Calcium Fluoride

The effectiveness of a hydroxyapatite (HAP) toothpaste and a fluoride toothpaste in preventing root tissue demineralization (root caries) was compared using an established pH-cycling caries model. Materials and Methods: Sixty dentin blocks were produced from the root tissue of extracted human teeth and were assigned to 3 test groups (n=20/group): 10% hydroxyapatite toothpaste (HAP), 1450 ppm fluoride toothpaste (fluoride), and artificial saliva (artsaliva). Early root caries lesions were developed in each sample by 7-day demineralization using a pH-cycling caries model. The daily cyclic treatment regimen consists of two 2-minute toothpaste-slurry treatment periods, one 6-hour acid challenge using acidified gel (pH 4.5), and then storage in remineralizing solution (artsaliva) for the rest of the time. Demineralization was assessed as the amount of mineral loss (∆z) using transverse microradiography (TMR). Pairwise comparisons (between treatments) were performed using analysis of variance (ANOVA), and then Tukey's HSD for multiple comparisons. All p-values are considered significant if p<0.05. Results: Both ANOVA and Tukey's HSD indicated no significant (ANOVA; n=20) difference in mean ∆z among the groups, with least ∆z (±Sd) in the HAP (1117±366) compared to fluoride (1392±334) and artsaliva (1406±223). Relative to control, HAP and fluoride inhibited root demineralization by 21% and 6%, respectively. Conclusion: Within the limit of the present study, the tested toothpaste containing 10% HAP is an effective root caries control toothpaste. Toothpaste containing 10% HAP was slightly more effective in preventing tooth demineralization than 1450 ppm fluoride provided as sodium fluoride. Thus, this study shows that HAP toothpastes can serve as an effective alternative to fluoride toothpastes for root caries management.

Thermoluminescence spectra of rare earth doped calcium fluoride samples, both powder and single crystal, were recorded over the temperature range from 25 K to 673 K. Although some broad band features exist, the spectra are dominated by the rare earth line transitions. The glow peak temperatures are slightly sensitive both to the ionic size of the dopants and the dopant concentration. By contrast, very considerable differences are generated by heat treatments, such as annealing followed by either fast or slow cooling. Comments are included on the reasons for such sensitivity in terms of association of dopant and intrinsic defect sites and why the results of dosimetry powder differ from those from single crystals.

Objective: The aim of the study was to verify the existence of a correlation between fluid filtration and tubular penetration of an endodontic sealer. Methods: Ten pairs of maxillary incisors with a single root canal, circular cross-section, similar sizes and dimensions were selected from a collection. Teeth from each pair were randomly divided in 2 groups. All canals were instrumented using NiTi WaveOne Primary instrument (#25) (Dentsply, Maillefer). In the group 1 all canals were irrigated with 1 mL of 5,25% NaOCl for 30s (Ogna, Muggiò, Italy), followed by 0.5 mL of 10% EDTA for 30 s (Ogna). In the group 2 it’s used the same protocol but without the EDTA. A final irrigation of 2.0 mL 5,25% NaOCl for 3m was performed. Root filling was performed with Thermafil-obturators (Dentsply Tulsa, Tulsa, OK) with TopSeal (Dentsply, Maillefer) mixed with 0.1 wt% alizarin to evaluate the penetration depth of the sealer into tubules with confocal microscope (Leica, Wetzlar, Germany). Microleakag...

Sub-20-fs deep ultraviolet (DUV) pulses are generated by using nondegenerate, chirped-pulse four-wave mixing of the fundamental and second-harmonic pulses from a commercial Ti:sapphire amplifier in a CaF 2 plate. The energy of the DUV pulses is 3.8 μJ, with a conversion efficiency from total pump energy to DUV of ∼3.8%. The DUV pulse is compressed using a pre-chirp, introduced via a fused silica window in the fundamental beam. The central wavelength of the DUV spectrum can be tuned from 257 to 277 nm by adjusting the cross angle between the two pump beams. The spectrum can reach a width of 16.8 nm, which can support a pulse duration of 8.7 fs.

Objectives: Evaluate the effect of preservatives, usually present in mouthrinse formulations, on fluoride reactivity with enamel. Methods: Ninety-six bovine enamel slabs (4 x 4 x 2 mm), 48 sound and 48 with caries-like lesions, were longitudinally sectioned through the center. Half of each slab was kept as control and the other one subjected during 10 min to 0.05% NaF solutions containing or not 0.2% methylparaben, 0.02% propylparaben or 0.35% benzoate. Two consecutive layers of enamel were removed from all slabs, by acid etching and fluoride acid extracted was determined with specific electrode. Results: Fluoride concentration in the half treated was subtracted from that found in the control and expressed as µg F/cm 2 of enamel surface. Fluoride reactivity with sound enamel was not affected by the preservatives (P > 0.05), but methylparaben increased the reactivity of 0.05% NaF solution with carious one (P < 0.05). The results suggest that methylparaben may improve fluoride reactivity with enamel, presenting caries-like lesions, but further studies are necessary to evaluate the mechanism.

