Cleansing implement and electrically powered dental cleansing device

The invention is directed to an electrically powered dental cleansing device (1) to which a cleansing implement (32) is fitted. In this manner, the cleansing implement (32) can be rotated about its longitudinal axis. The cleansing implement (32) is configured as an integrally formed part comprising a thin and elongate cleansing shaft (125). The cleansing shaft has at least one longitudinal edge and is provided with a plurality of serrations.

This invention relates to an electrically powered dental cleansing device 
comprising a cleansing implement which is rotatable about its longitudinal 
axis by a motor provided in the dental cleansing device. 
Such a dental cleansing device and a cleansing implement are known from 
German Patent No. 1,011,116. This patent discloses a pencil mounted on a 
shaft coupled to a drive unit. The pencil is comprised of a plurality of 
individual hairs of a length dimensioned such that the pencil is tapered 
towards a pointed free end. By means of the drive unit, the pencil can be 
rotated about its longitudinal axis for performing a tooth cleaning 
function. However, because of the relatively large dimensions of the 
pencil, this implement is not suitable for interproximal cleaning. 
From DE-OS 1,766,651 a device is known which can be used by dentists for 
grinding off amalgam fillings, for example. For tooth treatment, the 
device comprises an instrument similar to a blade which can be caused to 
perform a lifting motion by a drive unit. To increase the abrasive effect, 
the instrument can be coated with additional particles as grinding powder, 
for example. Considering, however, that the instrument has a width and 
thickness of several millimeters, this device is not suited for cleaning 
interproximal spaces. 
It is an object of the present invention to provide a dental cleansing 
device and a cleansing implement for an electrically powered dental 
cleansing device which enables in particular the interproximal spaces to 
be cleaned, which affords simple and secure manipulation, and which can be 
introduced into the interproximal spaces with particular ease. 
According to the present invention, this object is essentially accomplished 
in that the cleansing implement is configured as an integrally formed part 
comprising a thin, elongate cleansing shaft which is flexible. 
On account of the thin and elongate configuration of the cleansing shaft, 
the cleansing implement is also suitable for cleaning narrow interproximal 
spaces. Because the flexible cleansing shaft is adapted to be rotated 
about its longitudinal axis, it will automatically engage within the 
interproximal spaces. In the cleansing implement of the present invention, 
this automatic engaging action largely eliminates the possibility of 
injury otherwise occurring, for example, by improper manual insertion of 
dental floss into tight interdental spaces for lack of knowledge or 
experience of its user. Because the complete cleansing implement is formed 
as an integral part, economy of manufacture is achieved. 
In a feature of the present invention, the cleansing shaft includes at 
least one longitudinal edge. In use of the cleansing implement, this 
longitudinal edge wipes off plaque from the user's teeth. 
According to a further feature of the present invention, the cleansing 
shaft has an essentially square cross-section. As a result, the four 
longitudinal edges thus provided on the cleansing shaft make it possible 
to achieve an improved cleaning effect. 
Advantageously, the sides of the cleansing shaft of essentially square 
cross-section have a length of 0.3 mm, approximately. 
In a further feature of the present invention, a plurality of serrations 
project from the surface of the cleansing shaft. When the cleansing 
implement is in use, these serrations serve the function of removing 
plaque from the user's teeth. It will be understood that the cleansing 
shaft may also be provided with stiffening ribs on its longitudinal sides 
which act as cleaning edges. 
The cleansing shaft has preferably a length of between 10 and 15 mm. The 
thickness of the cleansing shaft is preferably in the range from 0.1 to 
0.5 mm. The height and width of the serrations are preferably within the 
range of 0.1 and 0.3 mm. 
In an advantageous further feature of the present invention, the cleansing 
implement is made of a plastics material. This allows economy of 
manufacture of the cleansing implement. 
By providing the cleansing shaft with an unbalance by designed accumulation 
of material, the cleansing shaft is deflected from its rest position in 
the manner of a whip during rotation, which has a highly beneficial effect 
on the cleaning of the interproximal spaces. 
In a still further feature of the present invention, the cleansing 
implement is adapted to be a push-fit on the dental cleansing device. This 
enables the user to substitute a new cleansing implement of like 
construction for a worn cleansing implement with ease and speed. 
In an extremely advantageous feature, the cleansing implement is made of 
polyester elastomer or a material exhibiting like or similar properties. 
owing to the special properties of this material, the shaft of the 
cleansing implement can be bent by an angle of up to 180 degrees 
particularly also during use, without the risk of shaft rupture. For one 
thing, this practically precludes the possibility of injury by a ruptured 
shaft, and for another thing, it enables the teeth to be cleaned also in 
the subgingival region even when the shaft is bent by 180 degrees, in 
which event the cleaning function is mainly performed by the bent area of 
the bent shaft. Utilizing this material for the cleansing implement or 
also for the shaft itself results in improved manipulation also for the 
inexperienced user, in addition to enhancing the cleaning effect. 
