Straddle type tooth brushing device

Earlier devices of the genre, had a yoke-like head for brushing the teeth, and a cowling of reentrantly folded flexible material interconnected with the arms of the head so as to straddle the slot between the arms. The midsection at the bight of the cowling had pleats between it and the wings of the cowling, and together they formed an articulated linkage between the wings for preserving the bias on the wings during the tooth brushing operation. In the present device, the arms 12 have only brackets 34 on the terminal end portions thereof, the relatively outboard portions 38 of which elbow out in front of the arms, like cowcatchers, below the terminal ends 20 of the arms. The portions 38 in turn have mitt-like brushes 50 thereon comprised of fields of spaced individual bristle of 0.010 inch in diameter or greater at the bases 64 thereof, collectively firm but individually spaced apart from one another at heights and densities enabling them to laterally deflect within the fields, and made of a thermoplastic resin material which is 47 or less in durometer on the Shore D Scale, so as to be ultra soft to the gums of the teeth. Now, with brackets so equipped, the arms 12 can forcibly pinch the portions 38 of the brackets together to the extent that the brushes 50 maintain a firm but comfortable grip on a row of teeth 3 at the level of the gingival sulcus 51 thereof, notwithstanding the absence of the linkage. Moreover, the arms and brackets can be pivoted crosswise the length of the row, to be oscillated through a pitman arm-like motion more in parallel to the gaps between pairs of teeth.

2. Technical Field 
This invention relates to a straddle-type tooth brushing device, and in 
particular, to a tooth brushing device of this type wherein there are 
means including a pair of elongated arms having brushes on the distal end 
portions thereof forming a head for straddling about a row of teeth to be 
cleaned, elongated support means including a handle, for supporting the 
head adjacent the row of teeth, and biasing means acting on the distal end 
portions of the arms from within the head to yieldably bias the brushes 
into engagement with the relatively inside and outside faces of the teeth 
when the head is straddled about the row thereof. The arms have 
longitudinal axes and are rigidly interconnected with the support means so 
as to form relatively rigid longitudinal extensions thereof, which project 
from the distal end of the support means in generally spaced parallel 
relationship to one another, and have an elongated slot in the space 
therebetween which opens to the outside of the device at the distal end 
portions of the arms, and has a central plane therein which extends 
between the longitudinal axes of the arms generally parallel thereto. The 
distal end portions of the arms have relatively laterally inwardly 
directed surfaces thereon which are relatively opposed to one another 
across the central plane of the slot and extend in planes generally 
parallel to the longitudinal axes of the arms, with relatively upper, 
lower and forward edges thereabout at the peripheries thereof, which are 
disposed relatively remote from, and adjacent to, the gum lines of the 
respective row of teeth being brushed, and forwardly of the surface, 
respectively, when the head is straddled about the row of teeth so that 
the central plane of the slot is aligned with the row of teeth. The 
brushes comprise discrete strands of thermoplastic resin material which 
are relatively upstanding on the relatively laterally inwardly directed 
surfaces of the distal end portions of the arms at individually spaced 
apart locations on the surfaces so as to be individually laterally 
deflectable in relation to one another, yet collectively operable on the 
respective surfaces to form mutually opposing fields of bristle for tooth 
brushing purposes when the head is straddled about a row of teeth and the 
brushes are engaged with the faces of the teeth. The arms are constructed 
of a stiff but resiliently flexible material, and the distal end portions 
of the arms are yieldably biased relatively toward one another by the 
biasing means, transverse the central plane of the slot in the relaxed 
state of the arms, to the extend that the user must forcibly wedge the 
teeth between the fields of bristle when inserting the teeth between the 
brushes to straddle the head about the row of teeth. As a consequence, the 
distal end portions of the arms take a pincers-like grip on the teeth 
transverse the row thereof, when the head is straddled about the row of 
teeth, and the user need not use his thumb and forefinger, nor any other 
part of his hand, to assert a grip on the teeth. Instead, his hand may 
remain on the handle of the device throughout the tooth brushing 
operation, and this facilitates manipulating the device since his hand 
need not be advanced forwardly onto the arms for purposes of asserting a 
grip, as was necessary in the prior art. 
3. Background Art 
Commercial versions of the device were placed on sale in October 1990, and 
have received widespread acceptance in the marketplace since then. 
