WO1999038539A1

WO1999038539A1 - A method and an apparatus for cleaning and sterilizing dental equipment

Info

Publication number: WO1999038539A1
Application number: PCT/DK1999/000047
Authority: WO
Inventors: Morten Skødt NIELSEN
Original assignee: Inter Select By Polti A/S
Priority date: 1998-02-02
Filing date: 1999-02-01
Publication date: 1999-08-05
Also published as: DK173324B1; AU2265299A; DK14498A

Abstract

The present invention relates to a method of cleaning and sterilizing dental equipment (80), which is intended to be introduced into the oral cavity of a patient, and which has an external surface and an internal channel defined by an internal surface, said method comprising a first step wherein the internal surface is affected by steam at such a temperature that the internal surface is sterilized. The invention is novel by an additional step wherein the external surface is affected by a relatively concentrated jet of steam at such a temperature that the external surface is sterilized, while a mechanical treatment of the external surface is performed by a brush-like means. The invention also relates to an apparatus for performing the method.

Description

A method and an apparatus for cleaning and sterilizing dental equipment

The present invention relates to a method and an appara- tus for cleaning and sterilizing dental equipment as defined in the introductory portions of claims 1 and 6, respectively. The invention thus specifically relates to cleaning and sterilization of dental equipment which is intended to be introduced into the oral cavity of a pa- tient, and which has an external surface and an internal channel defined by an internal surface, wherein, using steam and with a view to eliminating microorganisms and contaminations on the dental equipment after a treatment of a patient, the internal surface of the dental equip- ment is heated to effect sterilization, preferably to at least about 121 °C, so that the dental equipment concerned may be made ready for use on another patient. Heating of the surface to said minimum temperature ensures effective elimination of microorganisms that may cause diseases, such as hepatitis or the like-

Methods and devices of this type are generally known, where dental equipment in the form of a handpiece with e.g. a dental drill is arranged in an autoclave for ster- ilization treatment. During the course of this process, the dental equipment concerned is heated to temperatures of the order of about 121 °C in a closed chamber into which steam is introduced from a steam source. The dental equipment is arranged on suitable holders in the interior of the chamber prior to the actual treatment, and the chamber is normally always dimensioned to accommodate a high number of handpieces so that sterilization of many handpieces with drills may be performed during one and the same process. The known methods and devices, however, are inexpedient for a number of reasons. Firstly, it has been found by measurements that microorganisms and contaminations are still present on the dental equipment after the pre- scribed autoclaving, which has required subsequent treatment in the form of washing of the equipment with spirit. One reason for this may possibly be the structure of conventional dental equipment which has handpieces provided with a fluted surface which makes it easier for the den- tist to achieve a good grip of the dental equipment, but which may simultaneously create a not very accessible repository for microorganisms. Furthermore, the known devices are bulky, energy-intensive and usually also require complete filling of the chamber with dental equip- ment before the sterilization treatment is initiated. The known autoclaves are thus not expedient when just a single object is to be treated, such as a single handpiece with a dental drill mounted thereon. In addition, the cooling time after the completion of the steriliza- tion treatment is frequently quite long, and therefore it is normally not possible to use the dental equipment immediately after the completion of the autoclaving. As a result of the last-mentioned factors a dental clinic will typically be forced to purchase a relatively large number of each instrument, typically corresponding to the number of patients who are expected to visit the clinic during a working day. As the investment in such equipment accounts for a considerable percentage of the overall costs of running a dental clinic, there is thus a need for reduc- ing the required amount of dental instruments as far as possible, without this taking place merely by using a half-filled autoclave several times a day with the consequent operating costs.

An object of the invention is to remedy the drawbacks described above, an object being specifically to provide a method and an apparatus capable of ensuring such a reliable cleaning and sterilization treatment of dental equipment that no microorganisms and contaminations remain on the equipment after the treatment.

The above-mentioned objects are achieved by means of the features defined in the characterizing portion of claim 1, and a quite special and expedient apparatus for performing the method is defined in claim 6.

The method is thus defined in that the external surface is moreover affected by a relatively concentrated jet of steam at such a temperature that the external surface is sterilized, preferably to 121 °C, while performing a me- chanical treatment of the external surface by a brushlike means.

It has thus quite surprisingly been found possible to achieve the above-mentioned objects in this way, i.e. both to provide more sterile and better cleaned objects after a sterilization and cleaning treatment, and to achieve the described rationalization benefit as regards the required number of instruments to be purchased for a dental clinic.

