MOUTHPIECE FOR BREATHING APPARATUS

Abstract: A method of manufacturing a mouthpiece for a breathing apparatus comprises the steps of forming a mouthpiece blank with a dental impression, producing a mould (20) from the mouthpiece blank and then casting the mouthpiece from the mould (20). The cast mouthpiece thus manufactured has all of the advantages of a customised mouthpiece, whilst suffering none of the drawbacks associated with mouthpieces manufactured by a thermo-forming process.

Description: MOUTHPIECE FOR BREATHING APPARATUS The present invention relates to a mouthpiece for a breathing apparatus. A number of breathing apparatus are known for providing a person with a regulated flow of air and/or other gaseous substances, one example being the various types of self contained underwater breathing apparatus which are nowadays in widespread use by both commercial and recreational divers. The most popular arrangement of self contained underwater breathing apparatus comprises a cylinder of compressed air or gas, from which a supply of air or gas is delivered, via a breathing regulator, to a mouthpiece held between the diver's teeth. The majority of diving mouthpieces are manufactured to standard dimensions. However, the use of such a 'standard' diving mouthpiece often creates an uneven loading of the diver's tempromandibular joint which, over an extended period of time, may lead to discomfort, pain and, in extreme circumstances, blockage of the eustachian tube resulting in labyrinthine dysfunction with associated vestibular disturbances, vertigo and underwater disorientation. It has been shown that tempromandibular strain may be alleviated to a significant extent by providing the diver with his own 'customised' mouthpiece which is adapted to fit his particular dental structure. Hitherto, 'customised' mouthpieces have been manufactured as thermo-formable blanks which are heated and then bitten upon to form them with a unique dental impression. However, such arrangements have a number of significant drawbacks. Firstly, it is difficult to ensure the correct opening of the diver's mouth when forming the mouthpiece. Secondly, the thermo-forming process creates a risk of the diver burning or scalding his mouth. Thirdly, if during its lifetime the mouthpiece is subjected to high temperatures, for example by placing it in strong sunlight, it will become deformed. Another drawback of existing mouthpieces is that they are often unsuitable for partially dentate or edentulous divers who have difficulty retaining the mouthpieces between their teeth. I have now devised an arrangement which overcomes the above-mentioned limitations of existing mouthpieces. In accordance with the present invention, there is provided a method of manufacturing a mouthpiece for a breathing apparatus, the method comprising the steps of forming a mouthpiece blank with a dental impression, producing a mould from the mouthpiece blank and then casting the mouthpiece from the mould. The cast mouthpiece thus manufactured has all of the above-mentioned advantages of a customised mouthpiece, whilst suffering none of the drawbacks associated with mouthpieces manufactured by a thermo-forming process. Preferably the mouthpiece blank comprises a piece of malleable material such as wax, which is formed with a dental impression by shaping the piece of malleable material around and between the maxilla and a mandibular halves of a dental cast. The dental cast may be of the sort commonly used by dentists for preparing dentures, etc. Preferably the mouthpiece blank comprises first and second portions attached to one another, the first portion comprising the piece of malleable material which is formed with a dental impression before being attached to said second portion. Preferably the mould is produced by supporting the mouthpiece blank in a moulding flask, packing the moulding flask with moulding material, for example by a pressure packing or injection moulding process, and then removing the mouthpiece blank. Preferably, when casting the mouthpiece in the mould just described, a keying member is held within the mould cavity, i.e. the space left in the moulding material upon removing the mouthpiece blank. Having cast the mouthpiece, the keying member is then removed from the mouthpiece to form an airway through which the wearer may breathe. Also in accordance with the present invention, there is provided a kit for producing a mouthpiece for a breathing apparatus, the kit comprising a mouthpiece blank capable of being formed with a dental impression, a moulding flask, and a keying member arranged to support the mouthpiece blank within the moulding flask when forming a mouthpiece mould and for forming an airway in the mouthpiece during moulding. Preferably the kit comprises a plurality of mouthpiece blanks to accommodate a variety of dental profiles. Preferably the kit comprises a plurality of keying members, each corresponding with a respective type of breathing regulator fitting. An embodiment of the present invention will now be described with reference to the accompanying drawings, in which: FIGURE 1 is a perspective view of a wax substrate being formed on a dental cast, in accordance with the present invention; FIGURE 2 is a perspective view showing a regulator fitting attached to the formed substrate to provide a mouthpiece blank; FIGURE 3 is a perspective view of the lower half of a mould formed from the mouthpiece blank and used to cast a mouthpiece. Referring to the drawings, in order to produce a mouthpiece according to the present invention, the maxilla and mandibular halves 2, 4 of a dental cast are supported a predetermined distance apart from one another, as shown in figure 1, so that a wax substrate 6 may be shaped around and between the teeth of the cast. Thus, the substrate 6 is formed to provide a relatively thin portion extending over the front of the upper and lower teeth, and also opposite side portions which extend between the molar teeth of the upper set and the molar teeth of the lower set: the thin front portion is formed with a window 14. A member 8, having a portion 10 adapted to connect to a breathing regulator, is then fitted to the front of the shaped wax substrate 6 and secured by a quantity of sticky wax to form a mouthpiece blank. Whilst a mouthpiece blank of this two-part arrangement is convenient in that it allows the manufacturer to shape the relatively thin substrate very accurately around and between the teeth of the cast, the blank may instead comprise a unitary structure which may be shaped around a dental cast, or bitten upon by a person to form it with a dental impression. The mouthpiece blank is separated from the dental cast to allow its fit to be tested in the mouth of the diver so that any necessary adjustments may be made. For this purpose, a handel (not shown) may be temporarily fitted to the adaptor member 8. Once a satisfactory fit is obtained, the handle (if fitted) is removed, and an elongate member 12 passed through the window 14 in the substrate 6 and through an aperture 16 in the adaptor member 8 so that the elongate member 12 projects slightly from the latter. The projecting portion of the elongate member 12 is then held between the opposed edges of upper and lower halves of a moulding flask to support the mouthpiece blank within the interior of the flask. The flask is packed with a moulding material 18 so that when its two halves are separated and the mouthpiece blank removed, a mould is formed from which a mouthpiece blank may be cast, the lower half 20 of the mould thus formed is shown in Figure 3. When casting a mouthpiece, the elongate member 12 is reinserted into the mould so that, when this member is subsequently removed from the cast mouthpiece, an airway is formed through this mouthpiece. It will be appreciated that it is not essential that the blank is formed with a passage 14, 16 therethrough: however, the provision of this passage allows the insertion of the elongate member 12 to provide a convenient means for supporting the blank in the moulding flask. It will also be appreciated that whilst the above method is particularly suitable for the manufacture of customised mouthpieces for fitting to underwater breathing apparatus, the method may instead be used for manufacturing customised mouthpieces for various other breathing apparatus.