DISCLOSURE OF THE INVENTION 
I have since found that the articulated linkage in the earlier devices, can 
be dispensed with, and the arms terminated at the upper, lower and forward 
peripheral edges of the relatively laterally inwardly directed surfaces of 
the distal end portions of the arms, so that the respective arms are 
independent of one another transverse the central plane of the slot, to 
enable the device to undergo certain additional dynamics in the tooth 
brushing operation, if (1) the brushes on the surfaces comprise discrete 
strands of thermoplastic resin material which are 47 or less in durometer 
on the Shore D Scale, 0.010 inch in diameter or greater at the bases 
thereof, and relatively upstand on the surfaces at individually spaced 
apart locations on the surfaces so as to be individually laterally 
deflectable in relation to one another, yet collectively operable on the 
respective surfaces to form mutually opposing fields of bristle that are 
firm enough for tooth brushing purposes but ultrasoft to the gingival 
sulcus at the gum lines of the teeth when the head is straddled about a 
row of teeth and the brushes are engaged with the faces of the teeth, and 
(2) the distal end portions of the arms are so closely spaced apart from 
one another at the surfaces, and so yieldably biased relatively toward one 
another by the biasing means, transverse the central plane of the slot in 
the relaxed state of the arms, that the user must forcibly wedge the teeth 
between the fields of bristle when inserting the teeth between the brushes 
to straddle the head about the row of teeth. 
One way to provide the bias is to use a head wherein (1) the arms have main 
portions which cantilever from the distal end of the support means and 
terminate independently of one another at points relatively remote from 
the distal end of the support means where the slot has less than a tooth 
in width transverse the central plane of the slot, and (2) the main 
portions of the arms have extensions thereon which cantilever relatively 
laterally outwardly from the terminal end portions of the main portions to 
greater than a tooth in width on the opposing sides of the central plane 
of the slot, and have relatively outboard portions thereof which project 
relatively outwardly beyond the terminal ends of the main portions in 
directions relatively away from the distal end of the support means 
longitudinally thereof, to form distal end portions of the arms which are 
spaced apart from one another at the relatively laterally inwardly 
directed surfaces thereof and yieldably biased toward one another at said 
surfaces by the main portions, transverse the central plane of the slot in 
the relaxed state of the arms, to the extent that the user must forcibly 
wedge the teeth between the fields of bristle to straddle the row of 
teeth. 
For optimal firmness, the strands of bristle preferably upstand on 
substrates of the same resin material which cover the relatively laterally 
inwardly directed surfaces of the distal end portions of the arms in their 
entireties. In fact, in certain of the presently preferred embodiments of 
the invention, the brushes comprise monoliths of the thermoplastic resin 
material, which substantially encircle the distal end portions of the arms 
at the relatively laterally inwardly and outwardly directed surfaces 
thereof, and the relatively upper and lower peripheral edges thereof, and 
have the strands of bristle relatively monolithically upstanding on the 
relatively opposing inside surfaces of the monoliths, for engagement with 
the faces of the teeth. Also, in many of these embodiments, the monoliths 
have portions thereof which project relatively outwardly beyond and below 
the relatively forward and lower peripheral edges of the distal end 
portions of the arms, and form relatively depending lobes thereon 
consisting of the resin material alone, for engaging the sulcus and the 
gingiva of the teeth. In some embodiments, moreover, the relatively remote 
outside surfaces of the monoliths have grooves thereacross which subdivide 
the lobes into main body portions, and bottom portions therebelow which 
are hinged to the main body portions of the lobes for deflection by the 
gums in the tooth brushing operation. 
Preferably, the relatively bottom and leading edges of the lobes, relative 
to the gum lines of the teeth, are arcuately rounded; and preferably, the 
longitudinal axes of the arms are substantially coplanar with one another 
in a first cross sectional plane of the arms extending substantially 
normal to the central plane of the slot, and the terminal ends of the main 
portions of the arms are angled to the first cross sectional planes of the 
arms at the relatively inner peripheral edges thereof on the slot. 
In most of the presently preferred embodiments of the invention, the 
relatively laterally inwardly directed surfaces of the distal end portions 
of the arms are disposed at acute angles to the central plane of the slot 
in the direction relatively upwardly of the plane, and the strands of 
bristle are angled to the central plane of the slot in the opposite 
direction so that the fields of bristle incline apically to the gingival 
sulcus of the teeth, at approximately 45 degrees when the head is 
straddled about a row of teeth. In the relaxed state of the arms, however, 
the strands of bristle approach the central plane of the slot at greater 
than 45 degrees, and may even interdigitate with one another at the tops 
of the fields. 
