Oral health care mouthpiece

Abstract

Proposed concepts aim to provide solutions pertaining to a mouthpiece device for insertion into a subject's mouth during use, wherein the dental arch curvature of a rest configuration of the mouthpiece is set to be greater than the 90th percentile dental arch curvature of an intended user population.

Description

[0001] ORAL HEALTH CARE MOUTHPIECE

[0002] FIELD OF THE INVENTION

[0003] This invention relates to the field of oral health care, and in particular to the field of oral care devices.

[0004] BACKGROUND OF THE INVENTION

[0005] A growing area in the field of oral care devices is that of brushing mouthpieces. Brushing mouthpieces promise to offer the benefits of quicker cleaning times and improved performance. Additionally, the cleaning performance of a brushing mouthpiece may be less dependent on user technique than the cleaning performance of a traditional toothbrush.

[0006] A problem facing mouthpiece development is how to ensure proper alignment of the mouthpiece to a subject’s teeth and gums. The aim is to achieve a one-size-fits-all solution that may provide effective cleaning to a large user population. To achieve this, high flexibility of the mouthpiece brush is required such that it may adapt to the subject’s particular jaw shape. Additionally, for optimal cleaning, the subject is typically required to move the mouthpiece brush back and forth, which can only be done if the brush has sufficient flexibility.

[0007] It has also been shown that it is beneficial for incisor / canine cleaning for the portion of the brush adjacent to the facial side of the subject’s teeth have a higher stiffness compared to the portion of the brush adjacent to the lingual side. Besides this preferred stiffness imbalance, practically there is also more room for brush tufts on the facial side compared to the lingual side given the fact that the arc length of the facial side is longer than the arc length of the lingual side. This results in a similar stiffness imbalance in a brushing mouthpiece from a geometrical perspective.

[0008] The problem of achieving a one-size-fits-all mouthpiece may extend beyond the field of brushing mouthpieces to other types of mouthpiece devices. For example, light mouthpieces, whitening mouthpieces, and mouthguards.

[0009] SUMMARY OF THE INVENTION

[0010] The invention is defined by the claims.

[0011] According to examples in accordance with an aspect of the invention, there is provided a mouthpiece device for insertion into a subject’s mouth during use, wherein the subject is one of a plurality of members of an intended user population and the mouthpiece comprises: a dental tray extending in a longitudinal direction with a dental arch curvature and configured to accommodate a section of teeth and / or gums of the subject when in use; and a hinge arrangement configured to connect at least a first segment of the dental tray to a second segment of the dental tray, wherein the hinge arrangement is configured to permit rotation of the first segment relative to the second segment about an axis substantially orthogonal to the longitudinal direction to move the mouthpiece device from a rest configuration to a use configuration so as to decrease the dental arch curvature of the mouthpiece, wherein the mouthpiece is configured to be biased towards the rest configuration, and wherein the dental arch curvature of the mouthpiece in the rest configuration is set to be greater than the 90thpercentile dental arch curvature of the intended user population.

[0012] Proposed concepts thus aim to provide schemes, solutions, concepts, designs methods and systems pertaining to a mouthpiece device for insertion into a subject’s mouth during use, wherein the dental arch curvature of a rest configuration of the mouthpiece is set to be greater than the 90thpercentile dental arch curvature of an intended user population.

[0013] In particular, embodiments aim to provide a flexible mouthpiece designed such that the mouthpiece may deform from a rest configuration to a use configuration when the mouthpiece is inserted into a subject’s mouth. Further, the dental arch curvature of the mouthpiece in the rest configuration is set to be greater than the 90thpercentile dental arch curvature value of the intended user population. This means that the flexibility introduced by the hinge arrangement, that enables the dental arch curvature of the mouthpiece to be decreased from the rest configuration to the use configuration, enables the device to fit 90% of subjects in the intended user population.

[0014] A mouthpiece configuration is therefore proposed in which the dental arch curvature of the mouthpiece when it is in a rest configuration (where the rest configuration defines the shape of the mouthpiece when no external forces are acting on it) is designed for the tightest curvature of the intended user population. In this way, the device is only required to have freedom to straighten its arch in order to be suitable for use in the significant majority of the intended user population.

