Composition for air-polishing the surface of hard dental tissues

Abstract

The present invention relates to a composition (1) for air-polishing the surface of hard dental tissues, comprising at least: a first abrasive powder capable of polishing hard dental tissues, the first powder being present in the composition in a weight content of between 90% and 99.5%, and a second powder of at least one anti-caking agent, different from the first powder, comprising at least one sodium stearyl fumarate powder present, in the composition, in a weight content of between 0.5% and 5% and having a particle size D50 of between 5 μm and 200 μm, for example between 10 μm and 80 μm, at least 50% of the constituent particles of the second powder having a smallest dimension greater than 100 nm.

Description

Description Title of the invention: Composition for the air polishing of the surface of hard dental tissues Technical Field

[0001] The invention relates to a new composition for air polishing the surface of hard dental tissues and its use in an air polishing process. Previous technique

[0002] Powders intended for air polishing of teeth are generally based on glycine, erythritol, calcium carbonate, or sodium bicarbonate. In particular, an erythritol-based powder developed by EMS and available under the name "Perio Plus" is known for subgingival and supragingival use, and a sodium bicarbonate-based powder marketed by SATELEC under the name "Air'n'go Classic" is also known for supragingival use. Other known products include US 2018 / 0221260, which describes a product containing an abrasive agent for cleaning teeth; US 2015 / 125814, which describes compositions for air polishing the surface of hard dental tissues; and the publication by Khalefa et al., "Effects of air-polishing devices with different abrasives on bovine primary and second teeth and deciduous human teeth" (J Orofac Orthop 2013; 74:370-380; DOI 10.1007 / s00056-013-0168-6).

[0003] It is nevertheless desirable to improve existing air polishing treatments by reducing the projection of powder into the air during the treatment, so as to, on the one hand, reduce exposure to fine particles and, on the other hand, reduce the soiling generated by these suspended particles, while maintaining a formulation that flows. Description of the invention

[0004] The present invention relates to a composition for air-polishing the surface of hard dental tissues, comprising at least: - a first abrasive powder suitable for polishing hard dental tissues and having a D50 particle size between 5 µm and 150 µm, the first powder being present in the composition at a mass content between 90% and 99.5%, and - a second powder containing at least one anti-caking agent, different from the first powder, comprising at least one sodium stearyl fumarate powder present, in the composition, in a mass content between 0.5% and 5% and having a D50 particle size between 5 pm and 200 pm, for example between 10 pm and 80 pm, at least 50% of the constituent particles of the composition having a smallest dimension greater than 100 nm.

[0005] Hard dental tissues refer to enamel, dentin, and cementum.

[0006] Unless otherwise specified, D50 particle size refers to the size determined by the statistical particle size distribution at half the population. Generally, the particle size of each powder can be measured using a laser particle size analyzer such as the "Mastersizer 2000" sold by Malvern. The smallest particle size can be measured by scanning electron microscopy.

[0007] The invention is based on the choice of a composition in which the particles have a non-nanometric size. The invention thus differs from prior art solutions using a nanoparticulate anti-caking agent by producing a reduced generation of nanoparticles, thereby decreasing the risk of inhalation and reducing soiling during the procedure. The composition advantageously exhibits a mass fraction of respirable dust less than 500 mg / kg and a respirable particle emission rate of less than 60,000 / mg·s, these parameters being measured in accordance with standard EN 17199-5:2019 published in March 2019. Furthermore, the inventors have observed that the specific choice of the second powder according to the invention allows for a formula that flows without forming deposits in the solution, thus reducing the risk of causing discomfort to the patient during treatment.

[0008] In one example embodiment, sodium stearyl fumarate powder is present in the composition in a mass content of between 0.5% and 2%.

[0009] This characteristic advantageously facilitates the flow of the composition even further.

[0010] In one embodiment, sodium stearyl fumarate powder has a D90 particle size between 50 pm and 300 pm.

[0011] Unless otherwise stated, D90 particle size refers to the size given by the statistical particle size distribution at 90% of the population.