Preferably, the resin material has a hardness of about 24-27 on the Shore D 
Scale, depending on the diameter of the strands of at the bases thereof. 
Preferably too, the resin material has a Vicat softening temperature of 
140 degrees F or greater. 
In many of the presently preferred embodiments of the invention, the 
thermoplastic resin material is a polyolefin; and in certain of them, the 
material is a copolymer of ethylene and vinyl acetate, and the amount of 
vinyl acetate monomer in the copolymer is adjusted to constitute about 
9-28% by weight of the total gross amount of the copolymer, depending on 
the diameter of the strands at the bases thereof. In one group of 
embodiments, for example, the strands have a diameter of 0.040 inch at the 
bases thereof, and the vinyl acetate monomer constitutes about 18-25% by 
weight of the total gross amount of the copolymer. 
Preferably, the strands of are tapered from the bases thereof to a lesser 
diameter at the tips thereof. In certain of the presently preferred 
embodiments of the invention, they are conical and tapered to a point 
along the length thereof intermediate the bases and the tips thereof, and 
then tapered at an increased draft from the intermediate points thereof to 
the tips thereof. 
For the best combination, the longitudinal axes of the arms are 
substantially coplanar with one another in a first cross sectional plane 
of the arms extending substantially normal to the central plane of the 
slot at the terminal end portions of the main portions of the arms, those 
sides of the terminal end portions of the main portions of the arms which 
are disposed relatively adjacent to the gum lines of the row of teeth 
being brushed, are substantially coplanar with one another in a second 
cross sectional plane of the arms extending substantially normal to the 
central plane of the slot, and the extensions of the main portions of the 
arms take the form of brackets which have successively interconnected 
inboard and outboard portions, the relatively inboard portions of which 
project relatively laterally outwardly from the terminal end portions of 
the main portions of the arms, and the relatively outboard portions of 
which relatively depend from the relatively inboard portions of the 
brackets, and cantilever relatively outwardly beyond the terminal ends of 
the main portions of the arms in directions relatively away from the 
distal end of the support means longitudinally thereof, on the opposite 
side of the second cross sectional plane of the arms from the first cross 
sectional plane thereof. This has the effect of dog-legging the relatively 
outboard portions of the brackets in front of the terminal end portions of 
the main portions of the arms at a level relatively below the lower sides 
thereof, so that the relatively outboard portions of the brackets can be 
translated like cowcatchers along the length of a row of teeth, in 
juxtaposition with the relatively inside and outside faces thereof, and 
then when desired, pivoted into positions more parallel to the gaps 
between pairs of teeth, so that they then can be put through a pitman 
arm-like motion, crosswise the length of the row of teeth, to add a 
vertical component to their action. 
In some of the presently preferred embodiments of the invention, the arms 
are also fabricated from plastic resin material. Furthermore, in many of 
these embodiments, the support means and the arms are fabricated as a 
monolithic frame having the brushes molded therearound on the distal end 
portions of the arms.

BEST MODE FOR CARRYING OUT THE INVENTION 
Referring to the drawings, it will be seen that in general the device 
comprises a yoke-like head 2 for brushing the teeth 3, and elongated 
support means 4, such as a handle 6 having a "thumbprint" 7 and a shank 8 
on the distal end thereof, for supporting and manipulating the head 2 in 
the mouth 10 of the person whose teeth 3 are to be cleaned in a tooth 
brushing operation. The head 2 comprises a pair of elongated arms 12 which 
have longitudinal axes 14, and are rigidly interconnected with the shank 8 
so as to form relatively rigid longitudinal extensions thereof, which 
project from the distal end of the shank in generally spaced parallel 
relationship to one another so as to be insertable in the person's mouth, 
side by side of one another, when the device is put to use in a tooth 
brushing operation. The space between the arms forms an elongated slot 16 
which opens to the outside of the device at the end 16' thereof that is 
relatively remote from the distal end of the shank, and the slot has a 
central plane 18 which extends longitudinally thereof between the terminal 
ends 20 of the arms. Outriggered on the ends 20, and mutually opposed to 
one another across the plane 18 of the slot, is a pair of tooth brushing 
members 19 which are adapted to be straddled about a row of teeth 3 in the 
person's mouth, and translated along the length of the row in 
juxtaposition to the relatively inside and outside faces 22 and 24 of the 
teeth, respectively, when the arms are manipulated in the tooth brushing 
operation so that the plane 18 is generally aligned with the row of teeth, 
as in FIGS. 4-7 and 9-11. 
