Ultrasonic toothbrush

An ultrasonic toothbrush for daily removal of soft plaque including a handle constructed of a rigid material, a battery pack, an electronics driving module, a piezoelectric member, and a removable brush-head. The low voltage DC energy supplied by the battery pack is converted to an ultrasonic frequency DC current by the electronics driving module. The piezoelectric crystal resonates, expands and contracts volumetrically, in the tune with the frequency supplied by the electronics driving module and thereby converts the electronic energy into sound-wave energy. The sound-waves driving the dentifrices in the mouth of the user against the teeth causing mild cavitation within the dentifrices at the junction with the teeth, resulting in a loosening effect on the soft plaque on the surface of the teeth and in the periodontal pockets formed in the gums around the neck of the teeth. The loosened soft plaque is then dislodged by the bristle clusters of the toothbrush by the normal brushing movements of the user.

BACKGROUND 
1. Field of Invention 
This invention relates to toothbrushes. More particularly the invention is 
concerned with an apparatus facilitating the use of ultrasonic energy to 
assist an otherwise manual toothbrush in loosening and removing soft 
plaque from the teeth of the user on a substantially daily basis. 
2. Description of Prior Art 
Numerous attempts has been made to develop an apparatus to remove plaque or 
tartar from the surface of the teeth. Some of the devices utilized sonic 
and/or ultrasonic energy. The devices utilizing sonic or ultrasonic energy 
can be grouped into three distinct categories. 
One approach is the utilization of only fluids as a medium of energy 
transmission and plaque removal by placing an ultrasonic transducer into 
the middle of the mouth. This approach is impractical and physiologically 
dangerous due to the high energy levels it requires to be effective in 
absence of any mechanical scrubbing, and the uncontrolled, variable, user 
dependent distance between the transducer and the teeth. A typical example 
in U.S. Pat. No. 3,760,799. 
The second approach is the application of ultrasonic energy to vibrate the 
toothbrush. While these teachings are aged, no application to data has 
demonstrated the practical feasibility of carrying out the science in this 
manner. The fallacy of this approach is that while the toothbrush 
vibrates, it absorbs the ultrasonic energy, the vibrations are dampened 
out by the bristles and the friction between the bristles and the tooth. 
Consequently, the vibrating energy is consumed before it can be effective 
on the surface of the teeth. An other significant drawback of some these 
proposals is that the toothbrush or applicator is solidly attached, 
otherwise fixed to the transducer, making replacement of the brush 
difficult and expensive, taking the device out of the economically 
affordable daily dental hygiene device category for the general 
population. Examples of these devices can be found in the following U.S. 
Pats.: U.S. Pat. Nos. 4,192,035 and 4,333,197 and 4,787,847. 
The third and only theory reduced to practice to data is to remove hardened 
or calcified plaque colonies from the surface of the teeth on infrequent 
periodical basis. This art has been made available to professional 
dentists in the form of a high energy device that couples the ultrasonic 
energy to the teeth by a metal probe. While safe in the hands of the 
highly skilled and professionally trained dentists or hygienists, these 
devices are not suitable for daily use by the general population. Such 
devices could cause damage to the surface of the teeth and the surrounding 
tissue when utilized by un-trained novice consumers. What has occurred to 
data is that notwithstanding the teachings of the prior art, the ability 
to utilize ultrasonic energy to assist the consumer in the daily 
maintenance of oral hygiene in a safe and effective manner has remained 
unsolved. 
OBJECTS AND ADVANTAGES OF THE INVENTION 
Responding to the above described unsolved needs, this invention provides 
an ultrasonic toothbrush that is safe and effective to assist the consumer 
in the daily maintenance of oral hygiene. The invention attains this goal 
by positioning a piezoelectric transducer in the head section of an 
otherwise manual toothbrush. The piezoelectric crystal, resonating at or 
about its resonant frequency, emits ultrasonic waves between the bristles 
and couples the energy to the surface of the teeth via the dentifrice in 
the users mouth. 
An object of the present invention is to provide a safe sonic of ultrasonic 
energy coupling mechanism to the user's teeth to dislodge and remove soft 
plaque. 
An other object of the invention is to provide an effective cleaning device 
while reducing the sonic or ultrasonic energy level to the point where the 
daily application in the hands of an un-trained novice will not harm the 
surface of the teeth or the surrounding soft tissue. 
A further object is to provide an inexpensive removable brush component, 
independent from the sealed sonic or ultrasonic energy emitter, that can 
be easily replaced by the consumer.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring in detail to the drawings, the reference numerals herein refer to 
the like numbered parts in the drawings. In the following discussion, 
unless otherwise qualified, the term "ultrasonic" refers to either 
subsonic, sonic, or ultrasonic frequencies. 