The present invention also relates to an electrically powered dental 
cleansing device in which an elongate, thin and flexible cleansing 
implement is adapted to be coupled to a drive shaft received in a handle 
section and is rotatable about its longitudinal axis. 
Simple and secure manipulation of the dental cleansing device is 
essentially ensured in that in the dental cleansing device incorporating 
the features initially referred to an attachment is adapted to be 
push-fitted to the handle section, and that the cleansing implement is 
slidably received in the attachment. 
By slidably accommodating the cleansing implement in the attachment, the 
possibility is provided to optimally adapt the dental cleansing device for 
its individual uses. Thus, the cleansing implement is slidable out of the 
attachment when a user desires to use the dental cleansing device for 
interproximal cleaning. By contrast, when the dental cleansing device is 
not in use, the cleansing implement can be pushed back into the interior 
of the attachment, thereby obviating the possibility of contamination of, 
or damage to, the cleansing implement. The cleansing implement thus also 
meets hygienic demands, in addition to being usable for a prolonged 
period. For example, when it is desired to take the cleansing implement on 
trips, it is ensured that the cleansing implement is not contaminated or 
damaged by other objects or, conversely, that the cleansing implement does 
not contaminate or damage these objects. When the cleansing implement is 
worn after prolonged use, the attachment with the cleansing implement 
therein received can be pulled off the handle section, and a new 
attachment with a new cleansing implement can be substituted. During such 
replacement, the user has no contact with the cleansing implement itself, 
but rather, can simply exchange it together with the attachment. However, 
the possibility may also be provided to push the attachment onto the 
handle section separate from the cleansing implement, requiring only the 
cleansing implement itself to be exchanged following use or wear. 
In a feature of the present invention, the attachment has at the end remote 
from the handle section a guide tube in which the free end of the 
cleansing implement remote from the handle section is guided. When the 
cleansing implement is in the extended position relative to the 
attachment, the cleansing implement is located in position by the guide 
tube. This thus reliably prevents slippage or any other variation of the 
position of the cleansing implement during use. 
In this arrangement, it will be advantageous to provide the guide tube with 
an approximately hemispherical rounded portion at its free end remote from 
the handle section, preferably with a diameter in the range from about 1 
mm to about 4 mm, in particular about 2.5 mm. This rounded portion at the 
free end of the guide tube makes it easy for the user to probe the 
interproximal spaces, the rounded portion, when engaging against the 
teeth, being readily locatable centrally in the recesses existing in the 
region of the interproximal spaces. The * user, upon positioning the guide 
tube in the region of an interproximal space in this manner, may then 
slide the cleansing implement out of the attachment, inserting it in the 
interproximal space. Advantageously, the guide tube extends with its other 
end to the conical surface of the handle section, so that all parts coming 
into contact with the oral cavity are interchangeable if so desired, 
making the device suitable for use by several users, for example. 
In a further feature of the present invention, the guide tube includes a 
bent portion, with the bending angle being in the range from about 30 
degrees to about 150 degrees, in particular about 90 degrees. This 
facilitates the manipulation of the dental cleansing device as the user 
probes the interproximal spaces and introduces the cleansing implement 
therein for subsequently performing the cleaning operation. 
In another feature of the present invention, the attachment is provided 
with means for releasably locating the cleansing implement in a transit 
position in which the cleansing implement is completely received within 
the attachment. In this transit position, the attachment with the 
cleansing implement therein received can be handled independently of the 
handle section and offered for sale, for example. Securing the cleansing 
implement in the transit position prevents the cleansing implement from 
accidentally slipping within the attachment and being damaged in the 
process. 
It will be advantageous in this arrangement to provide the attachment with 
a sleeve-shaped portion having an inwardly projecting annular collar, and 
to provide the cleansing implement, at its end close to the handle 
section, with a disk-shaped base which includes an annular groove 
operatively associated with the annular collar and adapted for locking 
engagement with the annular collar to provide the transit position. By 
means of the annular collar and the annular groove, the cleansing 
implement is securely located in the transit position at low 
constructional expenditure. 
In an extremely advantageous independent further feature of the present 
invention, the cleansing implement has at its end close to the handle 
section means for providing a releasable coupling to a drive shaft in a 
non-rotating relationship thereto, the drive shaft being adapted to be 
driven by a motor housed in the handle section. In this manner, the 
cleansing implement can be caused to rotate about its longitudinal axis. 