Since the anticaries effect of a dentifrice with low fluoride concentration and low pH is unknown, the aim of the present study was to evaluate in situ the enamel remineralizing ability of this type of formulation. A double-blind crossover design employing 3 phases of 45 days was conducted. Six adult volunteers wore palatal devices containing 6 previously demineralized human dental enamel slabs, which were subjected 3 times a day to one of the following treatments: nonfluoridated dentifrice (negative control); dentifrice containing 1, 100 µg F/g, pH 7.0 (positive control); dentifrice containing 550 µg F/g, pH 5.5 (experimental). At the end of each phase, enamel remineralization was assessed in terms of cross-sectional microhardness, and loosely as well as firmly bound fluoride formation was determined on the enamel surface. Fluoridated dentifrices were more effective than the negative control in forming loosely and firmly bound fluoride on enamel (P < 0.05). However, the positive control formed more loosely bound fluoride than the other treatments (P < 0.05). Microhardness analysis showed that the fluoridated dentifrices were more effective than the negative control (P < 0.05) in remineralizing dental enamel, although no statistically significant difference was observed between them. Thus, the experimental dentifrice was shown to be effective in remineralizing dental enamel, and this may be attributable to its ability to form firmly bound fluoride on enamel. (J. Oral Sci. 49, 147-154, 2007

Near-infrared luminescent lanthanide (Ln)-doped nanomaterials are currently attracting high interest in view of their sharp f-f emission peaks and long luminescence lifetimes, which establish a unique value for the development of optical amplifiers, lasers and biosensors. To improve the optical pumping of the weakly absorbing lanthanide ions (Ln 3+ ), the doped nanoparticles are coupled with an organic dye sensitizer able to efficiently harvest light and subsequently transfer the absorbed energy to the emitter. However, this through-space "remote" sensitization is severely subjected to energy losses due to competitive energy migration or deactivation routes limiting the overall luminescence quantum yields. The implementation of the Förster's model of resonance energy transfer on the basis of advanced ultra-fast transient absorption and photoluminescence spectroscopy with the support of density functional theory calculations demonstrate that the sensitization efficiency from the dye to the doped nanoparticle is strictly regulated by the geometry and localization of the transition dipole moment of the dye molecule. Within the nanoparticle, the energy transfer pathways can be harnessed through the spatial confinement of 'energy bridges', accepting energy from the surface dyes and donating to core emitters. We show that the FITC (fluorescein-isothiocyanate) dye allows reaching exceptional sensitization efficiency close to unity for the NIR-emitting triad Nd 3+ , Er 3+ and Yb 3+ .

Pt-doped TiO 2 has been prepared and characterized by various surface analytical methods such as BET surface area, scanning electron micrographs (SEM), X-ray diffraction (XRD), energy dispersive X-ray micro analysis (EDX) and diffuse reflectance spectroscopy (DRS). Photodefluoridation of pentafluorobenzoic acid (PFBA) to fluoride ions has been carried out using TiO 2 and Platinum doped TiO 2 with UV-C (200-300 nm) light. The defluoridation was monitored by the ionometer with fluoride ion selective electrode. Photodeposition of 1.5% Platinum on the surface of TiO 2 enhances its photoactivity in pentafluorobenzoic acid defluoridation. In order to optimize the working conditions, effects of pH and initial PFBA concentration were analyzed. Addition of inorganic oxidizing species KIO 4, H 2 O 2 , (NH 4)S 2 O 8 and KBrO 3 strongly influenced the photocatalytic defluoridation of PFBA. The significant enhancement in the Pt-TiO 2 photoactivity under UV irradiation can be ascribed to the platinum deposits, acting as electron traps on the Pt-TiO 2 surface. The fluoride ions formed during photodefluoridation can be used for the production of CaF 2 .

Periodontal patients often report dentin hypersensitivity (DH) caused by root surface exposure or periodontal treatment. Tubular blocking technologies in toothpastes are effective for pain relief, but no specific chemical/physical agent has been reported for periodontal patients. This double-blind randomized clinical trial compared the effects of three technologies in reducing DH in periodontal patients. Eighteen (18) participants were randomly assigned into three groups: SEN (NOVAMIN technology); REG (REFIX technology); REGK (REFIX technology + potassium citrate). Periodontal patients presenting with DH were evaluated at 6 moments: T1 and T2 - immediately before and after scaling and root planing procedures (SRP); T3 - after polishing sensitive areas with their assigned dentifrice and T4, T5, T6 - after 2, 4 and 8 weeks of SRP respectively. Sensitivity was assessed by air blast (Schiff scale) and patients’ perceptions using the visual analogue scale (VAS). Data were analyzed by two...

suggest that either CaF 2-like deposits were not formed in plaque or, if these deposits had been formed, they were rapidly lost. The inability to form persistent amounts of CaF 2-like deposits in plaque may account for the relatively rapid loss of plaque fluid fluoride after the use of conventional fluoride dentifrices or rinses.

Background: The aim of this study was to investigate the potential of concentrated fluoride varnishes to reduce enamel loss from repeated cycles of citric acid erosion and toothbrush abrasion in vitro. Methods: Polished human enamel samples were exposed to fluoride varnishes: Bifluorid10 ® (NaF&CaF 2-45200 ppmF), Duraphat ® (NaF 22600 ppmF), Fluor-Protector ® (difluorsilane 1000 ppmF) and a control coating of copal ether varnish (0 ppmF) group and a deionized water group. For each group of 16 samples, nine cycles of erosion and nine cycles of erosion-abrasion [1 cycle = erosion (0.3% citric acid, pH 3.2, 5 min) + artificial saliva (1 h, pH 7.0) + abrasion (120 linear strokes in artificial saliva from Oral B medium soft brushes 300 g loading]. The change in the enamel surface was evaluated using optical profilometry. Results: Duraphat ® and Bifluorid10 ® applications had a median (IQR) step height of 4.21 um (1.59) and 5.01 um (1.02). This was statistically significantly less than Fluor-Protector ® 6.83 um (1.25), copal ether 7.22 um (1.97) and water 7.39 um (1.96) (p < 0.001). For erosion-abrasion, both Duraphat ® and Bifluorid ® had statistically lower step heights than the other products (p < 0.01). Conclusions: The action of fluoride in a range of single-application topical varnishes was effective in reducing enamel wear from erosion and erosion-abrasion in this laboratory study.