Claims: Claims 1) A method of manufacturing a mouthpiece for a breathing apparatus, said method comprising the steps of forming a mouthpiece blank with a dental impression, producing a mould from said mouthpiece blank and then casting said mouthpiece from said mould. 2) A method as claimed in Claim 1, wherein said mouthpiece blank comprises a piece of malleable material which is formed with a dental impression by shaping said piece of malleable material around and between the maxilla and a mandibular halves of a dental cast. 3) A method as claimed in Claim 2, wherein said malleable material comprises wax. 4) A method as claimed in any preceding claim, wherein said mouthpiece blank comprises a first portion and a second portion attached to one other, said first portion comprising said piece of malleable material which is formed with a dental impression before being attached to said second portion. 5) A method as claimed in any preceding claim, wherein said mould is produced by supporting said mouthpiece blank in a moulding flask, packing said moulding flask with moulding material and then removing said mouthpiece blank. 6) A method as claimed in Claim 5, wherein said moulding flask is packed by a pressure packing or injection moulding process. 7) A method as claimed in any preceding claim, wherein a keying member is held within the mould cavity during casting of said mouthpiece, said keying member being subsequently removed from said mouthpiece to form an airway in said mouthpiece through which the wearer may breathe. 8) A kit for producing a mouthpiece for a breathing apparatus, said kit comprising a mouthpiece blank capable of being formed with a dental impression, a moulding flask, and a keying member arranged to support said mouthpiece blank within said moulding flask when forming a mouthpiece mould and for forming an airway in said mouthpiece during moulding. 9) A kit as claimed in Claim 8, comprising a plurality of mouthpiece blanks to accommodate a variety of dental profiles. 10) A kit as claimed in Claim 8 or Claim 9, comprising a plurality of keying members, each corresponding with a respective type of breathing regulator fitting.

Inventors: HARDING RICHARD J, HAY BRIAN DOUGLAS, HARDING, RICHARD, J., HAY, BRIAN, DOUGLAS
Applicants: HARDING RICHARD J, HAY BRIAN DOUGLAS, HARDING, RICHARD, J., HAY, BRIAN, DOUGLAS
Application year: 1998
Main classification: A62B9
IPC codes: A62B9