However, the non-rotative coupling does not connect the cleansing 
implement with the drive shaft inseparably, but rather, the cleansing 
implement can be pulled off the drive shaft. As a result, the attachment 
with the cleansing implement received therein is fully functional in 
pushedon condition without further means, and it can be pulled off the 
handle section and replaced as a whole, for example. 
It will be an advantage in this arrangement to provide the cleansing 
implement and the drive shaft with a pin and an associated bore forming in 
assembled condition a press fit or having relatively associated 
complementary cross-sections. Such a simple structural approach provides 
the non-rotative coupling between the cleansing implement and the drive 
shaft. 
In an advantageous feature of the present invention, the drive shaft is 
coupled to a longitudinally slidable switch for energizing and 
deenergizing the motor, such that a displacement of the switch also 
involves a displacement of the drive shaft in the longitudinal direction, 
whilst, however, rotation of the drive shaft is independent of the 
position of the switch. Accordingly, when the user moves the switch from 
the off-position to the on-position, this has at the same time the effect 
of displacing the drive shaft in the longitudinal direction. Because the 
cleansing implement is coupled to the drive shaft, also the cleansing 
implement will be displaced in the longitudinal direction. Thus, actuation 
of the switch will cause the cleansing implement to be extended from the 
attachment. Simultaneously with the extension of the cleansing implement 
from the attachment, the switch will also energize the motor, so that the 
cleansing implement, through its non-rotative coupling to the drive shaft, 
will be caused to rotate about its longitudinal axis. With the dental 
cleansing device in the activated position, the user can then clean the 
interproximal spaces using the extended and rotating cleansing implement. 
The attendant energization of the motor as the cleansing implement is 
extended from the attachment has the advantage of enabling the user to 
introduce the cleansing implement into the interproximal spaces to be 
cleaned with greater ease. This introduction will be still further 
supported by the threading effect produced by the rotating cleansing 
implement. When the user returns the switch to the off-position, this will 
have the effect of retracting the cleansing implement into the attachment 
and stopping its rotation. 
It proves to be a great advantage that the switch for energizing the motor 
is slidable against a spring. As a result, the spring will automatically 
return the activated dental cleansing device to the off-condition should 
the user release the switch for whatever reason. This may occur, for 
instance, when the cleansing implement causes pain resulting from improper 
handling by its user. The spring will promptly act to deenergize the 
motor, pushing at the same time the cleansing implement back into the 
attachment. This protects the user from the possibility of pain or injury 
that may result from improper handling of the cleansing implement. The 
spring also ensures that the cleansing implement is outside the attachment 
only during the actual cleansing operation, being at all other times 
received inside the attachment in protected manner. 
From a structural point of view it will be an advantage in this arrangement 
when, with the switch in the off-position, the drive shaft is in an 
inoperative position retracted relative to the attachment, in which 
position the cleansing implement coupled to the drive shaft is received 
inside the attachment. By contrast, with the switch in an on-position, the 
drive shaft is conveniently in an operative position extended relative to 
the attachment, in which position the cleansing implement coupled to the 
drive shaft is at least in part outside the attachment. 
When in the operative position, it has proven to be particularly 
advantageous if a length in the range of about 8 mm to about 20 mm, in 
particular a length of about 12 mm, of the cleansing implement is outside 
the attachment. When the cleansing implement is pushed out of the 
attachment by about such a length, an optimum interproximal cleansing 
function can be performed. 
In a further advantageous feature of the present invention, the motor 
fixedly accommodated in the handle section has a motor shaft with 
longitudinally extending vanes, and the drive shaft has at its end close 
to the motor a cup-shaped receptacle with longitudinal ribs in its 
interior, with the vanes of the motor shaft engaging longitudinally in the 
space between the longitudinal ribs of the cup-shaped receptacle in an 
overlapping fashion. As a result, the non-rotative connection between the 
motor shaft and the drive shaft is independent of the position of the 
drive shaft relative to the longitudinal direction. By means of the vanes 
and the longitudinal ribs, the rotary motion of the motor is thus 
transmitted from the motor shaft to the drive shaft. When the drive shaft 
is displaced in the longitudinal direction by means of the switch, the 
overlapping arrangement of the vanes and the longitudinal ribs in the 
longitudinal direction ensures continued interengagement of the vanes and 
the longitudinal ribs, so that transmission of the rotary motion from the 
motor shaft to the drive shaft is maintained at all events. The position 
of the switch and thus the position of the drive shaft in the longitudinal 
direction accordingly does not affect the non-rotative coupling of the 
motor shaft to the drive shaft. 
According to an extremely advantageous, independent further aspect of the 
present invention, the attachment has at its end close to the handle 
section means for releasably locating the attachment in position on the 
handle section. In this manner, the attachment pushfitted to the handle 
section is securely held in place. When the user desires to separate the 
attachment from the handle section in order to replace, for example, a 
worn cleansing implement, this is still possible in a ready and simple 
manner. 
