Patent Description:
Automatic tooth brushing using cleaning mouthpieces has become an emerging technology. Several mouthpiece-based dental cleaning systems are in the development stage and claim in particular a short brushing time (e.g. <NUM>-<NUM> seconds). These systems hence have speed and ease of use as the main value drivers.

In this document, the term "mouthpiece" is used to refer to the part of a cleaning system which resides inside the mouth and is fitted to the teeth. Typically this is an arch to cover the teeth of a jaw or a pair of arches to cover the teeth of both jaws. The system will typically have other parts which remain external to the mouth, in use. Each arch of the mouthpiece for example has a base and side walls.

A dental cleaning system of this type for example comprises a mouthpiece which fits over the teeth of one or both jaws, with cleaning bristles facing the teeth. The mouthpiece or just the bristles are driven to move or vibrate relative to the teeth to provide a brushing action.

One issue that has been found is a lack of cleaning effectiveness, due to insufficient coverage/reach on the back molars and the gum line, lack of contour following of different jaw geometries, and due to limited kinetic energy transmitted to the teeth.

Difficulties are also found in providing sufficient energy transfer from an actuator to the bristles to enable sufficiently long bristle strokes and large amplitude needed to remove plaque. Vibrations/shaking of the jaw and head can also be a cause of discomfort.

By way of example, <CIT> discloses a dental cleaning system with an inner band along the inside surface of the teeth and an outer band along the outside surface of the teeth. The two bands and associated brush elements are moved towards and away from each other, vertically up/down or in small circular motions to clean the teeth.

Reference document <CIT> relates to appliances for cleaning teeth and/or massaging gums, and more specifically to power brush and massaging appliances which are self-contained within the mouth.

There is a need for an improved dental cleaning system, for addressing some or all of the issues outlined above.

The invention is defined by independent the claims. In particular, the above noted problems are at least partially solved by a mouthpiece according to claim <NUM> and dental cleaning systems according to claims <NUM> and <NUM>.

It should be understood that the detailed description and specific examples, while indicating exemplary embodiments of themouthpiece for a dental cleaning system and the dental cleaning system, are intended for purposes of illustration only and are not intended to limit the scope of the invention. These and other features, aspects, and advantages of the present invention will become better understood from the following description, appended claims, and accompanying drawings.

The invention provides a mouthpiece for a dental cleaning system and the dental cleaning system itself. The mouthpiece has a base and inner and outer arches. An actuator is used for applying motion (i.e. movement) to the inner arch and/or the outer arch, relative to the base. A coupling arrangement converts motion of one of the inner and outer arches in one direction relative to the base to motion in an opposite direction relative to the base of the other of the inner and outer arches. By forming the mouthpiece as a central stationary base enveloped by two contour-following and moving arches (coupled via the coupling arrangement), an anti-phase brushing motion at opposite tooth sites along the tooth arch is enabled, giving increased reach toward the molars as well as a reduction head shaking or device shaking inside the mouth.

<FIG> shows a first example of a dental cleaning system. The system comprises a mouthpiece <NUM> for insertion in the mouth of the user and an external part <NUM> for positioning outside the mouth of the user, in front of the user's mouth. The external part <NUM> for example functions as a handle of the system.

The mouthpiece comprises a first U-shaped channel for receiving the teeth of one jaw, and a second U-shaped channel for receiving the teeth of the other jaw. The mouthpiece is bitten onto by the user with their teeth in the two channels. The system may instead have only one channel, in which case the cleaning may be performed one jaw at a time.

In <FIG>, the features of one of the U-shaped channels can be seen (facing upwardly). The opposite, downward facing, U-shaped channel may be the same. The features of one of the U-shaped channels will be described.

For the shown U-shaped channel, the mouthpiece <NUM> comprises a base <NUM>, an inner arch <NUM> for positioning adjacent an inner surface of the teeth of a jaw of the user and an outer arch <NUM> for positioning adjacent an outer surface of the teeth of the jaw.

