جستجوی مقالات مرتبط با کلیدواژه « artificial saliva » در نشریات گروه « پزشکی »

The aim of this study was to compare two nickel-titanium (NiTi) closed coil springs (CCSs) from two different manufacturers regarding their force degradation over 4- and 8-week periods.   

In this in vitro experimental study, 20 NiTi CCSs from 3M® and GAC® were compared. The springs were extended until a tensile strength of 250 g was achieved, and the length of springs was recorded. They were then mounted on customized jigs according to the registered length, so as to keep them extended constantly. Springs from each manufacturer (n=10) were randomly divided into two subgroups (n=5): one subgroup was stored in artificial saliva and the other was stored in a dry environment. The forces were assessed 4 and 8 weeks later. Data were analyzed by repeated measures ANOVA and the Tukey post-hoc test (alpha=0.05).

The mean force of 3M® CCSs significantly decreased by 56% after 4 weeks and 14% after 8 weeks in dry condition, and by 46% after 4 weeks in wet environment; however, after 8 weeks in wet environment, the force decay was insignificant. The changes in force of GAC® CCSs in dry environment after 4 weeks and 8 weeks were not significant, indicating a constant force property. However, in artificial saliva, a statistically significant yet mild increase in force level was recorded.

The results showed a force decay for the 3M® CCSs after 4 weeks while for the GAC® CCSs, an almost constant force level was observed even after 8 weeks.

It may not be possible to treat large maxillofacial defects by surgical reconstruction alone. Prosthetic rehabilitation is invariably required to restore esthetics and function. Achieving adequate retention, stability, and support in these maxillofacial prostheses is a challenging task. This clinical report describes prosthetic rehabilitation of a midfacial defect following surgical resection of squamous cell carcinoma. The intraoral defect was restored with a maxillary obturator prosthesis with salivary reservoir, and the extraoral defect was restored with magnet‑retained facial prosthesis having an acrylic resin framework and an overlying silicone facial prosthesis.

Luting cement provides the connection between crowns and tooth structure. The sensitivity, solubility, and decomposition stages of the cement after the hardening stage are still subjects of relative controversy. These characteristics could lead to a poor connection between the braces and the teeth, increased probability of decay, and decalcification. The present study aimed to evaluate the adsorption and solubility of 4 types of glass ionomer cement.

Four luting cements were examined. A total of 10 specimens were prepared for each material following the manufacturer’s instructions, and the sorption and solubility were measured in accordance with the ISO 4049’s. Specimens were immersed in artificial saliva for 30 days, and were evaluated for sorption and solubility by first weighting them before incubation (W1), then immersing them in artificial saliva, dehydrating them in an oven for 24 hours, and weighing them again (W2 and W3, respectively). The data were analyzed using SPSS software version 21. One-way analysis of variance (ANOVA) followed by Tukey post hoc test was used to examine the differences among groups (α = 0.05).

As for the both sorption and solubility, there was a significant interaction between the sorption and solubility of all materials (P < 0.001). The sorption values in artificial saliva were highest for glass ionomer cement Riva Luting followed by GC Fuji 1 and Cavex, whereas the least value was observed for Meron (P < 0.000). As for solubility, it was significantly higher in Cavex followed by GC Fuji1 and Meron, but it was significantly lower in Riva Luting.

It was determined that the weight changes of glass ionomer cements significantly varied among all the materials. Riva Luting followed by GC Fuji 1 had the highest water sorption, and the solubility was significantly higher in Cavex followed by GC Fuji1. Meron improved both water sorption and solubility properties among all glass ionomer cements

Corrosion of Ni-Cr base dental alloys in saliva influences their application in prostheses. Corrosion behaviour of the NiCr alloy was studied using two techniques including weight lossdescribed by corrosion rate (CR) per mil per year (mpy)and potentiodynamic polarizationdescribed by corrosion potential (CP) in mV and current density (CD) in mA/cm2in artificial saliva with different pH.Surface morphology was studied using scanning electron microscopy (SEM). Statistical difference was assessed using one-way ANOVA and post-HOC Tukey-HSD tests with a difference significance of 95%. In weight loss method,CRwas 71.95±3.40, 17.26±1.03, 8.92±0.35 and 6.93±0.54mpy in pH values of 2.5, 5, 7 and 9, respectively. CR obtained in pH of 2.5 was significantly different with that in other groups, but those obtained in pH of 5, 7 and 9 were not significantly different. In polarization method, CPwere significantly different. CD measured in pH of 2.5 and 5 was significantly different with the rest of pH values. Corrosion rates in pH of 7 and 9 were not significantly different. The results obtained by both techniques are consistent. Corrosion resistance decreases as pH increases. In more acidic saliva, corrosion rate is greater likely due to the higher dissolution rate of Ni through weak passivation. However, the less acidic saliva leads to formation of more stable passive film on Ni and therefore the dissolution of Ni decreases leading to lower corrosion rates.

The retention and comfort of wearing prosthesis mainly depends on saliva. In reduced saliva conditions, such as xerostomia or radiation therapy, the oral mucosa tends to become dry and ulcerated, leading to the patient's inability to retain the prosthe-sis. Various techniques have been reported in the literature regarding the use of a reservoir with holes in dentures. The results have not been satisfactory because the flow of the salivary substitute could not be controlled and with frequent cleaning of the denture being necassary to maintain the patency of the reservoir holes. A newer technique for incorporation of a palatal reservoir with controlled artificial salivary flow in complete denture is being explained in this article, which improved the denture retention, comfort, mastication and speech of the patient.

