Acidulated Phosphate Fluoride Solution Research Articles

Effect of APF Treatment Of CAD/CAM Ceramics on Bond Strength

Hydrofluoric acid treatment is frequently used for the surface treatment of ceramic restoratives containing silica. However, hydrofluoric acid is extremely toxic and requires great care when used in chair-side situations. Acidulated phosphate fluoride (APF) solution is highly safe and widely used for caries prevention in both children and adults by application to the teeth. Use of a safer alternative to hydrofluoric acid is desirable, so this study aimed to investigate the effects of surface treatment with APF solution combined with heat treatment on bonding to CAD/CAM ceramics. Specimens of ceramics were distributed into five groups: Group A30, treated by 2% APF for 30 min; Group AH1, treated by APF with heat treatment (at 100⁰C for 1 min); Group AH5, treated by APF with heat treatment (at 100⁰C for 5min); Group HF, treated with 8% hydrofluoric acid, and Group CO, without etching treatment as a control. After treatment, specimens were bonded with dual-cured resin cement system. Tensile bond strength was measured after 24h. Mean bond strengths were as follows: Group CO, 11.03 MPa; Group A30, 12.96 MPa; Group AH1, 14.19 MPa; Group AH5, 17.15 MPa; and Group HF, 17.50 MPa. APF treatment combined with additional heat treatment offered effective bonding to CAD/CAM ceramics

Countermeasure for corrosion and hydrogen embrittlement of Ni-Ti superelastic alloy in acidic fluoride solution by adding sodium bicarbonate and hydrogen peroxide

ABSTRACT Development of countermeasure for corrosion and hydrogen embrittlement of Ni-Ti superelastic alloy in an acidulated phosphate fluoride (APF) solution has been attempted by adding NaHCO3 and H2O2 to the solution. Upon addition of only 0.001 M NaHCO3 to a 0.2% APF solution, almost no changes in corrosion current density and corrosion potential are observed. With an increasing NaHCO3 concentration up to 0.01 M, the corrosion current density substantially decreases and the corrosion potential slightly shifts in the noble direction. The corrosion loss significantly decreases and hydrogen absorption is slightly inhibited. Upon the combined addition of 0.01 M NaHCO3 and 0.001 M H2O2, the corrosion current density is lowest and the corrosion potential shifts in the noble direction. The corrosion and hydrogen absorption are substantially inhibited. The present study clearly indicates that the combined addition is exceptionally effective as a simultaneous countermeasure for corrosion and hydrogen embrittlement of the alloy.

Effect of CO2 Laser and 1.23% Acidulated Phosphate Fluoride on Acid Resistance and Fluoride Uptake of Human Tooth Enamel: An In Vitro Assessment

To evaluate the effectiveness of CO2 laser treatment before applying 1.23% acidulated phosphate fluoride (APF), through topically applied 1.23% APF solution, and after applying 1.23% APF on acid resistance and fluoride uptake of the enamel. Sixty non-carious human premolars were extracted due to the orthodontic reason and stored in distilled water solution under refrigeration. Using a water-cooled diamond disc, enamel slabs of 4 mm × 4 mm × 1.5 mm were cut from the buccal surface of each tooth. Sixty samples were randomly divided into one control group and five test groups of 10 premolars each. Solution was prepared for wet chemical analysis followed by fluoride analysis that was carried out using a fluoride ion selective electrode (Thermo Scientific Orion 4-Star Plus ISE Meter). The weight of enamel (WE) was determined from the amount of calcium (Ca) etched away considering the fact that the Ca content of the human enamel is 37.4 wt%. The subgroups were statistically analyzed using ANOVA for fluoride determination and evaluation of acid resistance. There was a significant increase in acid resistance of enamel slabs when treated individually or in combination of a low-power CO2 laser and 1.23% APF solution. Application of 1.23% APF solution after low-power CO2 laser treatment showed maximum increase in acid resistance. Application of a low-power pulsed CO2 laser through topically applied 1.23% APF solution resulted in a detrimental effect of the human tooth enamel with resultant decrease in acid resistance. High fluoride uptake does not necessarily indicate increased acid resistance. The present study provides evidence that a low-power CO2 laser can be used effectively in combination with topically applied 1.23% APF solution in order to make the enamel more resistant to acid attack, thereby helping in controlling dental caries.