The terms "upper" and "lower" will be used hereafter to refer to certain 
features of the head 2 which when the device is put to use, are disposed 
relatively remote from, and adjacent to, the gum lines of the respective 
row of teeth being brushed, respectively. The term "forward" refers to 
those features of the head which are relatively remote from the distal end 
of the shank in use. 
Referring now to FIGS. 1-7 in particular, it will be seen that the arms 12 
of the head 2 terminate independently of one another at the ends 20 
thereof relatively remote from the shank 8 of the handle 6, and both the 
longitudinal axes 14 of the respective arms, and the lower sides 26 of the 
terminal end portions 28 of the main portion of the respective arms, are 
substantially coplanar with one another in first and second cross 
sectional planes 30 and 32 of the arms, respectively, which extend 
substantially normal to the central plane 18 of the slot at the terminal 
end portions 28 of the arms. The end opening 16' of the slot 16, 
meanwhile, is less than a tooth in width transverse the central plane 18 
of the slot, but in lieu of greater width, the terminal end portions 28 of 
the arms have brackets 34 thereon which cantilever relatively outwardly 
from the arms on the opposing sides of the central plane 18 of the slot, 
to form wing-like extensions of the arms which can be straddled about a 
row of teeth, transverse the length thereof, and translated along the 
length of the row for the tooth brushing operation, as shall be explained. 
The brackets 34 have successively interconnected relatively inboard and 
outboard portions 36 and 38, respectively, as well as relatively 
intermediate portions 40 therebetween. The relatively inboard portions 36 
project relatively laterally outwardly from the terminal end portions 28 
of the arms, and the relatively intermediate portions 40 of the brackets 
are outriggered like gusset plates on them. The relatively intermediate 
portions 40 are also reentrantly folded about the axes 14 of the arms, so 
as to relatively depend from the relatively inboard portions 36 at acute 
angles to the central plane 18 of the slot, and for the most part on the 
opposite side of the second cross sectional plane 32 of the arms from the 
first cross sectional plane 30 thereof. The relatively outboard portions 
38 of the brackets are in turn cantilevered relatively rigidly outwardly 
from the forward edges of the intermediate portions, and relatively 
rigidly outwardly beyond the terminal ends 20 of the arms, in directions 
relatively away from the distal end of the shank 8 of the handle, 
longitudinally thereof. They also project at the same angles that the 
intermediate portions 40 have to the plane 18, and at locations on the 
opposite side of the second cross sectional plane 32 of the arms from the 
aforesaid first cross sectional plane 30 thereof. In this disposition, the 
relatively outboard portions 38 of the brackets have pairs of relatively 
laterally inwardly and outwardly directed surfaces 42 and 44 thereon, 
respectively, which in turn have upper, lower and forward edges 46, 47 and 
48 thereabout, at the peripheries thereof. Moreover, the relatively 
laterally inwardly directed surfaces 42 of the portions 38 are relatively 
opposed to one another, across the central plane 18 of the slot, and 
extend in planes generally parallel to the longitudinal axes 14 of the 
arms. The tooth brushing members 19 are mounted in turn on the portions 38 
so that the portions present fields of bristle 49 to one another at the 
surfaces 42 thereof, for engagement with the faces 22, 24 of the teeth in 
the tooth brushing operation. 
In the device disclosed in the earlier Applications, the relatively 
outboard portions 38 of the brackets were part of the cowling, and thus 
were interconnected with one another at the relatively upper peripheral 
edges 46 of their relatively opposing inside surfaces 42. Contrary to the 
invention disclosed in those Applications, however, the relatively 
outboard portions 38 of the brackets in the present device are terminated 
at both the relatively upper and lower peripheral edges 46, 47 of the 
relatively opposing inside surfaces 42 thereof, as well as at the forward 
edges 48 thereof, so as to increase the range of dynamics through which 
the device can be put in the tooth brushing operation. This is possible 
because the strands of bristle 49 on the brackets have an unusually low 
durometer hardness, yet firmness as well, which makes it possible to pinch 
the brackets together to the extent that they no longer need the 
articulated linkage of the cowling to retain a firm but comfortable grip 
on the teeth in the tooth brushing operation. If necessary or desired, 
moreover, the user can adjust the hardness of the bristle at the time of 
use, to render them more suitable to his level of comfort, as shall be 
explained. 
