Note: Descriptions are shown in the official language in which they were submitted.
BACKGROUND OF THE INVENTION:
This invention relates to tooth positioning appliances,
and in particular it relates to determining the extent to which
such an appliance has been used.
In the field of orthodontics, conventional orthodontic
devices such as bands or the like are often used for straighten-
ing teeth to bring them to a predetermined position of proper or
close to proper occlusion. To bring teeth into a final position
of desired orientation in the mouth, the orthodontists will often
use a tooth positioner, an example of which is shown in my Canadian
Patent No. 897,464, issued April 11, 1972. Other positioners of
this general type have been known for many years, as illustrated
for example in the Kesling Patent No, 2,467,432.
A problem has always been present with orthodontic ap-
pliances of any kind, and in particular of the type of positioner
described above. On occasion when a patient returns to the ortho-
dontist an entirely insufficient level of progress will be obser-
ved, It is critical for the orthodontist to know whether this
resulted from poor fitting of the positioner or from the simple
fact that the patient did not wear the positioner as directed,
Most patients in the field are children who might be embarrassed
to give a negative answer when asked whether or not they used the
positioner, But in any event, the fact remains that this problem
is continuously presented to the orthodontist and he currently
, has no means for accurately determining whether or not the patient
- has in fact been wearing the positioner except of course for his
, own subjective opinion as to the veracity of the patient's state-
i, ments,
Thus, there exists a need for a way to assist an ortho-
dontist in ascertaining whether or not a patient has in fact worn
the positioner, or for that matter whether he has worn other or-
thodontic appliances, as instructed,
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Sl~lMARY OF THE INVENTION:
Thus, it is a purpose of the present invention to
solve this problem in the art.
This purpose of the present invention is achieved
by providing an orthodontic appliance which has the capability
of changing its visual appearance, and in particular i'ncreasing
its opacity, in proportion to the time during which it is used.
More specifically, ~his purpose is achieved by provid-
ing a positioner constructed of a material which in fact changes
opacity during use. In a preferred embodiment, the positioner
is made of polyvinyl chloride, a proportion of which is water-
blush polyvinyl chloride. The proportion of water-blush and non-
blush polyvinyl chloride will depend on many factors. Many dif-
ferent proportions will give good results but in one pre~erred
embodiment a proportion of 50 percent water-blush to 50 percent
~on-blush polyvinyl chloride was used. This embodiment has the
property of being transparent under normal room conditions and
then at least to some extent transpa~ent upon maximum use, still
permitting the orthodontist to view the teeth within the ortho-
dontic a,ppliance when in use.
The inve~tion furthe~ includes a method for detect-
, ing cooperation by a patient, this method including making
; or/and selecting an orthodontic appliance such as a positioner
', of a material which changes its visual appearance such as by
increasing its opacity in proportion to the time used and then
~ observing the appearance of the positioner after alleged use
i,~ to determine whether or not the positioner was in fact used as
, directed.
Thus, it is an object of this invention to provide a
new and improved orthodontic appliance such as a positioner for
, overcoming the problem of
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108'~45~9
determining patient use.
It is another object of this invention to provide
¦ an orthodontic appliance such as a positioner formed of
polyvinyl chloride, at least a portion of which is water-blush
polyvinyl chloride which increases its opacity upon use.
I Another object of this invention to provide a
j method for detecting patient cooperation.
¦ Other objects and the advantages of the invention
will become apparent from the detailed description to follow,
together with the accompanying drawings.
.
BRIEF DESCRIPTION OF THE DRAWINGS:
There fol'lows a detailed description of a
preferred embodiment of the invention to be read together
with the accompany drawings in which:
' Figure 1 is a side elevational fragmentary view
¦ of a human mouth with maloccluded teeth.
Fiyure 2 is a perspective view, partially in full
outline, and partially in dotted outline, showing generally
the superior surface of a prefabricated tooth positioner
which could include the features of the present invention.
Figure 3 is a fragmentary section view through
a human mouth in the area of the central incisors showing
the tooth retainer in place.