Assessment of Inhibition of Mineral Loss from Human Tooth Enamel by Carbon Dioxide Laser and 1.23% Acidulated Phosphate Fluoride.

Aims and Objectives:The efficacy of carbon dioxide (CO2) laser irradiation combined with fluoride in inhibiting enamel demineralization has been demonstrated by several laboratory investigations. However, there are very few reports about the in situ or in vivo caries preventive effect of CO2 laser combined with topical fluoride on dental enamel. Hence, an in situ study was designed and carried out to assess inhibition of mineral loss from human tooth enamel by CO2 laser and 1.23% acidulated phosphate fluoride (APF).Material and Methods:Impressions of upper and lower arch of the volunteers were made in alginate impression material. Study models were poured, duplicated, and duly labeled. On the working model, appliances were fabricated in acrylic resin to fit the upper dental arch of the volunteers. Four enamel slabs (one from each group) were fitted on the palatal surface of the appliance as close as possible to posterior teeth. Surfaces of slabs were kept below the outer surface of acrylic. The analysis was done using SPSS version 15 (SPSS Inc., Chicago, IL, USA) Windows software program.Results:Statistically significant increase in inhibition of mineral loss of enamel slabs when treated individually or in a combination of low power CO2 laser and 1.23% APF solution. The application of 1.23% APF solution after low power CO2 laser treatment showed maximum inhibition of mineral loss.Conclusion:The combined use of this specific laser treatment plus fluoride was more successful than either laser treatment or fluoride alone in the inhibition of mineral loss in the mouth. The results of this study also suggest that the combination of low power laser treatment with fluoride therapy may be effective as a caries inhibition treatment.

Effect of topical fluoride application on enamel after in‐office bleaching, as evaluated using a novel hardness tester and a transverse microradiography method

This study evaluated the effect of topical fluoride application on enamel hardness after in-office bleaching. Twelve human incisors were cut along the long axis, resulting in 24 halves used in four treatment groups (n = 6 in each group): (i) untreated group (C); (ii) in-office bleaching material (B); (iii) treatment with surface reaction-type prereacted glass-ionomer varnish after in-office bleaching (B+PRG); and (iv) treatment with acidulated phosphate fluoride solution after bleaching (B+F). All specimens were subjected to pH-cycling for 4 wk. Knoop hardness was measured using a Cariotester. The decalcification of enamel was assessed quantitatively by measuring the integrated mineral loss (ΔIML). Games-Howell analysis was used to assess statistical significance of between-group differences. The Knoop hardness decreased significantly after bleaching for all groups. In treatment groups B+PRG and B+F, the Knoop hardness returned to the original unbleached values after the first pH cycle and did not change afterwards. In treatment groups C and B there was a gradual decrease in the Knoop hardness until the fourth pH cycle. The integrated mineral loss, ΔIML, was significantly higher in treatment group B+F after 2 wk than in the other treatment groups. After 4 wk, the ΔIML in treatment group B was significantly higher than in treatment group B+PRG. The application of fluoride-containing materials after bleaching results in recuperation of hardness to levels similar to those of unbleached enamel.

Corrosion behavior of zirconia in acidulated phosphate fluoride.

ABSTRACTObjective The corrosion behavior of zirconia in acidulated phosphate fluoride (APF) representing acidic environments and fluoride treatments was studied.Material and Methods Zirconia rods were immersed in 1.23% and 0.123% APF solutions and maintained at 37°C for determined periods of time. Surfaces of all specimens were imaged using digital microscopy and scanning electron microscopy (SEM). Sample mass and dimensions were measured for mass loss determination. Samples were characterized by powder X-ray diffraction (XRD) to detect changes in crystallinity. A biosensor based on electrochemical impedance spectroscopy (EIS) was used to detect ion dissolution of material into the immersion media.Results Digital microscopy revealed diminishing luster of the materials and SEM showed increased superficial corrosion of zirconia submerged in 1.23% APF. Although no structural change was found, the absorption of salts (sodium phosphate) onto the surface of the materials bathed in 0.123% APF was significant. EIS indicated a greater change of impedance for the immersion solutions with increasing bathing time.Conclusion Immersion of zirconia in APF solutions showed deterioration limited to the surface, not extending to the bulk of the material. Inferences on zirconia performance in acidic oral environment can be elucidated from the study.

