Acidulated Phosphate Fluoride Treatment Research Articles

Development of Root Caries Prevention by Nano-Hydroxyapatite Coating and Improvement of Dentin Acid Resistance.

There is no established method for optimizing the use of dentin to prevent root caries, which are increasing in the elderly population. This study aimed to develop a new approach for root caries prevention by focusing on bioapatite (BioHap), a new biomaterial, combined with fluoride. Bovine dentin was used as a sample, and an acid challenge was performed in three groups: no fluoride (control group), acidulated phosphate fluoride treatment (APF group), and BioHap + APF treatment (BioHap group). After applying the new compound, the acid resistance of dentin was compared with that of APF alone. The BioHap group had fewer defects and an increased surface hardness than the APF group. The BioHap group had the smallest lesion depth and least mineral loss among all groups. Using a scanning electron microscope in the BioHap group showed the closure of dentinal tubules and a coating on the surface. The BioHap group maintained a coating and had higher acid resistance than the APF group. The coating prevents acid penetration, and the small particle size of BioHap and its excellent reactivity with fluoride are thought to have contributed to the improvement of acid resistance in dentin. Topical fluoride application using BioHap protects against root caries.

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

Acquired acid resistance of human enamel treated with laser (Er:YAG laser and Co2 laser) and acidulated phosphate fluoride treatment: An in vitro atomic emission spectrometry analysis.

Background:Dental caries is essentially a process of diffusion and dissolution. If the aspect of dissolution can be curtailed some degree of prevention can be achieved.Aims:The present study was carried out to evaluate and compare the effect of Er:YAG laser and Co2 laser irradiation combined with acidulated phosphate fluoride treatment on in vitro acid resistance of human enamel.Design:An in vitro study was carried out on 30 human premolars to evaluate the enamel's acid resistance using an atomic emission spectrometry analysis.Materials and Methods:A total of 60 enamel specimens were prepared from 30 human premolars and were randomly assigned to 6 groups: (1) Untreated (control); (2) 1.23% acidulated phosphate fluoride (APF) gel application alone for 4 min; (3) Er:YAG laser treatment alone; (4) Co2 laser treatment alone; (5) Er:YAG laser + APF gel application; (6) Co2 laser + APF gel application. The specimens were then individually immersed in 5 ml of acetate buffer solution (0.1 mol/L, pH 4.5) and incubated at 37°C for 24 h, and the acid resistance was evaluated by determining the calcium ion concentration using the atomic emission spectrometry.Statistical Analysis:An ANOVA model was constructed (P value of 0.05), followed by Tukey's test for multiple pair wise comparisons of mean values.Results:Significant differences were found between the control group and the test groups (P < 0.001).Conclusions:Combining acidulated phosphate fluoride with either Er:YAG or Co2 laser had a synergistic effect in decreasing the enamel demineralization more than either fluoride treatment or laser treatment alone.

Nanostructural effect of acid-etching and fluoride application on human primary and permanent tooth enamels

This study examined the nanostructural effects of fluoride application and the acid-etching time with respect to the time elapsed after fluoride application on the primary and permanent tooth enamel layers using atomic force microscopy (AFM) and scanning electron microscopy (SEM). 192 non-carious teeth were assigned to sixteen experimental groups (n=12) including primary (1 to 8) and permanent (9 to 16) teeth, based on the timing of acid-etching with 37% phosphoric acid after an acidulated phosphate fluoride (APF) pre-treatment. The APF pre-treatment led to a decrease in surface roughness in both the primary and permanent teeth. After the APF treatment, the roughness in both primary and permanent teeth increased with the time elapsed. An acid-etching time of 40s led to increased nanostructural changes in the enamel surfaces compared to the conventional acid-etching time of 20s. This acid-etching process led to a higher roughness changes in the primary teeth than in the permanent teeth. To obtain proper enamel adhesion of a sealant after APF pre-treatment, it is important to apply acid-etching two weeks after pre-treatment. In addition, the acid-etching time should be prolonged to apply etching more quickly than two weeks, regardless of the primary and permanent teeth.