[0012] In one embodiment, the second powder further comprises a tricalcium phosphate powder present in the composition in a mass content of between 0.5% and 6% and having a D50 particle size of between 5 pm and 200 pm, for example between 5 pm and 60 pm.

[0013] This characteristic advantageously facilitates the flow of the composition even further.

[0014] In particular, tricalcium phosphate powder can have a D90 particle size between 40 pm and 100 pm.

[0015] According to one example, the second powder essentially comprises, or is made up of, sodium stearyl fumarate powder.

[0016] According to another example, the second powder essentially comprises, or is made up of, sodium stearyl fumarate powder mixed with tricalcium phosphate powder.

[0017] The abrasive particles of the first powder may have a Mohs hardness greater than or equal to 1, preferably between 1 and 5, preferably still between 1 and 3.

[0018] In one embodiment, the first powder comprises at least one of the following compounds: sodium bicarbonate, isomalt, calcium carbonate, glycine, a silicate, erythritol, or a mixture of these compounds. In particular, the first powder may comprise at least one of the following compounds: sodium bicarbonate, isomalt, or a mixture of these compounds.

[0019] For example, the first powder essentially comprises, or is made up of, at least one of the following compounds: sodium bicarbonate, isomalt, calcium carbonate, glycine, a silicate, erythritol, or a mixture of these compounds. In particular, the first powder may essentially comprise, or be made up of, at least one of the following compounds: sodium bicarbonate, isomalt, or a mixture of these compounds. More specifically, the first powder may essentially comprise, or be made up of, sodium bicarbonate or isomalt.

[0020] In one embodiment example, the first powder has a D50 particle size between 5 pm and 500 pm, for example between 10 pm and 80 pm.

[0021] In one embodiment example, the first powder has a D90 particle size between 50 pm and 300 pm.

[0022] In an example of a finished product, the composition includes: - the first powder, which essentially comprises, or is made up of, sodium bicarbonate, the first powder being present in the composition at a mass content of between 90% and 99.5%, and - the second powder which essentially comprises, or is made up of, a mixture of (i) sodium stearyl fumarate powder present, in the composition, in a (ii) tricalcium phosphate powder present in the composition in a mass content of between 0.5% and 5%, and (ii) tricalcium phosphate powder present in the composition in a mass content of between 0.5% and 6%.

[0023] According to one variant, the composition includes: - the first powder which essentially comprises, or is even made up of, isomalt, the first powder being present in the composition at a mass content of between 90% and 99.5%, and - the second powder which essentially comprises, or is made up of, sodium stearyl fumarate powder present in the composition in a mass content of between 0.5% and 5%.

[0024] In one embodiment, the composition further comprises a third powder of a desensitizing agent, different from the first and second powders.

[0025] The desensitizing agent can be chosen from sodium fluoride, potassium nitrate, oxalic acid, stannous fluoride or mixtures thereof.

[0026] The D50 particle size of the third powder can be between 0.5 pm and 500 pm.

[0027] The composition can be obtained by co-milling the constituent materials of the first and second powders to achieve the desired particle size. This co-milling process employs techniques that are well-established.

[0028] The present invention also relates to a dental air polishing tool comprising a nozzle and a reservoir comprising a composition as described above, the nozzle being configured to project said composition under pressure surrounded by a jet of liquid.

[0029] The present invention also relates to a composition as described above for the implementation of air polishing of hard dental tissues.

[0030] In this case, during air polishing, the composition surrounded by a jet of liquid is projected under pressure onto the fabric through a nozzle of an air polishing tool.

[0031] The present invention also relates to a method of air polishing a hard dental tissue, comprising the projection under pressure, onto said tissue, of the composition described above surrounded by a jet of liquid through a nozzle of an air polishing tool. Brief description of the drawings [Fig. 1] Figure 1 schematically illustrates an example of a dental treatment process implementing a composition according to the invention. [Fig. 2] Figure 2 represents a particle size distribution curve of a first example of composition according to the invention. [Fig. 3] Figure 3 represents a particle size distribution curve of a second example of composition according to the invention. [Fig. 4] Figure 4 schematically represents the test bench used for characterizing the powderiness of different compositions. Description of the implementation methods

[0032] The invention is now described by means of figures, which are provided for descriptive purposes to illustrate certain embodiments of the invention and which should not be interpreted as limiting the latter.