[0015] In currently available mouthpieces, mouthpiece arch design or configuration is based on an average jaw size and curvature of the intended user population. This means that the arch needs to have the flexibility to both straighten and bend further. Typically, the force used to induce this deformation of the mouthpiece from a rest configuration to a use configuration is generated by contact between portions of the mouthpiece device (for example bristles in a brushing mouthpiece) that are in contact with the teeth and / or gums of the user. This implies that there is required to be a force imbalance between the facial and lingual portions of the mouthpiece to generate a resultant bending force.

[0016] Due to the geometric configuration of the mouthpiece (i.e., the fact that the facial arch of the mouthpiece will always be longer than the lingual arch) there may be a natural stiffness imbalance that tends to straighten the arch. In the case of a brushing mouthpiece this is enhanced by the fact that optimal incisor / canine cleaning requires facial side brushing elements to be stiffer than lingual side brushing elements. These factors may result in it being more difficult to bend the dental arch of a mouthpiece device to have a tighter curvature than the designed curvature of the rest configuration.

[0017] It is proposed that by designing the dental arch curvature of the rest configuration of a mouthpiece to be greater than the dental arch curvature of 90% of the intended user population, in nearly all use cases, the dental arch of the mouthpiece is only required to straighten. This means that the device may leverage the natural stiffness imbalance between the facial and lingual sides of the mouthpiece to produce the resultant force required to deform the mouthpiece in use. Therefore, the proposed invention results in a flexible mouthpiece device that may be easier to deform from a rest configuration to a use configuration to fit the dental anatomy of a user.

[0018] Ultimately, an improved mouthpiece device for insertion into a subject’s mouth during use may be provided by the proposed concept(s).

[0019] In some embodiments, the plurality of members of the intended user population may share at least one demographic parameter, preferably wherein the demographic parameter comprises at least one of: a gender; an age; an ethnicity; and a nationality. Jaw sizes and curvatures may vary significantly between demographic groups. Restricting the intended user population to users that share certain characteristics (i.e. a target user demographic) may enable a better fitting mouthpiece to be designed.

[0020] In some embodiments, the dental arch curvature of the mouthpiece in the rest configuration may be set to be greater than the 95thpercentile dental arch curvature value of the intended user population, and preferably wherein the dental arch curvature may be set to be greater than the 99thpercentile dental arch curvature of the intended user population. This may allow for a straightening-only design of the device to be suitable for more members of the user population.

[0021] In some embodiments, the dental tray may comprise a plurality of first cleaning elements projecting from a first portion of the dental tray configured to be adjacent to the outer, facial / buccal surface of the teeth of the subject when in use; and a plurality of second cleaning elements projecting form a second portion of the dental tray configured to be adjacent to the inner, lingual surface of the teeth of the subject when in use. Cleaning elements may therefore provide cleaning of both sides of the subject’s teeth.

[0022] In some embodiments, the intrinsic stiffness value of the first cleaning elements is greater than the intrinsic stiffness value of the second cleaning elements. It has been shown that optimal cleaning of the incisors occurs when the brush elements contacting the facial surface of the teeth are stiffer than those contacting the lingual surface of the teeth.

[0023] In some embodiments, the first cleaning elements may project from the first portion of the dental tray a first distance, the second cleaning elements may project from the second portion of the dental tray a second distance, and the first distance may be shorter than the second distance. The stiffness of a cleaning element may directly relate to the length it projects from the surface of the mouthpiece. This design may therefore ensure a stiffness imbalance between the facial side of the mouthpiece and the lingual side of the mouthpiece as required for optimal cleaning.

[0024] In some embodiments, the number of first cleaning elements may be greater than the number of second cleaning elements. Due to the arc length of the outer facial surface of the mouthpiece being greater than the arc length of the inner lingual side of the mouthpiece, there is more space for cleaning elements on the outer side of the mouthpiece. Optimal cleaning may be provided by ensuring a similar density of cleaning elements on the facial and lingual portions of the mouthpiece.

[0025] In some embodiments, a cleaning element may be at least one of: a bristle; a tuft of bristles; a fibre; a group of fibres; an elongate projection that has an orifice for a waterjet; a rubber pillar; and a plastic pillar. Each of these elements may provide different cleaning benefits when used within a mouthpiece device.