Figure 4 is a fragmentary section view through
the human mouth in the area of the bicuspids showing the
', tooth retainer in place.
1~ Figure 5 is a fragmentary section view of the human
3~,~ mouth in the molar area showing the tooth retainer in place.
Figure 6 is a photograph showing in front perspective
view the tooth positioner of figures 1 thr~ugh 5, this figure
also illustrating the essentially transparent nature of the
positioner.
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', Figures 7 through 9 are photographs showing the
; positioner of figures 1 through 6 in front elevational view
¦ at three different stages of opacity which represent different
stages of use of the positioner of the present invention.
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DET~IL D~SCRIPTION OF THE PREFERRED EMBODI~NTS:
Like elements are designated by like numerals
throughout the several views.
Figure 1 is a view of a human mouth 10 wherein the
teeth 12 are obviously in need of correction by orthodontic
devices or the like. Maxillary molars 12a and 12b are in an
end-to-end relationship to their mandibular antagonists 12c
and 12d and the upper incisors are generally protrusive and
rotated in relation to the lower incisors. Conventional
orthodontic devices, such as bands and the like, may be used
for initially straightening the teeth of a mouth such as shown
in figure 1 to bring the teeth to a predetermined position
of proper or close to proper occulusion. To bring the teeth
into a final position of desired orientation in the mouth,
a tooth positioning retainer 20, such as shown in figure 2,
may be used. Retainer 20 is generally U-shaped in plan so
as to conform to typical human mouth configuration and is
generally H-shaped in cross section providing an upper or
superior tooth receiving trough 22 and a lower or inferior
tooth receiving trough 24. The side~ of troughs 22 and 24
are bounded by a lingual flange 26 which covers the rear of
the teeth of the upper and lower arch and a labial and buccal
flange 28 which cov~rs the front of the teeth of both arches.
Both the superior and inferior tooth receiving
surfaces 22 and 24 are provided with a plurality of tooth
receiving depressions or sockets, such as 22a, 22b, 22c,
22d, 223, and 22f, of different configurations for receiving
the different teeth of the mouth from the central incisors
through the cuspids and bicuspids, into the first molar, and
half of the second molar area. Alternatively, the positioner
can of course be made having only an upper trough 22 or only a
lower trough 24.
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8~499
~ s best seen in figures 3 through 5, the upper
lingual flange 30, which secures the lingual cingulum areas
of the upper anterior teeth and lingual surfaces of the lingual
cusps of the upper posterior teeth, includes an inwardly
directed rib 31 and covers a portion of the upper lingual
gingival area 32, and the lower lingual flange 34 generally
embraces the cingulum area of the lower anterior teeth and the
lingual surface of the lingual cusps of the lower posterior
teeth and includes an inwardly directed rib 35. This flange
also extends over a portion of the lower lingual gi,vgival
tissue 36. The lower labial and buccal flange 38 which
covers the labial and buccal surfaces of the lower anterior
and posterior teeth includes an inwardly directed rib 39 and
also extends over a portion of the lower labial and buccal
gingival tissue 40 and the upper labial and buccal flange
42 has an inwardly directed rib 43 and c,overs the entire
labial and buccal surfaces of the upper anterior and posterior
teeth and also embraces a small portion of the upper gingival
tissue 44.
The several ribs 31, 35, ~9 and 43 generally follow
the outline of the juncture of the teeth and the gingival
tissue. ~ach retainer of the set would be formed by being
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molded about a model set of teeth wherein notches are cut
closely adjacent the juncture of the teeth and the gingival
tissue so that when the retainer is formed by molding the same
about the teeth of the mold, the ribs would be so formed.
However, it is not intended that notches would be formed
in the teeth-of a patient but rather these ribs would generally
fit in the reduced area of the teeth adjacent the juncture of
the teeth and the gingival tissue. These ribs provide a means
for holding the retainer in place in a patient's mouth without
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the need for auxiliary fastening devices or the like.
These ribs also aid in retention of torque of the anterior
teeth by placing pressure apically in the gingival third of
the labial surface while maintaining the incisal edge in a
stable position as the fulcrum.
