Background Art Dental diseases include both dental caries (tooth decay) and a group of gum diseases, collectively referred to as"periodontal diseases". The most common aetiological factor or causative agent in both tooth decay and gum diseases is the presence of dental plaque.

Historically, tooth decay was the most common of all human diseases effecting man throughout the world. Tooth decay is the result of demineralisation of firstly, the outer layer of tooth enamel and then, subsequently, by a similar demineralisation of the inner body of dentine within the tooth. This demineralisation is brought about by an acid attack on the tooth surface. This acid is most commonly derived from acidogenic activity of the microbiological flora within the plaque mass, as the flora metabolise the carbohydrate content of that same plaque mass, or other sugar compounds within the diet of the host.

However, since the introduction of fluoride into water supplies, toothpastes, drinks, foods, tablets, special solutions and gels applied by the dental professional and through other avenues, the fluoride content of human tooth enamel has increased to the point where many teeth are now much more resistant to acid attack and so dental caries (tooth decay) has declined in significance and incidence throughout the world.

Nevertheless, this relative"strengthening"of human tooth enamel has not addressed the main cause of dental caries, namely that of the presence of dental plaque. Thus, more recently there has been an increase in tooth decay on those tooth surfaces which are not covered by human tooth enamel, such as the roots of the tooth.

Moreover, the gums which comprise soft gingival tissue and the collection of periodontal fibres, connective tissue, cementum, periosteum and bone, commonly referred to as the"periodontal apparatus"and which collectively support and retain the tooth in the mouth, also respond to the presence of dental plaque, to the point where this entire mechanism may break down and the tooth is lost.

Thus, periodontal or gum diseases themselves have now become amongst the most common of all diseases affecting humans throughout the world today and are now the major cause of adult tooth loss.

Ironically the most common cause of both tooth decay and gum diseases is dental plaque. Whilst the diagnosis, treatment and management of these two major dental diseases is within the exclusive domain and responsibility of the dental profession, nevertheless, primary responsibility for the control of the primary causative agent, dental plaque, lies with the individual.

Clearly, the incidence and resultant damage to human health caused by dental plaque would suggest that the tools available to the individual are inadequate.

The present inventor has thoroughly researched the derivation, accumulation and application of dental plaque. As a direct result of this research, the inventor has designed a toothbrush that addresses the very basic requirements of plaque control and this information, technology and appliance form the basis of this patent application.

Dental Diseases: The two most common and significant of all dental diseases are:- 1. Tooth decay-"Dental Caries" 2. Gum diseases-"Periodontal Diseases" Aetiology : The common primary causative agent to both these diseases is dental plaque.

SITES : 1. Local It is estimated that over 75% of dental diseases commence in between the teeth in the area referred to as the"inter-proximal"region and, more specifically and in the classic model, in an area extending from the point of contact between adjacent teeth to the gingival attachment level at the cemento- enamel junction, where the crown of the tooth meets the root of that tooth. This area may be referred to as the"embrasure triangle".

This site is the most important of all dental disease sites, since it contains both hard (tooth) and soft (gum) tissues and so plaque retention in this area may give rise to both tooth decay and gum disease. Indeed it is the site where most food and plaque accumulate. This area may be referred to as the "hot spot"of dental diseases.

Moreover, it is one of the most difficult sites to effectively clean. It is therefore a prime site of dental disease.

The next most significant site for dental diseases, especially periodontal diseases is around the gum line on either the outer ("facial","labial"or"buccal") or inner ("atrial","palatal"or"lingual") surfaces of each tooth or in the gingival sulcus. This factor may be exacerbated by angled, rotated, tilted, crossed or crowded teeth, all of which facilitate the retention of dental plaque and make its removal more difficult.

The next most significant site in the prevention and treatment of dental caries are the deep fissures, which may occupy an area of the top, biting or "occlusal"surface of the tooth. In these areas, small particles of food and/or plaque may be pushed into these fissures and be difficult to remove with conventional devices. Depending upon the local anatomy, these fissures may also represent a very thin layer of tooth enamel and so be more vulnerable to acid attack.

Similar to the fissures, the next most significant site for dental caries to occur, may be in the anatomical anomalies referred to as"pits". These defects in the tooth enamel are often deep and may occur on either the outer ("facial", "labial"or"buccal") or inner ("lingual","atrial"or"palatal") surfaces of the tooth.

2. Regional The above sites identify localised areas on or around the tooth and gum surfaces which are prone to most dental disease attack due to the accumulation and retention of dental plaque. It should be noted that dental plaque is generated daily within a normally healthy mouth. It is a sticky, viscous or gelatinous mass that may grow, unless removed effectively.

However, if dental plaque is let accumulate for more than one day, it may calcify to form calculus (sometimes called"tartar"). This is a harder, chalky mass which binds to the tooth surface and is much more difficult to remove than its softer precursor, dental plaque.

If left to grow and accumulate on the tooth surface, this calculus, being rough attracts more plaque around its mass and so the process continues, the calculus gets larger and more plaque accumulates around the tooth and/or gum surfaces.

