fluorapatite and calcium-phosphate--monobasic--anhydrous

Crystalline fluorapatite-coated hydroxyapatite (FA-HA) is studied using scanning electron microscopy (SEM), X-ray diffraction (XD), energy dispersive X-ray analysis (EDX), and EDX analysis mapping (EDXM). Fluoridated HA (fluorapatite) was prepared by reacting resorbable synthetic HA (OsteoGen, Impladent, Ltd, Holliswood, NY) with 4.3% sodium fluoride (NaF) for 2 minutes. After washing and drying, the resultant powder was subjected to physical property analysis using the methods listed above. SEM showed little evidence of surface change. Changes, if any, consisted of a slightly more distinct crystalline clarity on the surface of the FA sample. XD patterns showed significant random noise dispersion of the untreated HA sample compared with the lack of noise patterns in the treated FA sample. Characteristic monetite peaks were noted in analysis of the nontreated HA control sample, whereas there was no evidence of monetite in XD analysis of the treated FA material. It was determined that the fluoridation reaction, as described, served as a purification procedure of the initial HA reagent to eliminate a more soluble monetite contaminant. Also, the reaction of fluoride ion with surface HA (whether it be from or a combination of dissolution-reapposition or isomorphic substitution) produces a more purified, crystalline FA sample that was characterized by a more characteristic and sharp XD pattern. EDX analysis of the FA sample revealed a fluoride peak at 0.70 KeV that was not seen in the nonfluoridated control. EDX mapping showed an evenly distributed needle-like crystalline-shaped particulate pattern over the entire surface of the FA sample, which was lacking in the HA control. From a variety of analytic methods (as described), it was concluded that reaction of synthetic resorbable HA with 4.3% NaF solution at neutral pH produces FA-coated HA.

Topics: Apatites; Biocompatible Materials; Calcium Phosphates; Chemical Phenomena; Coated Materials, Biocompatible; Crystallization; Crystallography; Durapatite; Electron Probe Microanalysis; Humans; Hydrogen-Ion Concentration; Materials Testing; Microscopy, Electron, Scanning; Sodium Fluoride; Spectrometry, X-Ray Emission; Surface Properties; X-Ray Diffraction

The dissolution, reprecipitation and protein adsorption properties of amorphous CaP bioceramic thin films produced with an ion beam sputter deposition technique using hydroxyapatite (HA) and fluorapatite (FA) as starting materials were studied using Fourier transform infrared spectroscopy (FTIR) with attenuated total internal reflectance (ATR). Our studies showed that these amorphous CaP coatings dissolved to a greater extent when exposed to bovine serum albumin (BSA) in saline solution when compared to a protein free saline solution. Analysis of changes in infrared spectra revealed that coatings exposed to BSA solution exhibited a higher degree of crystalline structure after dissolution/reprecipitation than those exposed to saline alone. There was the indication that the association of inorganic and organic contents was achieved on the coating surface in BSA solution. We could detect no significant difference between the coatings produced from HA and FA targets.

Topics: Adsorption; Animals; Apatites; Biocompatible Materials; Calcium Phosphates; Cattle; Chemical Precipitation; Crystallization; Durapatite; Humans; In Vitro Techniques; Materials Testing; Microscopy, Electron, Scanning; Prostheses and Implants; Serum Albumin, Bovine; Sodium Chloride; Solutions; Spectroscopy, Fourier Transform Infrared; Surface Properties

Hydroxylapatite coatings are under clinical investigation in orthopaedics and dentistry. Bone formation on apatite coatings in the presence of gaps is important for clinical applications. The importance of the stability of the coating is not known at present. By varying the plasma-spray parameters, and by the addition of fluoride, the crystallinity and stability of calcium phosphates can be changed. It is suggested that bone formation is enhanced by dissolution of the apatite coating. We studied apatite coatings of varying stability with regard to their gap-healing characteristics, and we examined what the maximum gap would be that can be bridged if a coating is applied. Ti-6A1-4V implants coated with 62% crystalline hydroxylapatite, 30% crystalline hydroxylapatite or fluorapatite, or noncoated Ti-6A1-4V were implanted in 16 goats. The implants were surrounded by gaps of 1 or 2 mm, and the follow-up period was 6 weeks. Histological examination and histometry revealed that gaps of 1 mm can be bridged by bone if an apatite coating is applied. However, only a minimal amount of bone contact was seen on the apatite coatings with 2 mm gaps. Uncoated implants demonstrated no bone contact at all. Among the three different coatings there were no differences in gap healing. It can be concluded that in the goat, gaps of 2 or more mm between coated implants and host bone tissue inhibit bone deposition on the coating (p < 0.05), but the stability of the coating does not influence gap-healing characteristics.

