Field of application of the invention

The present invention applies to the oral hygiene industry. Namely, the present invention relates to brushes, having reduced dimensions, usable by a person to clean his/her teeth and gums. Brushes of this type are commonly called "toothbrushes".

As is known, toothbrushes generally comprise an elongated handle at which a brush is grippable by a person, and a "brushing head" connected to the handle by a stem and including a plurality of bristles for brushing teeth and gums. Toothbrushes substantially may be of two categories: "manual", in which the brushing head is exclusively moved by the person holding the brush, and "electric" or "oscillating", that is including, in the handle, an electric motor connected to the brushing head and adapted to rotate the bristles in oscillating manner around an axis which generally is parallel to the direction in which the bristles extend.

The present invention relates to an electric toothbrush comprising three brushing heads.

Overview of the background art

As mentioned above, the current electric toothbrushes comprise a brushing head which rotates in oscillating manner. The brushing head is substantially cylindrical and the axis around which the head rotates generally coincides with the axis of the cylinder, as the brushing head substantially is shaped. The current electric toothbrushes have a shape such that brushing the lingual surface (that is, facing the tongue) and the vestibular surface (that is, facing the wall of the oral cavity) of the molars and premolars generally is difficult and consequently not very efficient for the purposes of teeth cleaning.

Purposes of the invention

It is the object of the present invention to overcome the aforesaid drawbacks by indicating an electric toothbrush which allows the lingual and vestibular surface of the teeth, especially of the molars and premolars, to be brushed more effectively.

Summary and advantages of the invention

The object of the present invention is a toothbrush comprising:

• a handle extending lengthwise and at which said toothbrush is grippable by a person to brush his/her teeth and/or gums, said handle including a first end and a second end, opposite to said first end, said handle, at said first end, being capable of resting on a surface directly and/or by means of a support, it also being capable of resting on a surface, if said handle can be rested on a surface by means of said support:

- said handle being capable of resting on said support when the latter is resting on a surface and

- said toothbrush comprising said support;

• a stem extending lengthwise, said stem extending lengthwise at least partially along a specific direction, said shaft including a first end and a second end, opposite to said first end of said stem, said stem, at the first end thereof, being connected to said handle at said second end of the latter;

• a first brushing head including a first base and a first plurality of bristles, each bristle of said first plurality comprising a first end and a second end, opposite to said first end of said bristle, each bristle of said first plurality being connected to said first base at the first end thereof, said first brushing head, at said first base, being connected to said stem at said second end of the latter, said first brushing head being connected to said stem so that said first base, together with the bristles of said first plurality, are rotatable around a first rotation axis, said first rotation axis crossing said first base and not being parallel to said direction along which said stem at least partially extends;

• an electrically powerable actuator at least partially accommodated in said handle, said actuator including a shaft adapted to rotate around an axis thereof when activating said actuator;

• an electric accumulator electrically connected to said actuator to power the latter, said accumulator being at least partially accommodated in said handle;

• control means adapted to activate said actuator, said actuator being operable by a person by means of said control means, said control means being at least partially located at said handle so that said actuator is operable by a person by means of said control means when said person grips said toothbrush at said handle;

• first transmission means adapted to transmit a rotary motion of said shaft from the latter to said first brushing head so that a rotation of said shaft around the axis thereof induces a rotation of said first base, together with the bristles of said first plurality, around said first rotation axis, in which, according to the invention, said toothbrush further comprises:

• a first arm including a first end and a second end, opposite to said first end of said first arm, said first arm, at the first end thereof, being connected to said handle or to said stem;

• a second brushing head including a second base and a second plurality of bristles, each bristle of said second plurality comprising a first end and a second end, opposite to said first end of said bristle, each bristle of said second plurality being connected to said second base at the first end thereof, said second brushing head, at said second base, being connected to said first arm at said second end of the latter, said second brushing head being connected to said first arm so that said second base, together with the bristles of said second plurality, are rotatable around a second rotation axis, said second rotation axis crossing said second base and not being parallel to said direction along which said stem at least partially extends, nor (being parallel) to said first rotation axis;

• second transmission means adapted to transmit a rotary motion of said shaft from the latter to said second brushing head so that a rotation of said shaft around the axis thereof induces a rotation of said second base, together with the bristles of said second plurality, around said second rotation axis;

• a second arm including a first end and a second end, opposite to said first end of said second arm, said second arm, at the first end thereof, being connected to said handle or to said stem;