Hydrogen embrittlement behavior of Ni-Ti shape memory alloy with different microstructures in acidic fluoride solution

It is important to investigate the mechanism for the hydrogen embrittlement of Ni-Ti alloys in acidic fluoride solutions to improve the reliability and safety of these alloys as dental devices. Therefore, the hydrogen embrittlement behavior of Ni-Ti shape memory alloy immersed in acidic fluoride solution was investigated with a focus on the constituent phase in the microstructure of the alloy in this study. Three microstructures with different phases (parent single phase, mixture of parent and martensite phases, and martensite single phase) were prepared by tensile loading and unloading. The specimens were immersed separately in 50 mL of 0.2 % acidulated phosphate fluoride (APF) solution with pH 5.0 at room temperature (25 °C) for various periods. After immersion for 2 h, the tensile strengths of all the specimens were not significantly changed with respect to those of the non-immersed specimens. After immersion for 4 h, the tensile strengths of all the specimens immersed were decreased with respect to those of the non-immersed specimens, and the tensile strength of the martensite single phase specimen (C) was higher than that of parent single phase specimen (A) and the parent/martensite mixed phase specimen (B). After immersion for 6 h, the tensile strengths of all the specimens were decreased with respect to those of the specimens immersed for 4 h, and the tensile strength of specimen B was lower than that of specimens A and C. The susceptibility to hydrogen embrittlement of the Ni-Ti shape memory alloy with a microstructure including the parent phase tends to be high when the degree of corrosion is not significantly different for the alloy microstructure. Moreover, the effect of corrosion on the tensile strength of Ni-Ti shape memory alloy is significant when the microstructure includes the martensite phase. Hence, the significant degradation of tensile strength observed for specimen B was probably caused by a synergistic effect of hydrogen absorption and corrosion.

Effect of aging at room temperature on hydrogen embrittlement behavior of Ni-Ti superelastic alloy immersed in acidic fluoride solution

It is important to investigate the mechanism for the hydrogen embrittlement of Ni-Ti superelastic alloy in acidic fluoride solutions so that the reliability and safety of the alloy as a dental device can be improved. The purpose of the present study is to investigate the effect of aging at room temperature on the hydrogen embrittlement behavior of Ni-Ti superelastic alloy immersed in acidic fluoride solution. Specimens were immersed separately in 50 mL of 0.2 % acidulated phosphate fluoride (APF) solution with pH 5.0 at room temperature for 16 h. The hydrogen-charged specimens were aged for various periods at room temperature in air to adjust the hydrogen distribution. The specimen that was tested immediately after immersion in 0.2 % APF solution fractured near the critical stress for martensitic transformation without martensitic transformation. The tensile strength of the immersed specimen was partially recovered by aging at room temperature for 24 h. In addition, the tensile strength of the specimen immersed in 0.2 % APF solution was completely recovered by aging at room temperature for 240 h. After aging at room temperature for 24 h, the tensile strength of the immersed specimen was partially recovered. In addition, the tensile strength of the specimen immersed in 0.2 % APF solution was completely recovered by aging at room temperature for 240 h. These results indicate that the mechanism for the hydrogen embrittlement of Ni-Ti superelastic alloys aged at room temperature after immersion in 0.2 % APF solution is dependent on the aging time.

Corrosion and hydrogen absorption of commercially pure zirconium in acid fluoride solutions

The corrosion and hydrogen absorption of commercially pure zirconium have been investigated in acidulated phosphate fluoride (APF) solutions. Upon immersion in 2.0% APF solution of pH 5.0 at 25°C, a granular corrosion product (Na3ZrF7) deposits over the entire side surface of the specimen, thereby inhibiting further corrosion. In 0.2% APF solution, marked corrosion is observed from the early stage of immersion; no deposition of the corrosion product is observed by scanning electron microscopy. A substantial amount of hydrogen absorption is confirmed in both APF solutions by hydrogen thermal desorption analysis. The amount of absorbed hydrogen of the specimen immersed in the 2.0% APF solution is smaller than that in the 0.2% APF solution in the early stage of immersion. The hydrogen absorption behavior is not always consistent with the corrosion behavior. Hydrogen thermal desorption occurs in the temperature range of 300–700°C for the specimen without the corrosion product. Under the same immersion conditions, the amount of absorbed hydrogen in commercially pure zirconium is smaller than that in commercially pure titanium as reported previously. The present results suggest that commercially pure zirconium, compared with commercially pure titanium, is highly resistant to hydrogen absorption, although corrosion occurs in fluoride solutions.