An ultrasonic toothbrush 20, in accordance with the present invention, is 
shown in FIG. 1. The toothbrush comprises of a handle 22 constructed of a 
rigid material, a battery pack 24, an electronics driving module 26, a 
piezoelectric transducer 28, connecting wiring 30, and a removable 
brush-head 32 made of a flexible material that encompasses a plurality of 
bristle clusters 34. The toothbrush is shown in a typical cleaning 
position, the bristle clusters 34 in contact with the teeth 36 in the oral 
cavity 38. The low voltage DC energy supplied by the battery pack 24 is 
converted to an ultrasonic frequency DC current by the electronics driving 
module 26, which is connected to the piezoelectric transducer 28 by the 
connecting wiring 30. The piezoelectric crystal resonates, expands and 
contracts volumetrically, in tune with the frequency supplied by the 
electronics driving module 26 and thereby converts the electronic energy 
into sound-wave energy. The sound-waves driving the dentifrices in the 
mouth of the user against the teeth 36 causing mild cavitation within the 
dentifrices at the junction with the teeth, resulting in a loosening 
effect on the soft plaque on the surface of the teeth and in the 
periodontal pockets formed in the gums around the neck of the teeth. The 
loosened soft plaque is then dislodged by the bristle clusters 34 of the 
toothbrush 20 by the normal brushing movements of the user. 
The length of the bristle clusters 34 is selected to space the transducer 
28 within an effective and controlled optimum distance to the teeth, 
allowing the reduction of the sound energy to biologically safe levels for 
routine daily application without causing harm to the surface or root 
structure of the teeth, and the surrounding soft tissue. 
FIG. 2 and FIG. 3 illustrate the lock-in attachment methodology of the 
brush-head 32 to the handle 22. To achieve a firm attachment, the 
brush-head 32 incorporates a tapered tongue section 40 and the handle 
incorporates a matching groove 42. To install a replacement brush-head 32, 
the user engages the rigid nose 44 section of the handle 22 with the 
flexible mouth 46 section of the brush-head 32. Upon engagement, the user 
forces the brush-head 32 upon the handle 22 until the movement is stopped 
by the lower mating surfaces 48 and 50 of the brush-head 32 and handle 22 
respectively, and the tongue 40 snaps into the groove 42. 
FIGS. 4, 5, and 6 illustrate the un-locking methodology of the brush-head 
32 from the handle 22. The brush-head 32 incorporates a tapered abutment 
52 on each side that increases in size toward its mouth 46. The internal 
cavity of the mouth 46 is tapered 54, and increasing the size toward the 
abutments 52, forming a gap between the brush-head 32 and the handle 22 
adjacent to the abutments 52. A removal tool 56 constructed of a material 
with superior strength and rigidity to the flexible brush-head 32 
material, comprises a cavity that matches the lower and straight side 
dimensions of the brush-head 32 but larger than the brush-head 32 in the 
vertical dimension. As the user slides the rigid removal tool 56 upon the 
flexible brush-head 32, the sides with the abutments 52 of the brush-head 
32 deform inwardly, causing the top section of the brush head 32 with the 
tongue 40 to flex into the gap 47, out of the groove 42 of the handle 22, 
thereby un-locking the brush-head 32 from the handle 22. 
FIG. 7 shows an alternative embodiment of the invention, where the 
ultrasonic toothbrush 70 comprises of an AC line connector 66, a handle 
64, an electronics module 26, a low voltage high frequency DC connector 
58, and a replaceable brush element 62 that is further comprised of a 
plurality of bristle clusters 34, a piezoelectric transducer 28, 
connecting wiring 30, and an other connector 60. The electronic module is 
energized by conventional AC house current through the line connector 66, 
The AC house current is converted to a low voltage, ultrasonic frequency 
DC current by the electronics module 26, which is connected to the 
piezoelectric transducer 28 by the connecting wiring 30 through the 
connectors 58 and 60. The piezoelectric crystal resonates, expands and 
contracts volumetrically, in tune with the frequency supplied by the 
electronics driving module 26 and thereby converts the electronic energy 
into sound-wave energy. The sound-waves driving the dentifrices in the 
mouth of the user against the teeth 36 causing mild cavitation within the 
dentifrices at the junction with the teeth, resulting in a loosening 
effect on the soft plaque on the surface of the teeth and in the 
periodontal pockets formed in the gums around the neck of the teeth. The 
loosened soft plaque is then dislodged by the bristle clusters 34 of the 
toothbrush 70 by the normal brushing movements of the user. 
CONCLUSION, RAMIFICATIONS AND SCOPE OF THE INVENTION 
The reader can see that the invention provides a safe and effective 
ultrasonic toothbrush that can be utilized by any novice in the daily 
maintenance of oral hygiene. The fluid coupled ultransonic energy, where 
metallic contact with the teeth has been eliminated, and the relatively 
low level but effective energy provides outstanding safety for both the 
teeth and the surrounding soft tissue. The reduced energy requirement is 
made possible by the controlled distance between the piezoelectric 
transducer and the teeth, that is established by the length of the bristle 
clusters. 
While the preceding description contain many specificities, these should 
not be construed as limitations on the scope of the invention, but rather 
as an exemplification of a preferred and additional embodiments thereof. 
Many other variations are possible. Skilled artisans will readily be able 
to change dimensions, shapes and construction materials of the various 
components described in the embodiments and adopt the invention to all 
types of sonic energy applications, from subsonic through sonic to the 
ultrasonic range. Accordingly, the scope of the invention should be 
determined not by the embodiments illustrated, but by the appended claims 
and their legal equivalents.