• a third brushing head including a third base and a third plurality of bristles, each bristle of said third plurality comprising a first end and a second end, opposite to said first end of said bristle, each bristle of said third plurality being connected to said third base at the first end thereof, said third brushing head, at said third base, being connected to said second arm at said second end of the latter, said third brushing head being connected to said second arm so that said third base, together with the bristles of said third plurality, are rotatable around a third rotation axis, said third rotation axis crossing said third base and not being parallel to said direction along which said stem at least partially extends, nor (being parallel) to said first rotation axis;

• third transmission means adapted to transmit a rotary motion of said shaft from the latter to said third brushing head so that a rotation of said shaft around the axis thereof induces a rotation of said third base, together with the bristles of said third plurality, around said third rotation axis, said second and third brushing heads being opposed to each other at the bristles of said second and third pluralities, respectively, so that:

• said second brushing head faces said third brushing head at said second end of the bristles of said second plurality;

• said third brushing head faces said second brushing head at said second end of the bristles of said third plurality;

• the bristles of said second plurality are opposed to the bristles of said third plurality, the bristles of said second plurality being at such a distance from the bristles of said third plurality that a portion of space where a tooth of a person can be at least partially accommodated is interposed between the bristles of said second plurality and the bristles of said third plurality. The bristles of the second plurality therefore are not in contact with the bristles of said third plurality, said first brushing head, at the bristles of said first plurality, being opposed to said portion of space (interposed between the bristles of said second plurality and the bristles of said third plurality) so that said first brushing head faces said portion of space (interposed between the bristles of said second plurality and the bristles of said third plurality) at said second end of the bristles of said first plurality, said first rotation axis crossing said portion of space (interposed between the bristles of said second plurality and the bristles of said third plurality) so that a stretch of said first rotation axis is interposed between the bristles of said second plurality and the bristles of said third plurality, said first brushing head being opposed to said portion of space (interposed between the bristles of said second plurality and the bristles of said third plurality) so that if it were possible to translate said first brushing head along said first rotation axis, said first brushing head could be at least partially accommodated in said portion of space (interposed between the bristles of said second plurality and the bristles of said third plurality) and consequently, interposable between said second and third brushing heads, the bristles of said first plurality not being in contact with the bristles of said second plurality, nor (being in contact) with the bristles of said third plurality, said first, second and third brushing heads being shaped so as to be insertable into the mouth of a person.

The toothbrush of the invention, being provided with three brushing heads arranged as specified above, advantageously allows the lingual surface, the vestibular surface and the occlusal surface of the molars and premolars to be almost simultaneously brushed. Namely, by using the toothbrush of the invention, while the occlusal surface of a molar or a premolar is being brushed with the first brushing head, the second and third brushing heads brush the lingual surface and the vestibular surface of said tooth. This ensures more efficient brushing of the lingual or vestibular surface of a molar or a premolar with respect to the use of an electric toothbrush of the prior art.

Incidentally, the occlusal surface of a molar or a premolar of the lower arch is the upper surface of said tooth interposed between the lingual and vestibular surfaces thereof. Similarly, the occlusal surface of a molar or a premolar of the upper arch is the lower surface of said tooth interposed between the lingual and vestibular surfaces thereof.

Other innovative features of the present invention are illustrated in the description below and mentioned in the dependent claims.

According to an aspect of the invention, said first, second and third rotation axes are coplanar and incident in a single point.

According to this aspect of the invention, the lingual surface and the vestibular surface of a molar or a premolar are even more efficiently brushable.

According to another aspect of the invention, said second and third bases, and preferably said second and third brushing heads, are mutually symmetrical with respect to a symmetry plane including said first rotation axis.

Also, according to this aspect of the invention, the lingual surface and the vestibular surface of a molar or a premolar are even more efficiently brushable.

According to another aspect of the invention, said symmetry plane also includes said direction in which said stem at least partially extends lengthwise, said symmetry plane being arranged vertically when said handle, at said first end, is resting on a surface directly and/or by means of said support.

According to this aspect of the invention, the orientation of the second and third brushing heads with respect to the stem increases the brushing efficiency of the lingual surface and the vestibular surface of a molar or a premolar.

According to another aspect of the invention, said first and second rotation axes intersect so that the angle comprised between said first and second axes and crossing said first and second bases has an amplitude between 91 ° and 95°, said first and third rotation axes intersecting so that the angle comprised between said first and third axes and crossing said first and third bases has an amplitude between 91° and 95°.