[0026] In some embodiments, the hinge arrangement may comprise a plurality of hinges, and the dental tray comprises a plurality of tray segments including at least a first segment and a second segment, and wherein each of the plurality of hinges is configured to couple a pair of adjacent tray segments to permit rotation of a first of the pair of adjacent tray segments relative to a second of the pair of adjacent tray segments about an axis substantially orthogonal to the longitudinal direction. Thus, the dental tray may comprise more than two segments in order to provide further flexibility of the mouthpiece to adapt to the particular teeth and / or gum anatomy of the subject. In some embodiments, the plurality of hinges may be positioned along the lingual side of the dental tray, being the side of the dental tray adjacent to the inner surface of the subject’s teeth when the device is in use. The position of hinges along only the lingual edge of the dental arch of the mouthpiece is one possible configuration that ensures a straightening only design.

[0027] In some embodiments, the hinge arrangement may comprise a flexible segment configured to deform so as to permit rotation of the first segment relative to the second segment. Using a flexible portion in this way may be more robust than a traditional hinge arrangement.

[0028] In some embodiments, the hinge arrangement may comprise at least one of: a partial gap in the dental tray that extends radially; a knuckle and a pin; and a film hinge. The hinge arrangement is not limited to any particular form of hinge mechanism but may be realised by many different designs.

[0029] In some embodiments, the mouthpiece may be at least one of: a brushing mouthpiece; a light mouthpiece; a whitening mouthpiece; and a mouthguard. The design rule proposed by the present invention may be suitable for application to various different oral products that require a mouthpiece device to fit users of different jaw sizes and shapes.

[0030] Thus, there may be proposed concepts for providing a mouthpiece device for insertion into a subject’s mouth wherein the dental arch curvature of the rest configuration is configured to be greater than the 90thpercentile dental arch curvature of the intended user population.

[0031] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiment(s) described hereinafter.

[0032] BRIEF DESCRIPTION OF THE DRAWINGS

[0033] For a better understanding of the invention, and to show more clearly how it may be carried into effect, reference will now be made, by way of example only, to the accompanying drawings, in which:

[0034] Figs. 1A and IB are schematic diagrams of a mouthpiece device for insertion into a subject’s mouth during use according to a proposed embodiment, in a rest and use configuration respectively;

[0035] Fig. 2 is a schematic diagram depicting how dental arch curvature may vary for different subjects in a user population;

[0036] Figs. 3A and 3B are schematic diagrams of a mouthpiece device according to an alternative embodiment in a first use position and a second use position respectively; and Fig. 4 is a schematic diagram of a brushing mouthpiece device according to another embodiment.

[0037] DETAILED DESCRIPTION OF THE EMBODIMENTS

[0038] The invention will be described with reference to the Figures.

[0039] It should be understood that the detailed description and specific examples, while indicating exemplary embodiments of the apparatus, systems and methods, 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 apparatus, systems and methods of the present invention will become better understood from the following description, appended claims, and accompanying drawings. It should be understood that the Figures are merely schematic and are not drawn to scale. It should also be understood that the same reference numerals are used throughout the Figures to indicate the same or similar parts.

[0040] Implementations in accordance with the present disclosure relate to various techniques, methods, schemes and / or solutions pertaining to mouthpiece devices for insertion into a subject’s mouth during use, wherein the subject is one of a plurality of members of an intended user population. According to proposed concepts, possible solutions may be implemented separately or jointly. That is, although these possible solutions may be described below separately, two or more of these possible solutions may be implemented in one combination or another.

[0041] Embodiments of the invention aim to provide a mouthpiece device for insertion into a subject’s mouth during use, wherein the subject is one of a plurality of members of an intended user population, and wherein the dental arch curvature of the mouthpiece in a rest configuration is set to be greater than the 90thpercentile dental arch curvature value of the intended user population. This ensures that, for nearly all subjects, the mouthpiece is only required to straighten (decrease its curvature) to adapt to the jaw shape of the user. This may be advantageous, as for this design the resultant force required to deform the mouthpiece to fit the dental arch of a subject matches a stiffness imbalance present between the facial and lingual portions of the mouthpiece device.