Acidulated Phosphate Fluoride Application Changes the Protein Composition of Human Acquired Enamel Pellicle

We evaluated, by proteomic analysis, whether the chemical changes provoked on enamel by acidulated phosphate fluoride (APF) application alter the protein composition of acquired enamel pellicle. Enamel slabs, pretreated with distilled water (negative control), phosphoric acid (active control) or APF solution, were immersed in human saliva for pellicle formation. The adsorbed proteins were extracted and analyzed by liquid chromatography-mass spectrometry/mass spectrometry. Fifty-six proteins were identified, 12 exclusive to APF and 11 to phosphoric acid. APF decreased the concentration of histatin-1, but increased the concentration of S100-A9, which is confirmed by immunoblotting. The findings suggest that APF application changes the acquired enamel pellicle composition.

A comparison of tensile weld strength and microstructural changes in four arch wires, before and after immersion in 1.23% acidulated phosphate fluoride solution: An in-vitro study

The objective of this study is to evaluate and to compare the tensile weld strengths and microstructural changes in four archwires namely beta titanium, stainless steel (SS), blue elgiloy and timolium before and after immersion in 1.23% acidulated phosphate fluoride (APF) solution. The mean tensile weld strength of a weld joint of four arch wires were compared pre-fluoride (Group 1) with post fluoride (Group 2) and the microstructural characteristics of weld joints were evaluated under an optical microscope. The mean tensile weld strength for beta titanium was 445.64 N/mm 2, blue elgiloy was 363.26 N/mm 2, SS was 358.30 N/mm 2 and timolium was 308.62 N/mm 2. After immersion in fluoride the mean tensile strength for beta titanium was 427.16 N/mm 2, blue elgiloy was 359.86 N/mm 2, SS is 349.44 N/mm 2 and timolium is 294.86 N/mm 2. After immersion in fluoride, the beta titanium and SS had a smooth fusion at the center of weld assembly with characteristic nugget formation. The beta titanium weld assembly had greater tensile weld strength than other welded assemblies. Blue elgiloy ranked second, whereas SS and timolium were third and fourth respectively. The wires in descending order of their mean tensile weld strength, on evaluation of their weld joints were found to be: Beta titanium > blue elgiloy > SS > timolium. The reduction in tensile weld strength was statistically insignificant for all the archwires after exposure to 1.23% APF at 37°C for 90 min.

The effects of treated time of acidulated phosphate fluoride solutions on enamel erosion

The aim of this study was to reevaluate the treatment time of topical application of acidulated phosphate fluoride (APF) solution. Bovine intact enamel was treated with APF solution (pH 3.5, 9,000 ppm F) for 0, 1, 2, 3, 5, and 10 min. Fluoride penetration into the enamel was determined using electron probe micro analyser (EPMA), and the hardness of APF-treated demineralized enamel was evaluated via the micro Vickers technique. Micro Vickers hardness (HV) was significantly different in enamel treated with APF for 1 min and that treated for >2 min, and also between enamel treated for 2 and that treated for 3 min in samples demineralized for 2 h. No significant difference in the surface roughness (Ra) by confocal laser scanning microscopy was evident at the 3 and 5 min time points. The results of the EPMA analysis, HV, and Ra tests suggest a clinically beneficial effect of APF when applied for 3 min.