In a feature of the present invention, the handle section and the 
attachment include at least one projecting lug and one associated recess 
which are in relative engagement with the attachment fitted. Conveniently, 
the lug is provided on the handle section, while the recess is provided on 
the inside of the attachment. It is, however, also possible to provide the 
lug on the attachment and the recess on the handle section. The lug and 
the recess ensure secure location of the attachment on the handle section 
at low constructional expenditure. By suitably flattening the lug in 
particular in the push-on and pull-off direction of the attachment, 
fitting and removing the attachment is further facilitated for its user. 
Advantageously, the lug is associated with an opening extending through the 
attachment. This opening makes it easy for the user to check whether the 
lug is in proper locking engagement with the opening so that the 
attachment is completely fitted to the handle section. 
In a further feature of the present invention, the attachment has at its 
end close the handle section means for aligning the attachment in a 
clearly defined position to the handle section in the circumferential 
direction. In this manner, the attachment, when fitted to the handle 
section, is located in a clearly defined position in the circumferential 
direction. Also, the possibility of the attachment turning on the handle 
section in the circumferential direction is prevented. Operation and 
manipulation of the dental cleansing device is thereby further facilitated 
and improved for the user. 
In an advantageous feature of the present invention, the handle section and 
the attachment include at least one longitudinal ridge and one associated 
longitudinal groove which are in relative engagement with the attachment 
fitted. Conveniently, the longitudinal ridge is provided on the handle 
section, while the longitudinal groove is formed on the attachment. The 
reverse case is, however, also possible. The longitudinal ridge and the 
longitudinal groove afford simple constructional means for locating the 
attachment in a clearly defined position on the handle section in 
circumferential direction. 
Still further, it will be an advantage to provide one longitudinal ridge 
and one longitudinal groove each on either side of the lug and recess, 
respectively. The arrangement of two longitudinal ridges and longitudinal 
grooves further facilitates the insertion of the attachment in the handle 
section for the user. The symmetrical arrangement of the longitudinal 
ridges and longitudinal grooves affords the further advantage of providing 
the dental cleansing device with a visually balanced appearance. 
In still another feature of the present invention, three lugs and recesses, 
respectively, with associated longitudinal ridges and longitudinal 
grooves, respectively, are provided, which are arranged on the periphery 
of the handle section and, respectively, the attachment at partly 
non-uniform distances. As a result of this arrangement, the visual 
impression conveyed makes it easier for the user to properly fit the 
attachment to the handle section without further thinking. The location of 
the attachment on the handle section is thus visually expressed by the 
non-uniform arrangement.

FIG. 1 shows a dental cleansing device 1 with a cleansing implement 32 
attached. The dental cleansing device 1 includes a handle section 2 
receiving an electric motor drive means adapted to be turned on and off by 
the user. Adjoining the handle section 2 is a mounting section 101 serving 
the function of transmitting and, where applicable, converting, the rotary 
motion produced by the electric motor drive means. The cleansing implement 
32 is attachable to the head end of the mounting section 101. In FIG. 1, 
the cleansing implement 32 is arranged at the free end of the mounting 
section at an angle of about 90 degrees to the longitudinal axis of the 
mounting section 101 and the handle section 2. It is, however, also 
possible to arrange the cleansing implement 32 in the direction of the 
longitudinal axis of the mounting section 101 and the handle section 2 or 
to provide for adjustability between these positions. The cleansing 
implement 32 is attached to the free end of the mounting section 101 in 
such a manner as to be rotatable about its longitudinal axis by the 
electric motor drive means of the dental cleansing device 1. The 
rotational frequency may be about 3,000 1/min or higher, for example. 
The cleansing implement 32 will be explained in greater detail in the 
following with reference to FIGS. 2 to 4. 
The cleansing implement 32 of FIG. 2 is comprised of a mounting shaft 122 
and a cleansing shaft 125, with the mounting shaft 122 with its diameter 
of about 1.5 mm being significantly thicker than the cleansing shaft 125 
with a mean diameter of about 0.3 mm. By means of the mounting shaft 122 
the cleansing implement 32 is attached to the free end of the mounting 
section 101 of the dental cleansing device 1. In FIG. 2, the mounting 
shaft 122 is of a cylindrical configuration, but it is also possible to 
provide the mounting shaft 122 with a different cross-sectional area, or 
to provide the mounting shaft 122 with additional longitudinal grooves or 
longitudinal ribs for non-rotative connection of the cleansing implement 
32 with the electric motor drive means of the dental cleansing device 1. 