The U-shaped channel of the mouthpiece fits over the teeth of the jaw with the inner and outer arches <NUM>, <NUM> positioned against the inner and outer surfaces of the teeth. The user can bite on the base <NUM> (or an insert with cleaning elements mounted on the base; not shown in <FIG>) because it is intended to be static in use, whereas the inner and outer arches <NUM>, <NUM> are designed to move against the surface of the teeth, in the manner explained further below.

It is noted that in <FIG> and several other figures, cleaning bristles are omitted for the sake of clarity, because the focus of the invention relates to motion generation and reach. Bristles or tufts may be provided at various angles, length, packing density etc. on various parts of the mouthpiece: the inner arch, the outer arch and the stationary base.

There may be bristles on the base for the biting surfaces of the teeth or bristles may reach across from the sides to contact the biting surfaces. It is preferred that a tooth-contacting part with cleaning elements (bristles) is added on top of the base to enable brushing the occlusal tooth surfaces.

The external part <NUM> has an actuator <NUM> for applying movement to the inner arch and/or the outer arch, relative to the base. For a system with two U-shaped channels, a shared actuator is used. In this example, the actuator <NUM> is in front of the mouthpiece and therefore connects most simply with the outer arch <NUM>, as shown. It could however connect to the inner arch <NUM>. Similarly, in other examples where the actuator is inside the user's mouth within the U-shaped space formed by the inner arch, it may most easily connect to the inner arch instead of the outer arch.

The base <NUM>, the inner arch <NUM> and the outer arch <NUM> are coupled by a coupling arrangement <NUM>, <NUM>. The coupling arrangement <NUM>, <NUM> converts movement of one of the inner and outer arches in one direction relative to the base to movement in an opposite direction relative to the base of the other of the inner and outer arches. In paricular, each coupling arrangement connects between adjacent regions of the inner and outer arches. These regions are adacent, in that they are located at the same angular position around the jaw. The coupling arrangement connects between those adjacent regions. The coupling arrangements for examle perform a pivot funciton.

Thus, in the example shown in <FIG>, the actuator <NUM> imparts movement to the outer arch <NUM>, and the coupling arrangement <NUM>, <NUM> converts this movement to an anti-phase movement (i.e. in an opposite direction) of the inner arch.

By "opposite direction" is not necessarily meant a perfectly opposite movement vector. Instead, one direction is generally across the edge surfaces of the teeth from one side of the jaw to the other (e.g. right to left), and the opposite direction is generally across the edge surfaces of the teeth from the other side of the jaw to the one side of the jaw (e.g. from left to right).

The coupling arrangement <NUM>, <NUM> is not clamped when the user bites down, but is free to move. This may be enabled be providing the coupling arrangement at a different level to the tooth-contacting part of the base <NUM>.

The cleaning system thus has inner and outer arches for brushing the inner and outer surfaces of the teeth. The base is a central stationary part. The anti-phase coupling assists in providing reach to the rear molars and also provides cancellation of vibrations and hence reduces the shaking of the device inside the mouth.

The separation of the base from the arches means the user can bite down on the base without affecting the brushing performance. Biting on the mouthpiece will not cause an increased load on the motor, and hence will not dampen the driven vibrations. The system enables the desired brushing motion along the tooth arch to be implemented with sufficient transfer of energy to remove plaque and stains.

The coupling arrangement comprises coupling members <NUM>, <NUM> each extending between the inner and outer aches <NUM>, <NUM>. The coupling members <NUM>, <NUM> each connect to the base <NUM> at a location <NUM> between the inner and outer arches, via a flexible strut or web. The coupling members <NUM>, <NUM> and flexible struts function as hinges, with a main pivot point of the hinges being defined at some point on a flexible connecting member which extends between the base <NUM> and the location <NUM> where the coupling members connect to the base. The hinges thus rock about the pivot point to provide the anti-phase movement of the inner and outer arches. Some pivoting at the connections between the ends of the coupling members and the inner and outer arches allows the overall arrangement to have the required flexibility.