The purpose of this in vitro study was to compare marginal leakage of Class II amalgam restorations lined with different agents (two new generation dentin bonding systems, a cavity varnish and an amalgam liner). Forty freshly extracted human molar teeth were divided into five groups. Class II preparations were prepared in the mesial and distal surfaces of each molar. While the cavities in two groups were lined with two new generation bonding systems, the other two groups were treated with an amalgam lining material and a cavity varnish. Fifth group was used as control, without any lining. Amalgam* was hand‐condensed into each preparation. Specimens were thermocycled, stained and sectioned. Microleakage was graded using a stereomicroscope. Mean microleakage scores for occlusal and cervical margins were calculated and analised. For the leakage values on occlusal margins, Kruskal–Wallis test indicated no significant difference in all groups. For the leakage values on cervical margins, ...

Sodium silicate based glasses have been synthesized by melt quenching technique. The surface reactivity of resultant glasses has been analyzed by immersion studies in simulated body fluid solution (SBF) for different time duration. The formation of hydroxyapatite layer has been studied through weight change (loss/ gain) of glass sample and change in pH of SBF solution. The addition of Al 2 O 3 instead of P 2 O 5 in sodium silicate glasses increases the durability of glasses in SBF solution. The optical band gap decreases with increase of sodium oxide content with soaking time of glass in SBF.

Casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) complexes are anticariogenic and capable of remineralizing the early stages of enamel lesions. The use of fluoride prevents dental decay and the association of CPP-ACP with fluoride can increase remineralization. To evaluate the effect of CPP-ACP and CPP-ACPF creams associated with a fluoride dentifrice to prevent enamel demineralization in a pH cyclic model. Previously selected by surface microhardness (SH) analysis, human enamel blocks (n = 56) were submitted to daily treatment with dentifrice in a pH-cycling model. The enamel blocks were divided into four groups; G1: Crest™ Cavity Protection - Procter & Gamble (1,100 ppmF of NaF); G2: Crest™ +MI Paste (MP) - Recaldent™ GC Corporation Tokyo, Japan); G3: Crest™ + MI Paste Plus (MPP) - Recaldent™ 900 ppm as NaF, GC Corporation Tokyo, Japan), and G4: control, saliva. Specimens were soaked alternatively in a demineralizing solution and in artificial saliva for 5 d. The fluori...

This article reviews recent studies on: (1) the synthesis of novel calcium phosphate and calcium fluoride nanoparticles and their incorporation into dental resins to develop nanocomposites; (2) the effects of key microstructural parameters on Ca, PO4, and F ion release from nanocomposites, including the effects of nanofiller volume fraction, particle size, and silanization; and (3) mechanical properties of nanocomposites, including water-aging effects, flexural strength, fracture toughness, and three-body wear. This article demonstrates that a major advantage of using the new nanoparticles is that high levels of Ca, PO4, and F release can be achieved at low filler levels in the resin, because of the high surface areas of the nanoparticles. This leaves room in the resin for substantial reinforcement fillers. The combination of releasing nanofillers with stable and strong reinforcing fillers is promising to yield a nanocomposite with both stress-bearing and caries-inhibiting capabilit...

The low concentration of available calcium (Ca) in oral fluids limits the formation of Ca-mediated fluoride deposits that maintain oral fluoride (F) after a topical F treatment. The purpose of this study was to examine if a high concentration of Ca would increase salivary F when used before a F rinse or dentifrice. We found that a Ca pre-rinse (150 mmol/l Ca lactate) or Ca dentifrice (0.084 g Ca glycerolphosphate per gram dentifrice) used immediately before a 60 s 228-ppm F rinse (12 mmol/l NaF) produced a 4.6× or 3.6× increase (p &lt; 0.05) respectively in the 1 h salivary F concentrations over the F rinse alone. Reducing the post-Ca F rinse to 10 s still produced a significant 2.2× increase in salivary F compared to the 60 s F rinse alone. Used with a conventional 1,100 ppm F (i.e. 1,100 µg F per gram) NaF dentifrice (Crest), the above Ca pre-rinse increased 1 h salivary F levels by 2.3× over the F dentifrice alone. However, a F rinse given before a Ca rinse produced no increase i...

