fluorapatite and calcium-phosphate--dibasic--dihydrate

The present study investigated the effects of fluoride (F) concentration, lesion baseline severity (ΔZ(base)) and mineral distribution on lesion progression. Artificial caries lesions were created using three protocols [methylcellulose acid gel (MeC), hydroxyethylcellulose acid gel (HEC), carboxymethylcellulose acid solution (CMC)] and with low and high ΔZ(base) groups by varying demineralization times within protocols. Subsequently, lesions were immersed in a demineralizing solution for 24 h in the presence of 0, 1, 2 or 5 ppm F. Changes in mineral distribution characteristics of caries lesions were studied using transverse microradiography. At baseline, the protocols yielded lesions with three distinctly different mineral distributions. Secondary demineralization revealed differences in F response between and within lesion types. In general, lowΔZ lesions were more responsive to F than highΔZ lesions. LowΔZ MeC lesions showed the greatest range of response among all lesions, whereas highΔZ HEC lesions were almost unaffected by F. Laminations were observed in the presence of F in all but highΔZ HEC and CMC lesions. Changes in mineral distribution effected by F were most pronounced in MeC lesions, with remineralization/mineral redeposition in the original lesion body at the expense of sound enamel beyond the original lesion in a dose-response manner. Both ΔZ(base) and lesion mineral distribution directly impact the F response and the extent of secondary demineralization of caries lesions. Further studies - in situ and on natural white spot lesions - are required to better mimic in vivo caries under laboratory conditions.

Topics: Acetic Acid; Animals; Apatites; Calcium Fluoride; Calcium Phosphates; Carboxymethylcellulose Sodium; Cariostatic Agents; Cattle; Cellulose; Dental Enamel; Disease Progression; Dose-Response Relationship, Drug; Durapatite; Fluorides; Hydrogen-Ion Concentration; Lactic Acid; Methylcellulose; Microradiography; Minerals; Temperature; Time Factors; Tooth Demineralization; Tooth Remineralization

The present mechanistic in vitro study aimed to investigate dose-response effects of zinc and fluoride on caries lesion remineralization and subsequent protection from demineralization. Artificial caries lesions were created using a methylcellulose acid gel system. Lesions were remineralized for 2 weeks using citrate-containing artificial saliva which was supplemented with zinc (0-153 μmol/l) and fluoride (1.1 or 52.6 μmol/l) in a 7 × 2 factorial design. Lesions were also remineralized in the absence of zinc and citrate, but in the presence of fluoride. After remineralization, all lesions were demineralized for 1 day under identical conditions. Changes in mineral distribution characteristics of caries lesions after remineralization and secondary demineralization were studied using transverse microradiography. At 1.1 μmol/l fluoride, zinc exhibited detrimental effects on remineralization in a dose-response manner and mainly by preventing remineralization near the lesion surface. At 52.6 μmol/l fluoride, zinc retarded remineralization only at the highest concentration tested. Zinc enhanced overall remineralization at 3.8-15.3 μmol/l. At 76.5 and less so at 153 μmol/l, zinc showed extensive remineralization of deeper parts within the lesions at the expense of remineralization near the surface. Citrate did not interfere with remineralization at 1.1 μmol/l fluoride, but enhanced remineralization at 52.6 μmol/l fluoride. Lesions exhibiting preferential remineralization in deeper parts showed higher mineral loss after secondary demineralization, suggesting the formation of more soluble mineral phases during remineralization. In summary, zinc and fluoride showed synergistic effects in enhancing lesion remineralization, however only at elevated fluoride concentrations.

Topics: Animals; Apatites; Calcium Fluoride; Calcium Phosphates; Cariostatic Agents; Cattle; Citric Acid; Dental Caries; Dental Enamel; Dental Enamel Solubility; Dose-Response Relationship, Drug; Drug Synergism; Durapatite; Fluorides; Hydrogen-Ion Concentration; Lactic Acid; Methylcellulose; Microradiography; Minerals; Phosphates; Saliva, Artificial; Tooth Remineralization; Zinc; Zinc Compounds

