Efficacy of a toothpaste containing paeonol, potassium nitrate, and strontium chloride on dentine hypersensitivity: A double-blind randomized controlled trial in Chinese adults

Nitrates of cerium and samarium deposit on human enamel independently of a salivary pellicle

Objectives

The aim of this study was to analyze the precipitation of Cerium(III)nitrate hexahydrate [Ce(NO3)3] or Samarium(III)nitrate hexahydrate [Sm(NO3)3] solutions on human enamel with and without a salivary pellicle. Investigated parameters were At%Ce and At%Sm measured using energy dispersive x-ray spectroscopy (EDX) after test solution (two concentrations) application.

Materials and methods

Precipitation of Ce(NO3)3 and Sm(NO3)3 solutions was examined on human enamel with and without a salivary pellicle. 6 enamel specimens each were obtained from 12 freshly extracted human third molars. These specimens were ground flat and polished. A salivary pellicle was created on 3 of the 6 specimens per tooth by storing the samples in human saliva. Subsequently, an aqueous solution of Ce(NO3)3 was applied to 2 of the 6 specimens (one with, one without salivary pellicle) for 60 s. The same was carried out with an aqueous solution of Sm(NO3)3 on 2 further specimens. The remaining 2 specimens from each tooth were treated with demineralized water (negative control). Ce(NO3)3 and Sm(NO3)3 solutions were applied at 25 or 50 wt% (aqueous solutions). The test materials and concentrations were distributed using a randomization table. After 60 s exposure and rinsing with demineralized water, the elemental composition (Ce, Sm, Ca, P, O, N, Na, Mg) of the enamel surface was analyzed by EDX. Atomic percentages (At%), differences (ΔAt%) and calcium/phosphorous-ratios (Ca/P-ratios) were calculated and analyzed non-parametrically (α = 0.05).

Results

2.0-2.3 At%Ce (median) was detected on Ce(NO3)3-treated enamel and 0.4-0.7 At% Sm (median) was detected on Sm(NO3)3-treated enamel. Ce was only detected on the surfaces after application of Ce(NO3)3, Sm only after application of Sm(NO3)3. The Ca/P-ratio was significantly lower (1.37-1.59; p = 0.028) after the application of 25% and 50%Ce(NO3)3 as well as 50%Sm(NO3)3 compared to the control treatment (demineralized water; 1.61-1.63). After treatment with Ce(NO3)3, At%Ca and At%Na were significantly lower (p ≤ 0.043) compared to treatment with Sm(NO3)3. No significant differences were found between specimens treated with 25% or 50% lanthanide nitrate solution. Presence of a salivary pellicle had no significant influence on the measured At% with the exception of specimens treated with 50% Sm(NO3)3 with increased At%Sm (p ≤ 0.046).

Conclusions

Ce(NO3)3 and Sm(NO3)3 precipitate on human enamel independently of the presence of a salivary pellicle.

Little Ironweed and Java Tea in Herbal Toothpaste Reduced Dentine Permeability: An In Vitro Study

Aim

To determine the effect of an herbal toothpaste containing Little Ironweed and Java Tea, on reducing dentine permeability in vitro.

Materials and Methods

Dentine discs from human mandibular third molars were divided into three groups and brushed with herbal toothpaste, nonherbal toothpaste, or deionized water. Each group was immersed in artificial saliva (AS) or 6% citric acid. The permeability of each dentine disc was evaluated before and after saliva or acid challenge using a fluid filtration system. The morphology of dentine discs after treatment was observed using scanning electron microscopy (SEM). The mean permeabilities were statistically analyzed using analysis of variance and Tukey's test.

Results

The nonherbal and herbal toothpaste groups demonstrated reduced dentine permeability. AS immersion decreased dentine permeability in both toothpaste groups with values lower than the control group. Dentine permeability values increased after acid immersion in the toothpaste groups and were similar to each other. SEM revealed small granular crystal-like and round particles on the dentine surface and opening of dentinal tubules of both toothpaste groups. More dentinal tubules were opened after brushing with deionized water.

Conclusions

The reduction of dentine permeability caused by the herbal toothpaste was similar to that of the nonherbal toothpaste after brushing and the simulated oral conditions. Both herbal plants have the possibility to alleviate clinical hypersensitivity by reducing dentine permeability. Little Ironweed and Java Tea in the toothpaste composition is a potential choice for treating hypersensitive dentine.