[0042] Proposed concepts thus aim to provide a mouthpiece device which is designed such that in a rest configuration the dental arch curvature of the mouthpiece is set to be greater than the 90thpercentile dental arch curvature value of the intended user population to achieve an improved fit of the mouthpiece device to a subject’s teeth and gums in use. Referring now to Fig. 1 A and Fig. IB, there is depicted a mouthpiece device 100 for insertion into a subject’s mouth during use, in a rest configuration and a use configuration respectively.

[0043] The mouthpiece device 100 is inserted into a subject’s mouth during use, the subject being one of a plurality of members of an intended user population associated with the mouthpiece device 100. The plurality of members of the intended user population share at least one demographic parameter comprising at least one of: a gender; an age (or age range); an ethnicity; and a nationality. For example, the mouthpiece 100 may be designed for the population of European adult females. The mouthpiece 100 comprises a dental tray 110 extending in a longitudinal direction with a dental arch curvature which is configured to accommodate a section of teeth and / or gums of the subject when in use. In this exemplary embodiment, the mouthpiece device has a C- or U- shape configured to mimic the full dental arch shape.

[0044] In this exemplary embodiment, the dental tray 110 comprises a plurality of tray segments 115, including at least a first segment 111 and a second segment 112, connected by a plurality of hinges 125 that form the hinge arrangement 120. Each of the plurality of hinges 125 is configured to couple a pair of adjacent tray segments to permit rotation of a first of the pair of adjacent tray segments relative to a second of the pair of adjacent tray segments about an axis substantially orthogonal to the longitudinal direction. This allows for the orientation of each tray segment 125 relative to its neighbours to be adjusted. The plurality of hinges 125 are positioned along the lingual side of the dental tray 110, this being the side of the dental tray adjacent to the inner surface of the subject’s teeth when the device is in use. The plurality of hinges 125 in this exemplary embodiment are conventional hinge mechanisms formed of a knuckle and a pin.

[0045] Figure 1 A depicts the device 100 in a rest configuration with a rest dental arch curvature indicated by the dashed arc line 130. The rest dental arch curvature may be quantified by its curvature radius indicated by the arrow 135. The device 100 is biased towards the rest configuration such that when no external stress or strain is placed on the device 100 it lies in its rest configuration. In this way the rest configuration can be thought of as the natural configuration of the device 100. In use, due to the flexible nature of the mouthpiece its configuration may change from the rest configuration to a use configuration as it is inserted into a subject’s mouth. Once removed, the mouthpiece may return to its rest configuration. In design of the mouthpiece 100, the dental arch curvature in the rest configuration is set to be greater than the 90thpercentile dental arch curvature value of the indented user population.

[0046] In use, the mouthpiece device 100 is inserted into the subject’s mouth. Due to the different dental arch shapes present in the intended user population, this requires the mouthpiece to adapt to the particular anatomy of the teeth and / or gums of the subject. The flexibility of the mouthpiece device introduced by the hinge arrangement 120 allows rotation of at least a first segment of the plurality of segments 115 relative to a second segment of the plurality of segments 115 about an axis substantially orthogonal to the longitudinal direction to move the mouthpiece from the rest configuration to a use configuration. One example use configuration of the mouthpiece device 100 is depicted in Figure IB. Since the dental arch curvature of the rest configuration of the mouthpiece 100 is set to be greater than the 90thpercentile dental arch curvature value of the intended user population, for 90% of the members of the intended user population the use configuration has a smaller curvature than the rest configuration (as shown by the greater radius of curvature 145 shown in Figure IB). Therefore, the hinge arrangement 120 needs only to be configured to permit relative rotation of the plurality of segments 125 so as to decrease the dental arch curvature of the mouthpiece in order for the mouthpiece to be suitable for 90% of the intended user population.

[0047] To adjust the mouthpiece device from its rest configuration to a use configuration requires a resultant force. This may be produced either by manual manipulation or from the contact the mouthpiece device makes with the oral surfaces of the user. In many mouthpiece devices, a natural stiffness imbalance will be present between the side of the mouthpiece that is adjacent to the facial / buccal surfaces of the subject’s teeth when the device is in use and the side of the mouthpiece that is adjacent to the lingual surfaces of the subject’s teeth when it is in use. This stiffness imbalance will often mean that it is much easier to decrease the curvature of the mouthpiece from the rest configuration, than to increase it.