Some saliva substitutes have been shown to demineralize dentine in vitro. This effect is counteracted by the application of various fluorides. In contrast, remineralizing saliva substitutes might be supported by these treatments, depending on the dynamics during remineralization. The aim of this in vitro study was to evaluate the effects of fluoride mouthrinses or gels in combination with de-/remineralizing saliva substitutes on dentinal subsurface lesions.. Demineralized bovine dentine specimens were stored either in mineral water [saturation with respect to octacalcium phosphate (S(OCP)): 0.7], Glandosane (G, S(OCP): 0.3) or in a modified saliva substitute Saliva natura (SN, S(OCP): 1.9) for five weeks (37°C). Fluoride agents were applied twice daily for 10 min (n = 15/group): no treatment, Meridol mouthrinse, Elmex sensitive solution, ProSchmelz fluoride gel, Elmex gelée. After storage thin sections were prepared and mineral losses before and after storage were evaluated from microradiographs.. Specimens stored in G alone showed significantly higher mineral loss compared to those stored in water, SN or G in combination with any additional treatment (p < 0.05). Storage in SN and treatment with ProSchmelz fluoride gel led to significantly higher remineralization compared to all other groups (p < 0.05) and resulted in distinct mineral gain within the lesion body.. Under the in vitro conditions chosen, use of fluoride agents in combination with a demineralizing saliva substitute resulted in reduced mineral loss. Storage in modified Saliva natura in combination with the application of ProSchmelz fluoride gel induced the most pronounced remineralization also of deeper lesion areas.

Topics: Amines; Animals; Apatites; Calcium Fluoride; Calcium Phosphates; Cariostatic Agents; Cattle; Dental Caries; Dentin; Diamines; Drug Combinations; Durapatite; Fluorides; Gels; Microradiography; Minerals; Mouthwashes; Random Allocation; Saliva, Artificial; Temperature; Time Factors; Tin Fluorides; Tooth Demineralization; Tooth Remineralization

The aims of this study were: (1) to correlate surface (SH) and cross-sectional hardness (CSH) with microradiographic parameters of artificial enamel lesions; (2) to compare lesions prepared by different protocols. Fifty bovine enamel specimens were allocated by stratified randomisation according to their initial SH values to five groups and lesions produced by different methods: MC gel (methylcellulose gel/lactic acid, pH 4.6, 14 days); PA gel (polyacrylic acid/lactic acid/hydroxyapatite, pH 4.8, 16 h); MHDP (undersaturated lactate buffer/methyl diphosphonate, pH 5.0, 6 days); buffer (undersaturated acetate buffer/fluoride, pH 5.0, 16 h), and pH cycling (7 days). SH of the lesions (SH(1)) was measured. The specimens were longitudinally sectioned and transverse microradiography (TMR) and CSH measured at 10- to 220-microm depth from the surface. Overall, there was a medium correlation but non-linear and variable relationship between mineral content and radicalCSH. radicalSH(1) was weakly to moderately correlated with surface layer properties, weakly correlated with lesion depth but uncorrelated with integrated mineral loss. MHDP lesions showed the highest subsurface mineral loss, followed by pH cycling, buffer, PA gel and MC gel lesions. The conclusions were: (1) CSH, as an alternative to TMR, does not estimate mineral content very accurately, but gives information about mechanical properties of lesions; (2) SH should not be used to analyse lesions; (3) artificial caries lesions produced by the protocols differ, especially considering the method of analysis.

Topics: Acetates; Acrylic Resins; Anatomy, Cross-Sectional; Animals; Apatites; Buffers; Calcium Phosphates; Cariogenic Agents; Cariostatic Agents; Cattle; Dental Caries; Dental Enamel; Diphosphonates; Durapatite; Fluorides; Gels; Hardness; Hydrogen-Ion Concentration; Lactic Acid; Methylcellulose; Microradiography; Random Allocation; Solutions; Time Factors; Tooth Demineralization; Tooth Remineralization

The aim of the present study was to prepare nano-sized calcium fluoride (CaF(2)) that could be used as a labile F reservoir for more effective F regimens and as an agent for use in the reduction of dentin permeability.. Nano-sized CaF(2) powders were prepared using a spray-drying system with a two-liquid nozzle. The properties of the nano-CaF(2) were studied and the effectiveness of a fluoride (F) rinse with nano-CaF(2) as the F source was evaluated. The thermodynamic solubility product of the nano-CaF(2) solution was determined by equilibrating the nanosample in solutions presaturated with respect to macro-CaF(2). Reactivity of the nano-CaF(2) was assessed by its reaction with dicalcium phosphate dehydrate (DCPD). F deposition by 13.2 mmol/L F rinse with the nano-CaF(2) as the F source was determined using a previously published in vitro model.. X-ray diffraction (XRD) analysis showed pattern of low crystalline CaF(2). BET measurements showed that the nano-CaF(2) had a surface area of 46.3m(2)/g, corresponding to a particle size of 41nm. Transmission electron microscopy (TEM) examinations indicated that the nano-CaF(2) contained clusters comprising particles of (10-15) nm in size. The nano-CaF(2) displayed much higher solubility and reactivity than its macro-counterpart. The CaF(2) ion activity product (IAP) of the solution in equilibrium with the nano-CaF(2) was (1.52+/-0.05)x10(-10), which was nearly four times greater than the K(sp) (3.9 x 10(-11)) for CaF(2). The reaction of DCPD with nano-CaF(2) resulted in more F-containing apatitic materials compared to the reaction with macro-CaF(2). The F deposition by the nano-CaF(2) rinse was (2.2+/-0.3)mug/cm(2) (n=5), which was significantly (p<0.001) greater than that ((0.31+/-0.06)mug/cm(2)) produced by the NaF solution.. The nano-CaF(2) can be used as an effective anticaries agent in increasing the labile F concentration in oral fluid and thus enhance the tooth remineralization. It can also be very useful in the treatment for the reduction of dentin permeability.

