US3542519A - Toothbrush time-usage indicator - Google Patents

Description

m deze Q T TOP/VEYS NOV 24 1970 F. J. MoNTALTo ETAI- TOOTHBRUSH TIMEUSAGE INDICATOR Filed Feb. 18, 1969 g 07eC @geg/7 .7 -V 27M, WM

United States Patent Office 3,542,519 Patented Nov. 24, 1970 3,542,519 TOOTHBRUSH TIME-USAGE INDICATOR Francis J. Montalto, Chicago, Ill., and W. Kedzie Teller, deceased, late of Sarasota, Fla., by Virginia R. Teller,

administrator, Sarasota, Fla., assignors to Francis I.

Montalto, Chicago, Ill.

Continuation-impart of application Ser. No. 674,693, Oct. 3, 1967. This application Feb. 18, 1969, Ser. No. 800,836

Int. Cl. Gtlld 21 /00 U.S. Cl. 23-253 9 Claims ABSTRACT F THE DISCLOSURE A composition is included on an instrument. When used with a toothbrush the composition is placed near the toothbrush bristles. Then composition changes color, volume or appearance with the passage of a predetermined time period of toothbrush usage, so that upon expiration of the period a suitable indication is given the user to discard the toothbrush and use a new one.

This application is a continuation-impart of our copending application Ser. No. 674,698, filed Oct. 3, 1967, now abandoned.

This invention relates to time passage indicators and in particular to the use of an indicating mechanism for indicating the expiration of a predetermined period of time or period of usage of an instrument, such as a toothbrush.

The present invention can be incorporated into many instruments where the indication of the passage of a predetermined period of time or period of usage is desired. As an illustration of the principles of the invention, and not to be considered in any way as limiting the scope thereof, the invention is especially useful to indicate changes in the desired brushing ability, or the antibacterial conditions of a toothbrush.

Prior to 1938 when the first nylon bristled toothbrushes were sold, all toothbrushes were made with hog or wild boar bristles. Such natural bristles, even when of best quality, broke down, split and otherwise became ineffective for cleaning after four to eight months use. This self limiting life of a natural bristled brush manifested itself to the user who replaced it for a new one.

With the advent of nylon bristled brushes the toughness of this plastic bristle resisted wear for as long as several years. During this prolonged use a brush often became unsanitary through accumulation of biodegradable dcbris around and in the bristle sockets.

One attempt at alleviating this problem concerned the impregnation or treatment of both the nylon bristle and the plastic handle wih antibacterial and/ or germicidal ingredients to maintain these brushes in a sanitary condition for a predetermined period of time. Several such processes are presently used and are described, for instance, in U.S. Pat. 2,836,516 and 3,005,720. These antibacterial bristles and handles `gradually lose this quality of resisting bacterial growth in and around bristle sockets through leaching out of the active germicides. This takes place after four to six months continual use. Such loss in effectiveness is not noticeable to the brush user, hence he is not aware that the brush should be replaced, for its mechanical structure has changed only slightly.

The present invention provides a time passage indicator for instruments. In accordance with the principles of the present invention, there is provided an indicating mechanism combined with a toothbrush to serve as an indication to the user to replace the toothbrush with a new one after a predetermined period of time or period of use. If should be realized, of course, that the principles of this invention are applicable to toothbrushes with or without germicidal impregnation or treatment. That is, when used with toothbrushes not having germicidal impregnation, the indicating mechanism provides an indication of when the toothbrush should be replaced due to a loss of brushing ability. This period of time is usually recommended by the attending dentist for each patient, and some dentists recommend changing toothbrushes after one months usage. Also when used with toothbrushes impregnated 0r treated with antibacterial ingredients, the indicating mechanism provides an indication as to when the toothbrush should be replaced due to a loss of the ability of the toothbrush to resist bacterial growth.

