Process that confers antibacterial properties on toothbrushes

The invention concerns toothbrushes.

Objects of every-day use are the ordinary toothbru- shes made of plastic material

One of their chief drawbacks is the difficult of tho¬ roughly cleaning them, especially between the bristles, real or synthetic, and the area in which they are in¬ serted. In this area conditions are almost inevitably created for production of considerable quantities of bacterial flora which can lead to infection, sometimes serious infection, of the oral cavity and especially of the gums and teeth. By its very nature plastic material cannot adequately prevent incubation of noxious bacteria so that, seen from the aspects of health and hygiene,- ordinary tooth¬ brushes must be considered unreliable.

Subject of the invention is a process for conferring an ibacterial properties on toothbrushes. A layer of noble metal is laid on the toothbrush so as to cover at least the whole of the area in which there are holes placed to receive the bristles.

According to the various forms of utilization, the layer of noble metal can penetrate inside said holes and may be extended to form a peripheral ring round the base of the bristles. In one version the layer of noble metal consists of a separate plate coated with said metal and fitted into a seat made for it in the area containing holes for the bristles . In one version the layer of noble metal consists of a plate of noble metal.

In another version the layer of noble metal consists of a sheet of said metal fixed onto the area which contains the holes for bristles. At said holes the sheet may be funnel-shaped with a col- lar that adheres to the walls of the holes thus increas¬ ing the surface of the metal in contact with the bristles. The layer of noble metal may be applied by electroplating or by a transfer process in which pressure and heat are applied to a strip of said noble metal laid on the body of the toothbrush causing the pressed area of the strip to adhere to the body of the toothbrush.

The layer of noble metal can also be applied by a silk- screening process, by immersion or by some other process. Adhesion of the pressed metal to the body of the tooth- brush may be assisted by pretreating the strip with ad- hesives, glues, reactive products generally.

The noble metal may be silver or gold.

The toothbrush made by the process described can con¬ sist of a single bar of plastic material forming a handle and a base for the bristles, or can consist of at least two pieces, one being a bar for the handle and the other a head to carry the bristles. Association between the head and the handle is realized by an elastic joint, subs antially of the male-female type, said type of joint making it possible for the user to replace a part if worn out or for other reasons.

Association between head and handle can also be realized by connecting means such as a bayonet or thread, or by some other form of mobile connection. Association between head and handle may advantageously be realized by lateral projections on the body of the head, which projections can be pressed elastically in¬ side corresponding cavities present in the walls of a seat made in the handle to receive the body of the head, or may be realized by lateral cavities in the body of the head into which can be pressed lateral projections present in the walls of a seat made in the handle to receive the body of the head.

The invention clearly offers many advantages. The toothbrush is rendered a hygienic tool and is ste- rilized by action of the noble metal which, on contact with the bristles, carries out its bactericide action even through a vehicle of water that impregnates the bristles . Even those bristles which are not in direct contact with the noble metal are rendered hygienic and are sterilized by the metal ions transported by the water.

The advantages may be summarised as follows: longer life for the toothbrush, protection against infection, marked antibacterial action by the noble metals, espe¬ cially in view of the delicacy of the oral cavity and impossibility of achieving thorough internal cleansing with the toothbrushes at present in use. Characteristics and purposes of the invention will be made still clearer by the following examples of its execution illustrated by diagra matically drawn figures. Fig. 1 Plan view of the invented toothbrush of mono¬ lithic structure having a layer of silver on the area containing holes for the bristles. Fig. 2 As above but seen from the side, partly cut away. Fig. 3 Variant of the toothbrush in Fig. 1 with a layer of silver penetrating inside the bristle holes, side view partly cut away. Fig. 4 Variant of the toothbrush in Fig. 1 with a silver or silver-plated lamina fixed on the area contain- the bristle holes, side view partly cut away. Fig. 5 Variant of the toothbrush in Fig. 1 with a sheet of silver made with collars for the holes in the bris le-holding area of the toothbrush, side view partly cut away . Fig. 6 Variant of the toothbrush in Fig. l, plan view, showing a silver coating at least over all the bristle-holding part. Fig. 7 Side view of the toothbrush in Fig. 6. Fig. 8 Another toothbrush in two parts, a handle and head for the bristles, coated with gold in the area for the bristles, side view partly cut away.

Fig. 9 Plan view of the handle of Fig.8, from the inside.

Fig.10 Side view of the toothbrush in Fig. 9, partly cut away . Fig.11 Head of the toothbrush in Fig. 8, side view partly cut away . Fig.12 Front view of the toothbrush in Fig. 11, cut away . Fig.13 Plan view of the toothbrush head. Fig.14 Toothbrush head seen from below.

The toothbrush 10 consists of a body 11 of solid plastic material in which are dead holes 12 cut to receive bun¬ ches of bris les 13.

On the area 14, in which the holes 12 are made, a layer of silver 15 has been laid.

Said layer has been created by a process of transfer ap- plied to a strip of silver which, in the area 14 of the toothbrush, has been subjected to pressure and heat so as to determine its stable adhesion to the plastic ma¬ terial, aided by adhesives, glues and the like if needed. Alternatively the layer is formed by electroplating or by some other process.

Fig. 3 shows a variant 20 in which the layer of silver 22 is extended to the walls 24 of the holes 23 in the body 21 of the toothbrush.

A further variant 30 is seen in Fig. 4 in which the holes 33 for the bristles are in a slightly recessed area 32 of the body 31 of the toothbrush.

Onto this area 32 a silver or silver-plated lamina 34 is fixed by means of a chemical process using adhesives , glues and the like, or by mechanical fitting or by some other process .

Fig. 5 shows another variant 40 in which a separately prepared

/30351 PCMT94/00093

- 6 - silver-plated sheet 44 is fixed onto the slightly re¬ cessed area 42 of the body 41 in which are situated the holes 43 for the bristles, said sheet having funnel-shaped collars 45 that penetrate into the holes 43. In Figs. 5 and 6 a variant 50 is formed by coating at least the whole part 52, consisting of the head with bristles on the body 51 of the toothbrush, with a layer 53 of silver. This layer is applied by a process of electroplating. If desired the whole body of the toothbrush could of course be coated with silver.

In Fig. 8 is a variant formed of a toothbrush 60 in two parts: the handle 61 and a rectangular head 62 with joins 63 shaped as an arc of a circle.

At the front end 64 of the handle is a seat 65 for the head 62. In said seat is an aperture 66 to allow passage of the jutting part 67 fixed to the top of the head 62. Stability of said head inside the seat 65 in the handle is ensured by the pair of projections 70 on the sides 68 of the head 62 that penetrate into the corresponding ca- vities 69 in the side walls of the seat 65 in the head 62, as shown in Fig. 8, where the head 62 is associated to the handle 61 of the toothbrush 60.

By pressing said jutting part 67 inward with the fingers, the head 62 will be expelled from the handle and so can be replaced with another.

As the figures show, said head 62 has on:it a gold layer 72, equivalent to the silver layer 15 on the toothbrush 10, in the area 73 where the holes 74 for the bristles 75 are situated. Said layer is also obtained by a process of transfer from a strip of gold subjected, in the area 73 on the toothbrush, to pressure and heat such as will make

it adhere in a stable manner to the plastic material, if necessary assisted by adhesives, glues and the like. Alternatively the layer can be created by a silk-screen process or by immersion or by electroplating, or by some other process.

The invention covers all the variants already described and illustrated in Figs. 3 to 7, the only difference being that the noble metal is gold.