[0033] Figure 1 illustrates a process according to the invention in which the air polishing of a tooth D is carried out using a composition according to the invention. In the illustrated example, tooth D is an incisor. Of course, the process remains within the scope of the invention when another type of tooth is treated. The tooth D to be treated has on its surface a deposit of a substance S to be removed, such as a dental plaque deposit.

[0034] The dental air polishing tool 10 is used to project the air polishing composition 1 under pressure through the nozzle 11 of the tool 10. More specifically, the jet of composition 1 and a cone of liquid 15 surrounding this jet 1 are projected through the nozzle 11. The liquid 15 can, for example, be water. An example of a usable air polishing tool 10 is the air polisher marketed under the reference AIR-N-GO® by the company ACTEON. The projected composition 1 is as described above.

[0035] The impact of the composition 1 projected onto tooth D cleans the surface of tooth D and removes the deposit S. The nozzle 11 is located at a relatively short distance dl from the tooth D to be treated. Therefore, the jet of composition 1 impacts tooth D with a relatively high pressure, which removes the deposit S present on tooth D. The distance dl is, for example, less than or equal to 0.5 cm. The treatment of a tooth can, for example, last at least one second, and for example, approximately three seconds. In the example illustrated in Figure 1, the treated portion of the tooth is located above the gum: this is a supragingival dental treatment method, but the invention remains within the scope of the invention if the composition is used in a subgingival procedure.

[0036] Examples

[0037] A first air-polishing composition according to the invention, having the formulation detailed in Table 1 below, has been prepared. This composition is designated "composition A".

[0039] Composition A was obtained by inversion for 10 minutes at 10 rpm to homogenize the powder, followed by grinding to coat the sodium bicarbonate with the anti-caking agents (sodium stearyl fumarate and tricalcium phosphate). Grinding was carried out at 7000 rpm using a hammer mill equipped with an 800 µm screen. The final product was obtained by mixing for 20 minutes at 10 rpm. The particle size distribution curve of the resulting composition A is shown in Figure 2.

[0040] A second air-polishing composition according to the invention, having the formulation detailed in Table 2 below, was prepared. This composition is denoted "Composition B".

[0041] [Table 2]

[0042] Composition B was obtained by inversion for 10 minutes at 10 rpm to homogenize the powder, followed by co-milling to coat the isomalt with the anti-caking agent (sodium stearyl fumarate). Milling was carried out at 6000 rpm using a hammer mill equipped with a 200 µm screen. The final product was obtained by mixing for 20 minutes at 10 rpm. The particle size distribution curve of the resulting composition B is shown in Figure 3.

[0043] A third air-polishing composition, outside the scope of this invention, corresponding to the commercial Air Flow® Classic Neutral powder marketed by EMS, was tested. This composition is designated "composition C".

[0044] The powderiness of compositions A to C was characterized following the recommendations given in standard EN 17199-1:2019 "Workplace exposure - Measurement of the resuspension power of bulk materials containing or emitting of nano-objects and their aggregates and agglomerates (NOAA) or other particles in the alveolar fraction - Part 1: Requirements and choice of test methods" and more specifically by the method involving the vortex shaker (standard EN 17199-5:2019). In accordance with this standard, the following parameters were determined: - the mass fraction of respirable dust (mg / kg), determined by gravimetric analysis, and - the index of resuspension power in number of alveolar particles (1 / mg) and the emission rate in number (1 / mg. s), determined by measurements carried out using a Condensation Particle Counter (CPC).

[0045] For each composition, three 0.5 cm samples 3 were carried out in the bulk material. Before each test, these samples were conditioned for 24 hours in terms of temperature and relative humidity at 21°C ± 3°C and 50% ± 5% respectively.

[0046] The tests were carried out at 21°C ± 3°C and 50% ± 5% respectively in terms of temperature and relative humidity.