Topics: Apatites; Calcium Fluoride; Calcium Phosphates; Cariostatic Agents; Crystallography, X-Ray; Dentin Permeability; Fluorides; Mouthwashes; Nanoparticles; Tooth Remineralization

Bidirectional diffusion of the Ca and PO4 solutions into the fibrin gel was performed at various pH conditions and fluoride concentrations to generate organic/inorganic composite materials mimicking biomineralization. The minerals produced in this system had a higher crystallinity than those generated by the solution mineralization system. The minerals generated in fibrin gel varied depending on the pH conditions as follows: Dicalcium phosphate dihydrate (DCPD) in the noncontrolled pH solution, the DCPD and octacalcium phosphate (OCP) mixture at pH 7.4, and the OCP and hydroxyapatite (HAp) mixture at pH 9.0. When fluoride ions were added in the range of 2-500 ppm, the minerals produced at pH 7.4 altered from OCP/HAp to HAp/fluorapatite (FAp). In addition, the crystallinity of the obtained minerals increased with an increase in fluoride ion concentration, and the solubility was inversely correlated to crystallinity. In conclusion, we established a novel fabrication method for synthesizing organic/inorganic composite materials composed of fibrin and calcium phosphate and revealed that the characteristics of the minerals in the synthesized material can be controlled by the fabrication condition.

Topics: Apatites; Biomimetic Materials; Calcium Phosphates; Crystallization; Durapatite; Fibrin; Fluorides; Gels; Hydrogen-Ion Concentration; Microscopy, Electron, Scanning; Solubility; X-Ray Diffraction

To test whether fluoride in a resin-based Ca-PO4 ion releasing cement or coating with an acidic bonding agent for improved adhesion compromised the cement remineralization potential.. Cements were formulated without fluoride (Cement A) or with fluoride (Cement B). The treatment groups were A=Cement A; A2=Cement A+bonding agent; B=Cement B; B2=Cement B+bonding agent. The calcium, phosphate, and fluoride ion release in saliva-like solution (SLS) was determined from hardened cement disks without or with a coating of bonding agent. For the remineralization, two cavities were prepared in dentin of extracted human molars and demineralized. One cavity received composite resin (control); the other received treatment A, A2, B or B2. After 6 week incubation in SLS, 180 microm cross-sections were cut. The percentage remineralization was determined by transverse microradiography comparing the dentin mineral density under the cement to that under the control.. The percentage of remineralization (mean+/-S.D.) was A (39+/-14)=B (37+/-18), A2 (23+/-13), B2 (14+/-7). Two-way analysis of variance (ANOVA) and Holm-Sidak test showed a significant effect from the presence of bonding agent (p<0.05), but not from fluoride (p>0.05). The ion solution concentrations of all groups showed undersaturation with respect to dicalcium phosphate dihydrate and calcium fluoride and supersaturation for fluorapatite and hydroxyapatite suggesting a positive remineralization potential.. Compared to the control all treatments resulted in mineral increase. The remineralization was negatively affected by the presence of the bonding agent.

Topics: Apatites; Benzoates; Calcium; Calcium Fluoride; Calcium Phosphates; Cariostatic Agents; Dental Cements; Dentin; Dentin-Bonding Agents; Durapatite; Fluorides; Humans; Materials Testing; Methacrylates; Microradiography; Phosphates; Polymethacrylic Acids; Saliva, Artificial; Tooth Demineralization; Tooth Remineralization

Data obtained in a previous study suggested that brushite is the solubility-determining phase when enamel is first exposed to acid solution in a series of repeated equilibrations. Fluoride in solution might be expected to inhibit brushite formation, and experimental studies at low solid/solution ratio support this. We have now re-examined the effect at a very high ratio, in an attempt to mimic what happens in an enamel caries lesion. Powdered enamel was repeatedly exposed to HCl solution, 10-70 mmol/l, containing 2 ppm F, for 24 h, initially in a ratio of 1 g/3 ml. Ion activities were determined after 20 min and 24 h and potential plot diagrams constructed. In early repetitions the -log (Ca2+) (OH-)2 vs. -log (H+)3(PO4(3-)) points tended to follow the brushite line, rather than the hydroxyapatite (HAp) line which one would expect if enamel behaved as pure HAp. Solution F was below measurable limits after 20 min and F then had little influence on the brushite equilibrating phase. In later (> 13) repetitions, points fell closer to the HAp line, with or without F added to the acid solution. However, added F, which was not then completely removed from solution, caused the slope of the regression line through the points to approach the Ca/P ratio of HAp, and therefore may have had a small effect in reducing the brushite phase. It is concluded that high solid/solution ratio, a previously neglected factor in enamel dissolution studies, has a profound effect in increasing the manifestation of a brushite surface phase and reducing the inhibitory effect of F on this phase.