More specifically, the relatively outboard portions 38 of the brackets are 
now equipped with firm but ultra soft brushes 50 of thermoplastic resin 
material on the relatively opposing inside surfaces 42 thereof; and to 
take advantage of the ultra soft but firm body characteristics of the 
bristle 49 in the brushes, the arms 12 which operate to pinch the brushes 
together are constructed of a stiff but resiliently flexible material, 
which is of such lengths inward along the slot 16 from the end opening 16, 
thereof and relative to the widths of the arms transverse the central 
plane 18 of the slot, that when the brushes are spaced apart from one 
another transverse the plane 18 of the slot to the extent that the 
portions 38 of the brackets must once again be straddled about a row of 
teeth for the tooth brushing operation by relatively wedgibly inserting 
the teeth between the brushes until the fields of bristle engage the faces 
of the teeth at the gingival sulcus 51 thereof, the arms 12 and brackets 
34 respond, after yielding to the wedgible insertion of the teeth between 
the brushes, by so forcibly pinching the relatively outboard portions 38 
of the brackets relatively toward one another transverse the central plane 
18 of the slot, that notwithstanding the absence of the linkage, the 
brushes 50 maintain a firm but comfortable grip on the teeth at the level 
of the gingival sulcus when the relatively outboard portions 38 of the 
brackets are translated along the length of a row of teeth in the tooth 
brushing operation. Note FIGS. 4-7 and 9-11 in this connection. And in 
FIG. 1, note also the slight pinch to the slot, in the direction of the 
end opening 16' thereof. The brushes 50 are in fact glove-like monoliths 
52 of thermoplastic resin material, which substantially encircle the 
relatively outboard portions 38 of the brackets at the surfaces 42, 44 and 
the edges 46, 47 and 48 thereof, and have fields of spaced individual 
strands of bristle 49 relatively monolithically upstanding on the 
relatively opposing inside surfaces 54 thereof, much like the wings of the 
cowling which was formed on the device of application Ser. No. 499,022. 
There are also portions of the monoliths which project well outwardly 
beyond and below the relatively forward and lower peripheral edges 46 and 
47 of the portions 38 of the brackets, so as to form lobes 56 thereon 
consisting of the resin alone, which relatively depend from the bottom 
edges 46 of the portions 38, and project relatively forwardly from the 
forward edges 48 thereof. The lobes are also equipped with bristle, but 
are relatively "spineless" since the harder portions 38 of the brackets 
are disposed well above and behind them. This "spinelessness" leaves the 
lobes relatively limp and flaccid, and more easily deflectable crosswise 
the plane 18 of the slot, when the device is put to use. The lobes 56 may 
also have grooves 57 extending thereacross, at the relatively remote 
outside surfaces 58 thereof, which if deepened enough, will allow the 
relatively bottom portions 59 of the lobes to flap with respect to the 
main bodies of the monoliths, for reasons which will be explained. 
The relatively bottom and relatively leading edges 60, 62 of the lobes 56 
are also arcuately rounded about points disposed somewhat ahead of the 
terminal ends 20 of the arms, so that even the outline of the monoliths 
lends itself to the new dynamics of the device, as shall be explained. And 
for related reasons, the terminal ends 20 of the arms are mitered or 
chamfered to the planes 30 and 32 of the arms, at the relatively inner 
peripheral edges 63 thereof on the slot 16. 
Preferably, the relatively opposing inside surfaces 54 of the brushes are 
disposed at acute angles to the central plane 18 of the slot 16, in the 
direction relatively upwardly thereof, and the fields of bristle 49 are 
angled to the plane of the slot in the opposite direction, so that they 
will incline apically to the gingival sulcus 51 of the teeth, at 
approximately 45 degrees, when the brackets 34 of the device are straddled 
about a row of teeth in the manner of FIGS. 4 and 5. In the relaxed state 
of the device, however, the fields of bristle more closely approach the 
plane 18 of the slot, and may even interdigitate with one another at the 
tops thereof, as seen in FIG. 3. 
