U.S. patent application number 15/063297 was filed with the patent office on 2016-06-30 for device for the detection of non-cavitated early dental caries lesions.
The applicant listed for this patent is The Research Foundation of State University of New York. Invention is credited to Robi Chatterjee, Fred Confessore, Israel Kleinberg.
Application Number | 20160183839 15/063297 |
Document ID | / |
Family ID | 43970785 |
Filed Date | 2016-06-30 |
United States Patent
Application |
20160183839 |
Kind Code |
A1 |
Kleinberg; Israel ; et
al. |
June 30, 2016 |
Device For The Detection Of Non-Cavitated Early Dental Caries
Lesions
Abstract
The invention provides a device for detecting non-cavitated
caries lesions, including a measuring electrode having an
electrically conductive tip. The tip is dimensionally configured to
fit within a fissure and provide electrical contact with a
patient's tooth. A reference electrode is also included, the
reference electrode being configured for electrical contact with
the patient's body. A measuring means is also provided for
determining electrical conductance between the measuring electrode
and the reference electrode, wherein the device is further
configured to receive a current source for providing electrical
current between the measuring electrode and the reference
electrode.
Inventors: |
Kleinberg; Israel;
(Smithtown, NY) ; Confessore; Fred; (St. James,
NY) ; Chatterjee; Robi; (South Setauket, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
The Research Foundation of State University of New York |
Stony Brook |
NY |
US |
|
|
Family ID: |
43970785 |
Appl. No.: |
15/063297 |
Filed: |
March 7, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12940589 |
Nov 5, 2010 |
9277875 |
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15063297 |
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61259012 |
Nov 6, 2009 |
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Current U.S.
Class: |
433/27 |
Current CPC
Class: |
A61B 2562/0214 20130101;
A61B 5/0534 20130101; A61B 5/4547 20130101 |
International
Class: |
A61B 5/053 20060101
A61B005/053; A61B 5/00 20060101 A61B005/00 |
Claims
1. A device for detecting non-cavitated caries lesions, comprising:
a measuring electrode having an electrically conductive tip, said
tip being dimensionally configured to fit within a fissure and
provide electrical contact with a patient's tooth; a reference
electrode, the reference electrode being configured for electrical
contact with the patient's body; and measuring means for
determining electrical conductance between the measuring electrode
and the reference electrode, wherein the device is further
configured to receive a current source for providing electrical
current between the measuring electrode and the reference
electrode.
Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to detection of
dental caries lesions. More particularly, the present invention
relates to electrical devices and methods for detecting
non-cavitated early dental caries lesions.
BACKGROUND OF THE INVENTION
[0002] Dental caries is a disease that frequently occurs soon after
teeth erupt into the oral cavity, an environment that is generally
hostile to the teeth of most individuals. Sites particularly prone
to caries development are the occlusal surfaces of the posterior
teeth. This is largely because these surfaces possess a morphology
(i.e. pits, fissures and fossae) that favors retention of both
fermentable carbohydrate and bacterial biofilms. These two entities
are primary elements in dental caries causation. Combined, they
result in the production of the acid that leads to tooth
demineralization and the initiation and development of dental
caries lesions. More tooth decay occurs in occlusal locations and
to lesser degree in interproximal dentition sites (where teeth are
in contact with one another) than elsewhere in the human dentition.
This is because bacteria and fermentable carbohydrate collect more
easily there, and are protected from the caries inhibiting effects
of saliva, than occurs in other more salivary accessible dentition
locations.
[0003] Dental caries begins as a demineralization process which
leads to the development of pores and tunnels through the
protective, non-electrically conductive enamel (Longbottom, C. and
Huysmans, M. C. D. N. J. M. Electric measurements for use in caries
clinical trials. Caries Res. 29, 94-99, 1995. Longbottom C and
Huysmans M. C. D. N. J. M. Electrical measurements for use in
caries clinical trials. J. Dent. Res. 83 (Spec. Issue C) C76-C79,
2004). Continued demineralization eventually results in enamel
breaching. Once the enamel is breached, caries advances and spreads
rapidly through the underlying dentine, a tissue much less
mineralized than enamel. Such spreading is made easy because
dentine is traversed by numerous tubules. Many, if not most of
these dentinal tubules, especially in younger teeth, reach all the
way to the dental pulp (Pashley D. H. Theory of dentin sensitivity.
J. Clin. Dent. 5:65-67, 1994).
[0004] Non-cavitated caries lesions, particularly in the pits,
fissures and fossae of the posterior teeth are difficult to detect
and assess in humans. Teeth mainly involved include the first and
second primary molars and the premolars and molars of the permanent
dentition. These teeth and interproximal dentition sites are where
the majority of dental cavities occur.