The various pockets (such as 22a and 22b) in the
retainer for the upper and lower teeth are made so that the
teeth are snugly embraced by the retainer. The isthmus 46
which joins the lingual and buccal or labial halves of the
positioner is generally thin, though it differs in dimension
between the posterior region and anterior region so as to
resemble the normal relaxed clearance between the teeth with
the exception that the isthmus is slightly thinner in the
posterior region. This enablesall the occlusal and incisal
surfaces of the teeth to be ln contact with the positioner
at the same time when occlusal pressure is ap~lied. Any
change which might be made would be to increase the thickness
of the isthmus in the anterior region to enable a corrected
anterior vertical overbite to be effectively retained.
It has further been discoyered that it is
desirable to make the tooth positioner out of a semi-resilient
plastic transparent material. The transparency enables the
dental practitioner_to actually see where the tooth movement
will take place by observing blanching of tissue around the
teeth and also enables him to detect potential soft tissue
sore spots due to abnormal impingement of the flanges of the
tooth positioner.
A perspective photograph of an essentially
transparent posi~oner is shown in figure 6. It ~Jill be
noted that the upper and lower flanges A are thinner in the
horizontal or "lingual-labial" direction than is the thicker ,
isthmus portion 46 which is denoted by the letter B in figure ~.
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1 108'~499
The present invention is concerned in particular
with a specific problem facing the orthodontist, namely the
problem of obtaining the full cooperation of the patient.
On occasion a patient, having been instructed to wear a
positioner for certain periods of time each day will return
to the orthodontist's office at which time the orthodontist
will observe that the progress in terms of movement~of teeth
has not been satisfactory. It is critically important that
the orthodontist be aware of the reason for such insufficient
progress. Specifically, was it.because of an improperly
fitting positioner or was it simply due to the fact that the
patient did not wear the positioner as instructed. ~any
patients, especially children will be strongly inclined
to state that they have in fact been wearing the positioner
and the orthodontist is then left uniformed as to whether or
not such is actually the case.
The present invention seeks to overcome this
problem. In accordance with the present invention, the
ortllodontic appliance which may be any one of a large num~er
of available appliances but for the present discussion is taken
to be the above described positioner is formed of a material
such that under normal conditions it is essentially transparent
as described above ~nd as noted in figure 4, but wherein
the positioner has the characteristic of changing opacity
in proportion to the time that the positioner is in the mouth.
As a result thereof, if a patient returns to the
orthodontist office with insufficient progress, the orthodontist
can then simply visually inspect the positioner to determine
whether or not the patient has in fact been using the positioner.
For example, figure 7 shows a photograph illustrating
the positioner of figure 6 in front elevation view, this
positioner being essentially transparent just like that of
figure 6. If a patient returned to the orthodontis~'s office
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with the positioner appearing as in figure 7, the orthodontist
would be aware that it had not been worn regularly. The
photograph of figure 8 differs from that of figure 7. It is
more opague, especially around the thicker isthmus As will
be described in more detail below, this would indicate that
the positioner had probably been worn regularly at night
although not during the day. Finally, the very opague
positioner shown in the photograph of figure 9 would indicate
that the positioner has been worn every night plus approximately
two to four hours each day.
Although there are perhaps many materials with
which the present invention may be carried out, in a preferred
em~odiment, the present invention was developed by using
polyvinyl chloride, commonly referred to (and hereinafter
referred to) as PVC. Early PVC was known to have the ~~~~
disadvantage that it absorbed moisture and became cloudly.
This is known as water-blush PVC. Over the years, however,
many varieties of PVC have been developed including means
for eliminating this water-blush characteristic,.such that they
remain transparent even when subjectqd to high moisture
conditions.
