Effects of QMix and ethylenediaminetetraacetic acid on decalcification and erosion of root canal dentin.

The aim of this study was to evaluate the effect of initial NaOCl on the decalcification and erosion ability of EDTA and QMix. Sixty-maxillary-incisors were bisected longitudinally and the tooth-halves were used. The experiment was conducted in two-sets. In set-I, 80-tooth halves were treated in the presence or absence of initial NaOCl and EDTA. In set-II, 40-tooth halves were immersed in NaOCl and QMix. After each treatment, calcium-ion release was determined with flame photometry. The erosion was imaged using SEM. Initial NaOCl led to concentration- and time-dependent increase in calcium removal effect of 17% EDTA (p < .05). The rate of calcium removal and root canal wall erosion was considerably more severe with the use of 5% NaOCl for 3 min (p < .05). QMix as a final solution showed less decalcification and erosion than 17% EDTA when used 5% NaOCl as an initial irrigant (p < .05). Optimizing the concentration and application time of NaOCl can decrease the decalcification effect of chelating agents.

A new, fast and sensitive method for the determination of trace amounts of nitrite using differential pulse polarography.

Nitrite salts of sodium or potassium are being used for the protection of meat products. They provide color and taste of meat and they protect against clostridia. On the other hand, nitrite ions can interact with amines to form nitrosamines which are known as carcinogenic substances. They may also react with hemoglobin and reduce its oxygen carrying capacity. Thus, its concentration in food-stuff has to be controlled carefully by highly sensitive methods. A new DP polarographic method is established for the determination of nitrite. Nitrite cannot be determined directly with any analytical methods. Long and tedious procedures are necessary for many of them. In this polarographic method arsenite, As(III), ion is used for the reduction of nitrite. The nitrite is determined from the As(III) quantity left over after the reaction with nitrite. The peak of arsenite has been used since it is sharp and responds well for the standard addition of arsenite. The optimum conditions for the quantitative reaction between nitrite and arsenite have been studied. It was found that the pH for the reaction medium has to be 5-7, since nitrite is decomposed at lower pH values. The reaction medium has to be stirred for about 5 min with nitrogen gas in order to expel the NO gas formed and thus to shift the equilibrium to products side. The limit of detection, LOD, was found to be as 2 × 10(-7) M. No interference was observed from most common ions.

Preparation and properties of a new solid state arsenate As(V) ion selective electrode and its application.

In this study a new solid-state ion selective electrode which is easy to prepare and sensitive to arsenate ion concentration is prepared. The solid salts used in the electrode composition were Cu2S, Ag3AsO4 and Ag2S. The principal component of the electrode was Ag3AsO4. The measurements were made in constant ionic strength using 0.1M NaNO3 and at room temperature. The potentiometric response of electrodes prepared in various compositions was investigated against arsenate ion concentration. The highest slope was obtained with 40% Ag3AsO4, 30% Cu2S and 30% Ag2S. This electrode showed linear response for arsenate ion in the 10(-5)-10(-1) M concentration range. An analytically useful potential change occurred, from 1×10(-6) to 1×10(-1) M arsenate. The slope of the linear portion was about 19±2 mV/10-fold change in arsenate concentration. The lifetime of the electrode was more than two years, when used at least 4-5 times a day, and the response time was about 20-30s depending on the concentration changes. The interference of most common ions and the effect of pH (6-10) have been investigated. This electrode has been used for the determination of arsenate ion in beer sample.

Effects of oxidative irrigants on root dentin structure: Attenuated Total Reflection Fourier Transform Infrared Spectroscopy study.

AIM: The aim of this study was to compare the effect of oxidative irrigants on the organic and inorganic structure of root canal dentin. METHODOLOGY: Fifty human 2nd premolar roots were used in the study. The dentin specimens prepared from those teeth were immersed in liquid nitrogen for 15 min. The frozen composition was titrated in a mixer and the obtained dentin powder was kept frozen at -70°C until use. Ten groups of 50mg dentin powder were immersed in agents (A: Ozone for 100 or 200 sec, B: 5.25% NaOCl, C: 2.25% NaOCl, D: 2% Chlorhexidine, E: 0.9% NaCl (control)) for 5 or 10 min. An Attenuated Total Reflection Fourier Transform Infrared Spectrophotometer (ATR FT-IR) was used to analyze dentin powder. The data were statistically analyzed by using Kruskall-Wallis analysis of variance. RESULTS: In all groups, collagen degradation was significantly increased compared to the control and 2% CHX groups (p<0.05). The use of ozone increased collagen degradation significantly compared to the use of 2.25% NaOCl and 2% Chlorhexidine for 5 min (p < 0.05). No significant differences were observed between ozone and 5.25% NaOCl-treated groups (p > 0.05). CONCLUSIONS: The structural composition of human dentin was significantly affected by the use of oxidative irrigants at higher concentrations.

Conversion degrees of a colored compomer in different colors utilized by various curing times.