Assessment of Vickers hardness, microstructure, and surface roughness of dentin after initial dissolution by acidulated phosphate-fluoride

Acidulated phosphate-fluoride (APF) is widely used for the prevention of enamel caries. The topical application of fluoride is a promising treatment for improving the acid-resistance of tooth, promoting its remineralization, and improving its crystallinity. APF contains a high concentration of fluorine ions (9,000 ppm); it first decalcifies the apatite in dentin, generating calcium and phosphate ions, which bind to fluoride ions, thus precipitating calcium fluoride. APF is prepared as an acidic solution (pH 3.5) and is used to reinforce the enamel. However, dentin is less resistant to acid than enamel. As such, APF treatment at the same acidity carries a risk of weakening the dentin after application. In many cases, wedge-shaped defect (WSD), root caries, and attrition can cause dentin exposure, to which the APF can attach. Therefore, in this study, we analyzed the effect of APF treatment on dentin by measuring Vickers hardness, making observations with scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM), and measuring average surface roughness (Ra). The findings of this study suggested that an acidulated phosphate fluoride (APF) treatment of 3 min or longer caused marked dissolution of dentin and posed the risk of deterioration of its initial strength. Therefore, careful management is required to preclude dentin dissolution when performing APF treatment for preventing dental caries.

Effect of fluoride pretreatment on primary and permanent tooth surfaces by acid‐etching

This study observed the effect of fluoride application on a 37% phosphoric acid etching for 20 s of the enamel surfaces of primary and permanent teeth based on a clinical protocol employed in dental hospitals, through atomic force microscopy and scanning electron microscopy. Enamel samples were prepared from 84 exfoliated and noncarious teeth. Primary (groups 1-4) and permanent (groups 5-8) tooth samples were assigned randomly to one of eight groups based on the timing of acid-etching with 37% phosphoric acid after an acidulated phosphate fluoride (APF) treatment. Groups 1 and 5 received no fluoride application. Groups 2-4 and 6-8 were pretreated with fluoride and received acid-etching 2 weeks later (groups 2 and 6), 1 week later (groups 3 and 7), and immediately (groups 4 and 8). The acid-etching process led to a significant increase in roughness (p<0.0001), and the APF treatment led to a decrease in primary and permanent tooth surface roughness (p<0.005). An acid-etching procedure 2 weeks after performing an APF pretreatment might be recommended to obtain the maximum enamel adhesion of a resin composite.

Effects of fluoride treatment on phosphoric acid-etching in primary teeth: An AFM observation

The aim of this study was to examine the effect of fluoride application on 37% phosphoric acid-etching by atomic force microscopy (AFM) in primary tooth samples based on a clinical protocol used in a pediatric dental hospital. Enamel samples were prepared from 36 exfoliated and non-carious primary teeth. Primary tooth samples were randomly assigned to one of the four groups based on the timing of acid-etching with 37% phosphoric acid after an acidulated phosphate fluoride (APF) pre-treatment. Group 1 received no fluoride application, Group 2 was pre-treated with fluoride and then received acid-etching 2 weeks later. One week separated the fluoride treatment and the acid-etching in Group 3, while Group 4 received acid-etching immediately after the fluoride treatment. The vestibular enamel surfaces of each primary tooth sample were scanned in air at a resolution of 512 × 512 pixels and a scan speed of 0.8 line/s. On the enamel surfaces of the primary teeth after APF pre-treatment, debris were observed although the teeth were smoother than they were prior to APF. As a result, it was concluded that APF treatment is responsible for decreased primary tooth surface roughness. The enamel surfaces etched for 20 s showed that acid-etching was effective not only in removing scratches and debris, but also for evaluating enamel rod characteristics. Primary tooth enamel surfaces after etching showed minute structures caused by the decreased hydroxyapatite nanoparticle space, compared to those before etching. Also, acid-etching showed significantly increased roughness effects ( p < 0.0001, n = 9). Finally, as more time elapsed after APF pre-treatment, the roughness was decreased to a lesser degree ( p = 0.005, n = 9). We suggest that primary teeth etching 2 weeks after APF pre-treatment used clinically in pediatric hospitals may be effective to obtain properly etched enamel surfaces.

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.

Microtensile bond strength of a resin cement to feldpathic ceramic after different etching and silanization regimens in dry and aged conditions

