Dental hygiene tool with shield and germicidal seals

An extendable latex shield and internal seals are incorporated in a disposable dental hygiene tool for protecting sterility of standard dental handpieces. The flexible nature of the extendable shield allows storage in a first position, permitting the dental professional to easily attach the tool to the handpiece and to unroll the flexible shield to the extended position, thereby protecting the handpiece from splashing of saliva, blood, or other materials during use of the tool in dental procedures. Internal seals in the tool preclude fluids or other material from transfer through the interior of the tool into the dental handpiece. The combination of the present device precludes the contamination of the handpiece, thereby avoiding sterilization procedures and the inherent time loss, inefficiency, and cost associated with such procedures.

FIELD OF THE INVENTION 
This invention relates generally to the field of instruments for 
professional dental hygiene, including cleaning and polishing of teeth. 
More particularly, the present invention provides a disposable attachment 
for standard dental handpieces which incorporates internal seals and an 
external extendable shield to prevent contamination of the motorized 
handpiece to which the tool is attached for dental procedures. 
1. Background of the Invention 
Dental tools, by the nature of their use, are easily contaminated by saliva 
or blood of the patient during work by the dentist or dental technician. 
Further, dental tools and the handpieces to which they connect for power 
and manipulation are relatively complex pieces of machinery built to close 
tolerances. Contamination has typically been dealt with by the design of 
tools and handpieces for separation of the tools to allow individual 
sterilization or disposal separate from the handpiece. The potential for 
contamination of the handpiece, however, requires separate cleaning or 
sterilization. 
Recent health concerns due to the rise in Acquired Immune Deficiency 
Syndrome (AIDS) has created the need for greater care in assuring that 
dental instruments are not contaminated for the protection of both 
patients and professionals using the instruments. Disposable dental tools, 
particularly for tools used in dental hygiene such as cleaning and 
polishing of a patient's teeth assures that no contamination will be 
created by reuse of the tool. Exemplary of this type of tool are 
disposable prophy angles such as those sold under the trademark 
DENTICATOR.RTM., produced by the Denticator Co., Inc., and described in 
U.S. Pat. No. 3,727,313; VANTAGE.RTM.; or RITE-ANGLE.TM., produced by Ash 
Dentsply. These devices are primarily constructed of various plastic 
materials to reduce expense and are entirely disposable. 
Alternatively, removable dental tools such as prophy angles may be 
manufactured for easy sterilization due to the relatively small size and 
limited complexity of the tool itself. Difficulties in assuring adequate 
sterilization of such tools are present and typically autoclaving is 
required. Degradation of the tools due to high temperatures encountered in 
autoclaving limits the life of such tools or adds requirements for 
lubrication or other maintenance. 
Disposability or sterilization of tools such as prophy angles does not 
eliminate the potential for contamination of the handpiece, which holds 
the tool for use and provides power to the tool for operation. Dental 
handpieces are extremely complex and not amenable to autoclaving due to 
their size and requirements for disassembly. Further, degradation of such 
handpieces caused by sterilizing procedures makes the end cost of such use 
unacceptable. In addition, the requirement for sterilizing the handpiece 
between each use requires availability of a large number of handpieces to 
adequately accommodate patients in a regular office schedule. 
Protective devices for handpieces have been developed as exemplified by 
U.S. Pat. Nos. 4,752,223 to Carlson; No. 4,728,290 to Eisner, et al.; No. 
4,693,871 to Geller; and No. 4,266,935 to Hoppe. Carlson discloses a 
sanitary sheath for use with a dental handpiece which requires a removable 
mountable clip mounted to the handpiece for maintaining the sheath in 
alignment with the operative openings of the dental handpiece. Eisner 
similarly provides a protective covering employed in cooperation with a 
dental tool carrier and tightening and release mechanism tool for 
attachment and release of dental tools while employing the protective 
covering on a hand tool. Geller discloses a vacuum formed thermoplastic 
sheath with openings positioned for tool mating with the dental handpiece, 
and Hoppe provides a sterilized protective sheath having an elastic 
tubular casing employing a shape retaining hard synthetic resin plate for 
alignment with the bore in the hand tool. 
Each of these devices includes openings through which contamination may be 
transmitted to the handpiece and further requires complex retaining 
mechanisms or fabrication techniques to assure alignment of all openings 
required for operation of the tool with the handpiece. 
In addition, disposable tools such as prophy angles, as presently designed, 
provide the potential for contamination of the dental handpiece through 
transmission of saliva or blood internal to the disposable tool as well as 
splashing of blood or saliva beyond the disposable tool and onto the 
handpiece. 