The invention will be better understood from the following detailed description thereof taken in conjunction with the accompanying drawings in which:

FIG. l is a plan view of an embodiment of the invention illustrating a toothbrush incorporating the indicating mechanism according to the principles of the invention;

FIG. 2 is an elevational view partly in section of the upper portion of the toothbrush illustrated in FIG. 1 showing the indicating mechanism positioned in a cavity in the back of the toothbrush;

FIG. 3 is a fragmentary exploded view illustrating the upper half of the toothbrush having a cavity, and one form of the indicating mechanism in accordance with the principles of the present invention; and

FIG. 4 is a fragmentary plan view illustrating an alternative embodiment of the indicating mechanism and toothbrush combination of the present invention.

In accordance with one aspect of the present invention, FIGS. 1 to 3 show a toothbrush having a cavity filled with a material which dissolves in water slowly and which will wear away or leach out of the cavity to provide an indication of usage after a predetermined period of use of the toothbrush, the solubility rate of the material being a function of the period of toothbrush usage, thus a leachable mask is provided in this aspect of the invention.

As an example of the principles of this invention, in FIGS. 1 and 2 there is illustrated a toothbrush having the usual lower handle portion 12 and the upper head portion 14. A series of bristles 16 are held securely in the head portion 14 and protrude therefrom in a normal manner.

Referring specically to FIG. 2, it can be seen that within the upper portion 14 and preferably opposite the bristle 16, there is provided a cavity 18. As an example the cavity 13 can be approximately 64 inch in depth and :iig inch in diameter. The cavity 18 contains the indicating mechanism 20 which includes a composition 22 comprising a relatively insoluble bulk filler or base material mixed with a relatively soluble binder or adhesive to maintain the composition 22 within the cavity 18. The bulk filler or base material should have a solubility in water of between about 500 and about 2000 parts per million and comprise about to about 65% by weight of the composition. Such materials as anhydrous calcium sulfate, insoluble sodium metaphosphate, anhydrous dicalciurnphosphate, and potassium bitartrate are suitable for use as the bulk or base material, but other materials having appropriate solubility characteristics which are nontoxic also may be used. The binder used should be relatively water soluble. Such materials as gum tragacanth, and karaya gum, either plain or mixed with other materials such as polyoxyethylenes are suitable for uses as the binder. The binder should make up from about 5 to about 35% of the composition (on a dry basis), but may be used in greater or lesser quantity if the relative solubilities are changed.

The indicating mechanism 20 includes a suitable form of indication when the composition 22 has been leached out through contact with water. As an example, FIG. 2 illustrates the indicator as provided by a disc 24, approximately $64 inch thick, which has been snapped into the cavity 18 such that the disc 24 will be exposed to the toothbrush user after a predetermined period of time corresponding to the usage of the toothbrush 10. The disc 24 contains a suitable indication which is exposed to the user after the composition 22 has been leached out of the cavity 18.

The positioning of the elements involved in this aspect of the invention can best be seen by referring to the exploded view of FIG. 3. It is preferred, of course, that the indicating mechanism 20 be located in position on the toothbrush such that normal use of the toothbrush will enable the composition 22 to be progressively leached out of the cavity in accordance with the use of the toothbrush. Thus, the indicating mechanism can instead be placed on one or both sides of the upper head portion 14, immediately adjacent the bristles 16.

It was mentioned previously that any suitable indicator can be used. In the illustrations of FIGS. 1-3, the disc can be of a very bright color contrasting with the color of the toothbrush 10 or can include an indication such as R or X. Similarly, the base of the cavity 18 can be lined with a color contrasting with the color of the toothbrush 10 to provide the indication. An alternative emmodiment is shown in FIG. 4. In this embodiment, the base of the cavity 18 includes an indicator such as the illustrated "X.

The composition 22 must, of course, be nontoxic and nonirritating. Furthermore, the composition 22 must be capable of wearing away or being leached out of the cavity after a predetermined period of usage. For instance, if a 180-day usage indicator is desired, assuming twice daily use of the toothbrush, the solubility or dissolution time of the composition 22 should be about l,0801,800 minutes.