A common source of the calcium necessary for this process to occur is the calcium ions, resident within saliva. Thus, at sites where the saliva enters the mouth and subsequent accumulation of calculus takes place, the risk of

dental diseases commencing is increased. The most common sites so described are the inner surfaces of the lower anterior teeth (lingual surfaces of lower incisors) and the outer surfaces of the upper posterior teeth (buccal surfaces of upper molars). Any other site of surface roughness, which retains plaque, such as defective restorations or anatomical anomalies, also represents a disease risk site.

The present inventor has recognised that there exists a continuing need for an effective device for the maintenance of oral hygiene and in particular, the maintenance of good periodontal hygiene. As most individuals routinely brush their teeth with either electrically driven or manually driven toothbrushes, one approach is to improve such toothbrushes. In particular, given that the vast majority of the population utilises manually driven toothbrushes, it would be desirable to provide a manually driven toothbrush that allows an individual to substantially improve that persons oral hygiene. The approach that has been taken is to identify the clinical significance of the embrasure triangle and to provide a toothbrush that it particularly effective in cleaning this region.

Summary of the Invention Accordingly, the present invention consists in a toothbrush comprising a handle which extends to form a planar base in which there is mounted lowers ends of substantially vertically upstanding bristles, the planar base and the bristles forming a head, the bristles being arranged into nine tufts or more each consisting of a plurality of bristles, the tufts being substantially equally spaced apart in the planar base, upper ends of the bristles forming a square pyramidal shape with a base at a height of about 2mm to 10mm above the planar base and an apex with four planar sloping sides, each side of said shape having a slope of from about 45° to about 65° and a length of about 6mm to 10mm, the vertical height of the apex above the base of the square pyramidal shape being from about 4mm to 12mm.

In a second aspect, the present invention further consists in a toothbrush comprising a handle which extends to form a planar base in which there is mounted lowers ends of substantially vertically upstanding bristles, the planar base and the bristles forming a head, the bristles being arranged into two side- by-side arrays each comprising nine tufts or more, each tuft consisting of a plurality of bristles, the tufts in being substantially equally spaced apart in the planar base, upper ends of each array of the bristles forming a square pyramidal shape with a base at a height of about 2mm to 10mm above the

planar base and an apex with four planar sloping sides, each side of said shape having a slope of from about 45° to about 65° and a length of about 6mm to 10mm, the vertical height of each apex above the base of the square pyramidal shape being from 4mm to 12mm.

Disclosure of Invention Throughout this specification the word"comprise", or variations such as "comprises"or"comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

The present inventor has appreciated that the unique shape of the embrasure triangle requires an appropriately shaped brush head to properly access the area for effective cleaning purposes. Essentially the brush head must present an external profile that matches the contour of the dental arch.

Indeed it must be topographically trimmed so as to coincide with the triangular shape in three dimensions. This is achieved by the present invention through the square pyramidal shape that permits the brush head to seat in the embrasure triangle in a"lock and key"fashion. Thus, once the brush head is seated, it assists the user to retain the head in the triangle and affect cleaning.

At the same time, seating of the brush head in this fashion significantly reduces the tendency to brush laterally. Moreover, the brush head is useful for the cleaner of other surfaces of the teeth. Accordingly, it will be appreciated that the toothbrush of the invention represents a significant improvement in oral hygiene.

The bristles are arranged into nine tufts or more each tuft consisting of a plurality of individual bristles. Preferably in the first aspect of the invention, nine tufts will be used in an array of three rows, each row consisting of three tufts. It is, however, within the scope of this aspect of the invention to employ up to sixteen tufts in an array of four rows, each row consisting of four tufts.

In the second aspect of the invention, each of the arrays of tufts is as in the first aspect of the invention. For this aspect, each array is arranged in side- by-side relationship such that, for example, in the nine tuft array, the rows extend longitudinally with respect to the handle. Thus there will be in this case, three rows transverse the head, each row consisting of six tufts extending longitudinally.

It is preferred that the diameter of each tuft is from 1.5mm to 2. 0mm, most preferably about 1.75mm. Within each tuft, the bristles utilised may be have a filament diameter of from 0.01 mm to 0.05mm. A preferred filament diameter is about 0.02mm. A variety of materials may be used to form the bristles, provided that the bristles are sufficiently rigid to clean tooth enamel whilst being sufficiently soft so as to not damage the gums. It is important that the bristles present the necessary rigidity and essential flexibility in use so as to provide reasonable or acceptable longevity of functional performance. One may material that may be used to form the bristles is nylon 600. The person skilled in the art will appreciate that a number of other materials may be used that meet these functional requirements.

Each tuft will include a plurality of bristles. Whilst the number of individual bristles in a tuft may vary, generally the number will be around 30 per tuft.

The slope of the sides in the square pyramidal shape is from about 45° to about 65°. Such slopes are suitable for general use and appropriate for a universal toothbrush. In this case the height of the apex would be 4mm to 12mm, preferably about 7.5mm, whilst the height of the base of square pyramidal shape above the planar base would be 2mm to 10mm, preferably 5mm. However, the present inventor has appreciated that specific stages of dentition have specific requirements in relation to the slope. These considerations are also relevant to the height of the square pyramidal shape.