[0048] In currently available mouthpiece devices, that are designed for the average dental arch curvature of the plurality of members of the intended user population, for subjects with tighter than average dental arch curvatures the adjustment force is required to work against the stiffness imbalance of the mouthpiece. The proposed invention is therefore advantageous in that for 90% of subjects in the intended user population, adjusting the mouthpiece device from the rest configuration to the use configuration only requires applying a force that acts in the same direction as the intrinsic stiffness imbalance present in the mouthpiece and therefore adjustment of the mouthpiece is made easier. The mouthpiece device 100 may comprise other elements not shown that may relate to its use in an oral care device. For example, the mouthpiece device may comprise at least one of: a brushing mouthpiece; a light mouthpiece; a whitening mouthpiece; and a mouthguard, and the mouthpiece device 100 may further comprise cleaning and / or light emitting elements. It will be understood that the concepts of the present invention may be applied to any oral care product that comprises a mouthpiece.

[0049] The mouthpiece device 100 has a U- or C- shaped dental tray configured to receive the full maxillary or mandibular arch. Alternatively, the mouthpiece device 100 may be J- shaped so as to receive half a dental arch of the subject or of an even smaller shape to receive fewer teeth of the subject. Similarly, other aspects of the present invention may be implemented differently in different embodiments. The dental tray 110 is formed of discontinuous segments, however the concepts of the proposed invention may be applied equally well to a continuous mouthpiece device. In that instance, flexibility of the mouthpiece may be achieved by a hinge arrangement that comprises a flexible segment of the mouthpiece continuously separating a first segment of the continuous mouthpiece to a second segment, or alternatively the hinge arrangement may comprise a partial gap in the dental tray that extends radially.

[0050] The dental tray 110 may contain any number of segments greater than or equal to two. A greater number of segments provides greater flexibility, but fewer segments may allow greater treatment coverage in the case of an oral care product. The hinge arrangement 120 may comprise only one hinge element rather than a plurality and this may be any suitable hinge element that permits rotation of at least a first segment of the dental tray relative to a second segment of the dental tray about an axis substantially orthogonal to the longitudinal direction. For example, the hinge arrangement of a proposed embodiment may comprise at least one of: a film hinge, a partial gap in the dental dray extending radially, or a flexible segment configured to connect the first segment to the second segment and adapted to deform to permit rotation of the first segment relative to the second segment.

[0051] In this exemplary embodiment, the 90thpercentile dental arch curvature value of the intended user population is used to set the dental arch curvature of the rest configuration of the mouthpiece device 100 however other suitable statistical values may be used. For example, the dental arch curvature of the mouthpiece device 100 in the rest configuration may be set to be greater than the 95thpercentile dental arch curvature value of the intended user population, or the dental arch curvature of the mouthpiece in the rest configuration may be set to be greater than the 99thpercentile dental arch curvature value of the intended user population.

[0052] Referring now to Figure 2, there is provided a schematic diagram depicting how dental arch curvature may vary for different subjects in a user population.

[0053] The left-hand side of Figure 2 shows a first contour map 210 of the surface of a first subject’s dental arch. This first subject has a first dental arch curvature shown by the dotted semicircle 212. The first dental arch curvature may be quantified by the first curvature radius indicated by the arrow 214 in Figure 2.

[0054] The right-hand side of Figure 2 shows a second contour map 220 of the surface of a second subject’s dental arch. Both the second subject and the first subject are members of an intended user population and may share at least one demographic characteristic. The second subject has a dental arch curvature indicated by the dashed semicircle 222 with a corresponding second curvature radius 224. As can be seen from Figure 2 the first dental arch curvature of the first subject is greater than the second dental arch curvature of the second subject. A large range of dental arch curvatures may be present in the intended user population.

[0055] The intended user population is defined as the group of individuals the mouthpiece device has been designed to be suitable for. Mouthpiece arches may vary significantly in shape and size among the whole human population and therefore in order to achieve a well-fitting device, the intended user population may be restricted to a subset of the human population. The intended user population may be chosen to consist of individuals likely to share certain dental arch characteristics such as shape and size. This may correspond to restricting the intended user population to a particular demographic group e.g., restricting the intended user population to a particular age range or gender group.