<FIG> shows that the actuator <NUM> is mounted in a frame <NUM>. The frame <NUM> is rigidly coupled to the base <NUM> by a support plate <NUM> (shown more clearly in other figures) so that the base and the frame are static parts of the system.

The frame <NUM> also connects to the outer arch <NUM> by limbs <NUM>. These limbs <NUM> provide a movable coupling between the main body of the frame and the outer arch <NUM>. In particular, the limbs <NUM> allow rotation of the outer arch relative to the frame <NUM> about a rotation axis <NUM> behind the front of the mouthpiece. This movement is shown by arrow <NUM>.

In the example of <FIG>, the coupling arrangement comprises a first coupling member in the form of a hinge <NUM> along a first lateral side of the mouthpiece (the left side of the user's jaw) set forward from the back of the first lateral side. This first hinge <NUM> connects the inner arch, the outer arch and the base at that first lateral side. A second hinge <NUM> is along the other lateral side of the mouthpiece (the right side of the user's jaw) set forward from the back of the other lateral side. The second hinge <NUM> connects the inner arch, the outer arch and the base at that second lateral side. The coupling arrangement thus comprises hinges set forward from the back of the arches.

The coupling arrangement additionally has a first connector <NUM> between the inner and outer arches <NUM>, <NUM> at the back of the first lateral side and a second connector <NUM> between the inner and outer arches at the back of the second lateral side. These connectors <NUM>, <NUM> maintain the desired spacing between the inner and outer arches and allow a transfer of the anti-phase movement, but the anti-phase motion is initially generated by the first and second hinges <NUM>, <NUM>.

The actuator <NUM> in this example comprises a motor, with a rotating output shaft. An eccentric coupling <NUM> converts the rotation into a desired movement of the outer arch <NUM>. This desired movement may be a simple lateral oscillation (i.e. left to right), or it may be a more complex motion, such as a motion in a 2D plane (i.e. left to right and up-down, i.e. in a vertical plane in a normal orientation of the device) such as a circular motion. It may even be a 3D motion, with a component in the 2D plane (the vertical plane) as well a component parallel to the output shaft axis. This may be used to provide an additional tapping effect.

Thus, in a most basic example, the actuator applies a lateral <NUM> dimensional translational motion, thus providing movement of the arch along a single side-to-side axis. More complex motions are however possible. A combination of a tapping motion (i.e. in a direction across rather than along the tooth) and a sliding motion may enhance the cleaning result.

An eccentric motor may for example be integrated in the handle of the mouthpiece to actuate the outer arch with suitable frequencies in the range of <NUM>-<NUM> and strokes of about <NUM>-<NUM> to obtain a large range of reach towards the back teeth.

<FIG> shows the design of <FIG> from above.

<FIG> shows more clearly that the design of <FIG> has two U-shaped channels 10a, 10b back to back, to enable cleaning of the teeth of both jaws at the same time. and with cleaning elements such as bristles <NUM> projecting inwardly (towards the teeth) from the inner and outer arches.

There is a single shared actuator <NUM>, two back to back U-shaped channels 10a, 10b and two separate frames 54a, 54b.

<FIG> shows one unit which is an assembly of one U-shaped channel 10a of the mouthpiece <NUM> and one frame 54a (which connects to the outer arch) and excluding the support plate <NUM>, which is a separate part.

<FIG> shows an exploded view of the design of <FIG>.

The support plate <NUM> carries the actuator <NUM>, and it is sandwiched between the first and second frames 54a, 54b. The support plate has a mounting region <NUM> to which the bases 12a, 12b of the two U-shaped channels 10a, 10b of the mouthpiece <NUM> connect. The two bases and the mounting region are for example clamped together with bolts or screws.

<FIG> shows the shape of the mouthpiece <NUM> and the part of the frame <NUM> which connects to the outer arch of the mouthpiece, and how the anti-phase motion is induced by pairs of arrows pointing in different directions along the arches. The motion of the solid arrows takes place at one time, and the motion of the dashed arrows takes place at a subsequent time. This is provided to enable comparison with an alternative example which is shown in <FIG>.

