Fluoride plus functionalized ß-TCP: a promising combination for robust remineralization.

With more than 50 years of clinical success, fluoride serves as the gold standard agent for preventing tooth decay. In particular, the action of fluoride facilitates saliva-driven remineralization of demineralized enamel and alters solubility beneficially. Still, tooth decay remains problematic, and one way to address it may be through the development of new mineralizing agents. Laboratory and clinical studies have demonstrated that the combination of fluoride and functionalized ß-tricalcium phosphate (fTCP) produces stronger, more acid-resistant mineral relative to fluoride, native ß-TCP, or fTCP alone. In contrast to other calcium-based approaches that seem to rely on high levels of calcium and phosphate to drive remineralization, fTCP is a low-dose system designed to fit within existing topical fluoride preparations. The functionalization of ß-TCP with organic and/or inorganic molecules provides a barrier that prevents premature fluoride-calcium interactions and aids in mineralization when applied via common preparations and procedures. While additional clinical studies are warranted, supplementing with fTCP to enhance fluoride-based nucleation activity, with subsequent remineralization driven by dietary and salivary calcium and phosphate, appears to be a promising approach.

In vitro remineralization of human and bovine white-spot enamel lesions by NaF dentifrices: A pilot study.

The aim of this feasibility study was to evaluate the in vitro remineralization effects of four dentifrice systems using microhardness and fluoride uptake analyses. In vitro testing for the potential remineralization of the white-spot lesions in bovine and human enamel was performed using a 10-day pH cycling model. The study involved the following NaF silica-based dentifrices: 1) placebo (0 ppm F), 2) 500 ppm F, 3) 1150 ppm F, and 4) 500 ppm F plus functionalized tricalcium phosphate (fTCP). Each day consisted of four two-minute treatments, one four-hour acid challenge (pH = 5.0), and immersion in artificial saliva (pH = 7.0) between these events. After cycling, specimens were analyzed for surface microhardness (SMH), enamel fluoride uptake (EFU), and cross-sectional microhardness (CSM). Statistical analyses revealed significant differences (ANOVA, LSD, p<0.05) among the four groups, with the placebo and 500 ppm F dentifrices providing significantly less remineralization relative to the 1150 ppm F and 500 ppm F plus fTCP dentifrices. Notably, while CSM measurements for both enamel types generated similar profiles for the four groups, SMH and EFU revealed human enamel was more sensitive to the 500 ppm F dentifrice groups compared to bovine enamel. This apparent sensitivity may be due to the inherent structural differences between the two substrates.

Dentine remineralization by simulated saliva formulations with different Ca and Pi contents.

The understanding of the dentine remineralization process and the ability to reproduce it in vitro are essential to the development of preventive and therapeutic measures. This study investigated how simulated saliva formulations with different Ca and P(i) contents and degrees of saturation with respect to biologically relevant calcium phosphates may affect the remineralization of eroded dentine, as a function of time. Slabs of bovine root dentine (n = 8 per group) were flattened, polished, demineralised by 1% citric acid for 30 and 60 min and remineralized for 3, 7 and 14 days, by one of the following buffered (pH 7) solutions [Ca:Pi ratio, Ca/Pi concentrations (mM), ionic strength]: solution A: 1.6, 1.5/0.9, 0.115; solution B: 1.6, 2/1.25, 0.117; solution C: 1.6, 3.2/2, 0.121; solution D: 0.3, 1.11/3.7, 0.118; solution E: 0.3, 1.45/5, 0.122. Integrated mineral loss (30 and 60 min) was quantified by transverse microradiography after each remineralization period. ANOVA and regression analyses (alpha = 0.05) showed, irrespective of the demineralisation time, that the solutions C and E were able to remineralize dentine. This effect increased throughout the remineralization times and was significantly higher for E. Remineralization was successfully shown in vitro, under specific conditions of degree of saturation and Ca and Pi contents of the solutions. Optimum remineralization was observed for the solution E supersaturated with respect to relevant calcium phosphates, with low Ca:Pi ratio and highest Pi concentration.

Platinum-containing hyper-cross-linked polystyrene as a modifier-free selective catalyst for L-sorbose oxidation.

Impregnation of hyper-cross-linked polystyrene (HPS) with tetrahydrofuran (THF) or methanol (ML) solutions containing platinic acid results in the formation of Pt(II) complexes within the nanocavities of HPS. Subsequent reduction of the complexes by H2 yields stable Pt nanoparticles with a mean diameter of 1.3 nm in THF and 1.4 nm in ML. The highest selectivity (98% at 100% conversion) measured during the catalytic oxidation of L-sorbose in water is obtained with the HPS-Pt-THF complex prior to H2 reduction. During an induction period of about 100 min, L-sorbose conversion is negligible while catalytic species develop in situ. The structure of the catalyst isolated after the induction period is analyzed by X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. Electron micrographs reveal a broad distribution of Pt nanoparticles, 71% of which measure less than or equal to 2.0 nm in diameter. These nanoparticles are most likely responsible for the high catalytic activity and selectivity observed. The formation of nanoparticles measuring up to 5.9 nm in diameter is attributed to the facilitated intercavity transport and aggregation of smaller nanoparticles in swollen HPS. The catalytic properties of these novel Pt nanoparticles are highly robust, remaining stable even after 15 repeated uses.