The effects of treated time of acidulated phosphate fluoride solutions on enamel erosion

The effects of treated time of acidulated phosphate fluoride solutions on enamel erosion

Mechanical properties and surface characterization of translucent composite wire following topical fluoride treatment

To determine the effects of a fluoride prophylactic agent on the mechanical properties and surface quality of a preformed round translucent composite archwire while comparing it with nickel-titanium (Ni-Ti) and multistranded stainless steel wires. The wires were immersed in an acidulated phosphate fluoride solution (APF) or in distilled water (control) for 1.5 hours at 37°C. Flexural modulus of elasticity (E) and yield strength (YS) of the wires were measured using a three-point bending test in a universal testing machine. The springback ratio (YS/E) was calculated for each wire. The influence of fluoride treatment on properties of the wires was statistically analyzed using Student's t-test at α = .05. Surface changes were observed with a scanning electron microscope. Fluoride treatment produced a statistically significant reduction in E, YS, and YS/E of the composite wire (P < .05). In addition, a significant decrease in E of Ni-Ti wire was found after exposure to fluoride, upon comparison with distilled water control treatment. On the other hand, no significant effect of fluoride treatment was found on YS and YS/E of Ni-Ti wire and on studied properties of the multistranded stainless steel wire (P > .05). Corrosive changes in surface topography were observed after exposure to the fluoride agent and were more pronounced with the composite wire. These results suggest that using a topical fluoride agent with translucent composite wire could decrease the mechanical properties and might damage the surface of the wire, potentially contributing to prolonged orthodontic treatment.

Inhibition of hydrogen embrittlement of Ni–Ti superelastic alloy in acid fluoride solution by hydrogen peroxide addition

Inhibition of the hydrogen embrittlement of Ni-Ti superelastic alloy in an acidulated phosphate fluoride (APF) solution has been attempted by adding various amounts of H(2)O(2). In a 0.2% APF solution, hydrogen absorption is markedly inhibited by adding H(2)O(2), although corrosion is slightly enhanced by increasing the amount of added H(2)O(2). By adding a small amount of H(2)O(2) (0.001 M), in the early stage of immersion, hydrogen embrittlement is inhibited and corrosion is only slightly enhanced. Upon adding H(2)O(2), it appears that the dominant cathodic reactions change from hydrogen evolution to H(2)O(2) reduction reactions, or the surface conditions of the alloy are changed by H(2)O(2) with a high oxidation capability, thereby inhibiting hydrogen absorption. The present study clearly indicates that infinitesimal addition of H(2)O(2) into acid fluoride solutions is effective for the inhibition of the hydrogen embrittlement of the alloy.

Comparison of friction force between corroded and noncorroded titanium nitride plating of metal brackets

Titanium nitride (TiN) plating is a method to prevent metal corrosion and can increase the surface smoothness. The purpose of this study was to evaluate the friction forces between the orthodontic bracket, with or without TiN plating, and stainless steel wire after it was corroded in fluoride-containing solution. In total, 540 metal brackets were divided into a control group and a TiN-coated experimental group. The electrochemical corrosion was performed in artificial saliva with 1.23% acidulated phosphate fluoride (APF) as the electrolytes. Static and kinetic friction were measured by an EZ-test machine (Shimadazu, Tokyo, Japan) with a crosshead speed of 10 mm per minute over a 5-mm stretch of stainless steel archwire. The data were analyzed by using unpaired t test and analysis of variance (ANOVA). Both the control and TiN-coated groups' corrosion potential was higher with 1.23% APF solution than with artificial solution (P<0.05). In brackets without corrosion, both the static and kinetic friction force between the control and TiN-coated brackets groups showed a statistically significant difference (P<0.05). In brackets with corrosion, the control group showed no statistical difference on kinetic or static friction. The TiN-coated brackets showed a statistical difference (P<0.05) on kinetic and static friction in different solutions. TiN-coated metal brackets, with corrosion or without corrosion, cannot reduce the frictional force.

