Piezo-catalysis for nondestructive tooth whitening

Abstract

The increasing demand for a whiter smile has resulted in an increased popularity for tooth whitening procedures. The most classic hydrogen peroxide-based whitening agents are effective, but can lead to enamel demineralization, gingival irritation, or cytotoxicity. Furthermore, these techniques are excessively time-consuming. Here, we report a nondestructive, harmless and convenient tooth whitening strategy based on a piezo-catalysis effect realized by replacement of abrasives traditionally used in toothpaste with piezoelectric particles. Degradation of organic dyes via piezo-catalysis of BaTiO 3 (BTO) nanoparticles was performed under ultrasonic vibration to simulate daily tooth brushing. Teeth stained with black tea, blueberry juice, wine or a combination thereof can be notably whitened by the poled BTO turbid liquid after vibration for 3 h. A similar treatment using unpoled or cubic BTO show negligible tooth whitening effect. Furthermore, the BTO nanoparticle-based piezocatalysis tooth whitening procedure exhibits remarkably less damage to both enamel and biological cells.

Vibrational density of states of amorphous solids with long-ranged power-law-correlated disorder in elasticity

“…The elastic constants are related to the longitudinal and transverse local sound velocities asc T ≡ G/m 0 , c 2 L ≡ (K +4G/3)/m 0 = (λ+2G)/m 0 , respectively.The Lamé's constant is set to be λ = λ 0 , while the shear modulus includes a random spatial variation G(r) = G 0 [1+ΔG(r)]. The random function ΔG(r) is supposed to have a long-ranged power-law decay ΔG(r )ΔG(r + r) = B (r) ∝ γ 2 /(r 2 + ξ 2 ) 3/2 for some constants γ and ξ, in agreement with recent evidence for glasses and granular materials[69,70]. The explicit form of angular component in B(r) is not relevant to results and is not shown in the last expression.…”

“…Independent evidence supporting the existence of power-law spatially decaying correlations in elasticity have been shown in recent works [69,70]. All these facts point towards the importance of properly accounting for longranged power-law elastic correlations in the description of the vibrational properties of disordered systems.…”

“…The assumption of power-law-correlated disorder in elastic properties (elastic constants or stresses), supported by evidence found in glasses [69] and granular materials [70], has been key to derive the logarithmic enhancement ∼ −k d+1 ln k of Rayleigh scattering in glasses in our previous work [57], by accounting for the anisotropic character of wave propagation in the solid locally. The theory reproduces the boson peak in the DOS along with its dependence on the strength γ (or g), and on the characteristic scale b, of power-law-correlated disorder.…”

Thermocatalytic hydrogen peroxide generation and environmental disinfection by Bi2Te3 nanoplates

“…he generation of reactive oxygen species (ROS) is the backbone of advanced oxidation processes leading to widespread applications such as organic pollutant degradation 1,2 , cancer therapy [3][4][5] , and disinfection [6][7][8] . Among all different types of ROS, hydrogen peroxide (H 2 O 2 ) is more stable than others 9 .…”

Thermally activated giant piezoelectricity and enhanced interface elastic strain‐mediated magnetoelectric coupling

“…4 Pressure has also been used to induce MPB in the simple perovskite materials which could help in decreasing cost and expand the utility of piezoelectric materials. [5][6][7][8] More importantly, ambient temperature is one crucial factor for tuning of the ferroelectric phase stability and piezoelectric properties. Renault et al have systematically studied the temperature range for the existence of the electric field-induced orthorhombic (O) phase in <011> oriented Pb(Zn,Nb)O 3 -PbTiO 3 single crystals.…”