Through a transition area, the cleansing shaft 125 is connected with the 
mounting shaft 122 and serves to clean the teeth. The cleansing shaft 125 
of FIG. 2 has a length d of about 12 mm and a thickness of between 0.3 and 
0.4 mm.+-.0.1 mm, which is thus substantially smaller than its length. 
As becomes apparent from FIG. 3, the cleansing shaft 125 has a square 
cross-sectional area. The four corners of this square cross-sectional area 
form longitudinal edges 126 extending substantially along the full length 
d of the cleansing shaft 125. The cross-sectional length a of the square 
cross-section is about 0.3 mm. 
A plurality of projecting serrations 127 are provided on the surface of the 
cleansing shaft 125, that is, on the surface bounded by the longitudinal 
edges 126, as illustrated schematically in FIG. 4. The height b of these 
serrations 127 is about 0.2 mm. The width c of a tooth 127 thereof is 
equally about 0.2 mm. Starting from a broad base on the surface of the 
cleansing shaft 125, the serrations 127 are tapered towards a pointed end. 
The taper angle e of the serrations 127 is about 90 degrees. 
One end of the cleansing shaft 125 is advantageously provided with an 
essentially blunt, rounded portion 128 whose radius may be 0.2 mm, for 
example. This facilitates insertion of the cleansing implement into the 
interproximal spaces. 
The complete cleansing implement 32 comprised of mounting shaft 122 and 
cleansing shaft 125 is configured as an integral component made of a 
plastics material and suitable for manufacture by injection molding. It 
will be particularly advantageous to use a plastic fiber with properties 
similar to that of dental floss. Further, greater ease of manufacture of 
the cleansing implement 32 is obtained by using a plastics material with 
good flow properties. 
In use of the cleansing implement 32, it is particularly by means of the 
longitudinal edges 126 that plaque is wiped of f the teeth. The serrations 
127 serve to loosen the plaque bacteria from the teeth. It will be 
understood that the cleansing implement 32 is also suitable for removing 
food particles from the teeth. The thin and elongate configuration of the 
cleansing implement 32 also enables tight interproximal spaces to be 
cleaned. 
Because of the high rotational frequency of the cleansing implement 32 of 
about 3,000 1/min or higher, the flexible cleansing shaft 125 threads 
itself automatically into the interproximal spaces to be cleaned, also in 
cases where the user fails to position the dental cleansing device 1 
accurately, which is a frequent occurrence particularly at inaccessible 
locations of a person's teeth. Moreover, the high rotational frequency of 
the cleansing implement 32 provides for rapid and thorough removal of 
plaque, being thus superior to conventional interproximal cleaning 
instruments as, for example, hand-operated toothpicks. 
The cleansing shaft 125 or the complete cleansing implement 32 is 
preferably made of polyester elastomer, enabling the cleansing shaft 125 
to be bent also during use by an angle of up to 180 degrees while rotating 
at a frequency of about 3,000 1/min.+-.2,000 1/min. 
FIG. 5 shows a dental cleansing device 1 which is composed of a handle 
section 2 and an attachment 3 fitted thereto. The handle section 2 is of 
an elongate configuration with a circular cross-section. A portion 4 of 
the handle section 2 at the end close to the attachment 3 is of a reduced 
diameter compared to a portion 5 of the handle section 2 at the end remote 
from the attachment 3. The attachment 3 is equally of an essentially 
elongate configuration with a circular cross-section. The diameter of a 
portion 6 of the attachment 3 at the end close to the handle section 2 
corresponds to the diameter of the portion 4 of the handle section 2. At 
the end remote from the handle section 2, the attachment 3 is provided 
with a guide tube 7 of a reduced diameter which includes a bent portion 8. 
Fixedly mounted in the portion 5 of the handle section 2 is an electrically 
powered motor 9 connected to a voltage source 12, in particular a 
rechargeable accumulator, via an electric conductor 10. A longitudinally 
slidable switch 13 is equally housed in the portion 5 of the handle 
section 2. Provided on the switch 13 is an electrically conductive contact 
means 14 which in turn is e connected to the voltage source 12 via an 
electric conductor 11. The switch 13 further includes a coupling member 15 
serving to couple the switch 13 to a drive shaft 16. 
The drive shaft 16 extends through the entire portion 4 into the portion 5 
of the handle section 2 and has at its free end close to the motor 9 in 
the area of the handle section 2 a cup-shaped receptacle 17 with an 
opening 18. The motor 9, the drive shaft 16 and the cup-shaped receptacle 
17 are concentrically arranged with a common axis 19, with the opening 18 
of the cup-shaped receptacle 17 being provided at the end close to the 
motor 9. 
