Determination of molecular species of calcium salts of MDP produced through decalcification of enamel and dentin by MDP-based one-step adhesive

Abstract

Enamel and dentin particles were added to an experimental 10-methacryloyloxydecyl dihydrogen phosphate (MDP)-based one-step adhesive to react for 30 s. After enamel and dentin reactants were analyzed using X-ray diffraction (XRD) and phosphorus-31 nuclear magnetic resonance ( 31 P NMR) techniques, curve-fitting analysis was performed on the 31 P NMR spectra of enamel and dentin reactants. By varying the molar ratio of calcium chloride to MDP, a series of three types of MDP-Ca salts were synthesized. The molecular species of calcium salts of MDP (MDP-Ca salts) produced by decalcification of enamel or dentin were determined based on the XRD and 31 P NMR analysis results of these three types of synthesized MDP-Ca salts. Curve-fitting analysis showed that enamel and dentin developed several types of MDP-Ca salts and amorphous dicalcium phosphate dihydrate (DCPD) during decalcification. The molecular species of MDP-Ca salts produced by enamel and dentin were mono-calcium salts of MDP monomer and MDP dimer. In addition, dentin produced a di-calcium of MDP dimer.

Mini-interfacial fracture toughness as a new validated enamel-bonding effectiveness test

“…Despite the proven chemical interaction potential of the functional monomer MDP with HAp (Yoshida et al, 2004;Yoshihara et al, 2010Yoshihara et al, , 2011Yoshihara et al, , 2013Zhang et al, 2013), the SE bonding protocol appeared insufficient to reach a mini-iFT at enamel in line with that achieved with an E&R bonding protocol. The three most plausible reasons are: (1) the enamel bond depends largely on micro-mechanical interlocking in deep etch pits created by phosphoric-acid etching, while the etching capacity of functional monomers like MDP is insufficient to achieve adequate micro-retention at enamel; (2) MDP appears less capable of reaching/interacting with Ca within enamel HAp that has a higher crystallinity and is less crisscross oriented than dentinal HAp; at enamel, despite its higher mineral content, less MDP-Ca salt is produced than at dentin Yokota and Nishiyama, 2015); (3) the mild self-etch bonding is compromised by the enamel-smear complex, the latter being effectively removed by phosphoricacid etching and thus not interfering with bonding in case the more surface-aggressive E&R approach is applied . Bond-strength testing comparing MDP-free with MDPcontaining adhesives showed nevertheless that chemical interaction of MDP with HAp, while perhaps less relevant at short time, is crucial in maintaining interfacial stability over time.…”

Adsorption behavior of methacryloyloxydecyl dihydrogen phosphate on an apatite surface at neutral pH

“…As stated earlier, the 10-MDP-Ca salt is formed when 10-MDP-H 2 is applied to enamel or dentin surfaces; dicalcium phosphate dihydrate (DCPD) is also simultaneously formed on the demineralized mineral surface (3,5,11,13) and is transformed into HA when the surrounding pH recovers to neutral (16). Moreover, some 10-MDP-H 2 molecules will be neutralized in the form of 10-MDP À and 10-MDP 2À ionic species that will directly interact with Ca sites on HA and DCPD surfaces through charge interaction before polymerization.…”

“…Many investigations thus far have emphasized two chemical phenomena: chemical adsorption of 10-MDP onto the HA surface; and confirmation and characterization of the 10-MDP-Ca salt that precipitates on the mineral surface. Both phenomena have been studied by methods such as X-ray diffraction (3,7,8,(10)(11)(12)(13), transmission electron microscopy (3,9,12), X-ray photoelectron spectroscopy (5), nuclear magnetic resonance imaging (9,11,14), infrared spectroscopy (10), solubility testing of 10-MDP-Ca (1,6,9,10,15), and the adsorption of 10-MDP onto HA monitored by solidstate 31 P cross polarization magic angle spinning nuclear magnetic resonance (CP-MAS NMR) spectroscopy (3,11), when 10-MDP-H 2 was applied onto HA.…”

NMR study on the demineralization mechanism of the enamel and dentin surfaces in MDP-based all-in-one adhesive

“…In accordance with previous studies [24][25][26] , 0.200 g of enamel or dentin particles that had been prepared by cutting bovine crown teeth (2-2.5 years old) using an air turbine with a fine diamond bur (#105R, Shofu, Kyoto, Japan) were suspended in each EX adhesive (1.000 g), and the suspensions were then mixed for 30 s at 20°C. After the reaction, 30 mL ethanol was immediately added to each adhesive-enamel or -dentin suspension to stop further reaction of MDP with the enamel or dentin sample.…”

“…The curve-fitting analyses of the corresponding 31 P NMR spectra were performed by assuming that DCPD with an amorphous phase was also produced along with several types of MDP-Ca salts as described previously [24][25][26] . To analyze the 31 P NMR spectral patterns, we used OriginPro ® 9.1 Data Analysis and Graphing Software (OriginLab, Northampton, MA, USA).…”