Conveniently, stages of dentition may be divided into deciduous dentition, mixed dentition and adult dentition.

Thus in the case of deciduous dentition, it is preferred that the slope is from 45° to 55° whilst the height of the apex above the base of the square pyramidal shape is 4mm to 8mm and the height of the base of the square pyramidal shape above the planar base is 2mm to 5mm.

In the case of mixed dentition, it is preferred that the slope is from 50° to 60° whilst the height of the apex above the base of the square pyramidal shape is 5mm to 9mm and the height of the base of the square pyramidal shape above the planar base is 4mm to 6mm.

In the case of adult dentition, it is preferred that the slope is from 45° to 65° whilst the height of the apex above the base of the square pyramidal shape

is 6mm to 12mm and the height of the base of the square pyramidal shape above the planar base is 4mm to 10mm.

Brief Description of Drawings In order to better understand the nature of the invention, examples will be described in relation to the accompanying drawings in which: Figure 1 is a perspective view of a toothbrush head of the invention; Figure 2 is a side elevational view of the head of figure 1; Figure 3 is an end elevational view of the head of figure 1; Figure 4 is an end elevational view of the head of figure 1 with various important dimensions; Figure 5 is a perspective view of a planar base of the head of figure 1; Figure 6 is a perspective view of another planar base; Figures 7A and 7B are side elevational views of dentition showing the toothbrush of the invention in use; Figures 8A and 8B are top plan views of dentition showing the toothbrush of the invention in use; Figures 9A and 9B are end elevational views of dentition showing the toothbrush of the invention in use; and Figures 10A and 10B are end elevational views of dentition showing the toothbrush of the invention in use.

Modes for Carrying Out the Invention In figures 1,2 and 3 there is shown a toothbrush head 10 of the invention which comprises a rectangular planar base 11 and tufts 12 of bristles. As shown, the tufts 12 are arranged into two side-by-side arrays. In the first array, the tufts 12 extend vertically from the planar base 11 in which they are mounted, to a region 20 above which the bristles are formed into the shape of a square pyramid 14. The sides of the square pyramid 14 slope towards an apex 16. In the second array, the tufts 12 extend vertically from the planar base 11 in which they are mounted, to the region 20 above which the bristles are formed into the shape of a square pyramid 13. The sides of the square pyramid 13 slope towards an apex 15.

The various important dimensions of the head 10 are shown in figure 4.

Thus the angle EDF is 55°. This angle corresponds to the slope of the sides of each of the square pyramids 13 and 14. In addition, the length of the slope DE is 8mm with height BC 7.5mm and height AB 5mm. In this figure, BC

corresponds to the vertical height above the base of the square pyramids 13, 14 whilst AB corresponds to the height above the planar base 11.

As is best shown in figure 5, the planar base 11 is provided with an array of apertures 17 into which the tufts 12 bristles are mounted and affixed using adhesive, heat sealing or the like. In this case, there are three rows of tufts, each row having six tufts which extend longitudinally of the placement of a handle (not shown).

In figure 6, an alternate planar base 18 is shown. In this case, there is an array of apertures 19 consisting of four rows each of which includes eight tufts.

To illustrate the manner in which the toothbrush of the invention is utilised, reference is now made to figures 7-10 which show the toothbrush in a variety of cleaning orientations relative to teeth. In all of these figures, parts which are like those of figures 1-6 have been like numbered.

In figures 7A and 7B, brush heads 27 and 28 are shown positioned in relation to teeth 22 and gums 21. In relation to brush head 27, it will be seen that the apexes 16,15 are positioned over the embrasure triangle 24. It is evident that the shape and configuration of the square pyramidal shapes 13,14 will engage with the triangle. Likewise, brush head 28 is shown with the square pyramid 14 engaged in the embrasure triangle 24. At the same time, square pyramid 13 is engaged on other, upper surfaces 25 of the teeth shown.

Figure 7B shows that both square pyramids 13,14 may be engaged simultaneously on upper surfaces of the teeth, other then the embrasure triangle, for effective cleaning.

Similarly, figures 8A and 8B show the same brush heads of figures 7A and 7B respectively positioned adjacent the embrasure triangle but on the side and engaged in the side surfaces of the teeth.

In figures 9A and 9B the brush heads 27, 28 are positioned longitudinally respectively above or engaged with the upper surfaces 25 of the teeth. It is particularly evident in relation to brush head 27 that the square pyramid 14 is well adapted to engage the crown surface.

In figures 10A and 1 OB, the brush heads 27,28 are shown respectively positioned against the surface 29 of the embrasure triangle adjacent the gum and engaged with the tooth in that region.

From the foregoing description and examples, it is evident that the toothbrush of the present invention provides a means by which the individual

may through manual action ensure that the interproximal embrasure triangle is properly cleaned. This is achieved through the sloped, pyramidal shape the apex of which seats in the embrasure triangle to thereby facilitate an effective cleaning action. At the same time, the toothbrushes of the invention provide for effective manual cleaning of all of the oral tissues.

It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.