The invention relates to a natural whitening toothpaste formulation that does not contain abrasive dental silicas and a method of its preparation. Currently available whitening toothpastes for individual/home use are based on abrasive dental silicas, which mechanically remove enamel contamination making the teeth visually whiter. However, this procedure carries the risk of damage to the enamel due to excessive friction, which may contribute to the development of tooth decay or the emergence of hypersensitivity due to the exposure of nerve tubules. On the other hand, the charcoal that is currently used in toothpastes is generally activated charcoal, which is now suspected of causing cancer.

From the Chinese application CN108721190A, a toothpaste composition containing bamboo charcoal, silica and refreshing substances is known.

From the Spanish application ES2095812A1, a toothpaste with whitening, anti-tartar build-up and low abrasion properties is known, having a composition comprising (a) from 5 to 10% of xylitol, (b) from 0.7 to 1.1% of sodium lauryl sarcosinate, (c) 16 to 18% of silica, (d) a buffer consisting of (i) tetrasodium or tetrapotassium pyrophosphate and (ii) disodium (or dipotassium) dihydrogen pyrophosphate, including: (a) 3 to 7% of a proteolytic enzyme of low specificity or alternatively b) from about 0.3 to 3% of carbamide peroxide, where the percentages are percent by weight based on the weight of the total formulation. The toothpaste also comprises water, remineralizers, wetting agents, binders, opacifiers, dyes, flavors, sweetening agents and possibly preservatives.

On the other hand the toothpaste composition described in the French application FR2838643A1 comprises 30-50 wt.% of seawater (most preferably from the Cinque Terre Marine Park), 30-40 wt.% of sorbitol, 15-20 wt.% of hydrated silica, 2-5 wt.% of glycerin, 0.5-2 wt.% of cellulose gum, 1-4 wt.% of cocamidopropyl betaine; 1-2 wt.% of a flavor; 1- 2 wt.% of propylene glycol; 0.2-1 wt.% of pyrogenic silica, 0.2-1 wt.% of Fucaceae seaweed extract, 0.01-2 wt.% of sodium saccharin, 0.1-0.2 wt.% of allantoin, 0.01-0.2 wt.% of bisabolol, 0.12 wt.% of myristalkonium saccharinate, 0.035 wt.% of guaiazulene, 0.3 wt.% of sodium benzoate, 0.2 wt.% of methylparaben, 0.2 wt.% of titanium dioxide and 0.001 wt.% of brilliant blue CI 42090.

The aim of the present invention was to develop a whitening toothpaste without silica, fluorine and ethoxylated sodium lauryl sulfate using inactive charcoal.

The subject of the invention is a natural whitening toothpaste, characterized in that it comprises only silica-free abrasives, including from 1.5 to 3 wt.% of bamboo charcoal, and further it comprises from 2 to 4 wt.% of calcium hydroxyapatite, from 12 to 18 wt.% of rice flour, from 1 to 3 wt.% of perlite as well as excipients such as sweetening, flavoring, humectant and foaming agents adding up to 100 wt.%.

Preferably, the paste according to the invention among the excipients comprises at least one sweetening agent in an amount of 4.5 to 5.5 wt.% selected from stevia and xylitol.

Preferably, the paste according to the invention among the excipients comprises at least one flavoring agent, preferably menthol, in an amount of from 0.2 to 1.5 wt.%.

Preferably, the paste according to the invention among the excipients comprises at least one humectant, preferably sorbitol, in an amount of 17 to 28 wt.%.

Preferably, the paste according to the invention among the excipients comprises purified water in an amount of 32 to 37 wt.%

Preferably, the paste according to the invention comprises 10 wt.% of excipients that reduce odor, strengthen the gums, form a foam and give the paste the right consistency.

The invention also relates to a method of producing a natural whitening toothpaste, characterized by mixing bamboo charcoal in an amount of 1.5 to 3 wt.%, calcium hydroxyapatite in an amount of 2 to 4 wt.%, and rice flour in an amount of from 12 to 18 wt.%, perlite in an amount from 1 to 3 wt.%, at least one sweetening agent, preferably selected from stevia and xylitol, in an amount from 4.5 to 5.5% wt.%, at least one flavoring agent, preferably menthol in an amount of 0.2 to 1.5 wt.%, at least one humectant, preferably sorbitol in an amount of 17 to 28 wt.%, purified water in an amount of 32 to 37 wt.% and up to 10% wt. excipients that reduce odor, strengthen the gums, form a foam and give the paste the desired consistency, wherein:

(a) at first a mixture of at least one sweetening agent in water with the addition of excipients for reducing odor, strengthening the gums, and giving the paste a suitable consistency is prepared;

(b) then, after their complete dissolution, bamboo charcoal is added along with a part of the at least one humectant and at least one flavoring agent and the whole mixture is homogenized;

(c) a mixture of calcium hydroxyapatite with perlite is added to the mixture obtained in step (b), and the mixture is homogenized;

(d) a mixture of rice flour with the remaining part of at least one humectant is added to the mixture obtained in step (c), and the mixture is homogenized; (e) a mixture of sodium carboxymethyl cellulose and glycerin prepared immediately before the addition is added to the homogenized mixture obtained in step (d), and the obtained mixture is subjected to homogenization;

(f) a surfactant responsible for foaming properties is added to the homogenized mixture obtained in step (e), and the resulting mixture is then mixed and deaerated.