Unlike conventional extruded and tufted bristle of Nylon or the like, the 
strands of bristle 49 in my brush have a far greater diameter of at least 
0.010 inch at the bases 64 thereof; and when collected in fields for 
firmness, but individually spaced apart from one another at heights and 
densities enabling them to laterally deflect within the fields, this 
diameter enables the resin in the brushes to have a hardness or durometer 
of only about 24-47 on the Shore D Scale, depending on the actual diameter 
of the bristle at the bases thereof. This hardness is so low, of course, 
that the actual choice must be tempered by the practical considerations of 
marketing and point of use, lest the highly temperature sensitive resin 
soften to the point of distortion, for example, in the transport of the 
device to the marketplace. Therefore, the choice is commonly one in which 
the resin also has a Vicat softening temperature that is adapted to be 
form-sustaining for the marketing and point of use of the device, such as, 
for example, one of 140 degrees F. or greater for the United States. 
At the point of use however, the temperature sensitivity of the bristle 
actually has a positive side, in that the bristle may be briefly subjected 
to heat--or cold--such as under hot or cold tap water for a few seconds, 
by way of softening--or hardening--the bristle even more for the tooth 
brushing operation. 
The handle 6, sheath 8, arms 12 and brackets 34 of the device are commonly 
also fabricated from plastic resin material, but one which, of course, has 
the differing properties needed for them. Commonly, the handle, shank, 
arms, and brackets are fabricated as a monolithic frame, and then 
mitt-like brushes such as those seen at 50 in the drawings are molded 
around the relatively outboard portions 38 of the frame, using the process 
disclosed in application Ser. No. 499,922. Note the spacer studs 65 
incorporated into the brushes from that process. 
Polyolefins are one choice of thermoplastic resin for the brushes 50 when 
this process is used. In the process of application Ser. No. 499,922, for 
example, I have used certain copolymers of ethylene and vinyl acetate, and 
to get the desired hardness, have adjusted the amount of vinyl acetate 
monomer to constitute about 9-28% by weight of the total gross amount, 
depending on the diameter of the bristle at the bases thereof. I have 
taken care, however, that the resin also has a sufficiently high Vicat 
softening temperature to sustain its form in the marketing and use of the 
device. The Industrial Polymers Division of the DuPont Company of 
Wilmington, Del., 19898, provides a wide range of such copolymers under 
the trademark ELVAX, and I have used either selected semi-transparent or 
clear resins from among the group, or blends thereof, and I have found 
that both are highly suitable for my purposes. For example, when the 
strand of bristle in the fields of the same have a 0.040 inch diameter at 
the bases thereof, and are distributed at 0.010-0.025 inch spacings in the 
field, an ELVAX resin having an 18-25% vinyl acetate content by weight to 
the gross amount of the copolymer, will provide a suitable combination of 
softness and firmness to the bristle. I have also blended 30% of UE 634 
from Quantum Chemical Corporation's USI Division at Rolling Meadows, Ill., 
60008, with 70% of UE 652 from Quantum, and I have achieved fully 
satisfactory results from the blend. The U 652 has an 19% vinyl acetate 
content by weight, and the UE 634 a 28% vinyl acetate content by weight. 
Generally, as the diameter of the strands of bristle is decreased at the 
bases thereof, the vinyl acetate content is correspondingly decreased to 
get a satisfactory softness, but collective firmness in the fields of 
bristle. When the bristle diameter drops to as low as 0.010 inch, then 
DuPont's ELVAX 770 with a vinyl acetate content of 9.5% by weight can be 
employed in making up the resin material; and when the diameter rises to 
as much as, for example, 0.060 inch at the bases of the strands of 
bristle, DuPont's ELVAX 150 having a vinyl acetate content of 33% by 
weight, can be employed, but only when blended with some other lower 
content ELVAX resin which will raise the Vicat softening temperature to 
one which is acceptable for the marketing and use to be made of the 
device. ELVAX 150 has a Vicat softening temperature as low as 97% F., and 
in practice, a device with brushes of such a resin material thereon would 
be extremely difficult to market, so much as use, inasmuch as the brushes 
might very well melt when standing in the open sun in a shipping 
container, or on a truck, or when shipped to a country such as Mexico. 
Therefore, the selection of the resin material must always be a function 
of the marketing and use to be made of the device, including the location 
where it is to be put to use. 
To a far lesser extent, the choice of resin material is also a function of 
the height of the bristle. Conventional extruded Nylon tufted bristle are 
commonly 0.40 inch high. To be effective, bristle require at least 0.25 
inch in height. I have employed bristle in the range 0.25-0.35 inch for an 
adult device and 0.22-0.32 inch for a children's device. In the range 
0.22-0.40 inch, the foregoing resin selection is fully operable, but I 
prefer a bristle length of 0.35 inch for adults and 0.32 inch for 
children. I also prefer a resin providing a Vicat softening temperature of 
about 140 degrees F., and in accordance with that, one having a hardness 
of about 28-38 on the Shore D Scale. 