Topics: Apatites; Calcium; Calcium Hydroxide; Calcium Phosphates; Chemical Phenomena; Chemistry, Physical; Dental Caries; Dental Enamel; Dental Enamel Solubility; Durapatite; Fluorides; Humans; Hydrochloric Acid; Phosphates

The aim of this study was to improve the efficiency of the bone-char method of water defluoridation by pre-treating the water with brushite and calcium hydroxide. Various amounts of brushite, calcium hydroxide, and bone char were suspended batchwise in 100 mL of distilled water containing 0.53 mmol/L fluoride for 24 h under gentle agitation. At suitable intervals, pH and the concentrations of fluoride, calcium, and phosphate in the water were determined and, when possible, the degrees of saturation with respect to brushite, hydroxyapatite, and fluorapatite calculated. Bone char used alone took up fluoride slowly and inefficiently. The addition of brushite and calcium hydroxide resulted in high concentrations of calcium and phosphate, making the solutions highly supersaturated with respect to fluorapatite, and led to a 20-fold increase in fluoride removal from the water. The combined use of all three salts left low concentrations of phosphate in solution and optimized the fluoride uptake capacity. Repeated use of the same bone char for 18 consecutive runs demonstrated that uptake of fluoride by the bone char was improved by repeated use, provided that brushite and calcium hydroxide were added. Therefore, addition of the two salts to the water may prolong the life of the bone char indefinitely, ensure the removal of fluoride, and thus avoid the problem of determining when the bone char is exhausted. In conclusion, we show that the bone-char defluoridation technique can be improved by addition of brushite and calcium hydroxide to the water. The problem of high terminal pH remains, however, and further work is required to improve potability.

Topics: Animals; Apatites; Bone and Bones; Calcium; Calcium Hydroxide; Calcium Phosphates; Cattle; Charcoal; Chemical Precipitation; Crystallization; Fluoridation; Fluorides; Hydrogen-Ion Concentration; Solubility; Time Factors; Water Supply

The two-step brushite saturation, apatite precipitation method which has previously been shown to be effective for the partial defluoridation of water containing 10 ppm F has now been tested at lower concentrations. The method also reduced F concentrations in the range 1-5 ppm, but was less efficient at lower F levels. Although co-precipitation as fluorapatite is the intended mechanism here, experiments indicated that F adsorption on the seed material added to the defluoridation effect. When the contribution of co-precipitation was isolated it was found that this mechanism could, on its own, account for a reduction of 2.2-2.6 ppm F in water initially containing 3-5 ppm F. A computer program which determines equilibrium F concentrations when supersaturated solutions are induced to precipitate fluorapatite was used to estimate the maximum possible F removal from water by co-precipitation. Using saturation with brushite as a starting point for precipitation, F reductions similar to those found experimentally were predicted. Computer simulations also suggest that any desired reduction in F concentration may be achieved by adding sufficient Ca and phosphate and/or by raising the initial pH.

Topics: Adsorption; Apatites; Calcium; Calcium Phosphates; Charcoal; Chemical Precipitation; Computer Simulation; Durapatite; Fluoridation; Fluorides; Hydrogen-Ion Concentration; Models, Chemical; Phosphorus; Time Factors; Water Supply

Subsurface lesions in bovine enamel slices were remineralized. The remineralization solutions contained either 0.03, 0.3, or 1.0 ppm fluoride at either pH 5.5 or 6.8. The amount of remineralization was determined after periods of up to 610 h, using quantitative microradiography. The results showed that after 126 h of remineralization in the presence of 0.03 ppm fluoride significantly (p less than 0.05) more remineralization occurred at pH 6.8 than at pH 5.5. At 0.3 and 1.0 ppm fluoride no significant differences between pH 5.5 and pH 6.8 were observed. An interaction between fluoride and pH was observed. The observed differences in the rates of remineralization are explained by the formation and subsequent transformation of the precursors octacalcium phosphate (pH 6.8) and brushite (pH 5.5) into (fluor)apatites.

Topics: Animals; Apatites; Calcium Phosphates; Cattle; Densitometry; Dental Enamel; Fluorides; Hydrogen-Ion Concentration; Microradiography; Time Factors; Tooth Demineralization; Tooth Remineralization