Objectives This study evaluated the durability of bond strength between resin cement and a feldspathic ceramic submitted to different etching regimens with and without silane coupling agent application. Methods Thirty-two blocks (6.4 mm × 6.4 mm × 4.8 mm) were fabricated using a microparticulate feldspathic ceramic (Vita VM7), ultrasonically cleaned with water for 5 min and randomly divided into four groups, according to the type of etching agent and silanization method: method 1, etching with 10% hydrofluoric (HF) acid gel for 1 min + silanization; method 2, HF only; method 3, etching with 1.23% acidulated phosphate fluoride (APF) for 5 min + silanization; method 4, APF only. Conditioned blocks were positioned in their individual silicone molds and resin cement (Panavia F) was applied on the treated surfaces. Specimens were stored in distilled water (37 °C) for 24 h prior to sectioning. After sectioning the ceramic-cement blocks in x- and y-axis with a bonded area of approximately 0.6 mm 2, the microsticks of each block were randomly divided into two storage conditions: Dry, immediate testing; TC, thermal cycling (12,000 times) + water storage for 150 d, yielding to eight experimental groups. Microtensile bond strength tests were performed in universal testing machine (cross-head speed: 1 mm/min) and failure types were noted. Data obtained (MPa) were analyzed with three-way ANOVA and Tukey's test ( α = 0.05). Results Significant influence of the use of silane ( p < 0.0001), storage conditions ( p = 0.0013) and surface treatment were observed ( p = 0.0014). The highest bond strengths were achieved in both dry and thermocycled conditions when the ceramics were etched with HF acid gel and silanized (17.4 ± 5.8 and 17.4 ± 4.8 MPa, respectively). Silanization after HF acid gel and APF treatment increased the results dramatically (14.5 ± 4.2–17.4 ± 4.8 MPa) compared to non-silanized groups (2.6 ± 0.8–8.9 ± 3.1 MPa) where the failure type was exclusively (100%) adhesive between the cement and the ceramic. Significance Silanization of the feldspathic ceramic surface after APF or HF acid etching increased the microtensile bond strength results significantly, with the latter providing higher results. Long-term thermocycling and water storage did not decrease the results in silanized groups.

Combined effects of acidulated phosphate fluoride and argon laser on sound root surface morphology: an in vitro scanning electron microscopy study.

The purpose of this in vitro scanning electron microscopy (SEM) study was to evaluate the effects of combining low fluence argon laser (AL) irradiation and acidulated phosphate fluoride (APF) treatment on the surface morphology of sound human root surfaces. Previous in vitro investigations have shown that combined APF and AL irradiation of root surfaces provided a protective effect against cariogenic challenges. Twelve extracted human molars were sectioned into quarters, and each quarter assigned to 1 of 4 treatment groups: (1) no treatment/control; (2) low fluence (11.5 J/cm2) AL irradiation; (3) 1.23% APF for 4 minutes; (4) APF treatment followed by low fluence AL irradiation. Surface morphology alterations were compared among groups using SEM techniques. AL irradiation alone produced irregular textured surfaces with adherent globular material and fine microporsities in the background. APF treatment, alternatively, only created relatively smooth surface coatings that masked the original underlying root surface. Combining APF treatment followed by AL irradiation resulted in a surface coating composed of relatively small (2 to 3 microns) spherical to avoid precipitates, morphologically resembling calcium fluoride. Combining APF with AL irradiation may create a more reactive surface that possesses fluoride-rich mineral deposits and protects the underlying root surface from cariogenic challenges.

Ｉｎ ｖｉｖｏにおける各種フッ化物応用後の脱灰エナメル質へのフッ素取り込みと再石灰化

The fluoride uptake and remineralization of partially demineralized enamel after various fluoride applications for 10 days were investigated in vivo. The fluoride applications involved use of MFP dentifrice twice a day; 100ppmF mouthrinse once a day; acidulated phosphate fluoride (APF) applied only once; or no treatment (control). The degree of remineralization was evaluated by mineral vol% using microradiography. The following results were obtained.1) The fluoride uptake from dentifrice and mouthrinse were about 1.2-1.5 and 2-3 times higher than that of the controls, respectively. But statistically significant differences were not found between these three groups. The fluoride uptake from APF treatment was about 14-15 times higher than that of the controls, and statistically significantly higher than the other three groups from the first to the fifth layer.2) The remineralization was evident in all four groups except in one control case. The degree of remineralization in the dentifrice was nearly equal to that in the remineralized controls. Remineralization with the rinse was higher in the first and second layer (about 10-20μm depth) than that with the control and the dentifrice. The degree of remineralization for APF was the highest and the remineralization was evident from the surface to the bottom of the lesion area.

Combined effects of laser and fluoride on acid resistance of human dental enamel.

Specimens of human dental enamel were topically applied with solutions of sodium fluoride (NaF) or acidulated phosphate fluoride (APF) before and after laser irradiation. APF application after laser irradiation caused a remarkable increase in acid resistance of the enamel, while APF application before laser irradiation showed a lesser effect, similar to either APF treatment alone or laser irradiation alone. These results were consistent with observations made using a scanning electron microscope. APF application after laser irradiation produced a greater fluoride uptake in the enamel than APF application before laser irradiation, as shown by electron probe microanalyzer. NaF application caused lesser acid resistance and lesser fluoride uptake than APF application, even when the enamel was treated with laser irradiation.