In the preferred embodiment, the positioner was
made by mixing toge her a proportion of water-blush PVC
and a portion of non-water-blush PVC. I have tried many
different proportions from less than 5 percent water-blush
PVC up to nearly 100 percent water-blush PVC (the remainder
in each case being non-blush PVC). Almost all combinations
of water-blush and non-blush would be operable in the sense
that as long as they contained some water-blush PVC they would
increase opacity to some extent. The actual percentage might
depend in large part on the amount of opacity the orthodontist
desired as an indication of full cooperation. Other factors
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108Z49~
would also be considered in determining the proportions of
water-blush and non-blush. For example, if the positioner
were formed of a substantially completely water-blush material,
it might become almost completely opaque when worn for the
desired periods of time, ~hereby elminating the advantage
that i5 gained by transparency as described above. Thus,
the proportion should preferably be selected so as to retain
at least some transparency as a diagnostic aid even during
full cooperation.
In addition, the proportions should of course
be selected with direct reference to ~he period of time
that is is contemplated the patient will be instructed to
wear the positioner. Th~t is, the proportions should be
cho~sen ~h~l such that after the correct time of wear, the
positioner will have a high level of opacity ~onsistent with
the need for a certain degree of transparency.
As indicated above, tests have been conducted with
numerous proportions of water-blush and non-blush material.
Actually, about 25 percent water-blush PVC has been f~und
to be the lowest practical level forlobtaining what would
appear to be a meaningful indication of wear, i.e. a discernible
opacity. At the other end of the scale, however, some
transparency is retained even with samples using up to 90 to
95 percent water-~lush PVC although the transparency is
apparently reduced below what I woul~ consider to be an
acceptable level after about 75 percent water-blush PVC.
In my preferred embodiment, I have selected a
material which consists of approximately 50 percent water-blush
PVC and 50 non-blush PVC. The results obtained with such a
positioner are the subject of the photographs of figures 7
through 9. With this embodir~en~, if the patient only wears
the positioner at night, then the thicker central portion
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associated with the isthmus will become more opaque or
"milky" to a greater extent than the upper and lower flanges.
This is because the central portion is thicker and absorbs
the moisture to a greater extent. If the patient also wears
this positioner for two to four hours each day, the edges
will also become rather whitish and the positioner will
overall have a more milky or clouded appearance as ~n
figure 9.
The characteristics of this positioner are such
that when placed again into normal room conditions away from
the said high moisture conditions, for example when left
out of the mouth, the moisture will evaporate and the positioner
will return to its essentially transparent condition as
in figures 6 and 7. This can also be used as a diagnostic
tool. If the orthodontist is aware that the positioner has
not been used for several days, if it appears as in figure 8
he will nonetheless ~now that the patient has worn the
positioner for certain periods of time.
Another advantage of this particular embodiment,
i.e. 50 percent-50 percent is that e~en with maximum use,
i.e. full cooperation of the patient, there is still some
degree of transparency remaining in the positioner. This is
evident in figure 9_which represent maximum use and in which
the outlines of the tooth receiving grcoves can still be
seen. This is an extremely important feature since a great
deal of diagnostic significance lies in the fact that t~e
orthodontist can always see through the positioner to
determine what is happening to the teeth and supporting
structure while the appli~nce is placing pressure against
these tissues vi~ the forceable occlusal forces that the
patient is exerting while bitting into the positioner.
Actually, even the 50-50 embodiment is physically capable
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i of higher opacity such as upon boiling in water for an
j hour or so, whereupon it would become completely opaque,
! but the fact remains that such conditions would not occur
; in a patient since it would require that the patient wear
the positioner at all times for several days and even the
' most cooperative patient is asked to wear the po~itioner
¦ no more than approximately four hours per day plus the
1 night time.
; The invention has been described in considerable
i detail but it will be understood that the invention is
. capable of numerous modifications and variations apparent
¦ to those skilled in the art. For example, while the invention
has been described with reference to a specific type of
tooth positioner, it would of course be equally applicable
to any type of orthodontic appliance or other items intended
¦ to be used in the mouth for certain periods of time. Also,
! while the results using one certain proportion have been
described in detail, it will be understood that the other
described proportions can also be used to indicate wear
'I and hence achieve the advantages of ~he present invention.
Other modifications and variations will be apparent to
those skilled in the art.
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