Projecting outwardly from the radial outside of the cup-shaped receptacle 
17 are two relatively spaced annular collars 20, 21 defining an annular 
groove 22 therebetween for engagement by an annular collar 23 projecting 
inwardly from the coupling member 15. In this arrangement, the annular 
collar 23 engages with the annular groove 22 in such a manner that a 
displacement of the switch 13 in the longitudinal direction results at the 
same time in a displacement of the cup-shaped receptacle 17 likewise in 
the longitudinal direction. While the annular collar 23 is stationary in 
the circumferential direction, the cup-shaped receptacle 17 with its 
annular groove 22 is rotatable about the annular collar 23. The cup-shaped 
receptacle 17 is thus capable of rotating about the axis 19 irrespective 
of the position of the switch 13. It will be understood that a bearing or 
the like, not shown, may be arranged additionally in the area of the 
annular collar 23 and the associated annular groove 22, by means of which 
friction between the annular collar 23 and the annular groove 22 can be 
reduced, thereby facilitating the rotary motion of the cup-shaped 
receptacle 17 about the axis 19. 
At the end of the cup-shaped receptacle 17 close to the opening 18, a motor 
shaft 24 extends from the motor 9, the shaft being arranged concentrically 
with the axis 19 as is the motor 9. The motor shaft 24 is provided with at 
least one, preferably however, three vanes 25 projecting radially 
outwardly from the motor shaft 24 and extending in the longitudinal 
direction. The cup-shaped receptacle 17 has in its interior a 
corresponding number of longitudinal ribs 26 projecting radially inwardly 
and extending likewise in the longitudinal direction. The vanes 25 extend 
through the opening 18 into the interior of the cup-shaped receptacle 17, 
engaging in the space between the longitudinal ribs 26. In this 
arrangement, the vanes 25 and the longitudinal ribs 26 overlap 
longitudinally along a length which is greater than the maximum length of 
displacement of the switch 13 in the longitudinal direction. 
The vanes 25 and the longitudinal ribs 26 provide for transmission of the 
rotary motion of the motor shaft 24 to the cup-shaped receptacle 17 and 
thus to the drive shaft 16. The overlapping arrangement of the vanes 25 
and the longitudinal ribs 26 in the longitudinal direction enables the 
cup-shaped receptacle 17 to be displaced by means of the switch, without 
the transmission of the rotary motion of the motor shaft 24 to the drive 
shaft 16 being affected thereby. It will be understood that this coupling 
structure between the motor shaft 24 and the drive shaft 16 by means of 
the vanes 25 and the longitudinal ribs 26 may also be configured in a 
different manner, providing, for example, a suitable gearing or the like. 
Seated between the side of the annular collar 20 facing the portion 4 of 
the handle section 2 and the transition area between the portion 5 and the 
portion 4 of the handle section 2 is a spring 27 which is located in 
position by means of support walls 28, 29. The spring 27 produces a force 
acting in opposition to a displacement of the switch 13 towards the 
attachment 3. As a result, the spring 27 invariably urges the switch 13 
and thus the drive shaft 16 automatically into a direction away from the 
attachment 3 without any external influence. 
As described in the foregoing, the drive shaft 16 extends along the full 
length of the portion 4 of the handle section 2. At the end of the handle 
section 2 close to the attachment 3, the drive shaft 16 is guided by an 
annular collar 30 projecting inwardly from the handle section 2. Further, 
the drive shaft 16 projects at this end from the handle section 2 by a 
small amount, its free end being provided with a bore 31 extending 
concentrically with the axis 19. 
In the attachment 3 fitted to the handle section 2, a cleansing implement 
32 is longitudinally slidably received. The cleansing implement 32 
includes a cleansing shaft 33 of an elongate and thin configuration. 
Preferably, the cleansing shaft 33 is about 30 mm long with a diameter of 
about 0.5 mm. The cleansing shaft 33 is made of a plastics material, in 
particular a polyester elastomer as, for example, HYTREL.TM.. The 
cleansing shaft 33 is flexible, allowing bending by an angle of up to 150 
degrees, minimum, also as it rotates about its longitudinal axis. 
At its end close to the drive shaft 16, the cleansing implement 32 includes 
a circular base 34 connected to the cleansing shaft 33, as well as a pin 
35 connected to the base 34. The pin 35 of the cleansing implement 32 is 
received in the bore 31 of the drive shaft 16. The pin 35 and the bore 31 
may press-fitted together or, alternatively, the cross-sectional shapes of 
the pin 35 and the bore 31 may be conformed to each other, for example, in 
the form of a polygon or the like. 
As set forth previously, the attachment 3 is fitted to the handle section 
2. Further, the pin 35 is inserted in the bore 31 in a non-rotating 
relationship thereto. The cleansing shaft 33 extends from the base 34 to 
the guide tube 7 and is then passed through the guide tube 7. 