[0047] Figure 4 shows the schematic diagram of the experimental setup of test bench 2 using the vortex agitator 3 implemented for the characterization of powderiness. The test bench consists of a cylindrical container 5 containing a small volume (0.5 cm³) 3A sample E is subjected to continuous agitation in a circular orbital motion generated by the vortex shaker apparatus. Filtered air AF, maintained at a relative humidity of 50% ± 5%, passes through container 5 to transfer the aerosol released inside the container to a sampling and measurement section SPM. The AF air is obtained from dry air A, the flow rate of which is calibrated by a flow regulator 7. This air passes through a humidification system 9 and then a filter 12. Opening valve 13 allows the flow of AF air to the container. Valves 16 and 17 are opened to allow flow to the SPM section.

[0048] The SPM section is coupled to a stainless steel cyclone designed to collect the respirable aerosol fraction. An air sampling cassette containing a pre-weighed filter was used for gravimetric analysis. Downstream, a pump and a mass flow regulator control the flow rate through this cyclone. The respirable dust mass fraction obtained using the vortex shaker method was calculated. r ,vs, expressed in mg / kg, is calculated according to the following equation:

[0049] [Math.l]

[0050] With Arrif the mass collected by the filter in the alveolar fraction cyclone and mo the mass of the sample for testing.

[0051] The SPM section is coupled to an aerosol flow distributor, enabling real-time number concentration measurement with a condensation nucleus particle (CPC) counter. The resuspension power index (SPI) and the number emission rate (NER) were calculated over a 65-second period during which the concentration begins to rise from the background concentration (ti) after the vortex mixer starts to rotate.

[0052] The resuspension power index, expressed as the number of alveolar particles (Ivs) and the number of particles per milligram (1 / mg), is calculated by dividing the number of particles emitted during the first 65 seconds of the test by the mass m ti of powder placed in the test apparatus, such as:

[0053] [Math. 2]

[0054] With Ccpc(t) the concentration in number of particles per cubic centimeter (1 / cm³) 3) measured by the CPC at time t, Qvs the flow rate in the cylindrical tube during the test (in L / minute) and At C pc is the CPC time step, expressed in seconds.

[0055] The emission rate in number Evs of alveolar particles, expressed as the number of particles per milligram per second (1 / mg.s), is calculated by dividing the number of particles emitted per second during the entire test by the mass m ti of powder placed in the test apparatus, such as:

[0056] [Math.3]

[0057] The apparent density of the sample (p s ), expressed in g / cm² 3 is calculated such that:

[0058] [Math.4]

[0059] With m E ,o and m E ,2 the masses of the filled and clean container respectively and V E the volume of the test sample, namely 0.5 cm 3 .

[0060] Table 3 below presents the results obtained for the samples evaluated. The associated uncertainties correspond to the standard deviations calculated on the basis of three samples.

[0061] [Table 3]

[0062] Each of compositions A and B according to the invention has a limited mass fraction of respirable dust, less than 500 mg / kg, and significantly lower than that of composition C, which uses a nanoparticulate anti-caking agent. The compositions according to the invention thus present a greatly reduced inhalation hazard.

[0063] Furthermore, each of compositions A and B according to the invention exhibits a reduced emission rate of alveolar particles, less than 60,000 / mg.s, compared to that of composition C, which uses a nanoparticulate anti-caking agent. The compositions according to the invention thus exhibit reduced nanoparticle generation.

[0064] Further experimentation was carried out in comparison to a composition outside the scope of this invention, which also uses a non-nanomaterial composition but with an anti-caking agent (magnesium stearate and tricalcium phosphate) distinct from sodium stearyl fumarate. The formulation of this comparative composition is provided in Table 4 below.

[0065] The comparative composition was obtained by inversion for 20 minutes at 10 rpm to homogenize the powder, followed by grinding to coat the sodium bicarbonate with anti-caking agents (magnesium stearate and tricalcium phosphate). Grinding was carried out at 7000 rpm with a hammer mill equipped with an 800 µm screen. The final product was obtained by mixing for 40 minutes at 10 rpm. The comparative composition flows well but, compared to the compositions according to the invention, has the disadvantage of forming deposits in solution, which can be bothersome to the patient by, for example, creating a pasty film in the mouth.