When using the process of application Ser. No. 499,922, the brushes 50 are 
molded around the relatively outboard portions 38 of the brackets by the 
injection molding process described therein; and in accordance with that 
process, the bristle are tapered from the bases thereof to a lesser 
diameter at the tips 66 thereof. In fact, I have found that they commonly 
need at least 2% of draft to be parted from the injection mold; and in 
order to transfer the load at the tip of each bristle to a point part way 
up the length of the same, for stability, I commonly provide a conical 
bristle which is 0.040 inch in diameter at the base and 0.350 inch high, 
and which has about 1% of taper per side for 2/3 the length of the bristle 
from the bases thereof, and then about 1.5% of taper per side from that 
point upward to the tips of the bristle. At the 2/3 point, therefore, the 
bristle approximate 0.036 inch in diameter, and at the tips thereof, 0.010 
inch in diameter. 
For comparison, even the scrub brushes used in toilets are commonly 
extruded from Nylon at far less than 0.010 inch throughout their lengths. 
My bristle are considerably wider than these, therefore, and are even 
wider at their tips. But given the material of which they are made, and 
their monolithic character with their substrates 52, the bristle provide 
the collectively firm but ultra soft body characteristics needed for their 
tooth brushing function when the arms 12 of the device are constructed and 
sized as indicated to forcibly pinch the relatively outboard portions 38 
of the brackets together to the extent that the brushes 50 maintain a firm 
but comfortable grip on the teeth when the brackets are translated along 
the length of a row in a tooth brushing operation. 
The bristle 49 also provide a better support for toothpaste and powder, 
than do thin tufted bristle, because of the greater diameter in their 
bases and the firmness they provide when collected together in fields. 
At present I employ certain amorphous polyesters or polypropylene as the 
resin material for the frame, i.e., the handle, shank, arms, and brackets 
of the device. One such polyester is the EKTAR DN003 copolyester provided 
by the Eastman Chemical Division of Eastman Kodak Company at Kingsport, 
Tenn. An example of a polypropylene is the Tenite polypropylene P404K-038 
provided by Eastman Kodak Company. Frames with slots 13/8 inches long and 
0.050 inch wide at their end openings 16', and arms 3/16 inch wide, and 
made of such materials, are presently used for the device. 
The Bass technique of tooth brushing has always been a highly recommended, 
if not preferable, method of brushing one's teeth. Using it, the brush, 
conventional or otherwise, is translated along each gum line of each row 
of teeth, at roughly 45 degrees to the elevation of the teeth, so as to 
"rake" the sulcus 51 of the teeth like a plowshare without damaging the 
more tender gingival tissue of the gums. Ideally, however, the motion is 
not simply a continuous one in the lengthwise direction of the row of 
teeth, but is an oscillatory or back and forth motion in which short 
strokes are used to collectively advance the brush lengthwise of the row 
until the last tooth is reached. The object is to generate a "flicking" 
motion at the tips of the bristle, to dislodge any debris collected at the 
sulcus, as well as to scrub the faces of the teeth and massage the more 
tender gingiva. When using the device disclosed in the earlier 
Applications, an oscillatory motion could be generated lengthwise of each 
row of teeth, but because of the articulated linkage arched across the 
tops of the teeth, the device was limited in its ability to generate any 
vertical component to the "flicking" action of the tips of the bristle. 
Also, in the case of the teeth of more elderly persons, whose gums had 
receded over the years, the cowling could not reach the sulcus with the 
full effect intended for the device; and if the frontmost teeth of a row, 
at the bight thereof, were closely crowded so as to make for "corners" at 
the transition between the frontmost and rearmost teeth of the row, the 
device was rendered largely inoperative for the frontmost teeth because of 
the difficulty in turning the corners and maintaining contact with the 
sulcus as each turn was made. 