<FIG> shows how the anti-phase motion is induced using the design of the mouthpiece shown in <FIG>.

The actuator induces lateral movement as shown by the pair of arrows <NUM>. The coupling member <NUM> has the main hinge pivot point defined at some point on the flexible connect between the base <NUM> and the location <NUM>. The hinge point is in this example asymmetrically positioned between the inner and outer arches (although a symmetric arrangement is also possible, shown below). Thus, the movement of the outer arch is amplified (based on the ratio between the distances 92a, 92b). This compensates for a loss of motion causes by losses in the flexible hinge structure.

Thus, the asymmetrical hinge design provides improved transfer of motion between the outer arch and the inner arch.

As a general indication of the approximate range of movement which may be used, the anti-phase motion amplitude may be of the order of <NUM> to <NUM>. For example, the actuation amplitude may be around ±<NUM> with an actuation input of ± <NUM>. A larger actuation amplitude may be used, e.g. around <NUM>-<NUM> (half the width of a molar), for example using geared motors.

In the example of <FIG>, the hinges of the coupling arrangement are set forward from the back of the mouthpiece as explained above, and there are additional connectors <NUM>, <NUM>. An advantage of the example of <FIG> is that the coupling members transfer motion from the outer arch to the inner arch close to the actuator. This minimizes motion loss and allows the molar section to conform to the teeth.

<FIG> shows an alternative design, in which the coupling arrangement comprises a first hinge <NUM> at the back of a first lateral side (the left side) of the mouthpiece. This first hinge <NUM> connects the back of the inner arch <NUM>, the back of the outer arch <NUM> and the back of the base <NUM> at said first lateral side. A second hinge <NUM> is at the back of the opposite lateral side (the right side) of the mouthpiece. The second hinge connects the back of the inner arch <NUM>, the back of the outer arch <NUM> and the back of the base <NUM> at that opposite lateral side. This structure has fewer intricate parts.

The hinges are shown as symmetrical in this example, with the main pivot point mid-way between the inner and outer arches. Thus, it can be seen that different hinge designs are possible with symmetric or asymmetric positioning of the main hinge.

The examples above make use of coupling members formed as a first U-shaped coupling between the outer arch and the location <NUM> (where there is a strut connecting to the base), and a second U-shaped coupling between the location <NUM> and the inner arch. An alternative design makes use of first and second W-shaped couplings.

<FIG> shows a further alternative design of the coupling members <NUM>, <NUM>. A rigid strut <NUM> extends between the inner and outer arches, and a pivot or rocker bearing <NUM> provides the connection to the base <NUM>. There is thus a T-shaped connector with a pivot point at the interconnection of the three limbs of the strut.

The mouthpiece (base, coupling arrangement and arches) may be formed of a single material. However, in an example, the inner arch and outer arch are for example formed of a first material and the coupling arrangement, or portions of the coupling arrangement, are formed of a different material to the first material. The use of different materials enables the elastic coupling properties to be optimized.

<FIG> shows the design of <FIG> and shows regions A which may be formed of a different material (material A) to the remainder of the structure.

<FIG> shows the design of <FIG> and shows regions B and C which may be formed of a different material to the remainder of the structure. Regions B and C may be of the same material (material B), or they may be two different materials (materials B, C), both different to the main structure.

<FIG> shows the design of <FIG> and shows regions D which may be formed of a different material (material D) to the remainder of the structure. These regions formed of a different material are the joints between the coupling members and the arches and the joints between the coupling members and the base.

Materials A to D have for example a (relatively) low hardness and low Young's modulus to add flexibility and deformity to the hinges.

The material of the remainder of the structure has for example a (relatively) medium or high hardness and medium or high Young's modulus.