[0066] The inventors have produced another air-polishing composition according to the invention, having the formulation detailed in Table 5 below. This composition is designated "composition D".

[0067] [Table 5]

[0068] Composition D was obtained in the following manner: - Incorporation of glycine and sodium stearyl fumarate in a bottle, then placement in a vat within a cubic mixer from Erweka GmbH, - Mix for 20 to 160 minutes 1 , - sieving under 200 µm, and - Mix for 20 to 160 minutes 1 .

[0069] The resulting mixture was white and visually homogeneous, with the presence of some non-cohesive agglomerates.

[0070] The powder was well suspended, and good abrasion quality was achieved. The D50 size of the glycine was 82.3 µm, and that of the composition was 75 µm. The flowability of the composition was good, and it generated a reduced amount of nanoparticles.

[0071] The expression "between ... and ..." should be understood as including the boundaries.

Claims

Demands

1. Composition (1) for air polishing the surface of hard dental tissues (D), comprising at least: - a first abrasive powder suitable for polishing hard dental tissues and having a D50 particle size between 5 µm and 150 µm, the first powder being present in the composition at a mass content between 90% and 99.5%, the first powder comprising at least one of the following compounds: sodium bicarbonate, isomalt, calcium carbonate, glycine, a silicate, erythritol, or a mixture of these compounds, and - a second powder of at least one anti-caking agent, different from the first powder, comprising at least one sodium stearyl fumarate powder present in the composition in a mass content of between 0.5% and 5% and having a D50 particle size of between 5 pm and 200 pm, for example between 10 pm and 80 pm, at least 50% of the constituent particles of the composition having a smallest dimension greater than 100 nm.

2. Composition (1) according to claim 1, wherein sodium stearyl fumarate powder is present in the composition in a mass content of between 0.5% and 2%.

3. Composition (1) according to claim 1 or 2, wherein the sodium stearyl fumarate powder has a D90 particle size between 50 pm and 300 pm.

4. Composition (1) according to any one of claims 1 to 3, wherein the second powder further comprises a tricalcium phosphate powder present in the composition in a mass content of between 0.5% and 6% and having a D50 particle size of between 5 pm and 200 pm, for example between 5 pm and 60 pm.

5. Composition (1) according to claim 4, wherein the tricalcium phosphate powder has a D90 particle size between 40 pm and 100 pm.

6. Composition (1) according to any one of claims 1 to 5, wherein the first powder comprises at least one of the following compounds: sodium bicarbonate, isomalt, or a mixture of these compounds.

7. Composition (1) according to any one of claims 1 to 6, wherein the first powder has a D50 particle size between 10 pm and 80 pm.

8. Composition (1) according to any one of claims 1 to 7, wherein the first powder has a D90 particle size between 50 pm and 300 pm.

9. Composition (1) according to any one of claims 1 to 8, wherein the composition comprises: - the first powder, which essentially comprises sodium bicarbonate, the first powder being present in the composition at a mass content of between 90% and 99.5%, and - the second powder which essentially comprises a mixture of (i) sodium stearyl fumarate powder present in the composition in a mass content of between 0.5% and 5%, and (ii) tricalcium phosphate powder present in the composition in a mass content of between 0.5% and 6%.

10. Composition (1) according to any one of claims 1 to 8, wherein the composition comprises: - the first powder, which essentially comprises isomalt, the first powder being present in the composition at a mass content of between 90% and 99.5%, and - the second powder which essentially comprises sodium stearyl fumarate powder present in the composition in a mass content of between 0.5% and 5%.

11. Composition (1) according to any one of claims 1 to 10, wherein the composition further comprises a third powder of a desensitizing agent, different from the first and second powders.

12. A dental air polishing tool (10) comprising a nozzle (11) and a reservoir comprising a composition (1) according to any one of the claims 1 to 11, the nozzle being configured to project under pressure said composition surrounded by a jet of liquid (15).

13. Composition (1) according to any one of claims 1 to 11 for the implementation of air polishing of hard dental tissues.

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