Effect of dentifrice containing fTCP, CPP-ACP and fluoride in the prevention of enamel demineralization.

OBJECTIVE: To evaluate the effect of different fluoride- and calcium- and/or phosphate-containing products on their ability to prevent enamel demineralization under pH cycling conditions. MATERIAL AND METHODS: Enamel bovine specimens were assigned to the following groups: G1-MPP (MI Paste Plus, 0.2% NaF, Recaldent™, GC Corporation Tokyo, Japan); G2-FD (Crest™ Cavity Protection, 0.243% NaF, Procter & Gamble, USA); G3-CLP (Clinpro™ 5000, 1.1% NaF, 3M ESPE, USA); and G4-CO (Control without fluoride, Silica-based dentifrice; Daudt Ltda, Brazil). The specimens were soaked in demineralizing solution for 6 h and remineralizing solution for 18 h alternatively for 10 days. The toothpaste was prepared with deionized water in a 1:3 ratio (w/v) for three minutes daily. The solutions were renewed every 48 h. After cycling, enamel changes were analysed by percentage change of SMH (%SMH) and energy-dispersive X-ray spectroscopy (EDS). The %SMH value observed for G3-CLP (2.9 ± 39.2) was higher than that found in G4-CO (-13.0 ± 20.7), G1-MPP (-8.9 ± 20.9) and G2-FD (-3.9 ± 27.1). The %SMH was similar for all treatment groups (one-way ANOVA and Tukey's HSD; p < .05). The pH, Ca2+ and Ptotal in the remineralization solutions were not different among all groups (Kruskal-Wallis; p < .05). At 24 h, the Ca2+ concentration in the demineralization solution was significantly lower in G1-MPP. Ca2+ concentration increased in all groups after 48 h, except for G3-CLP. The EDX quantitative analysis showed that the atomic % of elements is lower level at G4-CO. CONCLUSIONS: The Clinpro™ 5000 demonstrated having the most protective effect against demineralization; however, the % SMH was similar for all groups.

Aerosol dilution as a new sample introduction strategy for microwave-induced plasma optical emission spectrometry.

A new sample introduction method using aerosol dilution for microwave-induced plasma optical emission spectrometry (MIP OES) is presented. Signal emissions from N2+ and OH species were monitored for plasma diagnostics and quantity of solvent plasma load (QSPL). The N2+/OH signal intensity ratio demonstrated that aerosol dilution is a desolvation process which can reduce the QSPL, increasing plasma energy. Efficiency of the system was observed with solutions containing the easily ionizable element (EIE) Na, without important alteration of the plasma physics at concentrations up to 5 g L-1. Atomic and ionic lines of Cr, Mn, V and Zn in saline solutions proved to have distinct variations. Despite the lower amount of analyte introduced, the LOQs of these elements were similar to the ones obtained from conventional nebulization. The analysis of two CRMs (fertilizer, NIST 695 and tomato leaves, NIST 1573a) resulted in percentage recoveries within 90-130%. Aerosol dilution in MIP OES (AD-MIP OES) brings increased robustness to the technique, once complex matrices can be introduced with the advantage of suppressing matrix interferences. Additionally, the sample is less prone to dilution error, and costs are saved due to increased life span of consumables since less sample matrix is introduced in the plasma.