PURPOSE: Compomers are widely used in primary teeth and are manufactured in different colors in order to make dental treatment acceptable in children. The aim of this in vitro study was to evaluate the degree of conversion (DC) of different colored compomers and of compomers with various curing times. METHODS: Sixty three cylindrical samples were prepared from a colored compomer (Twinky Star). These samples were of 7 different color groups, with 9 samples of each color. Each group was divided into 3 sub-groups, according to the curing time (20-30-40 seconds) with a light emitting diode light curing unit. The DC values from 3 different regions and depths were evaluated with a Fourier Transform Infrared Spectrometer before and after curing procedures for all groups. Data were calculated by using the baseline values; statistical analyses were done by using ANOVA test. RESULTS: Significant differences in DC results before and after curing were found among the groups (P<0.05). For all curing times, the silver colored samples showed the poorest DC results, which ranged from 13% to 18%. CONCLUSIONS: It was concluded that DC values of different colors were variable. The material properties could be improved by defining the proper polymerization time for each color.

Preparation and properties of a new solid state borate ion selective electrode and its application.

A new borate ion selective electrode using solid salts of Ag(3)BO(3), Ag(2)S and Cu(2)S has been developed. Detailed information is provided concerning the composition, working pH and conditioning of the electrode. An analytically useful potential change occurred from 1×10(-6) to 1×10(-1) M borate ion. The slope of the linear portion was 31±2 mV/10-fold changes in borate concentration. The measurements were made at constant ionic strength (0.1 M NaNO(3)) and at room temperature. The effect of Cl(-), Br(-), NO(3)(-), SO(=)(4), H(2)PO(4)(-) anions and K(+), Na(+), Cu(2+), Ag(+), Ca(2+) cations on borate response is evaluated and it was found that only Ag(+) had a small interference effect. The lifetime of the electrode was more than two years, when used at least 4-5 times a day, and the response time was about 20-30s. Borate content in waste water of borax factory, tap water of a town situated near to the borax factory and city tap water far from these mines were also determined. The validation was made with differential pulse polarography for the same water sample, and high consistency was obtained.

Preparation of a new solid state fluoride ion selective electrode and application.

A new solid state fluoride ion selective electrode composed of 70% Ag(2)S, 10% Cu(2)S and 20% CaF(2) has been developed. An analytically useful potential change occurred, from 1x10(-6) to 1x10(-1)M fluoride ion. The slope of the linear portion (1x10(-1)-1x10(-5)M) was about 26+/-2mV/10-fold concentration changes in fluoride. It was found that pH change between 1 and 8 had no effect on the potential of the electrode. There was no interference of most common cations such as K(+,) Na(+), Ca(2+) and Mg(2+) and anions such as Cl(-), NO(3)(-), SO(4)(2-) and PO(4)(3-). The lifetime of the electrode was more than 2 years, when used at least 4-5 times a day, and the response time was about 60s. The measurements were made at constant ionic strength (0.1M NaNO(3)) and at room temperature. This electrode has been used for the determination of fluoride ion in Ankara city tap water and in bottled spring water using standard addition method. The validation of the electrode has been made with a commercial fluoride ion selective electrode (Orion) and high consistency was obtained.

Fluoride release frompolyacid modified composites (compomers) in artificial saliva and lactic acid / Liberação de flúor por compósitos poliácidos modificados (compômeros) em saliva artifical e ácido lático

OBJECTIVES: The aim of this study was to assess the effect of different extraction media and time on the amount and pattern of fluoride release from compomers. MATERIAL AND METHOD: 42 specimens (n = 7 per group) in disc forms (7 mm diameter, 2 mm thickness) from three different compomers (were placed in artificial saliva (pH = 7.0) and lactic acid (pH = 5.2). The amount of the fluoride in these solutions were measured at 1st, 7th, 14th, 21th and 28th day time intervals by means of the fluoride ion selective electrode. The fluoride amount was calculated by concentration (ppm). The amount and the pattern of fluoride release was dependent on both the material, the storage medium and time. RESULTS: Fluoride release was evident for all the compomers but the rate of release varied considerably between the materials. Significant differences were also found between the different types of compomer (p < 0.01). A time dependent increase in the fluoride content was observed for all the compomers in both media. For all the tested materials, the fluoride release was higher in the lactic acid (p < 0.01). The amount of fluoride release was the most from Compoglass followed by Dyract AP and Glasiosite at 28th days, in both artificial saliva and lactic acid respectively. The least amount of fluoride release was observed at the first day.