Another useful composition employs a water-soluble surface active agent in combination with a water-insoluble organic compound. The presence of the insoluble compound reduces the rate at which the surface-active agent dissolves. Further, since surface active agents have the property of solubilizing insoluble organic compounds, the plug in the cavity dissolves smoothly and at a uniform rate. One such combination involves the use of sodium dioctylsulfosuccinate with microcrystalline wax. Since this combination results in a soft, somewhat greasy plug, it is advantageous to include a solid, inert filler in sufficient quantity to harden the plug and eliminate the greasy feel.

Any of a large variety of surface active agents and insoluble organic compounds may be used. Where the surface-active agent is rapidly soluble in water, it is necessary to use only a small proportion of this component and a large proportion of insoluble organic compound. Where the surface-active agent is slightly soluble or slowly soluble in water, higher ratios of the surface-active agent to the insoluble organic compound are used.

The surface-active agent may be anionic, cationic, amphoteric, or nonionic. The ionic charge characteristic is not relevant to its performance in this application. Examples of poorly soluble or slow dissolving surface-active agents include sodium dioctylsulfosuccinate, sodium stearate, sodium octadecylsulfonate, sodium hexadecylsulfonate, sodium octadecylsulfate, sodium pentadecylbenzene sulfonate, octadecyldimethylammonium chloride, sucrose monostearate, and the four mole ethylene oxide adduct of octadecanol. Examples of surface-active agents that are readily soluble in water include sodium laurate, sodium myristate, sodium lauryl sulfate, sodium dodecylbenzene sulfonate, eetylpyridinium chloride, sucrose monolaurate, and the ten mole ethylene oxide adduct of nonylphenol.

While we have illustrated anionic surface-active agents in the form of their sodium salts, other cations may be used, such as potassium, organic amine and magnesium. The choice of cation can greatly inuence the solubility of the anionic surface-active agent.

The water-insoluble organic component can be selected from a broad range of such compounds. These include various waxes, such as microcrystalline wax, paraffin wax, ceresin wax, and carnauba Wax, as well as stearic acid, stearyl alcohol, cetyl alcohol, hydrogenated tallow, glyceryl monostearate, rosin, glyceryl abietate and stearyl amine.

Another type of indicator which can be used employs a slowly volatile material which is placed over a marking, colored area or some other means which will be readily observed after a volatile material covering has been evaporated. The volatile material can have any one of a nurnber of forms. Thus it can be of wax-like consistency, or it can be a crystalline solid compressed under heat and pressure or fused to a denite form, or it can be a powder that is adhered together through the use of a binder. Alternatively, one may use a liquid material that has been gelled to a solid or a semisolid consistency through the use of a suitable gelling agent.

It is convenient and practical to place the volatile solid or semisolid in a depression or cavity in the handle of the toothbrush, or it can be adhered directly to the handle of the brush.

In one convenient form one can use a circular depression 5%6 inch in diameter by 3&2 inch deep. To observe a marking or color at the bottom of the depression after four months of exposure, one can use a material that boils at about 550 F. (288 C.). Using a material that boils at about this temperature, one can vary the indicator time by changing the dimensions of the depression. For example, by doubling the depth of the depression, while keeping the exposed surface area constant, the time required for complete evaporation would be doubled.

In general, by using materials that boil about 50 F. below about 550 F., the time required for complete evaporation will decrease twoor three-fold. Similarly, raising the boiling point by 50 F. will increase the time required for complete evaporation twoor three-fold.

Since the dimensions of the indicating device may vary, one can conveniently use materials that boil in the range of 450650 F. (232-343 C.). However, the preferred range is 500-600 F. (260-315 (3.). It will be evident that the factor which determines the evaporation rate of a material is its vapor pressure at ambient temperatures. Dissimilar compounds having the same boiling point can have quite different vapor pressures at very much lower temperatures. However, the temperature range specified above can be expected to include many useful materials.