Incidentally, an angle may cross one of the aforesaid bases since, by definition, it is a flat area between two half lines.

According to this aspect of the invention, in light of tests conducted by the Applicant, the inclination of the second and third rotation axes is optimal for the purposes of brushing the lingual surface and the vestibular surface of a molar or premolar.

According to another aspect of the invention, said first arm, at the first end thereof, is connected to said stem at said second end of the latter, said second arm, at the first end thereof, being connected to said stem at said second end of the latter.

According to this aspect of the invention, the overall dimensions of the assembly consisting of the stem and the first and second arms, are minimum. This advantageously facilitates the insertion of the three brushing heads into a person’s mouth.

According to another aspect of the invention, the bristles of said first plurality are, as a whole, substantially shaped as a cylinder having a base diameter between 5 mm and 7 mm, the bristles of said second plurality, as a whole, being substantially shaped as a cylinder having a base diameter between 5 mm and 7 mm, the bristles of said third plurality, as a whole, being substantially shaped as a cylinder having a base diameter between 5 mm and 7 mm. According to this aspect of the invention, in light of tests conducted by the Applicant, the dimensions of the bunch of bristles of each brushing head is optimal for the purposes of brushing the lingual surface and the vestibular surface of a molar or a premolar.

According to another aspect of the invention, said first rotation axis coincides with the longitudinal axis (that is, the axis of radial symmetry) of said cylinder, as the bristles, as a whole, of said first plurality substantially are shaped, said second rotation axis coinciding with the longitudinal axis of said cylinder, as the bristles as a whole of said second plurality substantially are shaped, said third rotation axis coinciding with the longitudinal axis of said cylinder, as the bristles as a whole of said third plurality substantially are shaped.

According to another aspect of the invention, the minimum distance between a point of the cylinder, as the bristles as a whole of said first plurality substantially are shaped and a point of the cylinder as the bristles, as a whole, of said second plurality substantially are shaped, is between 1 mm and 2 mm, the minimum distance between a point of the cylinder, as the bristles as a whole of said first plurality substantially are shaped and a point of the cylinder as the bristles, as a whole, of said third plurality substantially are shaped, is between 1 mm and 2 mm.

According to this aspect of the invention, in light of tests conducted by the Applicant, the distance between the bunches of bristles of the brushing heads is optimal for the purposes of brushing the lingual surface and the vestibular surface of a molar or a premolar.

According to another aspect of the invention, said first, second and third rotation axes are arranged horizontally when said handle, at said first end, is resting on a surface directly or by means of said support.

Brief description of the drawings

Further objects and advantages of the present invention will be apparent from the following detailed description of embodiments of the same and from the accompanying drawings, exclusively provided by way of non-limiting example, in which:

- Figure 1 shows a first perspective view of an electric toothbrush according to the present invention;

- Figure 2 shows a second perspective view of the toothbrush in Figure 1 ;

- Figure 3 shows a top plan view of the toothbrush in Figure 1 .

Detailed description of some preferred embodiments of the invention

Hereinafter in the present description, a figure may be illustrated also with reference to elements not expressly indicated therein but indicated in other figures instead. The scale and proportions of the various illustrated elements do not necessarily correspond to the real ones.

Figures 1 and 2 show an electric toothbrush 1 , the object of the invention, comprising a handle 2 extending lengthwise and at which toothbrush 1 is grippable by a person to brush his/her teeth and/or gums. Handle 2 includes a first end 3 and a second end 4, opposite to end 3. Handle 2 preferably substantially is cylindrical, with its (two) bases coincident with the ends 3 and 4, respectively. Handle 2 preferably is hollow and can be rested on a surface at base 3. When handle 2, and consequently toothbrush 1 , is resting on a surface at base 3 as shown in Figures 1 and 2, the longitudinal axis of the cylinder, as handle 2 substantially is shaped preferably is arranged vertically.