The obtained toothpaste, despite the lack of abrasive silicas (it comprises only non-silica abrasives, in particular bamboo charcoal), has good cleaning properties, and instead of fluoride the function of a remineralizing substance is realized by hydroxyapatite in combination with sorbitol and xylitol. The invention is illustrated by an embodiment in the drawings, wherein Fig. 1 shows a comparative enamel shade guide and Fig. 2 shows photographs of the teeth before and after the application of the toothpaste according to the invention.

Preparation:

Place the components of phase A in the process tank and start the agitator. Keep mixing until the ingredients are dissolved (the phase should be clear)

Mix the B phase ingredients and then add to the A phase ingredients, mix and homogenize. Add Phase C ingredients successively to the machine while mixing. Then homogenize.

Mix the components of phase D and add to the previous phases. Then homogenize.

Weigh the ingredients separately. Just before feeding into the machine, combine the ingredients.

Finally, add the raw material below. Stir, homogenize. Vent the mass.

The physicochemical parameters of the obtained paste are presented in Table 1.

Table 1. Physicochemical parameters of toothpaste 10 g of toothpaste was taken into two colorless glass vessels with a metal spatula. One of the vessels was left at room temperature + 22 °C, while the other was incubated in an incubator at + 45 °C. The stability of both samples was assessed after 24 hours, after 2 weeks and after 2 months by visual observation and measurement of physicochemical parameters. The toothpaste showed no visual signs of instability. The paste stability control results are shown in Table 2.

Table 2. Toothpaste stability study

* (+) - correct appearance, (+/-) - disturbing appearance, (-) - incorrect appearance

The tube with the paste was placed in an incubator at a temperature of + 40 °C, and then, after 24 hours, the sample was incubated at -18 ° C (1 cycle). Compatibility of the mass with the packaging was assessed after each cycle by visual observation of the tube for deformation, leakage and delamination of the packaging. After the third cycle, a visual observation of the mass in the tube was made, assessing the appearance, color and smell of the product. Table 3. Assessment of mass compatibility with packaging

Challenge test

The conservation effectiveness studies were carried out in accordance with the requirements of the Polish Pharmacopoeia, ed. X volume I (2014) p. 5.1.3. The results of the analysis are provided in Table 4.

Table 4

Application and apparatus study A total of 20 people aged 24 to 70 participated in toothpaste application studies.

An interview was conducted with each participant, which showed that 8 people had a tendency to gum bleeding, 14 people had plaque formation, and all had an altered tooth color with yellowish or gray discoloration.

Based on the interviews and individual assessments, it was found that 80% of respondents assessed that the cleaning properties (removal of tooth plaque) of the toothpaste were highly evident/evident, while for the remaining 20% of respondents the cleaning properties were average/typical for this type of product.

In the opinion of 95% of the probands, the tested toothpaste ensured proper oral hygiene without damaging the enamel and irritating the gums.

Simultaneously with the application studies, apparatus study was carried out on 10 people to confirm the whitening effect of the tested toothpaste. After 3 weeks of its regular use, the spectrophotometrically measured value of "L" increased in all probands, which proves that the teeth are whitened.

Teeth whiteness was measured using a Konica Minolta 600D spectrophotometer. The results of measurements of the "L" parameter informing about the brightening of the tooth color are presented in Table 5.

Table 5. Comparison of the "L" parameter before and after3 weeks of regular use of the paste increasing the measured values proves a improvement of measured parameter (teeth whitening). The whitening effect was also confirmed in a visual examination, which consisted in assessment of the color of the tooth enamel before and after the period of regular use of the toothpaste. The color of the teeth was lightened on average from 1 to 2 shades according to the A-D Shade Guide (Fig. 1). The shade guide divides the colors into four basic groups: A, B, C and D and the group of bleached BL teeth. The results of the comparison are shown in Table 6.

Table 6. Comparison of tooth shade according to the A-D Shade Guide before and after 3 weeks of regular toothpaste use. In order to illustrate the effect of the whitening toothpaste, pictures of the teeth were taken before starting the use of the toothpaste and after 2 weeks of using the product, (fig. 2).