In addition to having a suitable boiling point, the volatile material should be essentially insoluble in water. Otherwise, it may wash away and not provide the proper time indication.

Examples of compounds that are suitable for use as volatile time indicators include acertaphthene (277 C), benzophenone, 306 C.). a-bromonaphthalene (282 C.), a-chloronaphthalene (263 C.), dibenzylketone (331 C.), diphenyl (255 C.), diphenylmethane (266 C), uorene (298 C.), hexadecane (287 C.), a-naphthol (288 C), -naphthol (295 C.), pelargonic acid (254 C.), n-tetracosane (324 C.), and tributyrin (315 C.). Most of these compounds are solids at ambient temperatures and can be fused into plugs and forced into the depression on the handle of the toothbrush. Tributyrin illustrates a liquid that can be gelled with a polymeric material such as ethyl cellulose.

Another time indicator can use a redox indicator applied in its reduced form to the handle of a toothbrush, and which is capable of being oxidized to a dilerent color on exposure to air. Indicators of this description will change to the oxidized form fairly rapidly when exposed to air, that is, within a few days at most. However, by placing a barrier between the dye and the atmosphere the rate at which oxygen contacts the indicator can be greatly reduced and the time required for the redox indicator to undergo a color change can be greatly increased.

A convenient method of accomplishing the desired result is to coat one side of a plastic film with the indicator and adhere the coated side to a toothbrush handle. The time required for the indicator to change color will depend on the nature and the thickness of the plastic film. The redox indicator can be present on the film in solution or in undissolved form. The appearance is more attractive and the color change is more vivid if the indicator is in solution.

The following table shows the oxygen permeability of a number of plastic film materials.

Oxygen permeability cc./mil/100 sq. in /24 hr. Poly-para-xylylene 30 Polyvinylidene chloride 1.0 Polyethylene terephthalate 1.8 Polyethylene 350 Polytetrauoroethylene 770 Polystyrene 200 It is evident from this data that the time required for the redox indicator to be converted to its oxidized form can be made to vary over a very broad range depending upon the choice of film material. Thus, for lms of equal thickness it will take 350 times as long for the same quantity of oxygen to penetrate polyvinylidene chloride as will penetrate polyethylene.

The redox indicator that can be used in this device is one that can be oxidized by air to another color when the indicator is initially in reduced form. Often the indicator is colorless in reduced form and colored in oxidized form. In general, redox indicators with normal oxidation potentials of +0.76 volt or smaller are useful. The normal potential is expressed with reference to the potential of the normal hydrogen electrode. As thus expressed, the ferrous-ferrie ion couple has a noma] oxidation potential of +0.76 volt.

The following illustrate redox indicators that can be used in their reduced form. All of these are colorless in reduced form. The color of the oxidized form is shown following the name of the indicator: Safranine T (red), Neutral Red (red), Indigo monosulfonate (blue), Pheno safranine (red), Indigo tetrasulfonate (blue), Nile Blue (blue), Methylene Blue (green-blue), l-Naphthol-Z-sulfonic acid indophenol (red), 2,6-Dibromophenol indophenol (blue), Dphenylamine (violet), and Dphenylbenzidine (violet).

In some instances, the reduced form of the indicator is sensitive to ultraviolet light, and should be protected by including an ultraviolet light absorber in the film. An example of such an absorber is beta-methyl umbelliferone.

Another type of time indicator is one that dissolves to a small extent in water each time the toothbrush is used. This type of indicator is conveniently placed in a depression in back of the bristles. The important requirement is that the indicator dissolve uniformly and at a proper rate. While it is advantageous that the indicator continue to adhere to the walls of the depression until it has completely dissolved, this is not essential, since a mechanical retainer, such as a fine screen, can be placed on top of the depression to prevent the indicator from falling out.