Handle 2 preferably has a plurality of protrusions protruding transversely from the side surface of the cylinder, as (handle 2) preferably substantially is shaped. Namely, handle 2 preferably comprises three protrusions 5, 6, and 7 which are longitudinally aligned starting from base 4 so as to form two recesses 8 and 9 interposed between the protrusions 5 and 6 and between the protrusions 6 and 7, respectively. With respect to the side surface of the cylinder, as handle 2 preferably substantially is shaped, the protrusions 5, 6 and 7 preferably have the same height (that is, they preferably protrude by the same entity from the aforesaid side surface). Handle 2 preferably comprises a fourth protrusion 10 transversely protruding from the side surface of the cylinder, as handle 2 preferably substantially is shaped, on the side opposite to recess 9. Protrusion 10 preferably is more extended (that is, wider) but not as high as protrusions 5, 6 and 7. Handle 2 is grippable by a person by placing the thenar eminence at protrusion 10, close to base 3, and opposing the index, middle, ring and little fingers at the protrusions 5, 6 and 7. Handle 2 preferably accommodates therein an electrically powerable actuator comprising a shaft adapted to rotate around the axis thereof when activating the actuator. The latter is accommodated in handle 2 preferably so that the shaft is arranged parallel to this longitudinal axis of the cylinder, as handle 2 preferably substantially is shaped. The actuator is powered by an electric accumulator also preferably accommodated in handle 2. The accumulator preferably can be charged by connecting the same to the power grid. For this purpose, handle 2 could comprise an electric socket at base 3, which electric socket is couplable to an electric plug electrically connected to a suitable transformer connectable to the power grid. The charging method of the electric accumulator of an electric toothbrush herein described is known. Therefore, no further details will be provided. Alternative to the foregoing, the electric accumulator can be charged by electromagnetic induction, that is by providing a suitable coupling between an electromagnetic field emitter preferably connectable to the power grid and a receiver connected to the accumulator of toothbrush 1 and adapted to convert the electromagnetic field induced by the emitter into electric current. Also, the charging method of the electric accumulator of an electric toothbrush by electromagnetic induction is known. Therefore, no further details will be provided.

Should the electric accumulator of toothbrush 1 be chargeable by electromagnetic induction, the aforesaid receiver preferably is accommodated in handle 2 close to base 3, and the aforesaid emitter preferably is accommodated in a support which can be rested on a surface. Additionally, or alternative to being capable of resting on a surface "directly" at base 3, toothbrush 1 can be rested on a surface at base 3 by means of the aforesaid support. Namely, handle 2, and consequently toothbrush 1 , can be rested on the aforesaid support when the latter is resting on a surface. When handle 2 is resting on the aforesaid support at base 3, the emitter is electromagnetically coupled to the receiver and the accumulator can be charged by electromagnetic induction.

As shown in Figure 1 , handle 2 preferably comprises a button 11 close to base 4, preferably opposite to protrusion 5 and longitudinally aligned with protrusion 10. In other words, when toothbrush 1 is resting on a surface or on the above- mentioned support, button 11 is placed above protrusion 10. Button 11 is com- prised in the above-mentioned "control means" and can be pressed by a person to activate the actuator of toothbrush 1. Namely, button 11 can be pressed by a person with the tip of his/her thumb while gripping the toothbrush 1 at handle 2. Incidentally, the activation of the actuator is reversible. Once activated, the actuator is thus de-activatable, for example by pressing button 11 again and activatable again, for example, by pressing button 11 again. The activation of the electric motor of an electric toothbrush by means of a button placed at the handle of the toothbrush is known. Therefore, no further details will be provided.

Handle 2 has a height (corresponding to the distance between the bases 3 and 4) preferably of 11 cm and has a maximum width (corresponding to the maximum distance calculated on a plane arranged horizontally when toothbrush 1 is resting on a surface or on the aforesaid support at base 3, between two points of the side surface of handle 2) preferably of 2.5 cm. The distance of button 11 from base 3 (corresponding to the minimum distance between a point of base 3 and a point of button 11) is preferably 7.5 cm.

Toothbrush 1 comprises a stem 12 extending lengthwise from a first end 13 to a second end 14, opposite to end 13. Stem 12 extends lengthwise at least partially along a specific direction. Namely, stem 12 preferably substantially is frusto- conical with the major base corresponding to end 13 and the minor base corresponding to end 14. Stem 12, at base 13, is connected to handle 2 at base 4 of the latter. The bases 4 and 13 preferably match each other. This means that when toothbrush 1 is resting on a surface or on the above-mentioned support at base 3, the bases 4 and 13 preferably are arranged horizontally and the longitudinal axis (that is, the axis of radial symmetry) of the frustum of a cone, as stem 12 preferably substantially is shaped, is arranged horizontally.

