden elastics.