[0005] Presently, detection of caries development is mostly done by
a dentist or other dental care provider with a simple, pick-like
device, generally referred to as a dental explorer. Such detection
is performed by visual examination for indications of mineral loss,
and is done with or without x-rays. None of these tools is suitable
for detection of a high percentage of non-cavitated occlusal caries
lesions even when there is caries penetration into the dentine.
Many of these early developing caries lesions are not cavitated,
but do involve extensive tunneling through the enamel and such
tunneling may not be detectable. Such caries development is
frequently hard to discover until destruction of tooth substance
becomes more substantial and the dentine becomes progressively more
and more involved. As a consequence of the difficulty of their
discovery, these lesions are commonly referred to as hidden dental
caries (Weerheijm K L, van Amerongen W E, and Eggink C O. The
clinical diagnosis of occlusal caries: A problem. J. Dent. Child.
56, 196-200, 1989). Their early discovery is often missed or
involves much uncertainty. Not surprisingly, there is opportunity
for pulpal damage to occur and for teeth to be lost unnecessarily
(Verdonschot E. H., Wenzel A., Truin G. J. and Konig K. G.
Performance of electrical resistance measurements adjunct to visual
inspection in the early diagnosis of occlusal caries. J. Dent. 21:
332-337, 1993). Ironically, the anti-caries agent, fluoride, can be
detrimental to early detection, because it favors less cavitation
(Hudson P. and Kutsch V. K. Microdentistry: Current pit and fissure
caries management. Compendium 22: 469-483, 2001). This is because
fluoride reduces the solubility of the enamel covering the dentine,
thereby enabling the enamel to remain largely intact while
underlying dentine continues to be demineralized (Lussi A.,
Firestone A., Schoenberg V., Hotz P., and Stich H. In vivo
diagnosis of fissure caries using a new electrical resistance
monitor. Caries Res. 29: 81-87, 1995). For these reasons, it has
become very important that caries lesions be detected as early and
as easily as possible.
[0006] Because the enamel of freshly erupted teeth commonly exhibit
a certain degree of porosity, such teeth are more prone to dental
caries development than if they had been exposed in the mouth for
an extended period under non-cavity producing and mineralizing
conditions. Such improvement is called maturation and occurs
because many of these exposed teeth acquire calcium and phosphate
ions from saliva along with various proteinaceous accretions. These
changes involve increased enamel mineralization, reduced enamel
permeability and greater caries resistance. This is helped by
fluoride if applied or taken up naturally during the tooth
maturation process (Ie Y. L., Verdonschot E. H., Schaeken, M. J. M.
and vant Hof M. A. Electrical conductance of fissure enamel in
recently erupted molar teeth as related to caries status. Caries
Res. 29: 94-99, 1995). In contrast, in a caries-prone mouth where a
demineralization environment is present, an opposite result occurs
more readily, i.e. development of increased porosity and
cavitation.
[0007] Several approaches have been unsuccessfully used to detect
dental caries in its early stages. One of these involves testing
for a tooth's ability to conduct electrical current even when there
is no visible tooth mineral loss from the enamel and no cavitation
can be seen. Electrical resistance is associated with the presence
of intact, non-demineralized enamel; but, as a caries lesion
develops and enamel mineral is progressively lost, fluid can seep
therein and electrical resistance of the enamel correspondingly and
progressively decreases (Williams, D. L., Tsamtsouris A., and
White, G. E. Electrical resistance correlation with tactile
examination on occlusal surfaces. J. Dent. Res. 57: 31-35, 1978,
Longbottom C and Huysmans M. C. D. N. J. M. Electrical measurements
for use in caries clinical trials. J. Dent. Res. 83 (Spec. Issue C)
C76-C79, 2004).
[0008] Breaching of enamel occurs more easily in occlusal pit and
fissure sites. As noted above, these dentition locations are where
continual presence of acidogenic bacteria and fermentable
carbohydrate can undergo significant and continual interaction.
This favors prolonged generation of acid and in turn, prolonged and
extensive tooth demineralization. As this happens, a point is
reached where the enamel is sufficiently demineralized and porous
that saliva penetrates therethrough and because of the ions that
saliva contains, flow of electrical current can take place as a
result. The more extensive the demineralization, the more readily
these events occur and the easier it is to detect caries lesion
development.
[0009] Earlier investigators measured electrical resistance or
conductivity with direct current devices to determine if a tooth
had lost mineral and had become carious (Pincus, P. A new method of
examination of molar tooth grooves for the presence of dental
caries. J. Physiol 113: 13-14, 1951. Mumford, J. M. Relationship
between the electrical resistance of human teeth and the presence
and extent of dental caries. Brit. Dent. J. 100, 239-244, 1956.