Oral mucositis is the chief complication of head and neck chemotherapy. The current study was conducted to evaluate Hypozalix artificial saliva and propolis mouthwash efficacy for the prevention of chemotherapy-induced oral mucositis in leukemic patients.
The present double-blind clinical trial was carried out on 72 patients, undergoing chemotherapy. The patients were assigned to 3 groups. In the control group, CHX mouthwash and fluconazole were used by the subjects. In groups 1 and 2, Hypozalix and propolis mouthwashes were added to the combination therapy used in the control group. The results were compared between the three groups after 14 days.
Based on the results, 50% of the patients in the control group, 50% in group 1 and 95.8% in group 2 reported recovery from xerostomia. 29.17% of the patients in the control group, 87.5% in group 1 and 70.83% in group 2 exhibited easy mastication. 87.5%, 62.5% and 91.67% of the patients in group 2 exhibited easy swallowing, less waking up and a decrease in burning sensation, respectively(P use of Hypozalix spray or propolis mouthwash in association with CHX mouthwash and fluconazole simultaneously at start of chemotherapy, resulted in a decrease in chemotherapy complications after 14 days. in many cases use of propolis mouthwash yielded better results and the patients exhibited a greater tendency to continue to use it.

The aim of this study was to evaluate the effect of four commercially available mouthrinses on the color stability of one type of glass ionomer, giomer and compomer. 60 disc-shaped specimens, 180 in total (7*2mm), fabricated from each of the following materials: A resin modified glass ionomer Fuji II LC (GC International Corp), a giomer Beautifil II (SHOFU INC) and a compomer Ionosit (DMG). All specimens were stored in artificial saliva at 37˚C for 24 hours in an incubator. The initial colour value (L*,a*,b*) were recorded with spectrophotometer according to CIELAB scale. After baseline evaluation, the specimens were divided into five subgroups, according to the testing and control storage solutions (n=12). Randomly selected specimens from each material were immersed in 20 ml of the treatment solutions (Oral-B Pro Expert, Listerine, Colgate Plax, Irasha) at 37˚c for 24 hours. Each specimen was then subjected to second color measurement. The collected data was statistically analyzed using two-way analysis of variance (ANOVA) and Tukey’s HSD at a significance level of 0.05. All samples displayed color changes after immersion in the mouthrinses. The observed color difference showed that mouthrinses have a significant effect on the color shift of tested materials. A significant interaction was found between the materials and the mouthrinses. Overall, discoloration with all mouthrinses was significant when compared to the control specimens stored in artificial saliva. Oral-B induced the highest level of discoloration (ΔE*= 11.62 in Compomer) and the least discoloration was found with Irsha (ΔE*= 1.47 in RMGI). All tested restorative materials showed a color shift after immersion in mouthrinses, amongst which compomer displayed the highest change. Discolorations were clinically perceptible in most of the cases. Thus it can be concluded that daily use of mouthrinses increases the stainability of tested materials.

The aim of this study was to assess the galvanic behavior of different bracket and archwire combinations that are commonly used in orthodontic treatments. Three types of orthodontic archwires with a diameter of 0.016×0.022 inch and 80 standard edgewise maxillary central incisor brackets were selected. Three groups consisted of different wire-bracket couples and one group was just brackets as a control group. Each group had five samples. Four brackets were then connected to each wire by elastic bands made from electrochemically neutral material. The samples were immersed into capped containers of Fusayama-Meyer artificial saliva. After six weeks, the released nickel ions were quantified via ion absorption technique. The mean and the standard deviation of all four groups were calculated and the data were compared together with Kruskal-Wallis non-parametric statistical test. The highest concentration of released nickel ions was for bracket+ steel archwire and the least for the bracket without archwire. There were not significant differences among experimental groups, so it could be concluded that galvanic corrosion would not be a serious consideration through orthodontic treatment.

Most published results about the characteristics of NiTi wires are based on the mechanical laboratory tests on the as-received wires.The purpose of this study was to investigate the effect of saliva on load-deflection characteristics of superelastic NiTi wires. In this experimental study, 15 wires of three kinds of superelastic NiTi wires (Sentalloy, Force I and Truflex) were prepared. Five spe-cimens of each wire were tested in the as-received condition (T0) to provide base-line information and the remaining wires were divided into two groups of five. Half of them were kept inside artificial saliva for one month (T1), while the oth-ers were kept in air (T2). After 30 days, three-point bending test was done in a dental arch model and data from selected points on the unloading phase of the generated graphs were used for statistical analysis. Force I and Truflex showed significantly greater force than Sentalloy. The load values of Truflex and Force I after one month exposed to artificial saliva (T1) decreased significantly, but Sentalloy was not affected significantly. The pla-teau gap values were not considerably different among T0, T1 and T2. Saliva decreased the load of Force I and Truflex significantly, but it did not have a statistically significant effect on Sentalloy.

There are few studies on the electrochemical corrosion behavior of Nitinol at various pH and temperature. Considering the pH of mouth can alter at a wide range, the present study investigated the effects of various pH and temperature of artificial saliva on the electrochemical stability of commercial equiatomic Ni-Ti orthodontic wire. In this manner, cyclic polarization tests were performed at different temperatures and pH. Surface conditions of wires were evaluated with Scanning-Electron Microscopy. Decreasing of pH to the acidic pHs and increasing of temperature in these pHs cause to increasing of Igor, and C.R. and decreasing of E, and Epit. The SEM micrographs indicate that the surface of sample become smoother after cyclic potentiodynamic tests. In fact, cyclic potentiodynamic tests cause to a general corrosion on the surface of sample. Corrosion behaviour of NiTi completely relies on the characteristics of its passive layer. Decreasing of pH causes to partly dissolution of the passive layer of NiTi in the acidic pHs. Influence of temperature on the corrosion behaviour of NiTi, related to the pH of solution. It appears that pitting critical temperature of NiTi in the artificial saliva is higher than 42 ̊C.