The effect of calcium (Ca) concentrations and added ethanol on fluoride (F) depositions by experimental two–component rinses, each consisting of a Ca–containing and an F–containing component, was evaluated in an in vitro system. Among the tested rinses, a 3 mmol/l F two–component rinse with 200 mmol/l Ca and 10% v/v ethanol was found to produce the greatest F deposition relative to the F concentration in the rinse. Specifically, this rinse produced an F deposition that was about 7 times greater than a conventional 13.2–mmol/l sodium fluoride (NaF) rinse. In a second experiment, an in vitro pH cycling model was used to evaluate the potential anti–caries effects of 4 rinses: (1) placebo rinse (no F), (2) 13.2–mmol/l NaF rinse, (3) 52.6–mmol/l NaF rinse, and (4) the 3–mmol/l F two–component rinse in a 7–day in vitro pH cycling model. The changes in lesion mineral contents, delta(ΔZ), as assessed by quantitative microradiographic measurements, were as follows [mean ± standard deviation,...

Plaque ‘calcium-fluoride-like’ (CaF2-like) and fluoride deposits held by biological/bacterial calcium fluoride (Ca-F) bonds appear to be the source of cariostatic concentrations of fluoride in plaque fluid. The aim of this study was to quantify the amounts of plaque fluoride held in these reservoirs after a sodium fluoride rinse. 30 and 60 min after a 228 µg/g fluoride rinse, plaque samples were collected from 11 volunteers. Each sample was homogenized, split into 2 aliquots (aliquots 1 and 2), centrifuged, and the recovered plaque fluid combined and analyzed using microelectrodes. The plaque mass from aliquot 1 was retained. The plaque mass from aliquot 2 was extracted several times with a solution having the same fluoride, calcium and pH as the plaque fluid in order to extract the plaque CaF2-like deposits. The total fluoride in both aliquots was then determined. In a second experiment, the extraction completeness was examined by applying the above procedure to in vitro precipitat...

Growth of CaF 2 on Si͑001͒ is studied as a function of the substrate temperature during deposition for coverages from fraction of a monolayer ͑ML͒ up to several monolayers. Structural and morphological studies using atomic force microscopy, low-energy electron diffraction, and reflection high-energy electron diffraction are combined with measurements of core-level photoemission and x-ray absorption. Bonding between CaF 2 molecules and Si͑001͒ substrates is followed by monitoring core-level shifts and x-ray absorption line shape. It is found that a dissociative reaction occurs at high deposition temperatures ͑ϳ750°C͒, giving rise to a 1-ML-thick uniform wetting layer, which is bonded with the substrate through Ca atoms. This wetting layer changes the surface periodicity from double domain 2 ϫ 1+1ϫ 2 to single domain 3 ϫ 1. Three-dimensional CaF 2 elongated islands develop on top of the wetting layer, with their ͑110͒ planes parallel to the Si surface plane. At temperatures below 600°C no dissociative reaction takes place for CaF 2 ; nanodimensional islands develop in the form of rectangular-based huts. The crystallographic orientation of these islands is parallel to that of the Si͑001͒ substrate. The data are compared to results obtained on CaF 2 deposited on Si͑111͒.

The 229 thorium isotope presents an extremely low-energy isomer state of the nucleus which is expected around 7.8 eV, in the vacuum ultraviolet (VUV) regime. This unique system may bridge between atomic and nuclear physics, enabling coherent manipulation and precision spectroscopy of nuclear quantum states using laser light. It has been proposed to implant 229 thorium into VUV transparent crystal matrices to facilitate laser spectroscopy and possibly realize a solid-state nuclear clock. In this work, we validate the feasibility of this approach by computer modelling of thorium doping into calcium fluoride single crystals. Using atomistic modelling and full electronic structure calculations, we find a persistent large band gap and no additional electronic levels emerging in the middle of the gap due to the presence of the dopant, which should allow direct optical interrogation of the nuclear transition. Based on the electronic structure, we estimate the thorium nuclear quantum levels within the solid-state environment. Precision laser spectroscopy of these levels will allow the study of a broad range of crystal field effects, transferring Mössbauer spectroscopy into the optical regime.

Most of commercial phosphors consist of suitably doped polycrystalline compounds. The activation means has been usually discussed, less attention has been paid to the influence of fuels on host preparation in the final performance of the products. In this paper different fuels have been followed to synthesize phosphors based on Dy doped ZnAl 2 O 4 . The mechanoluminescence (ML) properties of the materials have been given special consideration. Finally, various ML curves have been recorded in order to assess which of the fuel yields the most efficient Dy doped ZnAl 2 O 4 compound. Dy doped ZnAl 2 O 4 compound has been prepared by solution combustion technique with fuels such as urea, hydrazine and carbohydrazide separately. It is observed that urea enhances the ML intensity of the sample used. XRD result confirms formation of the phosphor. It is suggested that recombination of the trapped charge carriers are responsible for ML in this system. Keywords: Mechanoluminescence, defects, d...

K‐Feldspar was used as a raw material for in situ synthesis of leucite particles by solid‐state reaction method. Prior to synthesis of leucite, K‐Feldspar was treated by oxalic acid (C2H2O4) to eliminate Fe content. The parameters affecting the structure and amount of Fe in K‐Feldspar was investigated to reach an optimal leaching condition. Next, kasilite removal was studied by introducing CaF2 to the composition of dental porcelain. To synthesis leucite, the prepared materials were heated up to 1450°C for 3 hours until fusion phenomena occurred, then cooled down to 865°C to permit the leucite crystals nucleate and grow. To find out the chemical composition of powder, XRF, EDX, and Atomic absorption spectroscopy were used. Fourier Transform Infrared Spectroscopy and X‐Ray Diffractometer and Scanning Electron Microscopy were employed to study the structure of mineral. Spectrophotometry was chosen to analyze whiteness index of powder after acid treatment. Differential Thermal Analysis...