To ensure effective elimination of microorganisms on the surface of the dental equipment, it is preferred that the internal surface is affected by steam for at least about 60 seconds, and that the steam impact on and mechanical treatment of the external surface is performed for a period of at least 45 seconds, preferably at least about 60 seconds .

In an expedient embodiment of the apparatus according to the invention, the steam nozzle and the brush-like means are integrated in one and the same unit, which comprises a handpiece by means of which the mechanical treatment may be performed, preferably manually. This solution is extremely expedient in terms of production and use.

In the above case it is moreover preferred to conduct a coolant, which may e.g. be nitrogen, under pressure through the internal channel in the dental equipment. This provides a very raid and effective cooling of the dental equipment which may thus be used quite shortly af- ter the completion of the cleaning and sterilization treatment .

The invention will be described more fully below with reference to the drawing which shows a presently pre- ferred embodiment. In the drawing:

fig. 1 shows a schematic view of an apparatus for working the invention, and

fig. 2 shows a schematic view of a particularly suitable implement which may form part of the apparatus shown in fig. 1.

In fig. 1, an apparatus for cleaning and sterilizing den- tal equipment 80 is generally designated 1. In this connection, the term "dental equipment" means conventional dental equipment, such as dental drills of metal which are not of the disposable type, and which are intended to be introduced into the oral cavity of a patient in the treatment of him. During a treatment of a patient, the dental equipment is connected with hoses which serve to supply a pressurized fluid, e.g. the propellant for a dental drill. For this purpose, the handpiece is provided with an internal channel which communicates with the hoses at one end, and which terminates e.g. in the dental drill at the other end. Dental equipment of this type must be cleaned and sterilized carefully after the completion of a treatment of a patient before it may be used on other patients. As will appear from the following, the use of the apparatus 1 does not necessitate confining the dental equipment 80 in a closed chamber during the sterilization and cleaning treatment, which is otherwise necessary when sterilizing in conventional autoclaves.

The apparatus 1 comprises a housing which may be sup- ported by wheels 5, and which may have an access lid giving access to the interior of the apparatus 1 for servicing the components mounted in the housing. The apparatus additionally comprises a top part 2 with holding means 65 intended to arrange the dental equipment 80 in e.g. a horizontal position during the sterilization treatment, there being moreover provided a bowl-shaped collecting tray 45 for collecting the liquid flowing out during the sterilization treatment.

Further, the apparatus 1 comprises means 10 for generating and storing steam in the form of a container having a water charging stub and a heating element which may be set to generate steam at a given pressure and at a desired temperature, which, however, is preferably at least about 121 °C. In the use of the apparatus, the steam is conveyed with a flow course which will be described more fully below, and any condensed liquid is collected in the collecting tray 45 and is returned by a return line 40 to a container 35 arranged in the housing. It will thus be appreciated that an essentially closed flow circuit is established in the use of the apparatus, and the apparatus 1 may therefore be used as a self-contained unit, i.e. with no requirement for permanent connection to external outlets or water supply. The means 10 for generating and storing steam comprise a first outlet which is connected with one end of steam connecting means 50 in the form of a flexible member, preferably a plastics hose. As this hose is flexible, the operations in the use of the apparatus are facilitated, as will appear from the following. A cleaning and sterilization implement in the form of a handpiece 55 with a through channel is mounted at the opposite end of the steam connecting means 50 via a connecting stub (not shown) , said channel conveying the steam forwards to a steam nozzle 60 which is arranged at the opposite end of the handpiece 55, and through which the generated steam may flow out as a relatively concentrated jet. Further, a brush-like means 58 is provided at the steam nozzle 60, which is preferably so arranged relatively to the brush that the steam flows out through the bristles, which are thus heated by the hot steam.

The apparatus 1 additionally comprises a container 25 for a coolant, which may preferably be nitrogen, which may be connected with a switching valve 30 via a sterilizing filter 26 and coolant connecting means 20, preferably in the form of a hose, said valve 30 being also connected with an additional outlet from the means 10 for generat- ing and storing steam. A tubular connecting means 70 extends from the switching valve 30 and terminates at the holding means 65 for the dental equipment 80 on the top part 2 of the apparatus 1. It will be appreciated that with correct operation of the switching valve 30 either steam or coolant may be conducted through the connecting means 70 and forwards to the holding means 65 for the dental equipment 80.

