The present invention relates to a method of reducing the extent of dispersion of material, particularly mercury, released when ^• creating a tooth with a dental instrument. The invention also relates to an arrangement fcr carrying out the method.

Mercury is released in a liquid or a gaseous state when drilling, grinding, polishing, filling or likewise treating teeth containing amalgam fillings. Free mercury vapour is produced by t e heat that is generated when drilling an amalgam tooth filling. Mercury vapours are also emitted frc mercury residues and amalgam residues that are present in the dentist's facilities. The residues of other dental repair materials can also cause problems. Such residues, in vapour, solid or liquid form, are liable to have a deleterious affect on the dentist, dental nurse, dental hygienist and patients.

In an attempt to avoid these problems, water is often sprayed onto a tooth as the tooth is being drilled, and a suction device comprising a tube of relatively large diameter is often held close to the drill by the dentist or dental nurse while drilling the tooth. The water and air sprayed onto the drill and the tooth cavity is delivered throuc.-i a tube fitted en the outside of the angle piece on which the drill tip is mounted, so that the resultant jet of water/air will impinge on the cavity from one side thereof. In so doing, the water jet rebounds against the tooth and is dispersed throughout the ambient space. The suction device used as water is sprayed onto the tooth is unable to extract all of the water that is dispersed, including the vapour that accompanies the water, this vapour consequently being dispersed throughout the room. When drilling or treating molars, it may be difficult to position the suction device close to the tooth being drilled, and consequently still larger quantities of mercury vapour may remain in the oral cavity and thereafter disperse into the room and also accompany saliva down into the patient's stomach and be drawn by suction into the patient's lungs.

With the type of water sprays and suction devices used hitherto, it is not possible to adapt water pressure and suction force in relation to one another. Consequently, the suction force may be too great to prevent adequate cooling of the tooth, while on the other hand the suction force may be too low in relation to the water and air pressure, resulting in further dispersion of loosened material in the oral cavity and in the surrounding space.

Present-day dental techniques tend to use new filling materials instead of amalgam, such as glass ionomers, composites, plastics, etc. It is expected that this tendency will be further increased as a result of legislation concerning the use of amalgam. This will probably influence the working situation of dentists and dental personnel, as a result of their greater exposure to the mercurial atmospheres that are generated when repairing and removing old amalgam fillings. Since these new materials have not been tested sufficiently, the nature of problems that may occur when drilling and repairing fillings comprised of these new materials is not known.

The object of the present invention is to overcome the aforedescri- bed drawbacks when treating teeth with a dental instrument.

To this end, the invention relates to a method of preventing the dispersion of material that is loosened or released when treating teeth with a dental instrument, said method being characterized by spraying coolant and optionally air and/or a binder onto the tooth in the working direction from at least one supply orifice in the instrument, and at the same time generating a suction effect through one or more openings located adjacent to or around the supply orifices in the instrument.

By "working direction" is meant here the direction in which the working implement, e.g. a drill tip or abrasive bit or abrasive wheel is attached to a holder provided on the instrument.

The invention also relates to a tooth treatment arrangement constructed for carrying out the inventive method. This arrangement includes a working implement and at least one coolant and air-

supply conduit, a conduit connected to a suction device for the removal of debris, vapours, minute particles, liquid and/or air, and optionally also a separate conduit for supplying a binder which chemically binds or sorbs the released material, wherein all conduits are arranged in an integrated, common housing and open into or are located adjacent to the working implement.

Irrespective of the dental material used, vapours and debris will depart as the tooth is being treated, these vapours and debris often being of an unhealthy nature. The inventive method and inventive arrangement enable these vapours, gases and debris to be isolated and captured at the location where they occur, and cause the same to be bound and carried away to a safe storage device, for instance to an amalgam separator. No gases, vapours, debris shall be permitted to enter the surrounding space or room from the tooth in the working process.

The inventive method and arrangement can also be used in dental hygiene work, for instance when grinding, polishing the teeth or other work carried out by the dental hygienist.