In order to contribute to better resource efficiency and industrial waste management leading to a sustainable production and consumption pattern new processes must be developed, which should be operated in such a way that waste production is reduced or avoided. Fluoride removal by precipitation generates huge amounts of a water rich sludge. Calcium fluoride is not recovered from the waste streams and it is not recycled due to the high water content and the low quality of the sludge. Crystallization process in a fluidized bed reactor (FBR) appears as an alternative technology to the conventional chemical precipitation process. In the crystallization process in a FBR silica sand is usually used as seed material, however silica is a deleterious impurity because it causes losses in the yield of HF and its content should be less than 1%. In this paper, granular calcite has been used as seed material in order to obtain synthetic calcium fluoride. According to the composition (CaF 2 497%, SiO 2 o1%), the synthetic calcium fluoride from the crystallization process in a FBR is able to be recycled as raw material for the manufacture of hydrofluoric acid leading to a reduction of raw materials consumption. The crystallization process in a FBR to remove fluoride from industrial wastewaters contributes to an environmental friendly production, because it allows to reduce the waste production as well as to increase the recovery of materials.

It was the aim of the current in vitro study to test the erosion-preventive potential of an experimental surface sealant (K-0184) and currently marketed self-etch adhesive systems under abrasive conditions. Ninety-six dentine specimens were randomly allocated to eight groups (n=12): (1) positive control (no treatment), (2) K-0184, (3) Shield Force Plus, (4) Xeno Select, (5) Scotchbond Universal, (6) Adhese Universal, (7) OptiBond All-In-One, and (8) Clearfil SE Bond. Before and after sealing, dentine specimens were measured profilometrically to determine the layer thickness of the protective agents.During 12 days, the specimens were demineralized daily for 5 min using hydrochloric acid (pH=3) and abraded by applying 600 brushing strokes (F=2.5 N). Calcium content in the hydrochloric acid was determined using atomic absorption spectroscopy. Calcium concentration was consistently highest in the positive control group (p &lt; 0.05 compared to all other groups). The lowest cumulated Ca ...

Different agents have been proposed to prevent the progression of acid induced dental substance losses, which are called erosive tooth wear (ETW), such as fluorides, calcium, and phosphate-based products; however, there is a need for a further increase in efficacy. Recently, the ability of polymers to interact with the tooth surface, forming acid resistant films, has come into the focus of research; nevertheless, there is still the need for a better understanding of their mode of action. Thus, this article provides an overview of the chemical structure of polymers, their mode of action, as well as the effect of their incorporation into oral care products, acid beverages, and antacid formulations, targeting the prevention of ETW. Recent evidence indicates that this may be a promising approach, however, additional studies are needed to confirm their efficacy under more relevant clinical conditions that consider salivary parameters such as flow rate, composition, and clearance. The sta...

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Broadly tunable picosecond pulses in the UV for nonlinear microscopy and lifetime measurements are not yet readily available. Complex synchronously pumped optical parametric oscillators with subsequent frequency doubling are typically used. We show that direct second harmonic generation of a visible picosecond supercontinuum source at 78 MHz renders pulses easily tunable from 250 to 430 nm. We find that an unexpectedly large numerical aperture and the use of thick crystals increase the efficiency of the frequency doubling process dramatically. The observed spectral width and efficiency are nearly two orders of magnitude larger than predicted by conventional theory. With broadband achromatic doubling, a 130 nm wide spectrum is achieved. Pulse durations of 17-35 ps are found in the UV and an average power between 1 and 70 lW. This qualifies the setup for most UV-based microscopic investigations. As first application, the fluorescence lifetime of two differing conformations of 2-(2 0hydroxyphenyl) benzothiazole is measured.

The effectiveness of a hydroxyapatite (HAP) toothpaste and a fluoride toothpaste in preventing root tissue demineralization (root caries) was compared using an established pH-cycling caries model. Materials and Methods: Sixty dentin blocks were produced from the root tissue of extracted human teeth and were assigned to 3 test groups (n=20/group): 10% hydroxyapatite toothpaste (HAP), 1450 ppm fluoride toothpaste (fluoride), and artificial saliva (artsaliva). Early root caries lesions were developed in each sample by 7-day demineralization using a pH-cycling caries model. The daily cyclic treatment regimen consists of two 2-minute toothpaste-slurry treatment periods, one 6-hour acid challenge using acidified gel (pH 4.5), and then storage in remineralizing solution (artsaliva) for the rest of the time. Demineralization was assessed as the amount of mineral loss (∆z) using transverse microradiography (TMR). Pairwise comparisons (between treatments) were performed using analysis of variance (ANOVA), and then Tukey's HSD for multiple comparisons. All p-values are considered significant if p<0.05. Results: Both ANOVA and Tukey's HSD indicated no significant (ANOVA; n=20) difference in mean ∆z among the groups, with least ∆z (±Sd) in the HAP (1117±366) compared to fluoride (1392±334) and artsaliva (1406±223). Relative to control, HAP and fluoride inhibited root demineralization by 21% and 6%, respectively. Conclusion: Within the limit of the present study, the tested toothpaste containing 10% HAP is an effective root caries control toothpaste. Toothpaste containing 10% HAP was slightly more effective in preventing tooth demineralization than 1450 ppm fluoride provided as sodium fluoride. Thus, this study shows that HAP toothpastes can serve as an effective alternative to fluoride toothpastes for root caries management.