A large number of very slowly soluble inorganic and organic compounds can be used. For example, sodium silicates are available that exhibit a very broad range of solubility rates, depending on the ratio of Na2O:SiO2 and the degree of hydration. Pellets may be prepared from concentrated solutions of these in water and dried to the appropriate water content. In general, it is advantageous to include a water-insoluble inert filler, such as silica,

chalk, or calcium phosphate, in the composition. The use of such fillers reduces shrinkage during the drying of the pellet.

The following example will serve to illustrate several indicator compositions contemplated by this invention, but it is understood that these are set forth merely for illustrative purposes and many other compositions are within the scope of the present invention.

EXAMPLE I In a series of experiments plastic plates (1/4 inch by 6 inches by 6 inches) were prepared with a series of holes drilled in checkerboard fashion on 3A inch centers. These holes were 3;/16 inch in diameter and 1/{52 inch deep.

Mixtures of various materials shown in Table 1 were made into paste form. Two holes in opposite quadrants of the plastic plate were carefully filled to the surface of the plate with each formula. The plates were then dried for one week after `which running tap water was flowed over the surface so as to afford an opportunity to leach and wear away the various filler formulae. This ow of water was conducted for two minutes at 7 a.m. and 7 p.m. each day. The plate was placed on edge for draining and dry ing after each two-minute bath.

Observations were made at desirable intervals to record evidence of leaching. Through this in vitro proccess it was found that the following formulae showed desirable evidences of wearing and leaching. In other words, if some degree of leaching was found after one month but sufficient resistance so that the filler was only partially washed away, such an experiment indicated a possible tiller for practical use in a brush handle.

lCmix contains 00.5 parts powdered karaya gum and 0.5 parts Union Carbidc's PolyoxY (2,000,000 m01. wt. ethylene oxide polymer).

N ute: All amounts are grams.

Toothbrushes with drilled holes as previously described were filled with several of the above formulations using a spatula to press the paste into the depression. The paste was allowed to dry for one week minimum before the toothbrush `was placed in use. In several use tests, brushes with composition or mixture A showed complete leaching in from four to eight weeks, while brushes with composition B showed leaching to expose the bottom of the cavity in about four to six months.

It is to be understood, of course, that instead of forming the composition 22 into a paste for placement into the cavity 18, it is possible to have preformed tablets made of the composition. Such a tablet would be pressed into the cavity 18 in darnp form and allowed to dry whereby the composition 22 would adhere to the cavity walls. Alternatively, the composition may be dry iitted into the cavity and held in place frictionally or by using an insoluble adhesive.

Another suitable indicating mechanism can be provided by drilling an auxiliary depression or cavity in the bottom of the cavity 18. This auxiliary cavity can extend below the bottom of cavity 18 by approximately 1/2 of an inch and can be approximately 1/32 inch in diameter. In an experiment, the auxiliary cavity was filled with a dye tablet using sugar beads coated with the following solution:

Grams FD&C Red #2 dye 0.05 Water 0.2 Gum tragacanth 00.25

The beads were dried as they were stirred so that individual color tablets resulted and of such a size that could be pressed into the auxiliary cavity. Thus, as the composition 22 was leached from the cavity 18, the dye tablet was exposed and gave off an intense red color which indicates the discard warning.

Instead of a water soluble mixture, the indicating mechanism could include suitable mixtures or compositions which wear away or leach out after a predetermined time of exposure to air. In the alternative suitable mixtures which change colors, such as from white to red upon a predetermined exposure, can be utilized.

EXAMPLE II A composition was prepared of the following materials:

G. Dioctyl ester of sodium sulfosuccinic acid (100%) 7.5 Microcrystalline wax (190/ 195 F.) 2.5 Dicalcium phosphate, anhydrous 5.