Relationship between Hydrogen Absorption and Corrosion Behavior of Ti-6Al-4V Alloy Immersed in Acidic Fluoride Solutions

The relationship between hydrogen absorption and the corrosion behavior of Ti-6Al-4V alloy has been examined by immersing the alloy in acidulated phosphate fluoride (APF) solution with various concentrations. Upon immersion in 0.1 mass% APF solution, no hydrogen absorption is observed despite the occurrence of general corrosion. In 0.2% APF solution, slight hydrogen absorption occurs soon after immersion, and then the surface of the specimen becomes uniformly covered with a crystalline corrosion product (Na3AlF6), thereby inhibiting further hydrogen absorption. In APF solutions with concentrations higher than 0.4%, the amount of absorbed hydrogen increases with increasing concentration of APF solution and immersion time. The type and morphology of corrosion products sensitively depend on the concentration of APF solution. Upon immersion in 0.4% APF solution, crystalline and massive Na3AlF6 are observed on the surface of the specimen. In 1.0% and 1.5% APF solutions, Na3AlF6 with a foldlike shape and granular Na3AlF6 and Na3TiF6 are observed. In 2.0% APF solution, only granular Na3TiF6 is observed. The corrosion potentials and anodic polarization curves are analogous in all APF solutions except the 0.2% and 0.4% APF solutions. In contrast, the current density of cathodic polarization curves increases with the concentration of APF solution. The results of the present study suggest that the corrosion products play an important role in the hydrogen absorption behavior of Ti-6Al-4V alloy.

Surface roughness and gloss of indirect composites etched with acidulated phosphate fluoride solution

Objective. To evaluate the surface characteristics of indirect composites etched with acidulated phosphate fluoride (APF) solution. Material and methods. APF solution was applied to specimens of six composite materials. The surface morphological change was measured with a confocal laser scanning microscope. Gloss measurement and scanning electron microscope (SEM) observation were also performed. Results. The APF-treated surface showed various patterns due to the difference in the filler incorporated in each composite. The surface properties could be evaluated precisely from the surface roughness parameters. The arithmetical mean deviation of roughness profile (Ra) parameter of the specimens treated with APF solution was higher than those of the specimens untreated with APF, except New Meta Color Infis (IF). The difference in etching influence of each composite material was shown conclusively in the maximum height of the profile (Rz) parameter. Gradia (GR) and Gradia Forte (GF) were etched three times more deeply than that of IF categorized microfilled composite. The mean width of the profile element (RSm) decreased significantly after APF treatment, except in IF. Gloss was reduced apparently in all materials, indicating that gloss reduction was sensitive to slight surface changes. Conclusions. Specific filler particles of prosthodontic composite materials were etched by APF application. The surface roughness parameters, such as Rz and RSm, properly described various surface topographic features. Gloss was strongly correlated to surface roughness, as defined by these parameters, and especially to the initial change of surface roughness.

Effects of potential on hydrogen absorption and desorption behaviors of titanium in neutral fluoride solutions

The effects of potential on the hydrogen absorption and desorption of commercial pure titanium immersed in neutral 2.0% and 0.2% NaF solutions for 24 h have been investigated by hydrogen thermal desorption analysis. Hydrogen absorption occurs in both solutions under less noble potentials than −1.2 V versus a saturated calomel electrode. The amount of absorbed hydrogen increases with decreasing applied potential. Under the same applied potential, the amount of hydrogen absorbed in the 2.0% NaF solution is larger than that in the 0.2% NaF solution. Hydrogen thermal desorption is observed in the temperature range from 250–300 to 700 °C. For the 2.0% NaF solution, compared with the 0.2% NaF solution, the amount of hydrogen desorbed in the high temperature range is large. The hydrogen desorption behavior for neutral NaF solutions under the applied potential is not necessarily consistent with that for acidulated phosphate fluoride solutions without the applied potential reported previously.

Fracture of sustained tensile-loaded Ti–0.2% Pd alloy in acid and neutral fluoride solutions

The fracturing of Ti–0.2 mass% Pd (Ti–0.2Pd) alloy in acid and neutral fluoride solutions has been investigated by a sustained tensile-loading test. In 2.0% acidulated phosphate fluoride (APF) and neutral 2.0% NaF solution, the time to fracture of the Ti–0.2Pd alloy is shorter than that of commercial pure titanium for the same applied stress. In 2.0 and 0.2% APF solutions, fractures are characterized by a cup-cone mode irrespective of applied stress. In 2.0 and 0.2% NaF solutions, transitions from cup-cone to shear modes of the fractures are observed with decreasing applied stress. The results of the present study suggest that the susceptibility to fracturing of the Ti–0.2Pd alloy is higher than that of commercial pure titanium.