Most of these shortcomings were attributable to the fact that the 
articulated linkage of the cowling of the device in the earlier 
Applications, also functioned as a means for determining the "drop" of the 
wings of the cowling down the faces 22, 24 of each tooth as the device 
translated thereacross. Referring now to FIGS. 4-11 herein, it will be 
seen that the terminal ends 20 of the arms 12 now provide the only limit 
on the depth to which the brushes 50 can reach in gripping the teeth of a 
row in a tooth brushing operation, and they, the arms, can be pivoted to 
any angle desired, relative to the length of the row, to adjust the "drop" 
of the brushes. This is to say, the brushes now resemble cowcatchers that 
are underslung in front of the ends 20, below the second cross sectional 
plane 32 of the arms, and the device can not only be driven along the 
length of each row, as in the past, and quickly but progressively stopped, 
advanced and stopped again with an oscillatory motion, while the terminal 
end portions 28 of the arms "ride above" the tops of the teeth; but in 
addition, when desired, the arms can be relatively lifted and canted or 
angled to the row, crosswise the length thereof, so as to introduce a 
shoveling or scooping motion to the oscillatory movement of the brushes, 
much like that of a pitman arm. This compound movement will arcuately 
"flick" the tips of the bristle back and forth in the sulcus, with a 
vertical component, so as to more effectively sweep the debris from the 
same in the manner illustrated as best possible in FIG. 10. In addition, 
and at the same time, if desired, the user may also rotate the head of the 
device to one side or the other of the row of teeth, as in FIGS. 6 and 7, 
to adjust the "drop" of the corresponding brush down the face of the teeth 
on that side, and to lightly massage the gums 67 of the teeth while 
sweeping the sulcus on that side as shown. Significantly, throughout the 
entire panoply of motion, it is the bristle on the relatively limp, 
flaccid lobes 56 of the brushes which sweep arcuately up and down, as well 
as back and forth, along the sulcus and over the tender gingiva of the 
gums, and do all of the "brushing" in these delicate areas; and of course, 
this is desirable because the lobes have the least "spine" of all of the 
components of the head, so as to cause the least irritation to these 
tender areas. Given grooves 57 of sufficient depth, moreover, the bottom 
portions 59 of the lobes will be hinged somewhat to the main bodies of the 
monoliths, so as to be deflected by the gums when they are pressed against 
them. But to simplify the drawings, this feature is not illustrated per 
se. 
Ultimately, when the user reaches the endmost tooth at each end of each 
row, he may sharply angle the head of the device to the tooth, 
horizontally, to scrub the backsides of the tooth, and this is illustrated 
in exaggerated manner in FIG. 8. 
Given his ability to angle the device to the length of each row, and given 
the offset between the arms and the brushes, the user may also use the 
device in the manner of FIG. 11 to brush between pairs of teeth on 
parallels to the gaps 68 therebetween. This is particularly so in the case 
of the frontmost teeth of a row, and in fact is particularly advantageous 
in the case of these teeth if they sharply "corner" with respect to the 
rearmost teeth in the row. Also, the device may be oriented toward one 
side of the mouth initially, to angle the bristle into the gaps 68 in one 
direction, and then reversed to angle the bristle in the opposite 
direction, perhaps exchanging hands for this purpose, if need be. Angled 
in this way, the device can be worked up and down along the length of a 
row, to effectively brush the gaps between pairs of teeth, while limited 
in its "drop" onto the gums of the teeth by the terminal ends 20 of the 
arms, which serve as a limit stop for the oscillatory motion of the 
device, as seen in FIG. 11. Of course, the terminal ends 20 of the arms 
also serve as a limit stop for the scooping action of the brushes when the 
device is employed in the manner of FIGS. 9 and 10 and rotated as 
described, but this action commonly has an insufficient vertical component 
to produce engagement of the terminal ends of the arms with the teeth. 
The arcuate outline of the bottom and leading edges 60, 62 of the lobes, 
and the chamfered or mitered edges 63 of the terminal ends of the arms, 
are consistent with the pitman-like motion recommended for the device, and 
contribute to the user's sense of direction in the various operations 
described. 
Typically, the brushes 50 are in fact elongated somewhat in the direction 
longitudinally of the device, to enable the leading edge portions 62 of 
the lobes 56 to gently massage the gums as seen in FIG. 10. 
Sometimes, a user may choose to brush the teeth to be cleaned when the 
bristle 49 are at room temperature, and then run the bristle for a few 
seconds under hot (or cold) tap water at a sink, to render the bristle 
changed in durometer for the next stage of his/her operation. 
As in the earlier Applications, the hardness of the bristle may also vary 
from one area of each field to another. In particular, the bristle on the 
lobes, or the hinged bottom portions 59 of the lobes, may be still softer 
than the bristle employed on the main bodies of the brushes. Likewise, the 
density of the bristle may vary from one area to another, and once again, 
reference can be made to the forgoing Applications for various techniques 
for achieving this.