Topics: Alloys; Animals; Apatites; Biocompatible Materials; Calcium Phosphates; Durapatite; Female; Femur; Goats; Materials Testing; Osseointegration; Prostheses and Implants; Surface Properties; Titanium

Our objective was to develop and perfect a model for the assessment of risk of dental caries onset in children. Even though dental caries prevalence in children is continuing to decline, there is still a significant minority for whom it is a problem. In this study, we sought to ascertain whether a set of variables selected in a previous cross-sectional study could be used to differentiate between caries-free six-year-olds who would or would not subsequently present with clinically-detectable caries. A total of 472 caries-free six-year-olds--286 from a fluoridated community and 186 from a fluoride-deficient community--was selected. Clinical examinations for DMFS, dental fluorosis, and plaque were conducted. Stimulated whole saliva was collected for analysis of mutants streptococci, lactobacilli, total viable flora, and fluoride, calcium, and phosphate concentrations. A questionnaire was used for collection of demographic data as well as information on prior fluoride exposure, dietary habits, and oral hygiene practices. By means of linear discriminant analyses, it was possible to predict correctly which children would develop caries within six to 12 months (sensitivity) in 82.8% of cases and which children would not develop caries during that period (specificity) in 82.4% of cases.

Topics: Apatites; Calcium Phosphates; Child; Dental Caries; Dental Plaque Index; Discriminant Analysis; DMF Index; Durapatite; Fluoridation; Fluorides; Forecasting; Humans; Hydroxyapatites; Lactobacillus; Longitudinal Studies; Male; Models, Statistical; New Hampshire; New York; Predictive Value of Tests; Risk Factors; Saliva; Sensitivity and Specificity; Streptococcus mutans; Surveys and Questionnaires

Ion adsorption and ion exchange are two methods commonly used in small home units to treat drinking water to bring the fluoride concentration to within acceptable limits. However, the necessary flowthrough system is often difficult to arrange where there is no piped supply and gradual exhaustion of the active agent is not easily detected. In an attempt to overcome these problems a defluoridation method based on the precipitation of a sparingly soluble fluoride salt, fluorapatite, has been studied. Samples of simulated high-fluoride drinking waters, approximately 10 ppm F, were saturated with brushite, resulting in a state of supersaturation with respect to fluorapatite. Subsequent seeding with hydroxyapatite caused a lowering of the calcium, phosphate, and fluoride concentrations in solution, indicative of fluorapatite precipitation. Repeating the process had an additive effect. Bone char was a less effective seed than hydroxyapatite with water containing fluoride only, but was a more effective seed with simulated Kenyan borehole water containing additional salts. Sixty-minute brushite saturation and apatite seeding steps were generally more effective than 10-min steps. The results suggest that apatite coprecipitation may be a convenient low-technology way to defluoridate drinking water, although prior testing might be useful to ensure adequate removal of fluoride.

Topics: Apatites; Calcium; Calcium Carbonate; Calcium Phosphates; Chemical Precipitation; Durapatite; Fluoridation; Fluorides; Hydrogen-Ion Concentration; Hydroxyapatites; Minerals; Phosphorus; Solubility; Time Factors; Water Supply

Four salivary calculi and synthetically prepared hydroxyapatite, tricalcium phosphate and B-type carbonated fluorapatite or hydroxyapatite were treated under excited oxygen atmosphere. All these samples were studied by Electron Spin Resonance at 100 K. The presence of paramagnetic ozonide ions was observed only in the salivary calculi and in the hydroxyapatite. This indicates that the dominant apatite phase in salivary calculi is weakly carbonated hydroxyapatite.

