Powder and process for cleaning teeth by use of such powder

Abstract

The invention relates to a powder for use in a powder jet device for cleaning teeth, wherein the powder comprises granules having an average particle size of 20 μm to 220 μm and the granules comprise primary particles and a binder, wherein the primary particles have an average particle size smaller than the average particle size of the granules. The invention also relates to a process for preparing the powder and the use of the powder for cleaning teeth.

Claims

1. Powder for use in a powder jet device for cleaning a tooth surface by powder spraying, the powder comprising: granules having an average particle size of 20 pm to 220 pm; wherein the granules comprise primary particles and a binder; and wherein the primary particles have an average particle size smaller than an average particle size of the granules.

2. The powder according to claim 1, wherein the average particle size of the granules is 25 pm to 150 pm.

3. The powder according to claim 1, wherein the binder is a dietary fibre, a polysaccharide, a synthetic polymer, a salt, a sugar, an amino acid, the same material as the material of the primary particles, or mixtures thereof.

4. The powder according to claim 1, wherein the binder is made of a material selected from the group consisting of cellulose, hemicellulose, methyl cellulose, cellulose derivatives, maltodextrins, corn dextrins, gum arabic, gum xanthane, guar gum and mixtures thereof.

5. The powder according to claim 1, wherein the granules comprise 80-99.5% by weight of the particles and 0.5-20% by weight of the binder.

6. The powder according to claim 1, wherein the average particle size of the primary particles is 5 pm to 40 pm.

7. The powder according to claim 1, wherein the granules break during powder spraying into fragments.

8. The powder according to claim 7, wherein the powder after the breaking has an average particle size of 10 pm to 75 pm.

9. The powder according to claim 1, wherein the size reduction in a powder jet device, defined by (1-(d.sub.50 after nozzle/d.sub.50 at 0.5bar))x100%, is at least 20%.

10. The powder according to claim 1, wherein the primary particles are made of a material selected from the group consisting of organic salts, inorganic salts, sugars, amino acids, alditols, and mixtures thereof.

11. The powder according to claim 1, wherein the primary particles are made of a material selected from the group consisting of sodium hydrogen carbonate, mannitol, erythritol, glycine, trehalose, tagatose, and mixtures thereof.

12. Process for cleaning teeth, wherein the powder according to claim 1 is sprayed through a nozzle onto a tooth surface together with a gaseous carrier medium.

13. The process according to claim 12, wherein the granules break in the nozzle or when hitting the tooth surface.

14. (canceled)

15. Process for preparing a powder according to claim 1, comprising the steps that a binder is mixed with water, the resulting mixture is sprayed onto the primary particles and the particles are dried to form the granules.

Description

EXAMPLES

[0031] The following examples provide preferred powders according to the invention. Example 1

[0032] Erythritol granulated with Nutriose®

[0033] The experiment was carried out in a pilot batch fluidized bed of conical shape. Initial particle mass 1 kg, inlet air temperature 80 ° C., liquid feed rate 10 ml min.sup.-1 and relative air spraying pressure 1.5 bar were chosen as process parameters. A solution of 5% Nutriose® was sprayed for 20 min. During the experiment, all process parameters (air inlet temperature, air flow rate, liquid feed rate and spraying pressure) were kept constant. At the end of the experiment the granulated powder was removed and the solid content checked to be more than 98%.

[0034] Example 2

[0035] Erythritol granulated with Cellulose

[0036] The experiment was carried out in a pilot batch fluidized bed of conical shape. Initial particle mass 1 kg, inlet air temperature 80 ° C., liquid feed rate 8.6 ml min.sup.-1 and relative air spraying pressure 1.5 bar were chosen as process parameters. A solution of 7% Methyl cellulose was sprayed for 15 min. During the experiment, all process parameters (air inlet temperature, air flow rate, liquid feed rate and spraying pressure) were kept constant. At the end of the experiment the granulated powder was removed and the solid content checked to be more than 98%.

[0037] Example 3

[0038] Erythritol granulated with Maltodextrin

[0039] The experiment was carried out in a pilot batch fluidized bed of conical shape. Initial particle mass 1 kg, inlet air temperature 80 ° C., liquid feed rate 10 ml min.sup.-1 and relative air spraying pressure 1.5 bar were chosen as process parameters. A solution of 20% Maltodextrin was sprayed for 20 min. During the experiment, all process parameters (air inlet temperature, air flow rate, liquid feed rate and spraying pressure) were kept constant. At the end of the experiment the granulated powder was removed and the solid content checked to be more than 98%.