In addition to extracting released filling material effectively by suction, the result afforded when applying the invention can be further improved by binding the released material with the aid of a binder. For instance, this binder may be effective in binding vapour or liquid chemically, or by physically absorbing or adsorbing the released material.

Selenium and selenium compounds are examples of binding agents suitable for binding mercury vapour, for instance. Different forms of selenium are also able to bind other metals and plastics. Sulphur, carbon, active carbon and different compounds thereof are examples of effective mercury binding agents.

The coolant may consist in a liquid jet, a liquid mist, air, a gel, either individually or in combination.

The actual coolant may be alcohol, since alcohol will prevent mercury vapours from being taken up in the blood and has a protective effect against the ingress of mercury into the brain.

The invention will now be described in more detail with reference to the accompanying drawings, in which

Fig. 1 is a sectioned view of one embodiment of the inventive arrangement;

Figs. 2-5 illustrate different embodiments of the front part of the arrangement shown in Fig. 1; and

Fig ^' . 6 is a sectioned view of a further embodiment of the inventive arrangement.

In Fig. 1

B identifies an angle piece; 1 identifies a drill tip or drill bit; 2 identifies binder delivery passageway/passageways;

3 identifies coolant delivery channel/channels;

4 identifies a channel/channels through which debris, vapours, fine particles, liquid, air are carried away;

5 identifies the front part of the angle piece with the drill tip attached thereto; and

6 identifies a surface on the part 5 from which the drill tip protrudes.

Figs. 2-5 illustrate the front part 5 of the angle piece, which functions as a holder for the drill tip or bit 1. The drill tip projects out from the surface 6 of the holder 5. The delivery channels and the suction channel open out at the surface 6 or outside the surface 6.

Fig. 2 shows the delivery channel 3 extending through the actual drill tip 1, and shows the suction channel orifice 4 located concentrically with the drill tip 1 and extending partially therearound. In the case of the Fig. 3 embodiment, the outlet end of the delivery channel 3 has the form of a narrow tube around the

drill tip 1. This tube terminates somewhat short of the end of the drill tip. In the case of this embodiment, th'a suction channel orifice 4 forms a complete ring around the drill tip 1. Fig. 4 illustrates other conceivable configurations of the suction channel orifice 4. For instance, the orifice may have the form of one or more parts of a circle concentrical with the drill tip. In the embodiment shown in Fig. 5, the suction channel 4 has several outlet orifices disposed around the drill tip 1.

In Fig. 6

A identifies a binder delivery channel;

B identifies a suction channel;

C identifies a coolant delivery channel;

D identifies a drill tip; and E identifies a coolant delivery tube.

In the case of the Fig. 6 embodiment, coolant is delivered in the form of a covering mantle around that part of the tooth being worked and assists in preventing released mercury from dispersing in the oral cavity and in the surrounding room space. The suction channel is located inwardly of the channel A through which binder is delivered and, in turn, surrounds the drill tip and the coolant delivery channel.

Alternatively, the suction channel may be located furthest out, so as to surround both the coolant delivery channel and the binder delivery channel.

It is also conceivable for the suction channel or the binder delivery channel to be placed nearest the drill tip and to place the coolant delivery channel further out.

In each particular embodiment, it is necessary to mutually adapt the coolant and the binder flow rates and the suction force, so as to maintain the dispersion of mercury at the lowest possible level.

0

Example

Tests have been carried out with a conventional angle piece with which water and air were delivered in conduits provided on the underside of the angle piece, such as to direct the water and air obliquely onto the end of the drill tip, there being used a conventional suction means. Considerable quantities of water were observed to splash against the tooth being drilled, and the suction means was found to be unable to suck away all of the water.

The outwardly located delivery conduits of this angle piece were then blocked and the air and water delivery channels were con¬ figured in the manner shown in Fig. 3. A plastic hose coupled to a suction means was fitted over the angle piece in a manner to form an opening around a part of the periphery of the front end 5. The hose terminated well short of the surface 6, so as not to impede the dentists's view while drilling was in progress. The tooth was in full view while drilling was in progress and almost no water was seen to splash from the patient's mouth.