In the use of the apparatus 1 shown in fig. 1, the dental equipment is first placed in the holding means 65, which may e.g. just be formed by a clamp-like device, and the connecting means 70 is connected with the through channel in the dental equipment, which, as mentioned, may be a conventional dental drill with a handpiece having a drill mounted thereon. Then steam from the container 10 is al- lowed to flow through the connecting means 70 and thereby through the internal channel in the dental equipment 80 by correct setting of the switching valve 30. The hot steam will immediately give rise to a temperature increase in the interior of the dental equipment, as the surface of the internal channel of the dental equipment rapidly assumes the temperature of the steam. When the pressure in the steam container is suitably selected, blowing through the channel will moreover occur, causing organic matter in the dental drill to be blown out and, together with the released steam, to be conducted down into the collecting tray 45. It is noted in this connection that the temperature of the steam should be about 121 °C as a minimum, since effective elimination of microorganisms usually cannot be ensured at temperatures below this value. The described process may basically be compared with the conditions in an autoclave, except that an autoclaving chamber proper is not used. A minimum treatment time of about 60 seconds is preferred, after which period of time the external temperature of the den- tal equipment, because of the conduction of heat, will also assume a value approximately corresponding to the temperature of the internal surface.

Immediately after the external surface of the dental equipment 80 has reached the desired, elevated temperature because of the conduction of heat, a sterilization and cleaning treatment of the external surfaces of the dental equipment 80 is performed according to the invention by means of the steam nozzle 60 and the brush-like means 58, respectively, which are mounted on the handpiece 55. When this treatment is to be performed, an in- terrupt valve (not shown) is activated so that steam flows out of the container 10, through the flexible hose 50 and out from the steam nozzle 60 in the form of a relatively concentrated jet. The handpiece is now recip- rocated so that the bristles 58 mechanically act on the dental equipment 80 by rubbing against the surface of the equipment 80, while steam flows directly out on the surface from the nozzle 60 which is held in the immediate vicinity of the surface. The combined effect of this me- chanical action and of the steam jet has surprisingly been found, by comparative tests, to provide a better cleaning and sterilization than sterilization in the known autoclaves, as described initially. An external treatment as described above and of a duration of about 60 second has thus been found to provide complete elimination of microorganisms.

After the completion of the cleaning and sterilization treatment, the dental equipment concerned will typically assume a temperature corresponding to the temperature of the steam over its entire cross-section. To reduce the required cooling time before the dental equipment may be used again, the switching valve 30 may be switched now so that the coolant in the coolant container 25 under pres- sure may be caused to flow through the internal channel in the dental equipment 80 via the tubular connecting means 70. When a coolant in the form of e.g. nitrogen with a suitably low temperature is selected, it is possible to provide a suitably rapid cooling of the dental equipment to a desired temperature. The cooling may optionally be controlled automatically by means of automatically operating control devices, such as a timer, which automatically interrupts the connection to the coolant container after a predetermined period of time. The table below shows the result of a comparative test where ATP measurements have been performed (by the so- called Hy-lite test) of correspondingly loaded dental equipment (a dental drill), which has been subjected to treatment in an autoclave and by the method according to the invention, respectively, using a brush of mean hardness (bristles of polyester PBT having a diameter of 0.15 mm) and after an internal steam treatment of a duration of 60 seconds and an external treatment with steam and brush for 60 seconds. The autoclaving was performed at a temperature of 121 °C for 20 minutes.

Autoclave Invention

Measurement in channel in drill (Super Torque 625) 156 9

Measurement of drill surf. 4100 11

(All numerical values below 50 are usually assumed to represent sterile conditions) .

Fig. 2 shows a cross-section through a particularly preferred embodiment of the handpiece 55 which, in this case, is formed as an elongated, cylindrical housing hav- ing an insert 57 with radially inwardly extending bristles 58. These bristles 58 define a cylindrical through channel 59 which extends in the longitudinal direction of the housing. The handpiece 55 is moreover provided with a connecting stub 56 which serves to connect the handpiece 55 with the steam connecting means 50. A nozzle-like outlet 60 for steam is provided directly at the connecting stub 56, so that steam conducted from the container 10 can penetrate into the cylindrical channel 59 through openings in the insert 57 and between the bristles 58. It will be appreciated that, prior to the cleaning and the sterilization, the dental equipment 80 10

concerned, which will preferably be held by the holding means 65, is passed through the channel 59, and mechanical treatment of the surface of the dental equipment 80 is performed by manually reciprocating the handpiece 55 so that the bristles 58 rub against each other, while steam is conducted into the channel 59 through the nozzle 60. This movement is performed for a given period of time, which may be quite short, e.g. about 2 minutes, following which the handpiece 55 may optionally be left on the dental equipment 80 for affecting it with steam alone, e.g. for a total period of time of about 15 minutes. After the completion of the sterilization, coolant is conducted through the dental equipment through the connecting means 70, if the dental equipment per se is formed with an internal channel, as described above.