Mayuzumi, Y, Suzuki, K and Sunada, J. A method of diagnosing
incipient caries in pits and fissures by measuring electrical
resistance. J. Dent. Res. 43, 431, 1964. Takeuchi, M., Kizu, T.,
S{acute over (h)}imizu, T., Eto, M. and Amano, F. Sealing of the
pit and fissure with resin adhesive. II. Results of nine months'
field work, an investigation of electrical conductivity of teeth.
Bull Tokyo Dent Coll 7, 60-71, 1966. Williams, D. L., Tsamtsouris
A., and White, G. E. Electrical resistance correlation with tactile
examination on occlusal surfaces. J. Dent. Res. 57: 31-35, 1978).
Others subsequently used alternating current and measured impedance
to do essentially the same thing (White G. E., Tsamtsouris A., and
Williams D. L. A longitudinal study of electronic detection of
occlusal caries. J. Pedod. 5, 191-201, 1981. Pitts N. B. Clinical
diagnosis of dental caries: a European perspective J. Dent. Educ.
65: 972-978, 2001). In each case, a cavity detecting device was
provided, including a measuring probe made of a conducting metal, a
direct or alternating current source, a resistance source, an
impedance or conductance detector, and a reference electrode
suitable for application, generally by attachment to a non-oral
soft tissue part of the body. The human body is sufficiently
conductive electrically to enable complete electrical continuity
via the body between the measuring probe (i.e. the indicator
electrode) and a reference electrode usually attached by adhesive
means to a body surface such as the ventral surface of the forearm
or the back of the neck or by means of a metal hook, the end of
which is immersed in the mouth saliva usually by curling around the
lower lip.
[0010] Tooth enamel is electrically non-conductive unless it is
breached by demineralization or fracture. When this occurs, fluid
at or entering the breached enamel site enables completion of an
electrical circuit that allows current to flow. The electrical
current used may be as low as a few micro-amperes (.mu.A) in
magnitude. Hence, it is safe even for use in medically compromised
patients. In addition, the procedure is painless.
[0011] It has previously been found that special precautions have
to be taken while making measurements to ensure electrical
continuity without causing any peripheral electrical conductance to
saliva or other moisture on the tooth or to saliva or other
conductance means elsewhere in the mouth. Such isolation of the
measuring electrode from surrounding saliva is an absolute
requirement for success. Complete isolation can be achieved by
using a rubber dam (Williams, D. L., Tsamtsouris A., and White, G.
E. Electrical resistance correlation with tactile examination on
occlusal surfaces. J. Dent. Res. 57: 31-35, 1978). However, such
use of a dam is cumbersome and is not practical when an extensive
mouth examination is required. Instead, most investigators have
used a stream of air from an air syringe in an attempt to dry the
tooth around but not at the measuring site. To do this simply,
consistently and rapidly has been a major problem.
[0012] Ricketts et al. used a stream of air surrounding the
measuring electrode to isolate the measuring site from surrounding
surface electrical conduction (Ricketts, D. N. J. Kidd, E. A. M.,
and Wilson, R. F. A re-evaluation of electrical resistance
measurements for the diagnosis of occlusal caries. Brit. Dent. J.
178: 11-17, 1995). However, the large size of the measuring tips
used by these investigators prevented accurate measurements.
Further, such large tips, with their drying feature, were not
suitably shaped or sized for many of the sites that required more
effective probing.
[0013] Current methods often yield false and/or variable readings.
Current methods also lack the ability to rapidly and consistently
detect non-cavitated caries lesions early and accurately.
Basically, detection of non-cavitated caries lesions requires
electrical linkage between the measuring electrode at the enamel
surface measuring site and fluid within the caries lesion.
Detection also requires the absence of any electrical conductance
immediately around the lesion site. Furthermore, a method of
instantly knowing that detection is operating properly is
necessary.
SUMMARY OF THE INVENTION
[0014] The invention provides a device for detecting non-cavitated
caries lesions, including a measuring electrode having an
electrically conductive tip. The tip is dimensionally configured to
fit within a fissure and provide electrical contact with a
patient's tooth without the addition of an external electrical
conducting means between measuring tip and tooth. Various fluids
have been used in the prior art for this purpose. A reference
electrode is also included, the reference electrode being
configured for electrical contact with the patient's body. A
measuring means is also provided for determining electrical
conductance between the measuring electrode and the reference
electrode, wherein the device is further configured to receive a
current source for providing electrical current between the
measuring electrode and the reference electrode.