Because of the bent portion 8 of the guide tube 7, the cleansing shaft 33 
includes likewise a correspondingly bent portion 36. In the Figures, an 
angle of about 90 degrees is provided for the bent portions 8 and 36. It 
will be understood that the bent portions 8 and 36 may also be bent at 
different angles, particularly at angles in the range from about 30 
degrees to about 150 degrees. 
The free end of the guide tube 7 is provided with an essentially 
hemispherical rounded portion 37. The diameter of this rounded portion 37 
amounts to a value in the range from about 1 mm to about 4 mm, in 
particular a value of about 2.5 mm. 
The dental cleansing device 1 illustrated in FIG. 5 provides two modes, an 
off-mode in which the cleansing implement 32 is in the inoperative 
position, and an onmode in which the cleansing implement 32 is in the 
operative position. FIG. 5 shows the cleansing implement 32 in both the 
inoperative and the operative position, illustrating the base 34 and the 
pin 35 of the cleansing implement 32 twice, once for each position. 
However, the drive shaft 16 and the other parts of the dental cleansing 
device 1 are all shown in the off-mode and thus in their inoperative 
positions. 
FIGS. 6 and 7 are provided for a better understanding of the on and 
off-modes with the related operative and inoperative positions. FIG. 6 
shows the cleansing implement 32 in the inoperative position, while FIG. 7 
shows the operative position thereof. In the subsequent description, 
reference will be preferably made first to the two last-mentioned FIGS. 6 
and 7, while for the explanation of the mode of function FIG. 5 will be 
referred to preferably. 
In the inoperative position shown in FIG. 6, the cleansing implement 32 and 
in particular the cleansing shaft 33 are fully received in the interior of 
the attachment 3. The base 34 and the pin 35 are in the immediate 
proximity of the end of the handle section 2 close to the attachment 3. In 
contrast thereto, in the operative position shown in FIG. 7, the cleansing 
implement 32 is not fully received inside the attachment 3. The free end 
of the cleansing shaft 33 projects from the free end of the guide tube 7. 
Preferably, the cleansing shaft 33 projects from the guide tube 7 with a 
length of about 10 mm to about 15 mm, in particular about 12 mm. This is 
accomplished by longitudinal displacement of the base 34 and the pin 35 of 
the cleansing implement 32 away from the handle section 2. The base 34 and 
the pin 35 are then no longer in the proximity of the handle section 2, 
but rather, approximately in the transition area between the portion 6 of 
the attachment 3 and the guide tube 7. The base 34 and the pin 35 are 
displaced within the attachment 3 by a length corresponding precisely to 
the amount by which the cleansing shaft 33 projects from the guide tube 7. 
In the inoperative position the switch 13 is in its off-position as shown 
in FIG. 5. The contact means 14 is not in electrical contact with the 
electrically conductive surface of the motor 9. The motor 9 is accordingly 
off. The motor shaft 24 and thus the drive shaft 16 and the cleansing 
implement 32 do not rotate. Due to the position of the switch 13 and the 
force exerted by the spring 27 on the cup-shaped receptacle 17, also the 
drive shaft 16 is in the inoperative position illustrated in FIG. 5. As a 
result, the retracted position of the drive shaft 16 towards the motor 9 
also causes the cleansing implement 32 to be in its inoperative position 
illustrated in FIG. 6, in which in particular the cleansing shaft is fully 
received in the interior of the attachment 3. 
When a user then shifts the switch 13 in the longitudinal direction towards 
the attachment 3, the contact means 14 will contact the electrically 
conductive surface of the motor 9. The circuit for energization of the 
motor 9 will thereby be closed via the conductor 10 the voltage source 12, 
the contact means 14, and the conductor 11. The motor shaft 24 will thus 
be caused to rotate about the axis 19. By means of the vanes 25 and the 
longitudinal ribs 26, this rotary motion will be transmitted to the drive 
shaft 16. Via the bore 31 and the pin 35, the rotary motion will then be 
transmitted to the cleansing implement 32, causing the cleansing shaft 33 
to rotate about its own axis partly rectilinearly and partly along its 
bent portion 36. 
Displacement of the switch 13 by the user results at the same time in a 
displacement of the drive shaft 16 in the same direction through the 
annular collar 23 and the annular groove 22. This motion is transmitted to 
the cleansing implement 32 via the bore 31 and the pin 35. As a result, 
the cleansing shaft 33 moves from its inoperative position away from the 
handle section 2 in the direction of its operative position illustrated in 
FIG. 7. When the switch 13 has completed its displacement travel to its 
maximum permissible on-position, the amount of extension of the cleansing 
shaft from the guide tube is at its maximum, as shown in FIG. 7. The 
rotating and fully extended cleansing shaft 33 then enables the user to 
clean the interproximal spaces. 