Although the brush-like means 58 and the nozzle 60 have been described above as being integrated in a handpiece, it will be appreciated that the handpiece may optionally be connected with automatically acting devices which produce the desired movement of the bristles across the external surface of the dental equipment. Thus, in this situation, the handpiece is not operated manually.

Claims

11P a t e n t C l a i m s :

1. A method of cleaning and sterilizing dental equipment (80) which is intended to be introduced into the oral cavity of a patient, and which has an external surface and an internal channel defined by an internal surface, said method comprising a first step wherein the internal surface is affected by steam at such a temperature that the internal surface is sterilized, c h a r a c t e r i z e d by an additional step wherein the external surface is affected by a relatively concentrated jet of steam at such a temperature that the external surface is sterilized, while performing a mechanical treatment of the external surface by a brush-like means.

2. A method according to claim 1 and intended for handpieces for drills, polishing equipment, rinsing equipment or similar dental equipment, which is preferably metal- lie, c h a r a c t e r i z e d in that the first step and the second step are performed for at least 45 seconds, preferably at least about 60 seconds, and that the temperature of the steam is selected to be at least about 121 ┬░C, preferably at least 121 ┬░C.

3. A method according to claim 2, c h a r a c t e r i z e d in that the first step is performed for at least 60 seconds, and that the second step is then initiated.

4. A method according to any one of the preceding claims, c h a r a c t e r i z e d in that the dental equipment (80) is cooled by means of a sterile coolant immediately after the heating, said coolant being conducted through the internal channel. 12

5. A method according to any one of the preceding claims, c h a r a c t e r i z e d in that the steam has a temperature of at least about 150 ┬░C and a pressure of at least about 4 bars.

6. An apparatus (1) for cleaning and sterilizing dental equipment (80) which is intended to be introduced into the oral cavity of a patient, and which has an external surface and an internal channel defined by an internal surface, said apparatus (1) comprising means (10) for generating and storing steam, at least one steam nozzle (60) which is connected with the means (10) for generating and storing steam via first steam connecting means (50), and by which an external surface of the dental equipment (80) may be affected by steam at such a temperature that the external surface is sterilized, and additional connecting means (70) for connecting the internal channel with the means (10) for generating and storing steam, whereby the internal surface may be affected by steam at such a temperature that the internal surface is sterilized, preferably at least about 121 ┬░C, c h a r a c t e r i z e d in that the steam nozzle (60) is adapted to be advanced across the external surface, and that the apparatus (1) additionally comprises a brush-like means (58) by which a mechanical treatment of the external surface may be performed, while the external surface is affected by steam from the steam nozzle (60) .

7. An apparatus according to claim 6, c h a r a c - t e r i z e d in that the apparatus (1) moreover comprises a handpiece (55) by which the steam nozzle (60) and the brush-like means (58) are connected to be advanced together across the external surface, and that the first steam connecting means (50) comprise a flexible hose. 13

8. An apparatus according to the preceding claim, c h a r a c t e r i z e d in that the apparatus (1) moreover comprises at least one container (25) for a sterile coolant, preferably nitrogen, and coolant con- necting means (20) for connecting the internal channel with the container (25) for a sterile coolant.

9. An apparatus according to the preceding claim, c h a r a c t e r i z e d in that the apparatus (1) moreover comprises a switching valve (30) for selectively connecting the internal channel with the coolant connecting means (20) or the means (10) for generating steam via the additional connecting means (70) .

10. An apparatus according to the preceding claim, c h a r a c t e r i z e d in that the switching valve (30) is adapted to be controlled automatically.

11. An apparatus according to any one of the preceding claims 6-10, c h a r a c t e r i z e d in that the apparatus (1) comprises holding means (65) for holding the dental equipment (80) during cleaning and sterilization, and that a substantially bowl-shaped means (45) is arranged in association with the holding means for collect- ing condensed steam which has run through the internal channel in the dental equipment (80) .

12. An apparatus according to any one of the preceding claims 6-11, c h a r a c t e r i z e d in that the means (10) for generating steam comprise a container for water and a heating element.