Understanding surface and interfacial lateral organization in material and biological systems is critical in nearly every field of science. The continued development of tools and techniques viable for elucidation of interfacial and surface information is therefore necessary to address new questions and further current investigations. Sum frequency spectroscopy (SFS) is a label-free, nonlinear optical technique with inherent surface specificity that can yield critical organizational information on interfacial species. Unfortunately, SFS provides no spatial information on a surface; small scale heterogeneities that may exist are averaged over the large areas typically probed. Over the past decade, this has begun to be addressed with the advent of SFS microscopy. Here we detail the construction and function of a total internal reflection (TIR) SFS spectral and confocal fluorescence imaging microscope directly amenable to surface investigations. This instrument combines, for the first time, sample scanning TIR-SFS imaging with confocal fluorescence microscopy.

Objectives-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. Methods-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 nano sample 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. Results-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 46.3 m 2 /g, corresponding to a particle size of 41 nm. Transmission Electron Microscopy (TEM) examinations indicated that the nano CaF 2 contained clusters comprising particles of (10 to 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) × 10-10 , which was nearly four times greater than the Ksp (3.9 × 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) μg/cm 2 (n = 5), which was significantly (p < 0.001) greater than that ((0.31 ± 0.06) μg/cm 2) produced by the NaF solution. Significance-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.

Objectives-Fluoride (F) releasing dental restoratives are promising to promote remineralization and combat caries. The objectives of this study were to develop nanocomposite containing calcium fluoride nanoparticles (nCaF 2), and to investigate the long-term mechanical durability including wear, thermal-cycling and long-term water-aging behavior. Methods-Two types of fillers were used: nCaF 2 with a diameter of 53 nm, and glass particles of 1.4 μm. Four composites were fabricated with fillers of: (1) 0% nCaF 2 + 65% glass; (2) 10% nCaF 2 + 55% glass; (3) 20% nCaF 2 + 45% glass; (4) 30% nCaF 2 + 35% glass. Three commercial materials were also tested. Specimens were subjected to thermal-cycling between 5 °C and 60 °C for 10 5 cycles, three-body wear for 4×10 5 cycles, and water-aging for 2 years. Results-After thermal-cycling, the nCaF 2 nanocomposites had flexural strengths in the range of 100-150 MPa, five times higher than the 20-30 MPa for resin-modified glass ionomer (RMGI). The wear scar depth showed an increasing trend with increasing nCaF 2 filler level. Wear of nCaF 2 nanocomposites was within the range of wear for commercial controls. Water-aging decreased the strength of all materials. At 2 years, flexural strength was 94 MPa for nanocomposite with 10% nCaF 2 , 60 MPa with 20% nCaF 2 , and 48 MPa with 30% nCaF 2. They are 3-6 fold higher than the 15 MPa for RMGI (p < 0.05). SEM revealed air bubbles and cracks in a RMGI, while composite control and nCaF 2 nanocomposites appeared dense and solid. Significance-Combining nCaF 2 with glass particles yielded nanocomposites with long-term mechanical properties that were comparable to those of a commercial composite with little F release, and much better than those of RMGI controls. These strong long-term properties, together with their F release being comparable to RMGI as previously reported, indicate that the nCaF 2 nanocomposites are promising for load-bearing and caries-inhibiting restorations.

Glass ionomer cements (GICs) are widely used in dentistry because of their remineralizing and cariostatic potential induced by fluoride. In vitro studies have reported cell toxicity triggered by GICs; however, the influence of hydroxyapatite (HAp) must be considered. The aim of this study was to evaluate the effect of HAp in decreasing the cytotoxicity of the GIC 3M Vitrebond in vitro. Samples of 3M Vitrebond (powder, liquid and light-cured) were incubated in Dulbecco&#39;s modified Eagle&#39;s medium-Ham&#39;s F12 (DMEM-F12) for 24 hours at 37°C. Subsequently, the light-cured medium was treated with 100 mg/mL of HAp overnight. Toxicity of conditioned media diluted 1:2, 1:4, 1:8 and 1:20 was analyzed on human gingival fibroblasts (HGFs) using light microscopy and the fluorometric microculture cytotoxicity assay. The amounts of calcium fluoride (CaF2) were determined by the alizarin red S method. The exposure of HGFs to light-cured induced cell death and morphological changes such as...

This study evaluated the synergy of professional acidulated fluoride gel (APF) or fluoridated dentifrice application combined with Er,Cr:YSGG laser irradiation on the formation of CaF2 -like products (CaF2 ), in vitro. Thus, 272 bovine enamel slabs were randomly distributed among eight groups: G1: untreated enamel; G2: treated with fluoridated dentifrice (NaF, 1,100 μgF/g); G3: treated with acidulated phosphate fluoride gel (APF, 1.23% F(-) ); G4: irradiated with Er,Cr:YSGG laser at 8.5 J/cm(2) ; G5 and G6: combination of pre-irradiation with Er,Cr:YSGG followed by dentifrice or APF application, respectively; G7: combination of dentifrice application followed by Er,Cr:YSGG irradiation; G8: combination of APF application followed by Er,Cr:YSGG irradiation. After treatments, samples were evaluated by scanning electron microscopy, and the content of CaF2 was determined by an ion specific electrode. Both APF and dentifrice application promoted the formation of CaF2 on enamel, whereas Er...