Stem 12 preferably is hollow and has a height (corresponding to the distance between the bases 13 and 14) preferably of 11 cm.

Toothbrush 1 comprises three brushing heads 15, 16 and 17.

The brushing head 15 includes a plurality of bristles 20, each of which comprises a first end 21 and a second end 22, opposite to end 21. The brushing head 15 further includes a base 23 (identified above as "first base") to which each bristle 20 is connected at end 21. The brushing head 15, at base 23, is con- nected to stem 12 at end 14. Namely, the brushing head 15 is connected to stem 12 so that base 23, together with the bristles 20, is rotatable around an axis identified above as "first rotation axis". The latter is not parallel to the direction along which stem 12 extends. Namely, the rotation axis of the brushing head 15 preferably is arranged orthogonally to the longitudinal axis of the frustum of a cone, as stem 12 preferably substantially is shaped, and therefore preferably is arranged horizontally when handle 2 is resting on a surface or on the above- mentioned support at base 3. The rotation axis of the brushing head 15 preferably is arranged parallel to a straight line (intersecting the longitudinal axis of the cylinder, as handle 12 preferably is shaped, it also (said straight line) arranged horizontally when handle 2 is resting on a surface or on the above-mentioned support at base 3) joining protrusion 5 to button 11 , that is, to the straight line along which protrusion 5 and button 11 may be considered mutually opposite. Namely, the longitudinal axis of the cylinder, as handle 2 preferably is shaped, coincides with the longitudinal axis of the frustum of a cone, as stem 12 preferably is shaped, and is orthogonally incident with the rotation axis of the brushing head 15.

The bristles 20 preferably, but not necessarily, are arranged parallel to the rotation axis of the brushing head 15. The bristles 20 are, as a whole, preferably substantially shaped as a cylinder having a base diameter preferably between 5 mm and 7 mm, and more preferably of 6 mm. The rotation axis of the brushing head 15 preferably coincides with the longitudinal axis of the cylinder, as the bristles 20 as a whole preferably substantially are shaped.

Base 23 preferably is shaped as a solid of revolution. More preferably, but not necessarily, base 23 is shaped as a hemisphere overlapping, at the base circle, a frustum of a cone at the major base of the latter. The bristles 20, at end 21 , are connected to base 23 at the minor base of the aforesaid frustum of a cone. The rotation axis of the brushing head 15 preferably coincides with the longitudinal axis (that is, with the axis of radial symmetry) of the solid of revolution, as base 23 preferably substantially is shaped.

The width of the brushing head 15 (intended as the distance between the point of the aforesaid hemisphere furthest from the base circle of the hemisphere and the base of the cylinder, as the bristles 20 as a whole at which there are the ends 22 of the bristles 20, preferably substantially are shaped) preferably is of 1 cm.

The plurality of bristles 20 was identified above as "first plurality".

Toothbrush 1 comprises drive means adapted to transmit a rotary motion of the electric actuator shaft from said shaft to the brushing head 15 so that a rotation of said shaft around the axis thereof induces a rotation of base 23, together with the bristles 20, around the rotation axis of the brushing head 15. The aforesaid drive members are comprised in the above-mentioned "first drive means", preferably are accommodated in handle 2 and stem 12, and preferably include one or more drive shafts and/or joints and/or gears. The methods with which a rotary motion can be transmitted from the rotating shaft of the electric actuator of an electric toothbrush to a brushing head thereof substantially are known. Therefore, no further details will be provided.

Toothbrush 1 comprises a first arm 18 including a first end 18a and a second end 18b, opposite to end 18a. Arm 18, which preferably is hollow, is connected to handle 2 or stem 12 at end 18a. As can be seen in Figures 1 and 2, arm 18, at end 18a, preferably is connected to stem 12 at end 14. Arm 18 preferably is arched and preferably is arranged with the concavity thereof facing the brushing head 15. Schematizing arm 18 by means of a line, the latter preferably lies on a plane which preferably is arranged orthogonally to the longitudinal axis of the frustum of a cone, as stem 12 preferably substantially is shaped. The line, as arm 18 can be schematized, is further preferably coplanar to the rotation axis of the brushing head 15.