[0040] Example 4

[0041] Erythritol granulated with Gum Arabic

[0042] The experiment was carried out in a pilot batch fluidized bed of conical shape. Initial particle mass 1 kg, inlet air temperature 80 ° C., liquid feed rate 7 ml min.sup.-1 and relative air spraying pressure 1.5 bar were chosen as process parameters. A solution of 1% Gum arabic was sprayed for 30 min. During the experiment, all process parameters (air inlet temperature, air flow rate, liquid feed rate and spraying pressure) were kept constant. At the end of the experiment the granulated powder was removed and the solid content checked to be more than 98%.

[0043] Example 5

[0044] Abrasiveness on Aluminium surface

[0045] Abrasiveness is tested by projecting powder with a nozzle directly on a surface at 45° and 2mm of projected distance using an EMS Airflow® prophylaxis master device. This surface is made of pure aluminium (99.5%). The application time is 30 seconds. The plate is put on an elevator to reach the distance of 2 mm. The nozzle is fixed in a resin mould in order to fix well the nozzle position. The mass is known by weighing the powder chamber before and after the test. Every measurement is repeated at least three times. The depth of the holes was measured by a laser profilometer.

[0046] Measurement of average particle sizes and size reduction

[0047] To measure the size reduction there are two possibilities: [0048] 1) To measure the average particle size of the powder with a laser diffraction unit, of a Malvern Mastersizer with Scirocco dispersing unit, at 0.5 bar and 1.5 bar. Here the size reduction can be defined as: (1-(d.sub.50 at 1.5bar/d.sub.50 at 0.5bar))x100% [0049] 2) To measure the average particle size of the powder in a Malvern Mastersizer with Scirocco dispersing unit at 0.5 bar (average granule size) and to measure the average particle size after the nozzle of a powder jet device by spraying the powder directly in the laser diffraction unit using an air polishing device such as EMS Airflow® prophylaxis master at maximum pressure (average particle size after nozzle). Here the size reduction can be defined as (1-(d.sub.50 after nozzle/d.sub.50 at 0.5bar))x100%.

[0050] The size reduction of the powder according to the invention, defined by (1-(d.sub.50 after nozzle/d.sub.50 at 0.5bar))x100%, is preferably at least 20%, more preferably at least 30%, even more preferably at least 35% and most preferably 35 to 75%. The size reduction of the powder according to the invention, defined by (1-(d.sub.50 at 1.5bar/d.sub.50 at 0.5bar))x100%, is preferably at least 20%, more preferably at least 30%, most preferably 30 to 70%.

[0051] Table 1 shows the trend of average particle size of three different powders, in accordance with Examples 1 to 3, in function of the dispersing pressure of a laser diffraction measurement unit. The average particle size at 0.5 bar is the average particle size of the granules.

TABLE-US-00001 TABLE 1 Average particle size (μm) in function of the dispersing pressure Erythritol Erythritol Erythritol granulated with granulated with granulated with Nutriose ® cellulose maltodextrin d.sub.50 at P = 0.5 Bar 91.8 μm 143.0 μm  150.4 μm d.sub.50 at P = 1.0 Bar 71.3 μm 92.3 μm 110.5 μm d.sub.50 at P = 1.5 Bar 61.5 μm 85.9 μm 101.9 μm d.sub.50 at P = 2.5 Bar 38.8 μm 65.0 μm  78.4 μm

[0052] The invention is described further below with reference to FIGS. 1 and 2 (FIGS. 1 and 2).

[0053] FIG. 1 shows the average particle sizes before the nozzle (average granule sizes d.sub.50,g) and the average particle sizes after the nozzle (average particle sizes after breaking d.sub.50,p-b) of three different powders (erythritol granulated with Nutriose®, cellulose, and maltodextrin) in accordance with Examples 1 to 3 when using them in an Airflow® prophylaxis master. The average particle sizes before the nozzle are about 90 μm to 150 μm and average particle sizes after breaking are about 45 μm to 70 μm.

[0054] FIG. 2 shows the abrasiveness on an aluminium surface in accordance with Example 5. The abrasiveness on an aluminium surface of the two different powders in accordance with the invention (erythritol granulated with Nutriose® and Gum Arabic) are compared with erythritol particles without binder. The abrasiveness of the powders according to the invention is significantly lower than the abrasiveness of erythritol primary particles, i.e. erythritol particles without binder.

[0055] It has been demonstrated that the powders according to the invention have average granule sizes sufficiently high to avoid the handling difficulties of small particles and simultaneously provide particle sizes at the tooth surface that allow a gentle and efficient cleaning of teeth, including cleaning subgingival tooth surfaces.