Most of commercial phosphors consist of suitably doped polycrystalline compounds. The activation means has been usually discussed, less attention has been paid to the influence of fuels on host preparation in the final performance of the products. In this paper different fuels have been followed to synthesize phosphors based on Dy doped ZnAl 2 O 4. The mechanoluminescence (ML) properties of the materials have been given special consideration. Finally, various ML curves have been recorded in order to assess which of the fuel yields the most efficient Dy doped ZnAl 2 O 4 compound. Dy doped ZnAl 2 O 4 compound has been prepared by solution combustion technique with fuels such as urea, hydrazine and carbohydrazide separately. It is observed that urea enhances the ML intensity of the sample used. XRD result confirms formation of the phosphor. It is suggested that recombination of the trapped charge carriers are responsible for ML in this system.

Materials a n d Methods Study was conducted on 36 exfoliated or extracted primary anterior teeth. Criteria for inclusion were noncarious primary teeth (either extracted or exfoliated). Teeth with white spots and cracked areas were excluded. Teeth were cleaned and stored in distilled water until required.

Calcium fluoride-like materials ("CaF 2 ") formed on dental surfaces after professional fluoride application are unstable in the oral environment but can be retained longer with a daily NaF mouthrinse. We tested the effect of twice daily 0.05% NaF rinses on the retention of "CaF 2 " formed on enamel and dentine after applying acidulated phosphate fluoride (APF). "CaF 2 " formed on enamel/dentine by APF application significantly decreased after exposure to artificial saliva and the 0.05% NaF rinse was ineffective to avoid this reduction. These findings suggest that the combination of APF and 0.05% NaF is not clinically relevant, either for caries or dental hypersensitivity.

Purpose: To evaluate the microtensile bond strength (µTBS) and the presence of marginal gaps (MG) on composite restorations submitted to erosive and abrasive challenges. Methods: Seventy bovine incisors were sectioned in two halves; one half was used for the µTBS assay and the other for the MG measurement. For µTBS, the dentin on the incisal edge was exposed, the adhesive system was applied (Single Bond 2), and composite blocks were built (Filtek Z250). For MG, two rounded-shaped cavities were prepared and restored with the same materials. Specimens (n=10/µTBS and n=10/MG) were distributed into 7 groups: G1-control; G2-abrasive challenge (2 brushing cycles, for 35 days); G3-erosive challenge (two 90 s immersions into 20 mL of a citric solution, for 35 days); G4, G5, G6, and G7-abrasive challenge performed 0, 15, 30 or 60 min before the erosive challenge. Beamshaped specimens were tested for µTBS until failure. MG was measured by means of qualitative scores, recorded in 8 regions from the margin. Results: No significant differences in µTBS means or MG scores were detected among the tested experimental groups. Conclusion: The abrasive and erosive challenges were not able to affect the bond of a conventional two-step adhesive system to tooth substrates.

Although the cariostatic role of enamel-bound and solution fl uoride (F) has been the subject of some debate, a small increase in the concentration of F in oral fl uids, such as plaque fl uid and saliva, appears to have a profound effect on the de-and remineralization process [ten Cate, 1990; Margolis and Moreno, 1990; Featherstone, 2000]. This observation has focused attention on the labile or the so-called 'loosely-bound' F reservoirs [Arends and Christoffersen, 1990] that can maintain the free F concentration in plaque fl uid and saliva. Although numerous studies pointed to calcium fl uoride (CaF 2) or phosphate-contaminated 'calcium fl uoride-like' deposits [Fejerskov et al., 1981; Rölla and Saxegaard, 1990; Arends and Christoffersen, 1990; Øgaard, 2001] as important bioavailable F reservoirs, especially on oral hard tissue, studies by Rose et al. [1996] suggest that some of the F in plaque is held as bacterial calcium-fl uoride (Ca-F) complexes. Regardless of the nature of this binding, the above studies suggest that bioavailable oral F reservoirs are in the form of Ca-F moieties. Unfortunately, during F dentifrice or rinse usage, the amount of applied F, typically

Low‐energy ion scattering (LEIS) probes the atomic composition of the outer surface. Well‐defined reference samples are used for the quantitation. For elements like fluorine and calcium, it is not easy to find suitable, clean, and homogeneous references, since fluorine is a gas and calcium is a very reactive metal. In contrast to surface analytic techniques such as XPS, the extreme surface sensitivity of LEIS makes it difficult to use stable compounds like CaF2 as reference, since these compounds are not homogeneous at the atomic scale. With LEIS, CaF2 is not expected to show an atomic ratio F/Ca = 2.0. Thus, before CaF2 can be used as reference, its atomic surface concentrations have to be determined. Here, 3‐keV He+ scattering by a LiF(001) single crystal, an evaporated layer of Ca, and a Cu foil are used as basic references. High‐purity CaF2 is available in two forms: a single crystal and a powder. For a practical reference, powders are preferred, since if bulk impurities segrega...