Topics: Apatites; Calcium Phosphates; Durapatite; Electron Spin Resonance Spectroscopy; Humans; Hydroxyapatites; Oxygen; Salivary Duct Calculi; Spectrum Analysis

Dicalcium phosphate dihydrate (DCPD) may play a significant role in the caries lesion since it is a stable calcium phosphate phase under acidic conditions. The reaction of DCPD and fluoride, forming fluorapatite (FAP), may provide a potentially promising treatment regimen for remineralization of caries lesions in vivo. The purpose of this study was to determine whether a two-step DCPD and inorganic wash with fluoride can remineralize artificial caries-like lesions in vitro. We used the single-section technique to facilitate quantitation of the same tissue before and after the experimental regimen. The two-step remineralizing treatment was repeated three times and consisted of a two-minute saturated DCPD treatment (pH 2.1) followed by a 24-hour inorganic wash. Lesion parameters were recorded before and after treatment by the taking of polarized light photomicrographs of each section after imbibition in several media. The changes in the tissue following treatment were expressed as a percent change in the area of the initial pre-treatment lesion. Significant reductions (p < 0.02) in lesion pore volume were observed in all aqueous media examined. In the lesions after imbibition in quinoline, remineralization was also apparent from the significant increase in the area of the dark zone following treatment. This two-step DCPD treatment appears to remineralize artificial caries-like lesions effectively, but additional work is needed to determine whether it affords any protection against subsequent cariogenic challenges.

Topics: Apatites; Calcium Phosphates; Cariostatic Agents; Dental Caries; Dental Enamel; Fluorides; Follow-Up Studies; Humans; Hydrogen-Ion Concentration; Image Processing, Computer-Assisted; Microscopy, Polarization; Photomicrography; Porosity; Quinolines; Tooth Remineralization; Water

Topics: Apatites; Calcium Fluoride; Calcium Phosphates; Carbonates; Chemical Phenomena; Chemical Precipitation; Chemistry, Physical; Crystallization; Microscopy, Electron, Scanning; Silicon Dioxide; Spectrophotometry, Infrared; X-Ray Diffraction

It has been shown in laboratory and animal studies that tooth enamel becomes considerably more reactive toward low levels of fluoride after receiving pre-treatment which forms dicalcium phosphate dihydrate (DCPD) in the enamel as an intermediate. This in vitro study was undertaken to determine the effect on human enamel fluoride uptake of incorporating DCPD-forming rinses into a conventional fluoride rinsing program. In one group, enamel samples received a one-minute rinse with 0.2% NaF each day for 20 days. Samples in the second group were treated identically, except that they were also given a one-minute DCPD-forming rinse prior to the first, sixth, eleventh, and sixteenth fluoride rinses. At the end of the rinsing program, all samples were washed in 1 M KOH to remove labile fluorides. The enamel biopsy data showed that the fluoride uptake resulting from 0.2% NaF alone was not statistically significant, whereas uptake produced by the DCPD-forming plus NaF rinses was significant. The results suggest that the DCPD-forming rinse may improve the efficacy of fluoride rinse programs.

Topics: Apatites; Calcium Phosphates; Dental Enamel; Fluorides; Humans; Hydrogen-Ion Concentration; Mouthwashes; Sodium Fluoride

Various etching methods are examined with respect to their ability to induce the surface nucleation and growth of fluorapatite from solutions of low, sustained supersaturation with respect to hydroxyapatite and fluorapatite. The constant composition kinetics method enables the rates of remineralization to be precisely determined, and the possibility of the direct growth of fluorapatite on calcium fluoride crystals in calcium phosphate solutions of low supersaturation has also been examined.

Topics: Acid Etching, Dental; Animals; Apatites; Calcium Fluoride; Calcium Phosphates; Cattle; Crystallization; Dental Enamel; Durapatite; Hydroxyapatites; Time Factors; Tooth Calcification