The present invention eliminates the deficiencies of the devices referenced 
to provide in combination a disposable tool incorporating protection for 
the handpiece and eliminating the potential for internal contamination of 
the handpiece. 
SUMMARY OF THE INVENTION 
The present invention is a dental hygiene tool incorporating a low cost 
plastic barrel portion having a first opening for engaging the dental 
handpiece and a head mounted to the barrel portion distal the first 
opening to rotatably carry a cleaning cup for prophy paste or other 
appliance. An axle carried within the barrel portion incorporates a tang 
received in the drive chuck of the handpiece and a drive gear for 
transmission of power from the axle. The tool head carries a second 
rotating axle having a mating gear engaging the drive gear of the first 
axle. The cup or other appliance is attached to the second axle opposite 
the mating gear to extend from the tool head. 
A latex sheath sealingly affixed at a first end to the external surface of 
the barrel portion provides an extendable covering for the handpiece which 
is unrolled over the interface of the barrel portion with the handpiece 
and substantially the entire handpiece thereby precluding external 
contamination of the handpiece. A first O-ring carried internally by the 
tool head engages the second axle in a friction fit to provide a seal 
preventing transmission of saliva, blood, or other fluids through the 
interior of the tool head. A second O-ring carried internal to the barrel 
portion engages the first axle with a friction fit to provide a second 
seal precluding transmission of any fluids or materials penetrating the 
first O-ring in the tool head from being transmitted through the barrel 
portion to the drive chuck or interior of the handpiece. 
A germicidal gel coating on the first and second O-rings provides 
additional defense against transmission of viral or bacterial matter 
through the O-ring seals. 
Upon completing use of the tool, the invention, including the barrel 
portion, tool head and extendable sheath, is removed from the handpiece 
and disposed of in a proper manner, thereby precluding any contamination 
of the handpiece which could be transmitted to the next patient or dental 
professional.

DETAILED DESCRIPTION 
The embodiment of the invention shown in the drawings is employed with 
standard low speed dental handpieces 10 as represented generally in FIG. 
1. A dental handpiece incorporates a rotating power transmission cable 12 
attaching to a planetary gear of other transmission arrangement 14 in the 
base of the handpiece a handle 16 provides a grasping surface for the 
operator to use the handpiece and internally carries drive means for 
transmitting power from the planetary gears. A standard knurled nut and 
threaded attachment 18 is employed for removable attachment of the power 
cable to the handpiece and the handpiece incorporates disassemble sections 
16A and 16B for cleaning and maintenance of the drive means within the 
handle. Knurled grips 16C and 16D are provided to improve the operators 
grip on the handpiece and for use in disassembling the sections. 
As best seen in FIG. 2, the handpiece incorporates a chuck 20 for 
transmitting rotational power from the handpiece to the tool employed. 
Standard handpieces provide a slip fit arrangement for attachment of a 
tool to the handpiece with key slots for securing and orienting the tool. 
The dental hygiene tool 22 incorporating the present invention, as shown in 
the drawings, incorporates a first barrel portion 24 having an open end 26 
which is received in a slip fit arrangement on the handpiece. A key slot 
28 in the barrel receives a key on the handpiece for alignment of the tool 
to provide proper orientation for use with the handpiece and to prevent 
rotation of the barrel on the handpiece during its use. A first axle 30 is 
carried within the barrel portion and terminals at a first end in a tang 
32 which is received within the chuck of the handpiece. Power transmitted 
from the flexible cable to the handpiece and through the handpiece is 
provided to the axle by rotation of the chuck. The axle in the embodiment 
shown in the drawings is supported within the barrel portion by a slip 
ring 34 providing a bearing surface riding on the inner cylindrical 
surface 36 of the barrel portion. A shoulder 35 on the first axle contacts 
a protrusion 37, on the inner circumference of the barrel to constrain 
longitudinal motion of the axle within the barrel portion. The first axle 
terminates opposite the tang in a drive gear 38 for transmitting the 
rotational motion from the chuck through the axle. 
A tool head 40 extends from the barrel portion opposite the open end 
attachment for the handpiece. The tool head encloses a second axle 42 
which incorporates a mating gear 44 which engages the drive gear on the 
first axle. In the embodiment shown in the drawing the positioning of the 
two axles and the associated gears provides a 90.degree. angle for driving 
the rubber cup 46 comprising the appliance for cleaning or polishing 
teeth. This appliance typically comprises a fluted rubber cup for 
containing prophy paste, however, alternate appliance arrangements may be 
employed using the present invention. 