[0056] Figure 2 depicts one possible method of measuring and defining the dental arch curvature. A circular arc shape is fit to the mesial (frontal) teeth of the subject and the dental arch curvature quantified by the radius associated with this circular arc shape. In particular, the curvature is equal to 1 / / ?, where A is the determined curvature radius. Fitting the circular arc shape in this way may be achieved manually (i.e., by eye) or via a computer program.

[0057] The curvature may also be quantified if the curve of the subject’s dental arch is fit to a mathematical function. Historically, there are many ways in which a dental arch may be described mathematically, including parameterisation of the arch as a polynomial, parabola, or ellipse. The curvature of the arch is then defined as the derivative of the unit tangent vector at any point along the dental arch curve. In particular, for a curve parameterised in terms of the length along its arc such that it can be written as (s) = (x(s),y(s)), the tangent vector of the curve at a point 5 along the curve is defined as, T(s) = (x'(s),y'(s)).

[0058] The curvature of the curve is then given by the expression: The two methods of calculating curvature presented here produce broadly equivalent results.

[0059] The curvature of the dental arch is likely to vary between the distal and mesial portions of the arch. In other words, not all points of the dental arch may be well fit by the same circular arc. For the purpose of the proposed invention, the dental arch curvature of a subject or mouthpiece device may be defined as: an average curvature value taken across the entire arch; the curvature measured at the central front point of a dental arch; or the maximum curvature present in a set of curvature values calculated at a sample of points along the dental arch.

[0060] Statistical data on dental arch measurements and curve fittings for various possible intended user populations have been extensively analysed and published in scientific research journals. For example, studies carried out have explored mathematical modelling of dental arches (AlHarbi et al., 2008. Mathematical Analyses of Dental Arch Curvature in Normal Occlusion.. Angle Orthod, March, 78(2), pp. 281-287; and Fu, K. et al., 2021. Analysis of dental and basal bone arch form correlations in skeletal Class II malocclusion. American Journal of Orthodontics and Dentofacial Orthopedics, February, 159(2), pp. 202- 209.), the differences between dental arch forms of subjects with different nationalities (Celebi, A. A., et al., 2016. Comparison of arch forms between Turkish and North American. Dental Press Journal of Orthodontics, March, 21(2), pp. 51-58.), and the classification of different arch forms (Aljayousi, M., et al., 2021. Maxillary and mandibular dental arch forms in a Jordanian population with normal occlusion. BMC Oral Health, March, 21(105) , pp. 105). Any similar such sampled patient data may be analysed to determine percentile dental arch curvature values for an intended user population.

[0061] In detail, sampled measurements of positions, orientations, and shapes of subjects’ teeth may be used to determine a quantitative dental arch curvature value for each sampled subject using the methods outlined above. The subjects are chosen to all be members of the intended user population. The dental arch curvature values of the sample can then be used to determine the underlying statistical distribution of curvature values in the intended user population as a whole. For example, the dental arch curvature values may be fit to a Gaussian distribution. The percentile curvature values of the fitted statistical distribution can then be calculated and used in the proposed invention. In this way, sampled dental arch data such as that used in the research outlined above may be used to determine the dental arch curvature of a mouthpiece device in its rest position.

[0062] Referring now to Figures 3 A and 3B, there is depicted a schematic diagram of a mouthpiece device 300 according to an alternative embodiment, in a first use configuration and a second use configuration respectively.

[0063] Some oral care products that contain mouthpiece devices may require the user to adjust the position of the mouthpiece during use in order to ensure that all surfaces of the teeth and gums of the user are treated. For example, in the case of a brushing mouthpiece a user may be required to move the mouthpiece back and forth across the surfaces of their teeth and gums to ensure optimal cleaning. The proposed mouthpiece design may also provide the flexibility required for this purpose.

[0064] The mouthpiece device 300 is a J-shaped device comprising a plurality of dental tray segments 115 which are configured to accommodate a portion of a subject’s teeth and gums (which are depicted in Figure 3 A by the shaded arch 310). Adjacent dental tray segments are coupled together by the plurality of hinges 125 which permit adjustment of the orientation of a tray segment relative to its neighbour. In particular, the plurality of hinges 125 permit the rotation of a first of a pair of neighbouring tray segments relative to the second of the pair of tray segments, about an axis substantially orthogonal to the longitudinal direction defined by the subject’s dental arch 310.