Arm 18, at end 18b, is connected to the brushing head 16. The brushing head 16 preferably is identical to the brushing head 15. Namely, the brushing head 16 includes a plurality of bristles 25, each of which comprises a first end 26 and a second end 27, opposite to end 26. The brushing head 16 further includes a base 28 (identified above as "second base") to which each bristle 25 is connected at end 26. The brushing head 16, at base 28, is connected to arm 18 at end 18b. Namely, the brushing head 16 is connected to arm 18 so that base 28, together with the bristles 25, is rotatable around an axis identified above as "second rotation axis". The latter is not parallel to the direction along which stem 12 extends, nor is it parallel to the rotation axis of the brushing head 15. Namely, the rotation axis of the brushing head 15 and the rotation axis of the brushing head 16 preferably are incident, and consequently also coplanar. The plane in which the rotation axes of the brushing heads 15 and 16 lie preferably is arranged orthogonally to the longitudinal axis of the frustum of a cone, as stem 12 preferably substantially is shaped, and therefore preferably is arranged horizontally when handle 2 is resting on a surface or on the above-mentioned support at base 3. As shown in Figure 3, the rotation axes of the brushing heads 15 and 16 intersect so that angle 24 between said axes and crossing the bases 23 and 28 has an amplitude preferably between 91 ° and 95°, and more preferably, between 93° and 94°.

The bristles 25 preferably, but not necessarily, are arranged parallel to the rotation axis of the brushing head 16. The bristles 25, like the bristles 20, are, as a whole, preferably substantially shaped as a cylinder having a base diameter preferably between 5 mm and 7 mm, and more preferably of 6 mm. The rotation axis of the brushing head 16 preferably coincides with the longitudinal axis of the cylinder, as the bristles 25 as a whole preferably substantially are shaped. Base 28, like base 23, preferably is shaped as a solid of revolution. More preferably, but not necessarily, base 28 is shaped as a hemisphere overlapping, at the base circle, a frustum of a cone at the major base of the latter. The bristles 25, at end 26, are connected to base 28 at the minor base of the aforesaid frustum of a cone. The rotation axis of the brushing head 16 preferably coincides with the longitudinal axis of the solid of revolution, as base 28 preferably substantially is shaped.

The width of the brushing head 16 (intended as the distance between the point of the aforesaid hemisphere furthest from the base circle of the hemisphere and the base of the cylinder, as the bristles 25 as a whole at which there are the ends 27 of the bristles 25, preferably substantially are shaped) preferably is of 1 cm.

The plurality of bristles 25 was identified above as "second plurality".

As shown in the drawings, the brushing head 16 is connected to arm 18 so that (that is, it is oriented so that) the bristles 25 extend from base 28 on the side of the brushing head 15, but without coming into contact with the bristles 20 of the latter. In particular, the minimum distance between a point of the cylinder, as the bristles 20 as a whole preferably substantially are shaped, (corresponding to the point closest to the brushing head 16 of the circumference serving as perimeter of the base of said cylinder formed by the ends 22 of the bristles 20) and a point of the cylinder, as the bristles 25 as a whole preferably substantially are shaped, (corresponding to the point closest to the brushing head 15 of the circumference serving as perimeter of the base of said cylinder formed by the ends 27 of the bristles 25) preferably is between 1 mm and 2 mm.

Toothbrush 1 comprises drive means adapted to transmit a rotary motion of the shaft of the electric actuator from said shaft to the brushing head 16 so that a rotation of said shaft around the axis thereof induces a rotation of base 28, together with the bristles 25, around the rotation axis of the brushing head 16. The aforesaid drive members are comprised in the above-mentioned "second drive means", preferably are accommodated in arm 18, preferably include one or more drive shafts and/or joints and/or gears, and preferably provide a connection between base 28 and the drive means which transmit the rotary motion of the shaft of the electric actuator to the brushing head 15. Preferably, the transmission of a rotary motion from the shaft of the electric actuator to the brushing head 16 therefore does not directly occur, rather preferably by means of the above-mentioned drive means which transmit the rotary motion from the shaft of the electric actuator to the brushing head 15. The fact that arm 18 preferably is arched is not a problem since the transmission of the rotary motion may, for example, occur by means of one or more universal joints.

