WO1996022744A1

WO1996022744A1 - Appliance for dental prosthesis identification

Info

Publication number: WO1996022744A1
Application number: PCT/GB1996/000175
Authority: WO
Inventors: Jonathan Paul Shepherd; Douglas Georges Telford
Original assignee: University Of Wales College Of Medicine
Priority date: 1995-01-26
Filing date: 1996-01-26
Publication date: 1996-08-01
Also published as: GB9601614D0; GB2297261A; GB9501522D0

Abstract

A dental appliance comprises a plurality of false teeth (10) mounted on a plate (11) of transparent plastics material. A small ceramics wafer (12) is incorporated in the plastics material. A two-dimensional matrix code is printed or etched onto the wafer, such that the code can be used to determine the identity of the wearer of the dental appliance, say in the event that that person is found dead.

Description

APPLIANCE FOR DENTAL PROSTHESIS IDENTIFICATION

This invention relates to a dental appliance such as bridge, crown or denture, or to a medical appliance such as a prosthetic.

Often the only way of identifying dead bodies is from their dental records, and it will be appreciated that this process is long and time consuming. Sometimes, the dead person may have been wearing a set of dentures, which makes identification difficult because, for example, sets of dentures are often indistinguishable. Also, in the event of a fire in which a person wearing dentures dies, it may be very important to identify that person by tracing back the denture.

We have now devised a dental appliance which can be identified, for example when the person wearing the appliance is found burnt. In accordance with this invention, as seen from a first aspect, there is provided a dental appliance incorporating identification means which comprises a machine-readable code formed on a thermally resistant substrate.

In the event of a fire, a forensic scientist can retrieve the identification means from a badly burnt body in order to identify who the person is by reading the code. Preferably a data base is kept of all the persons wearing dental appliances in accordance with this invention, thus the personal details of any dead person wearing such an appliance can be found by entering the code into the data base.

The dental appliance may comprise a false tooth, in which case the machine-readable code is preferably formed on said false tooth. Alternatively, the identification may be disposed on a tooth support portion of the dental appliance. Preferably the tooth support portion comprises a transparent plastics material, said identification means being embedded in said plastics material. The surface of the substrate is thus protected by the transparent plastics material so that the code is not worn away or discoloured inside the mouth.

Preferably the transparent plastics material comprises methyl methacrylate.

The substrate may comprise a disc, tablet, label or wafer of refractory material, such as ceramics. Silica and alumina are both refractory ceramics materials. Preferably the material is able to withstand temperatures of at least 800°C. In an alternative embodiment the substrate may comprise a false tooth or crown formed from a thermally resistant material such as porcelain, the code being formed directly on the surface of the tooth or crown. Preferably, the machine-readable code can be read optically. A bar code is a well known optically-readable code. However, bar codes tend to be large and contain relatively small amounts of data. Furthermore, bar codes are prone to errors. Thus, preferably the optically-readable code comprises a two dimensional matrix of light and dark coloured regions which represent binary 0 and 1. Such two dimensional matrix codes are small and can contain significantly more data than bar codes. Furthermore, it is possible to perform error correction on damaged codes, in order to retrieve the data.

A large proportion of the population do not wear false teeth, and hence the only way of identifying the majority of dead bodies is from their dental records. A disadvantage of this is that the dead person may have no dental records. In any event, it is not practical to search for dental records without initially knowing who the dead person may be.

Thus, in accordance with this invention, as seen from a second aspect, there is provided a medical appliance incorporating identification means which comprises a machine- readable code formed on a thermally resistant substrate.

An increasing number of persons are being fitted with medical appliances, and thus if any such person is found dead their body can easily be identified from the machine-readable code. Another advantage of incorporating identification means in or on medical appliances is that the wearers of certain appliances can easily be traced from records e.g. in the event that the appliance manufacturer discovers faults with those appliances.

A number of different manufacturers may manufacture the same medical appliance, and thus it is often difficult to tell who has made a particular appliance, for example in the event that the wearer wishes to sue the manufacturer of a faulty appliance. However, the manufacturer of a particular appliance in accordance with this invention can easily be traced from records by reading the code.

