Effect of Sodium Trimetaphosphate on Hydroxyapatite Solubility: An In Vitro Study

Abstract

This study evaluated the effect of different concentrations of sodium trimetaphosphate (TMP) with and without fluoride (F) on the concentration of calcium (Ca), phosphorus (P) and F in hydroxyapatite (HA). Synthetic HA powder (0.15 g) was suspended (n=6) in solutions (75 mL) of TMP at 0%, 0.1%, 0.2%, 0.4%, 0.6%, 0.8%, 1.0%, 2.0%, 4.0%, 6.0%, 8.0% and 10% concentrations in the presence and absence of 100 ppm F and subjected to a pH-cycling process. The precipitates were filtrated, dried at 70° C for 24 h and ground onto a fine powder. The concentrations of F (KOH (CaF 2 ) and HCl (FA) soluble), Ca (Arsenazo III), and P (molybdate method) in HA were determined. The Ca P, and Ca/P ratio data were subjected to Tukey's test and the F data were subjected to Student-Newman-Keuls test (p<0.05). The addition of TMP to the samples reduced F deposition to 98% (p<0.001). The groups containing 100 ppm F and 0.4% or 0.6% TMP exhibited a higher Ca concentration than the group containing only 100 ppm F (p<0.05). Furthermore, the HA treated with 0.2% and 0.4% TMP and 100 ppm F showed a higher Ca/P ratio than the other groups (p<0.001). In conclusion, TMP at 0.2%, 0.4% and 0.6% concentrations combined with F seemed to be able to precipitate HA with low solubility. However, especially at high concentrations, TMP interferes with F deposition on HA.

Cyclotriphosphate associated to fluoride increases hydroxyapatite resistance to acid attack

“…Considering the results of this study and data from literature, 16,26,27 the synergistic action of F and TMP seems to differ from data reported by Gonzalez et al 34 Increased fluoride concentrations (acid-soluble F) was shown to promote a decreased intensity of the OH vibrational-band region assigned to the Ca 3 -OH bending mode (at 632 cm 21 ) in the IR spectra, what indicates the presence of F ions in the CHA. 35 Moreover, the appearance of weak bands at 669-719 cm 21 ( Figure 5) indicates a partial replacement of OHby F -.…”

“…[10][11][12][13][14][15][16][17][18][19][20] The data from adsorption of TMP to CHA [ Figure 6(g)] showed a dose-response pattern and was influenced by presence of fluoride in the medium. It was possible to observe that fluoride reduced TMP adsorption to CHA, confirming that TMP and fluoride compete for the same binding sites 26,27 and can, therefore, modulate its effects depending on the TMP concentration. [10][11][12][13][14][15][16][17][18][19][20] Unlike previous studies, in which TMP and/or F remained in contact with hydroxyapatite in the solutions during 3 consecutive pH-cycles (3 h), without assessment of F and TMP adsorption to hydroxyapatite, 26,27 in the present study CHA was treated during only 1 min with each treatment solution, followed by a single pH-cycle (1 h), aiming to simulate an acid challenge similar to that occurring in the oral cavity.…”

“…Despite it is well known TMP and F must be combined at a suitable molar ratio to promote a synergistic effect, [10][11][12][13][14][15][16][17][18][19][20] detailed data regarding the interaction between F and TMP with the tooth structure are scarce. Previous studies showed that the adsorption of TMP and F involve the same hydroxyl (OH) binding sites, 26,27 what seems to explain the need of an appropriate molar ratio to achieve optimum results. Despite the above-mentioned studies provided new insights into the interactions between TMP and hydroxyapatite, it is noteworthy that they were conducted using pure hydroxyapatite (i.e., after calcination), and that TMP and/or F solutions remained in contact with hydroxyapatite throughout the entire duration of the pH-cycle.…”

Sodium trimetaphosphate and hexametaphosphate impregnated with silver nanoparticles: characteristics and antimicrobial efficacy

“…Among the phosphate salts, sodium trimetaphosphate (TMP) and sodium hexametaphosphate (HMP) have been effective in reducing enamel demineralization and improving remineralization. They are inorganic cyclophosphates with the capacity to adsorb hydroxyapatite and protein through hydroxyl (Souza et al 2013;Delbem et al 2014) and amino (Leone et al 2008;Li and Chang 2008) attachment sites. Added to low concentrations of fluoride in an appropriate proportion in oral health products, they provide a greater protective effect than conventional fluoride products (da Camara et al 2014;Manarelli et al 2015;Takeshita et al 2015;Conceicao et al 2015;da Camara et al 2016).…”

Sodium Trimetaphosphate as a Novel Strategy for Matrix Metalloproteinase Inhibition and Dentin Remineralization

“…Exponential decrease of Ca 2+ in enamel in the presence of STMP has been reported [McGaughey and Stowell, 1977;Souza et al, 2013]. When used at high concentrations, SMTP has the ability to supersaturate the enamel surface and further sequester Ca 2+ from hydroxyapatite due to its strong ability to complex metal ions, resulting in mineral loss [da Camara et al, 2016].…”