The dioctyl ester of sodium sulfosuccinic acid and the wax were melted together and the dicalcium phosphate was dispersed in the hot melt. The hot melt was used to till circular depressions :iig inch in diameter by 142 inch deep in a polystyrene panel. The panel was immersed in water at 25 C. for 2 minutes, once every hour for a total of eight immersions per day. The panel was allowed to dry in air between immersions. After 200 minutes of irnmersion, the center of each pellet was worn through, with some pellet material still remaining around the rim.

On the basis of this test, the pellet would appear to act as a 3month time indicator if the teeth were brushed once each day. If we assumed two brushings each day, each for two minutes, it would probably be necessary to increase the depth of the depression to 1A.; inch for a 3month time indication.

Therefore, the foregoing detailed description has been given for clearness of understanding only, and no unnecessary limitations should be understood therefrom, as modiications will be obvious to those skilled in the art.

What is claimed is:

1. A toothbrush time-usage indicator comprising:

a toothbrush having bristles maintained in a portion thereof;

indicating means located on said toothbrush in close proximity to said bristles for indicating to the user the expiration of a predetermined period of usage of said toothbrush;

water-soluble masking means covering said indicating means to render said indicating means non-visible before the expiration of said predetermined period of usage of said toothbrush, said water soluble means including:

a water-soluble composition comprising a relatively insoluble iller and a relatively soluble binder,

said composition having a solubility rate corresponding to the desired predetermined period of usage of said toothbrush.

2. A toothbrush according to claim l wherein said insoluble ller is selected from the group consisting of anhydrous calcium sulfate, anhydrous dicalcium phosphate, insoluble sodium meta phosphate, potassium bitartrate, and mixtures thereof.

3. A toothbrush according to claim 1 in which the binder is a slightly water soluble or slowly water soluble surface active agent and the insoluble filler is a wax.

8 4. A toothbrush time-usage indicator according to claim 1, wherein said visible indicating water-soluble means includes an indicator bearing member not exposed until after the wearing and leaching away of said water soluble composition.

5. A toothbrush time-usage indicator according to claim 4, wherein said indication bearing member comprises a portion of said toothbrush.

6. A toothbrush having bristles maintained in a portion thereof;

indicating means on the toothbrush in close proximity to said bristles for indicating the expiration of a predetermined period of usage of said toothbrush;

said indicating means including a water-soluble composition comprising a relatively insoluble filler and a relatively soluble binder, said composition having a solubility rate corresponding to the desired predetermined period of usage; and

said composition, on a dry basis, including from about to about 65% by weight of said filler and from about 5% to about 35 by weight of said binder.

7. A toothbrush having bristles maintained in a portion thereof;

indicating means on the toothbrush in close proximity to said bristles for indicating the expiration of a predetermined period of usage of said toothbrush;

said indicating means including a water-soluble composition comprising a relatively insoluble filler and a relatively soluble binder, said composition having a solubility rate corresponding to the desired predetermined period of usage; and

said indicating means further including an indicationbearing member positioned in the base of a cavity formed in the toothbrush near the bristles, said indication-bearing member being intermediate the cavity base and said Water soluble composition, whereby after the wearing and leaching away of said water soluble composition from said cavity, said indicationbearing member is exposed indicating the expiration of said predetermined period of usage of said toothbrush.

8. A toothbrush having bristles maintained in a portion thereof; and

indicating means on the toothbrush in close proximity to said bristles for indicating the expiration of a predetermined period of usage of said toothbrush;

said indicating means comprising a material which evaporates slowly placed over an indicia of use.

9. A toothbrush having bristles maintained in a portion thereof; and

indicating means on the toothbrush in close proximity to said bristles for indicating the expiration of a predetermined period of usage of said toothbrush;

said indicating means comprising a redox compound covered by a plastic layer which is slowly oxygen permeable.

References Cited UNITED STATES PATENTS 2,216,333 10/1940 White et al 15-167 UX MORRIS O. WOLK, Primary Examiner R. M. REESE, Assistant Examiner U.S. Cl. X.R.

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