Toothbrush 1 comprises a second arm 19 including a first end 19a and a second end 19b, opposite to end 19a. Arm 19, which preferably is hollow, is connected to handle 2 or stem 12 at end 19a. As shown in Figures 1 and 2, arm 19, at end 19a, preferably is connected to stem 12 at end 14. Arm 19 preferably is arched and preferably is arranged with the concavity thereof facing the brushing head 15. Schematizing arm 19 by means of a line, the latter preferably lies on a plane which preferably is arranged orthogonally to the longitudinal axis of the frustum of a cone, as stem 12 preferably substantially is shaped. The line as arm 19 can be schematized is further preferably coplanar to the rotation axes of the brushing heads 15 and 16. The arms 18 and 19 preferably are mutually symmetrical with respect to a symmetry plane including the rotation axis of the brushing head 15. Preferably, said symmetry plane includes the longitudinal axis of the frustum of a cone, as stem 12 preferably substantially is shaped. Said symmetry plane therefore preferably is arranged vertically when handle 2, and consequently toothbrush 1 , is resting on a surface or on the aforesaid support at base 3.

Arm 19, at end 19b, is connected to the brushing head 17. The brushing head 17 preferably is identical to the brushing heads 15 and 16. Namely, the brushing head 17 includes a plurality of bristles 30, each of which comprises a first end 31 and a second end 32, opposite to end 31. The brushing head 17 further includes a base 33 (identified above as "third base") to which each bristle 30 is connected at end 31 . The brushing head 17, at base 33, is connected to arm 19 at end 19b. Namely, the brushing head 17 is connected to arm 19 so that base 33, together with the bristles 30, is rotatable around an axis identified above as "third rotation axis". The latter is not parallel to the direction along which stem 12 extends, nor is it parallel to the rotation axis of the brushing head 15. Namely, the rotation axes of the brushing heads 15, 16 and 17 preferably are incident in a single point, and also coplanar. As mentioned above, the plane in which the rotation axes of the brushing heads 15, 16 and 17 lie preferably is arranged orthogonally to the longitudinal axis of the frustum of a cone, as stem 12 preferably substantially is shaped, and therefore preferably is arranged horizontally when handle 2, and consequently toothbrush 1 , is resting on a surface or on the above-mentioned support at base 3. As shown in Figure 3, the rotation axes of the brushing heads 15 and 17 intersect so that angle 29 between said axes and crossing the bases 23 and 33 has an amplitude preferably between 91 ° and 95°, and more preferably, between 93° and 94°.

The bristles 30 preferably, but not necessarily, are arranged parallel to the rotation axis of the brushing head 17. The bristles 30, like the bristles 20 and 25, are, as a whole, preferably substantially shaped as a cylinder having a base di- ameter preferably between 5 mm and 7 mm, and more preferably of 6 mm. The rotation axis of the brushing head 17 preferably coincides with the longitudinal axis of the cylinder, as the bristles 30 as a whole preferably substantially are shaped.

Base 33, like the bases 23 and 28, preferably is shaped as a solid of revolution. More preferably, but not necessarily, base 33 is shaped as a hemisphere overlapping, at the base circle, a frustum of a cone at the major base of the latter. The bristles 30, at end 31 , are connected to base 33 at the minor base of the aforesaid frustum of a cone. The rotation axis of the brushing head 17 preferably coincides with the longitudinal axis of the solid of revolution, as base 33 preferably substantially is shaped.

The width of the brushing head 17 (intended as the distance between the point of the aforesaid hemisphere furthest from the base circle of the hemisphere and the base of the cylinder, as the bristles 30 as a whole at which there are the ends 32 of the bristles 30, preferably substantially are shaped) preferably is of 1 cm.

The plurality of bristles 30 was identified above as "third plurality".

As shown in the drawings, the brushing head 17 is connected to arm 19 so that (that is, it is oriented so that) the bristles 30 extend from base 33 on the side of the brushing head 15, but without coming into contact with the bristles 20 of the latter. In particular, the minimum distance between a point of the cylinder, as the bristles 20 as a whole preferably substantially are shaped, (corresponding to the point closest to the brushing head 17 of the circumference serving as perimeter of the base of said cylinder formed by the ends 22 of the bristles 20) and a point of the cylinder, as the bristles 30 as a whole preferably substantially are shaped, (corresponding to the point closest to the brushing head 15 of the circumference serving as perimeter of the base of said cylinder formed by the ends 32 of the bristles 30) preferably is between 1 mm and 2 mm.