[0065] The mouthpiece device 300 is biased towards a rest configuration and the dental arch curvature of the mouthpiece device 300 in the rest configuration is set to be greater than the 90thpercentile dental arch curvature of the intended user population the mouthpiece has been designed for.

[0066] In use, the subject may move the mouthpiece device 300 from a first use configuration, shown in Figure 3A, to a second use configuration shown in Figure 3B. In this exemplary embodiment this involves moving the mouthpiece to a distal section of the user’s teeth and gums so as to ensure treatment coverage of the molars and / or premolars. The front portion of a subject’s dental arch in most cases has a greater curvature than the distal portion of subject’s dental arch. Thus, provided calculation of the 90thpercental dental arch curvature value comprises analysing dental arch curvature values of the intended user population that comprise at least one of frontal dental arch curvature values, maximum dental arch curvature values calculated across the entirety of the arch, both first and second use configurations will have dental arch curvature values less than that of the rest configuration of the mouthpiece. Therefore, even for a mouthpiece device which is moved along the dental arch during use, the straightening-only design described herein is suitable for the majority of users.

[0067] Referring now to Figure 4, there is depicted a simplified diagram of a brushing mouthpiece 400 according to a proposed embodiment.

[0068] The brushing mouthpiece 400 comprises a continuous dental tray 410 comprising a first segment 411 and a second segment 412. The first and second segments of the dental tray are connected by a hinge arrangement 420 that permits rotation of the first segment relative to the second segment about an axis substantially orthogonal to the longitudinal direction to move the mouthpiece from a rest configuration to a use configuration so as to decrease the dental arch curvature of the mouthpiece. In this exemplary embodiment, the hinge arrangement 420 comprises a partial gap extending radially inwards from the lingual portion of the mouthpiece so as to permit straightening of the mouthpiece.

[0069] The dental tray 410 further comprises a plurality of first cleaning elements 430 projecting from a first portion of the dental tray which is configured to be adjacent to the outer, facial / buccal surface of the teeth of the subject when in use, and a plurality of second cleaning elements 440 projecting from a second portion of the dental tray configured to be adjacent to the inner, lingual surface of the teeth of the subject when in use. In this example, the cleaning elements comprise tufts of bristles. The intrinsic stiffness value of the plurality of first cleaning elements 430 is greater than the intrinsic stiffness of the plurality of second cleaning elements 440. The first cleaning elements 430 project from the first portion of the dental tray a first distance and the second cleaning elements project from the second portion of the dental tray a second distance, and the first distance is shorter than the second distance. The configuration of the stiffnesses and lengths of the first and second bristles in this way may provide optimal cleaning of the subject’s oral surfaces but leads to a stiffness imbalance between the outer, facial portion of the mouthpiece, and the inner lingual portion. As can be seen from Figure 4, The number of first cleaning elements 430 is greater than the number of second cleaning elements 440 due to the longer arc length of the facial portion. This leads to a further geometrically caused stiffness imbalance between the facial side of the mouthpiece and the lingual portion of the mouthpiece.

[0070] The dental arch curvature of the mouthpiece 400 in its rest configuration is set to be greater than the 90thdental arch curvature of the intended user population. This means that in order for the mouthpiece to be suitable for use in at least 90% of the intended user population, the hinge arrangement 420 is only required to permit rotation of the first segment 411 relative to the second segment 412 so as to decrease the curvature of the mouthpiece (i.e. the partial gap 420 is configured to extend from the facial portion of the mouthpiece). In this way, the stiffness imbalance of the mouthpiece due to the bristle configuration works to deform the mouthpiece to fit a user. In traditional mouthpieces which are designed to fit the average dental arch curvature of an intended user population, deformation forces are required to work against this natural stiffness imbalance in some use cases. It will therefore be understood that the proposed invention is particularly advantageous in application to brushing mouthpieces.

[0071] Although in this exemplary embodiment the first and second cleaning elements comprise tufts of bristles, in other embodiments other cleaning elements may be provided. For example, the first and second cleaning elements may comprise at least one of: a bristle; a tuft of bristles; a fibre; a group of fibres; an elongate projection that has an orifice for a waterjet; a rubber pillar; and a plastic pillar.