The second axle incorporates a slip ring 48 which bears on the cylindrical 
inner surface of the tool head acting as a bearing for rotational motion 
of the second axle. A pin 50 integral with the inner upper surface of the 
tool head is received in an axial depression (not shown) in the second 
axle to further constrain motion of the second axle within the tool head. 
The arrangement of the drive gear and mating gear, as shown in FIG. 2, 
provides structural support urging the second axle onto the pin thereby 
preventing longitudinal motion of the second axle. 
The barrel portion and tool head of the embodiment of the invention shown 
in the drawings is molded using standard injection molding techniques for 
ABS, polyethylene or other rigid plastic. Fabrication of the axles from 
teflon, nylon, or similar materials provides a low friction interface for 
the slip rings with the inner surfaces of the molded barrel and tool head, 
thereby eliminating the requirement for complex bearing assemblies. 
An extendable sheath 52 fabricated from flexible latex rubber in the 
embodiment shown in the drawings is attached to the exterior cylindrical 
surface of the barrel portion proximate the open end of the barrel 
attaching to the handpiece. In a presently preferred embodiment, the latex 
sheath is adhesively bonded to the external cylindrical surface of the 
barrel portion. In alternative embodiments, a thermal bond or elastic fit 
with mechanical restraining means are employed for attachment of the 
sheath to the barrel portion. Flexibility of the sheath allows storage in 
a rolled position shown in the drawings. In this position the open end of 
the barrel portion of the tool is visible for ease of attachment to the 
handpiece. Upon attachment of the invention to the handpiece, the latex 
shield is unrolled to extend over the handpiece as shown by phantom 52'. 
The length of the sheath is adjustable in varying embodiments for 
handpieces of differing size and may be sufficient to cover the 
transmission means and other portions of the handpiece in addition to the 
handle. Flexibility of the latex sheath accommodates handpiece having 
varying angles and differing diameters of the handle are accommodated by 
elasticity in the cylindrical sheath. A thin walled latex sheath allows 
the dental professional to use the handpiece with normal tactile response. 
The present invention prevents contamination of the dental handpiece 
through transmission of saliva, blood or other materials internal to the 
tool head and barrel portion through the use of a two barrier seal. A 
first O-ring 54 is constrained within the tool head for friction contact 
with the second axle, thereby providing a seal preventing fluids from 
being transmitted from the exterior of the tool and the prophy cup or 
other appliance through the interior spaces of the tool head. A second 
O-ring 56 is constrained in the barrel portion for frictional contact with 
the first axle thereby providing a second seal to prevent any fluids or 
materials penetrating the first O-ring from reaching the handpiece through 
the interior of the barrel portion. In the embodiment shown in the 
drawings, the second O-ring is constrained between the protrusion 37 and 
an additional protrusion 58 on the interior circumference of the barrel 
portion. Similar protrusions on the interior of the tool head constrain 
the first O-ring in contact with the second axle. Those skilled in the art 
will recognize alternative embodiments for grooving of the interior 
surface of the tool head and barrel portion for constraining the O-rings 
therein. 
Prior to insertion in the invention, one or both of the O-rings are coated 
with a germicidal gel to provide additional protection against 
transmission of bacterial or viral contaminants present in the saliva, 
blood or other materials emanating from the patient or the dental 
procedure being performed. The gel provides additional mechanical barrier 
to transmission of the fluids and lubrication for rotation of the axles 
within the O-rings. In alternative embodiments, other sealing means are 
employed as replacements for the O-rings. Exemplary of such sealing means 
would be brush seals or close tolerance flanges surrounding the axles, the 
flanges or axle provided with integral grooves to contain the germicidal 
gel. 
In the embodiment of the invention shown in the drawings, protruding ribs 
60 are provided on the exterior of the barrel portion providing a grip to 
assist the dental professional in attaching the dental hygiene tool to the 
handpiece and as a gripping surface during use of the dental hygiene tool 
in combination with the handpiece. 
Upon completion of hygiene procedures on a patient, the dental hygiene tool 
of the present invention is removed from the handpiece for disposal. 
Disconnection of the barrel portion from the handpiece may be accomplished 
with the latex shield in the rolled or unrolled position and the entire 
dental hygiene tool with shield is disposable. The extended shield 
precludes external contamination of the handpiece during hygiene 
procedures leaving the handpiece ready for immediate use with the next 
patient. 
Having described the invention in detail as required by the patent 
statutes, those skilled in the art will recognize modifications and 
substitutions for elements of the embodiment disclosed. Such substitutions 
and modifications fall within the intent and scope of the present 
invention as defined by the following claims.