Dental erosion develops through chronic exposure to extrinsic/intrinsic acids with a low pH. Enamel erosion is characterized by a centripetal dissolution leaving a small demineralized zone behind. In contrast, erosive demineralization in dentin is more complex as the acid-induced mineral dissolution leads to the exposure of collagenous organic matrix, which hampers ion diffusion and, thus, reduces further progression of the lesion. Topical fluoridation inducing the formation of a protective layer on dental hard tissue, which is composed of CaF(2) (in case of conventional fluorides like amine fluoride or sodium fluoride) or of metal-rich surface precipitates (in case of titanium tetrafluoride or tin-containing fluoride products), appears to be most effective on enamel. In dentin, the preventive effect of fluorides is highly dependent on the presence of the organic matrix. In situ studies have shown a higher protective potential of fluoride in enamel compared to dentin, probably as the organic matrix is affected by enzymatical and chemical degradation as well as by abrasive influences in the clinical situation. There is convincing evidence that fluoride, in general, can strengthen teeth against erosive acid damage, and high-concentration fluoride agents and/or frequent applications are considered potentially effective approaches in preventing dental erosion. The use of tin-containing fluoride products might provide the best approach for effective prevention of dental erosion. Further properly designed in situ or clinical studies are recommended in order to better understand the relative differences in performance of the various fluoride agents and formulations.

This study was designed to evaluate the effect of four remineralizing agents on surface topography of dentin. Materials and methods: 75 Teeth were divided according to the remineralizing agents into five treatment groups (Control C, CPP-ACP A, NovaMin V, n-HA N & NaF F) 15 teeth each. Time of pH cycling periods were divided to (one week (W1), two weeks (W2) and five weeks (W5) Results: Regarding all of pH cycle periods (W1, W2&W5); there was statistically significant difference between mean dentinal tubules diameter values of the control group on one hand and each of A, V, N and F groups on the other hand. However, there was no statistically significance difference between all those remineralizing agents. The N groups showed the lowest mean value of dentinal tubules diameter while the F groups showed the highest mean value of dentinal tubules diameter. Conclusions: Surface topography of dentin is positively affected by the application of remineralizing agents. Increasing the application rate (pH cycling periods) of the remineralizing agents significantly affect the surface topography of dentin.

ORIGINAL RESEARCH highly soluble and release large amounts of F during a drop in the pH; hence, it provides a significant cariostatic effect and promotes remineralization on the enamel surface. 5 IntroductIon Dental caries, an infectious microbial disease of multifactorial origin, is the result of tooth demineralization due to the interaction of diet, host factors and microbial flora over a period of time, leading to the destruction of calcified tissues of the teeth. 1 There are many preventive strategies that have been advocated to counter dental caries, and among them, F application is a widely accepted and extremely effective treatment modality. 2 American Dental Association has also recommended periodic topical F treatment for children and adults who are at moderate to high risk of developing dental caries. 3 The kinetic effect of F is mainly appreciated by two methods. The first is the incorporation of KOH-insoluble F compounds into the enamel. The alkali insoluble F (F bound to the apatite) is KOH insoluble F, which is structurally incorporated F in the enamel crystallites and prevents demineralization of the enamel during an episode of acid attack. 4 Alternatively, calcium-F (CaF 2) like precipitates, composed of KOH-soluble F, are formed and deposited on the enamel surface. Studies have shown that these deposits are 1,2,5,

Growth of CaF 2 on Si͑001͒ is studied as a function of the substrate temperature during deposition for coverages from fraction of a monolayer ͑ML͒ up to several monolayers. Structural and morphological studies using atomic force microscopy, low-energy electron diffraction, and reflection high-energy electron diffraction are combined with measurements of core-level photoemission and x-ray absorption. Bonding between CaF 2 molecules and Si͑001͒ substrates is followed by monitoring core-level shifts and x-ray absorption line shape. It is found that a dissociative reaction occurs at high deposition temperatures ͑ϳ750°C͒, giving rise to a 1-ML-thick uniform wetting layer, which is bonded with the substrate through Ca atoms. This wetting layer changes the surface periodicity from double domain 2 ϫ 1+1ϫ 2 to single domain 3 ϫ 1. Three-dimensional CaF 2 elongated islands develop on top of the wetting layer, with their ͑110͒ planes parallel to the Si surface plane. At temperatures below 600°C no dissociative reaction takes place for CaF 2 ; nanodimensional islands develop in the form of rectangular-based huts. The crystallographic orientation of these islands is parallel to that of the Si͑001͒ substrate. The data are compared to results obtained on CaF 2 deposited on Si͑111͒.

Understanding the interaction mechanism between polymeric flocculants and solid particles in two oppositely charged solutions: bentonite and calcium fluoride, is of great practical and fundamental importance. In this work, inorganic flocculants based on aluminum(III) or iron(III); cationic, anionic and non-ionic organic flocculants were used. The solution pH, which highly influenced the flocculation performance of the system, has been used as a function of turbidity removal, sediment volume and velocity. Results show that the flocculation of inorganic polymers does not depend on the zeta potential but on the solution pH, contrary for cationic and anionic polymers. Non-ionic polymer was independent on both. By varying the final pH of the heterogeneous solution formed of flocs-liquid, it was found for inorganic polymers, the optimum condition of pH < 3 to separate inorganic flocculant particles from flocs. Inductively coupled plasma atomic emission spectrometer and X-ray fluorescence analysis proved the reversibility of flocculation process by indicating the concentration of flocculant representative atom (Al or Fe) in the flocs and in the emerging solutions when the flocculation was optimized and the reversibility was effective. As results, weak forces were suggested as responsible for inorganic polymers flocculation where electrostatic interaction and hydrogen bonds may enroll the mechanism of organic flocculants.