When the user releases the switch 13, it will be shifted back to its 
off-position by the force of the spring 27. This will also cause the 
cleansing implement 32 to return to its inoperative position. At the same 
time, the contact means 14 will stop contacting the motor 9, causing the 
motor 9 to be off. The dental cleansing device 1 is again in the 
off-condition previously explained. 
FIG. 8 shows the attachment 3 with the cleansing implement 32 received 
therein as a separate part, that is, detached from the handle section 2. 
The attachment 3 has about centrally in its portion 6 an inwardly 
projecting annular collar 38. Further, the circular base 34 of the 
cleansing implement 32 is provided with an annular groove 39 conformed to 
the annular collar 38. In the transit position of the cleansing implement 
32 shown in FIG. 8, the annular groove 39 is in locking engagement with 
the annular collar 38. This securely captures the cleansing implement 32 
inside the attachment 3. The annular collar 38 and the annular groove 39 
are arranged such that in the transit position described the cleansing 
implement 32 is fully received within the attachment 3. 
When the attachment 3, with the cleansing implement 32 in locking 
engagement therewith, is fitted to the handle section 2, this has the 
attendant effect of inserting the pin 35 into the bore 31. Shortly before 
the attachment 3 is completely push-fitted to the handle section 2, the 
annular collar 38 will be disengaged from the annular groove 39, so that 
the cleansing implement 32, rather than being held captive inside the 
attachment 3, will then be coupled to the drive shaft 16 through the pin 
35 and the bore 31. 
When the attachment 3 is withdrawn from the handle section 2, the base 34 
will abut the annular collar 38, causing the pin 35 of the cleansing 
implement 32 to be pulled out of the bore 31. The cleansing implement 32 
will not remain coupled to the drive shaft 16, but rather, it will be 
pulled off together with the attachment 3. 
Referring to FIGS. 9 to 11, it will now be explained how the attachment 3 
is fitted to the handle section 2. As shown, the attachment 3 includes 
three openings 40, 41 and 42 spaced at an angle of about 90 degrees on the 
periphery of the attachment 3. In the absence of a fourth opening, the 
three openings 40, 41 and 42 provided are partly non-uniformly spaced on 
the periphery of the attachment 3. Each of the openings 40, 41 and 42 is 
associated with a respective lug 43, 44 and 45 projecting approximately 
radially outwardly from the handle section 2. 
In the area of overlap with the handle section 2, the attachment 3 has an 
increased diameter to enable the lugs 43, 44 and 45 of the handle section 
2 to engage the respective openings 40, 41 and 42 of the attachment 3. 
This is illustrated in FIG. 9. The lugs 43, 44 and 45 are of a flattened 
configuration in the longitudinal direction, thus enabling the user to 
insert and withdraw the handle section 2 in and from the attachment 3 
without major effort. In the locked condition illustrated in FIG. 9, the 
lugs 43, 44 and 45 engaging the respective openings 40, 41 and 42 are 
visible to the eye. 
As appears particularly from FIG. 10 showing a cross-sectional view of the 
attachment 3, each of the openings 40, 41 and 42 is associated with a 
respective pair of longitudinal grooves 46, 47 and 48. Correspondingly, 
each of the lugs 43, 44 and 45 is associated with a respective pair of 
longitudinal ridges 49, 50, 51, as becomes apparent particularly from FIG. 
11 showing a cross-sectional view of the handle section 2. When viewed in 
the circumferential direction, one longitudinal groove is provided on 
either side of the openings 40, 41 and 42, and one longitudinal ridge is 
provided on either side of the lugs 43, 44 and 45. The longitudinal 
grooves 46, 47 and 48 and the longitudinal ridges 49, 50 and 51 are 
conformed to each other such as to be in relative engagement when the 
attachment 3 is fitted to the handle section 2, the longitudinal ridges 
49, 50 and 51 then sliding along inside the longitudinal grooves 46, 47 
and 48. 
By means of in particular the longitudinal grooves 46, 47 and 48 and the 
longitudinal ridges 49, 50 and 51, the attachment 3 is located in a 
clearly defined position on the handle section 2 in the circumferential 
direction. Obviously, not all of the longitudinal ridges, longitudinal 
grooves, openings and lugs may be necessary for such a location. In the 
simplest case, a single lug will suffice which engages an associated 
through opening or a non through-going recess, thereby locating the 
attachment 3 in a clearly defined position on the handle section 2 in the 
circumferential direction. Equally obviously, such a location can also be 
accomplished by means of other structural arrangements.