By way of example, the main material may be polyethylene (with elastic modulus <NUM> GPa and Poisson's ratio <NUM>. While this is one option of food grade material for parts with flexure design (living hinges), there are also other materials such as polyamides (e.g. Nylon) and a thermoplastic elastomer that can be used for this application.

The hinges are designed for low stress, long life and minimal loss of energy in the system. The parts may be made by 3D printing or by injection molding, for example.

The overall system can be described as a compliant spring system. The system may for example be driven at its resonance frequency, reducing the power needs of the system. The frequency may also be tuned individually to the resonance frequency, using feedback of the amplitude, since damping on the teeth may vary from person to person, and also parts of the system may be customized for better fitting.

As explained above, a <NUM>-dimensional reciprocating brushing motion may be used. <FIG> shows a modification in which the limbs <NUM> are made thinner and have a cutout <NUM> to create an additional degree of freedom in their movement. This can be used to generate a 3D motion from a 2D eccentric drive. For example, by actuating with a circular trajectory, a more complex (2D) circular brushing motion is generated. By adding another pivot point, a complex 3D motion can be generated, e.g. circular motion superimposed by a tapping motion.

In the example above, the actuator is in front of the mouthpiece, i.e. outside the mouth. In another set of examples, instead of forming the actuator outside of and in front of the mouthpiece, the actuator may be arranged in a space partially surrounded by the inner arch. Thus, it may be for positioning inside the user's mouth. This may enable a more compact device.

One option is to use a similar actuator to that shown above, for example for driving the inner arch (which is then closer to the actuator).

<FIG> instead shows an alternative actuator design.

The actuator comprises a dual shaft motor <NUM> with swash plates at the output shafts. A first swash plate <NUM> connects to a back of one same lateral side of the inner and outer arches <NUM>, <NUM>, and a second swash plate <NUM> connects to a back of the other same lateral side of the inner and outer arches. Thus, each swash plate ensures opposite motion of a common end of the inner and outer arches. The two shafts for example rotate in the same direction.

<FIG> shows a further alternative actuator design.

The actuator comprises a dual shaft motor <NUM>, with two swash plates at the output shafts. A first swash plate <NUM> driven by one shaft connects to a back of opposite lateral sides of the inner arch <NUM>, and a second swash plate <NUM> driven by the other shaft connects to a back of opposite lateral sides of the outer arch <NUM>. Thus, each swash plate ensures opposite motion of the two ends of a respective one of the inner and outer arches, and the two swash plates operate in anti-phase with each other. They may for example rotate in opposite directions.

The benefits of anti-phase brushing motion in combination with larger reach can be achieved in this way.

In <FIG>, the swash plates function as the coupling arrangement. The overall swash plate design again connects between adjacent regions (the ends in these examples) of the inner and outer arches, and the adjacent ends are made to move in opposite directions by the overall swash plate design.

The U-shaped channels of the mouthpiece allow occlusal bristles to be added on the stationary base. The incisors bite on the front base part to hold the stationary part stationary. This stationary part may be covered with a (tooth-contacting) cleaning structure (e.g. rough surface or short <NUM>-<NUM> bristles to have some cleaning of the top incisors). The thickness of this stationary part can be increased to make room for occlusal bristles on the molar-premolar areas.

Claim 1:
A mouthpiece (<NUM>) for a dental cleaning system, comprising:
a base (<NUM>);
an inner arch (<NUM>) for positioning adjacent an inner surface of the teeth of a jaw of a user; and
an outer arch (<NUM>) for positioning adjacent an outer surface of the teeth of the jaw,
an actuator coupling for connection to an actuator (<NUM>) for applying motion to the inner arch and/or the outer arch, relative to the base,
wherein the base (<NUM>), the inner arch (<NUM>) and the outer arch (<NUM>) are coupled by a coupling arrangement (<NUM>,<NUM>),
wherein the coupling arrangement couples to adjacent regions of the inner and outer arches, and converts motion of said region of one of the inner and outer arches in one direction relative to the base to motion in an opposite direction relative to the base of said region of the other of the inner and outer arches.