OBJETIVOS: O objetivo deste estudo foi determinar o efeito de diferentes meios e tempo na quantidade e padrão de liberação de flúor por compômeros. MATERIAL E MÉTODO: 42 espécimes (n = 7 por grupo) em discos (7 mm de diâmetro, 2 mm de espessura), três compômeros diferentes, foram colocados em saliva artificial (pH 7,0) e ácido lático (pH 5,2). A quantidade de flúor nas soluções foram medidas a intervalos semanais, do 1º ao 28º dias (quatro semanas) por meio de eletrodos seletivos para íons flúor. A quantidade de flúor foi calculdada por concentração(ppm). A quantidade e o padrão da liberação de flúor variou consideravelmente tanto do material, do meio de armazenamento e tempo. RESULTADOS: A liberação de flúor foi evidente por todos os compômeros, mas a taxa de liberação variou consideravelmente entre os diferentes tipos de compômeros (p < 0.01). Um aumento relacionado com o tempo no conteúdo de flúor foi observado para todos os compômeros em ambos os meios. Para todos os materiais testados, a liberação de flúor foi maior no ácido lático (p < 0.01). A quantidade de liberação de flúor foi maior pelo Compoglass®, seguido pelo Duract AP® e Glasiosite® aos 28 dias, tanto na saliva artificial como no ácido lático respectivamente. A menor liberação de flúor foi observada no primeiro dia.

Time-dependent decalcifying effects of endodontic irrigants with antibacterial properties.

The aim of this study was to investigate the extent of calcium ion (Ca(2+)) removal on root dentin after treatment with 1.25% NaOCl, 2.5% NaOCl, 5.25% NaOCl, 2% chlorhexidine (CHX), 2% iodine potassium iodide (IKI), and MTAD in 3 immersion time periods. Extracted human mandibular premolars were bisected longitudinally, and the root halves (n = 70) were isolated with nail varnish, leaving the root canal exposed. The specimens were immersed in the test solutions, during which the amount of Ca(2+) release into the solutions was determined at 5, 10, and 15 minutes by flame photometry. The decalcifying effect of 5%, 2.5%, and 1.25% NaOCl and 2% IKI significantly increased within time (P < .05), with 5% NaOCl extracting the greatest amount of Ca(2+) at all treatment times. For 2% CHX and distilled water, a significant increase in the amount of Ca(2+) extraction from root dentin was only evident at 10 minutes (P < .05) and did not change at 15-minute readings. Between the 5- to 10-minute and 10- to 15-minute intervals, the greatest amount of increase in the rate of Ca(2+) extraction from root dentin was observed in the 2.5% NaOCl group. At 15 minutes, 2% CHX and distilled water showed the least amount of change. Among the test solutions, MTAD extracted the least amount of Ca(2+) at 5 minutes.

Calcium loss from root canal dentin following EDTA, EGTA, EDTAC, and tetracycline-HCl treatment with or without subsequent NaOCl irrigation.

The aim of this study was to determine the extent of calcium removal on root canal dentin after 17% EDTA, 17% EGTA, 15% EDTAC, and 1% tetracycline-HCl treatment; with or without subsequent use of 2.5% NaOCl. Extracted single-rooted human teeth were bisected longitudinally and the root halves (n=100) were isolated with nail varnish, leaving the root canal exposed. The samples were immersed in the test solutions for 1 and 5 minutes, after which the amount of calcium ion (Ca(2+)) release into the solutions was determined by flame photometry. Regardless of treatment time, all single (treatment solution only) and combined (treatment solution with subsequent NaOCl application) irrigation regimens removed significantly more Ca(2+) than control treatment (distilled water). Compared with other groups, treatment with 17% EDTA and 17% EDTA + 2.5% NaOCl resulted in the maximum amount of Ca(2+) removal from root canal dentin (p<0.05). All combined-treatment groups except 17% EGTA + 2.5% NaOCl removed significantly more Ca(2+) than their single-treatment versions (p<0.05). Within each test group, extending the treatment time to 5 minutes resulted in significantly more Ca(2+) removal (p<0.05).

Preparation and application of a new glucose sensor based on iodide ion selective electrode.

An electrode for glucose has been prepared by using an iodide selective electrode with the glucose oxidase enzyme. The iodide selective electrode used was prepared from 10% TDMAI and PVC according our previous study. The enzyme was immobilized on the iodide electrode by holding it at pH 7 phosphate buffer for 10min at room temperature. The H(2)O(2) formed from the reaction of glucose was determined from the decrease of iodide concentration that was present in the reaction cell. The iodide concentration was followed from the change of potential of iodide selective electrode. The potential change was linear in the 4x10(-4) to 4x10(-3)M glucose concentration (75-650mg glucose/100ml blood) range. The slope of the linear portion was about 79mV per decade change in glucose concentration. Glucose contents of some blood samples were determined with the new electrode and consistency was obtained with a colorimetric method. The effects of pH, iodide concentration, the amount of enzyme immobilized and the operating temperature were studied. No interference of ascorbic acid, uric acid, iron(III) and Cu(II) was observed. Since the iodide electrode used was not an AgI-Ag(2)S electrode, there was no interference of common ions such as chloride present in biological fluids. The slope of the electrode did not change for about 65 days when used 3 times a day.