It is envisaged that the identification means could be fitted to medical prosthetic appliances or surgical implants, such as artificial hips, knees, heart valves or limbs. In one embodiment the substrate may be bonded onto a portion of the appliance. In an alternative embodiment the identification means may be embedded in a transparent plastics portion of the appliance.

Preferably the substrate comprises a refractory material, such as ceramics.

An embodiment of this invention will now be described by way of example only and with reference to the accompanying drawings, in which:

FIGURE 1 is a plan view of a denture in accordance with this invention;

FIGURE 2 is a sectional view along the line II-II of Figure 1; and

FIGURE 3 is a diagram of a machine readable code of the denture of Figure 1. Referring to Figures 1 and 2 of the drawings, there is shown a denture comprising a plurality of artificial teeth 10 formed from porcelain. The teeth 10 are set in a so-called plate 11 which is formed from a transparent methyl methacrylate plastics resin. The plate 11 is formed from an impression which is taken from the patient's mouth.

A thin ceramics wafer 12 is incorporated into the plate as it is formed. The label 12 comprises a machine-readable code on one side, and the label 11 is thus arranged close to a surface of the plate such that its code is readable through the plastics resin.

The code is marked on the ceramics wafer 12 by thermal transfer printing, using a high temperature resistant material ribbon. Alternatively, the code may be ink jet printed onto the wafer, preferably using a ceramics ink. It is also possible to mark the wafer using a laser beam. In one embodiment a laser is fired at a smooth surface of the wafer, so that the areas of wafer exposed to radiation are roughened, and so appear as a different colour owing to diffusion of light on the surface. In another embodiment, say where the ceramics material would be unaffected by laser radiation, a coloured dye is fired onto the wafer surface and then areas of this dye are removed using the laser. It will be appreciated that the plastics resin of the plate 11 entirely surrounds the wafer, and thus protects the wafer surface against abrasion, staining and chemical attack.

Referring to Figure 3 , the machine-readable code 32 comprises a two-dimensional code, or so-called data-matrix code. These codes comprise light and dark areas which represent binary 0 and 1 respectively. The code comprises an outer boundary 30 that is used by the optical reading apparatus to find the code and to define the size and orientation of the matrix. The data 31 is contained within the perimeter of the boundary 30. Such data matrix codes are as small as 3 x 3 mm and can hold between 1 and 2,000 alpha-numeric characters, for example a 3 x 3 mm code can hold 50 alpha-numeric characters.

In a fire, the ceramics wafer 12 is unaffected by the heat, and thus a forensic scientist can easily determine who the person is by reading the matrix-code and entering it into a computer data base, which stores the matrix codes and personal details of all persons wearing such dentures or other dental appliances.

Claims

1) A dental appliance incorporating identification means which comprises a machine-readable code formed on a thermally resistant substrate.

2) A dental appliance as claimed in claim 1, comprising a false tooth.

3) A dental appliance as claimed in claim 2, in which the machine-readable code is formed on said false tooth.

4) A dental appliance as claimed in claim 1, comprising a tooth support portion, said identification means being disposed on said tooth support portion.

5) A dental appliance as claimed in claim 4, in which the tooth support portion comprises a transparent plastics material, said identification means being embedded in said plastics material.

6) A dental appliance as claimed in claim 1, in which the substrate comprises a refractory material.

7) A dental appliance as claimed in claim 6, in which the substrate comprises a ceramic material.

8) A dental appliance as claimed in any preceding claim, in which the machine-readable code can be read optically.

9) A dental appliance as claimed in claim 8, in which the optically-readable code comprises a two dimensional matrix of light and dark coloured regions which represent binary 0 and 1.

10) A medical appliance incorporating identification means which comprises a machine-readable code formed on a thermally resistant substrate. 11) A medical appliance as claimed in claim 10, in which the substrate is bonded onto a portion of the appliance.

12) A medical appliance as claimed in claim 10, in which the identification means is embedded in a transparent plastics portion of the appliance.

13) A medical appliance as claimed in any of claims 10 to 12, in which the substrate comprises a refractory material.

14) A medical appliance as claimed in claim 13, in which the substrate comprises a ceramics material.