[0072] Variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure and the appended claims. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. If the term “adapted to” is used in the claims or description, it is noted the term “adapted to” is intended to be equivalent to the term “configured to”. Any reference signs in the claims should not be construed as limiting the scope.

Claims

CLAIMS1. A mouthpiece device ( 100) for insertion into a subj ect’ s mouth during use, wherein the subject is one of a plurality of members of an intended user population and the mouthpiece comprises: a dental tray (110) extending in a longitudinal direction with a dental arch curvature and configured to accommodate a section of teeth and / or gums of the subject when in use; and a hinge arrangement (120) configured to connect at least a first segment (111) of the dental tray to a second segment (112) of the dental tray, wherein the hinge arrangement is configured to permit rotation of the first segment relative to the second segment about an axis substantially orthogonal to the longitudinal direction to move the mouthpiece device from a rest configuration to a use configuration so as to decrease the dental arch curvature of the mouthpiece, wherein the mouthpiece is configured to be biased towards the rest configuration, and wherein the dental arch curvature of the mouthpiece in the rest configuration is set to be greater than the 90thpercentile dental arch curvature value of the intended user population.

2. The mouthpiece device of claim 1, wherein the plurality of members of the intended user population share at least one demographic parameter, preferably wherein the demographic parameter comprises at least one of: a gender; an age; an ethnicity; and a nationality.

3. The mouthpiece device of any preceding claim, wherein the dental arch curvature of the mouthpiece in the rest configuration is set to greater than the 95thpercentile dental arch curvature value of the intended user population, and preferably wherein the dental arch curvature of the mouthpiece in the rest configuration is set to be greater than the 99thpercentile dental arch curvature value of the intended user population,4. The mouthpiece device of any preceding claim, wherein the dental tray comprises: a plurality of first cleaning elements (430) projecting from a first portion of the dental tray configured to be adjacent to the outer, facial / buccal surface of the teeth of the subject when in use; anda plurality of second cleaning elements (440) projecting from a second portion of the dental tray configured to be adjacent to the inner, lingual surface of the teeth of the subject when in use.

5. The mouthpiece device of claim 4, wherein the intrinsic stiffness value of the first cleaning elements (430) is greater than the intrinsic stiffness value of the second cleaning elements (440).

6. The mouthpiece device of any of claims 4 and 5, wherein the first cleaning elements (430) project from the first portion of the dental tray a first distance, the second cleaning elements (440) project from the second portion of the dental tray a second distance, and the first distance is shorter than the second distance.

7. The mouthpiece device of any of claims 4-6, wherein the number of first cleaning elements (430) is greater than the number of second cleaning elements (440).

8. The mouthpiece device of any of claims 4-7, wherein a cleaning element is at least one of: a bristle; a tuft of bristles; a fibre; a group of fibres; an elongate projection that has on orifice for a waterjet; a rubber pillar; and a plastic pillar.

9. The mouthpiece device of any preceding claim, wherein the hinge arrangement (120) comprises a plurality of hinges (125) , and the dental tray (110) comprises a plurality of tray segments (115) including at least a first segment (111) and a second segment (112), and wherein each of the plurality of hinges is configured to couple a pair of adjacent tray segments to permit rotation of a first of the pair of adjacent tray segments relative to a second of the pair of adjacent tray segments about an axis substantially orthogonal to the longitudinal direction.

10. The mouthpiece device of claim 9, wherein the plurality of hinges is positioned along the lingual side of the dental tray, being the side of the dental tray adjacent to the inner surface of the subject’s teeth when the device is in use.

11. The mouthpiece device of any preceding claim, wherein the hinge arrangement comprises a flexible segment configured to deform so as to permit rotation of the first segment relative to the second segment,12. The mouthpiece device of any preceding claim, wherein the hinge arrangement comprises at least one of: a partial gap in the dental tray extending radially; a knuckle and a pin; and a film hinge.

13. The mouthpiece device of any preceding claim, wherein the mouthpiece is at least one of: a brushing mouthpiece; a light mouthpiece; a whitening mouthpiece; and a mouthguard.

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