The bases 28 and 33, and preferably the brushing heads 16 and 17, are mutually symmetrical with respect to a symmetry plane including the rotation axis of the brushing head 15. Preferably, said symmetry plane includes the longitudinal axis of the frustum of a cone, as stem 12 preferably substantially is shaped. Said symmetry plane therefore preferably is arranged vertically when handle 2, and consequently toothbrush 1 , is resting on a surface or on the above- mentioned support at base 3. In light of the foregoing, the plane with respect to which the bases 28 and 33, and preferably the brushing heads 16 and 17, preferably are symmetrical coincide with the plane with respect to which the arms 18 and 19 preferably are symmetrical.

Toothbrush 1 comprises drive means adapted to transmit a rotary motion of the shaft of the electric actuator from said shaft to the brushing head 17 so that a rotation of said shaft around the axis thereof induces a rotation of base 33, together with the bristles 30, around the rotation axis of the brushing head 17. The aforesaid drive members are comprised in the above-mentioned "third drive means", preferably are accommodated in arm 19, preferably include one or more drive shafts and/or joints and/or gears, and preferably provide a connection between base 33 and the drive means which transmit the rotary motion from the shaft of the electric actuator to the brushing head 15. Preferably, the transmission of a rotary motion from the shaft of the electric actuator to the brushing head 17 therefore does not directly occur, rather preferably by means of the above-mentioned drive means which transmit the rotary motion from the shaft of the electric actuator to the brushing head 15. Similarly to that said for arm 18, the fact that arm 19 preferably is arched is not a problem since the transmission of the rotary motion may, for example, occur by means of one or more universal joints.

In light of the foregoing, the heads 16 and 17 are opposed to each other at the bristles 25 and 30, respectively, so that:

• the brushing head 16 faces the brushing head 17 at end 27 of the bristles 25;

• the brushing head 17 faces the brushing head 16 at end 32 of the bristles 30;

• the bristles 25 are opposed to the bristles 30.

The bristles 25 are at such a distance from the bristles 30 that a portion of space 34 where a tooth of a person can be at least partially accommodated is interposed between the bristles 25 and 30. Therefore, the bristles 25 are not in contact with the bristles 30. As shown in Figure 3, head 15, at the bristles 20, is opposed to the portion of space 34 so that the brushing head 15 faces the por- tion of space 34 at end 22 of the bristles 20.

The bristles 20 are not in contact with the bristles 25, nor with the bristles 30.

The minimum distance between a point of the cylinder, as the bristles 25 as a whole preferably substantially are shaped, (corresponding to the point closest to the brushing head 18 of the circumference serving as perimeter of the base of said cylinder formed by the ends 27 of the bristles 25) and a point of the cylinder as the bristles 30 as a whole preferably substantially are shaped, (corresponding to the point closest to the brushing head 17 of the circumference serving as perimeter of the base of said cylinder formed by the ends 32 of the bristles 30) preferably is between 5 mm and 7 mm.

Again, as shown in Figure 3, the rotation axis of the brushing head 15 crosses the portion of space 34 so that a stretch of said rotation axis is interposed between the bristles 25 and the bristles 30. The brushing head 15 is also opposed to the portion of space 34 so that if it were possible to translate the brushing head 15 along the rotation axis thereof, the brushing head 15 would be at least partially accommodated in the portion of space 34 and consequently, interposable between the brushing heads 16 and 17.

The brushing heads 15, 16 and 17 and the arms 18 and 19 are shaped, as a whole, so as to be insertable into the head of a person.

Advantageously, by using toothbrush 1 , while the occlusal surface of a molar or a premolar is being brushed with the brushing head 15, the brushing heads 16 and 17 brush the lingual surface and the vestibular surface of the aforesaid tooth.

Stem 12, together with the arms 18 and 19 and the brushing heads 15, 16 and 17 preferably can be disconnected from handle 2 and reconnected to the later an indefinite number of times (that is, the connection between stem 12 and handle 2 is reversible). Advantageously, in this case brushing heads 15, 16 and 17 (and/or arms 18 and 19) of various sizes and/or at various mutual distances can be provided according to age, and consequently, the sizes of the dental arches of the person using toothbrush 1. Incidentally, in this case also the above-mentioned drive means adapted to transmit a rotary motion of the shaft of the electric actuator from said shaft to the brushing heads 15, 16 and 17 can be disconnected and reconnected from/to the shaft of the electric actuator an indefinite number of times.

On the basis of the description provided for a preferred embodiment, it is apparent that some changes can be made by those skilled in the art without de- parting from the scope of the invention as defined by the following claims.