[0015] The invention also provides a method for detecting
non-cavitated caries lesions. The method includes the steps of
providing a reference electrode for electrically conductive contact
with a patient's body, and providing a measuring electrode having
an electrically conductive tip, which is dimensionally configured
to fit within a fissure and provide electrical contact with a
patient's tooth without the addition of electrical conducting means
between measuring tip and tooth. The measuring electrode is
configured to fit within a fissure and provide electrical contact
with a patient's tooth. Electrical current is provided between the
measuring electrode and the reference electrode, and electrical
conductance between the measuring electrode and the reference
electrode is determined.
[0016] These and other objectives and advantages of the present
invention will be more readily apparent from the following detailed
description of the drawings and preferred embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Non-limiting and non-exhaustive embodiments of the present
invention are described with reference to the following drawings.
In the drawings, like reference numerals refer to like parts
throughout the various figures unless otherwise specified.
[0018] FIG. 1A is a schematic representation of a probe being
introduced into a fissure, according to the present invention;
[0019] FIG. 1B is a schematic representation of a fissure having a
narrow slit;
[0020] FIG. 1C is a schematic representation of a fissure having
the shape of a constricted hourglass;
[0021] FIG. 1D is a schematic representation of a fissure having an
inverted Y-shaped division;
[0022] FIG. 2A is a schematic representation of a fissure in enamel
before drying;
[0023] FIG. 2B is a schematic representation of a fissure in enamel
after drying;
[0024] FIG. 2C is a schematic representation of detection via a
prior art electrode probe after drying;
[0025] FIG. 2D is a schematic representation of detection via an
electrode probe according to the present invention;
[0026] FIG. 3A is a schematic perspective view of a hand-held
measuring probe, according to the present invention;
[0027] FIG. 3B is a schematic perspective view of a removable
measuring tip mounted to the probe of FIG. 3A.
[0028] FIG. 4A is a schematic representation of a measuring tip,
according to the present invention;
[0029] FIG. 4B is a schematic side view of a measuring tip,
according to the present invention;
[0030] FIG. 5 is a schematic representation of the components of an
embodiment of the present invention;
[0031] FIG. 6 is a schematic front view of the front panel of an
embodiment of the present invention;
[0032] FIG. 7 is a graph showing the relationship between
electrical conductance and demineralization;
[0033] FIG. 8 is a graph showing the relationship between
electrical conductance and probe tips of different tip diameters in
a molar tooth fissure site;
[0034] FIG. 9 is a graph showing the relationship between
electrical conductance and commercially available explorer tip
diameters in a molar tooth fissure site; and
[0035] FIG. 10 is a graph showing the relationship between
electrical conductance and the diameter of different commercially
available dental explorers in another (less accessible than in FIG.
10) molar tooth fissure site.
[0036] FIG. 11 is a graph comparing detection of carious and sound
tooth surfaces at baseline and after 14 months by visual-tactile
(VT) and electrical conductance (EC) means as per Tables 6 and
7.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0037] FIG. 1A is a schematic representation of a probe being
introduced into a fissure 120. As used herein, the term "fissure"
may include any tooth pits, fissures, fossae, or other similar
regions or irregularities in the tooth. As indicated in FIG. 1A,
early dentinal caries lesions 140 may form and spread out below the
enamel 110. These early dentinal caries lesions 140 are very common
and are usually incapable of being detected through a traditional
visual-tactile inspection or by x-rays. Conventional measuring
probes 130 are either too large or not properly tapered to reach
sufficiently into the pits and fissures where these lesions are
mostly found, as will be described below in more detail (see FIGS.
2C and 2D). The size and shape of the measuring electrode tip 130
is crucial to early caries lesion detection 140 and in the
obtaining of consistent and accurate measurements.
[0038] As seen in FIG. 1A, the fissure 120 formed in the enamel 110
may begin as a wide opening at the top of the enamel and become
narrower towards the dentin. It will be understood that fissures
120 may also be formed in the enamel 110 in various shapes. For
example, fissures 120 may be wide at the top and gradually
narrowing toward the bottom as seen in FIG. 1A. The fissures 120
may also have almost the same width from top to bottom or include
extremely narrow slits as seen in FIG. 1B. Fissures 120 may also
include inverted Y-shaped divisions (FIG. 10) or be formed as
constricted hourglasses (FIG. 1D). In some embodiments, the width
of the fissure 120 ranges from about 0.05 to about 0.3 mm. In at
least some embodiments, the width of the fissure 120 ranges from
about 0.1 to about 0.2 mm. The length of the fissure 120 may be
from about 0.5 mm to about 1.5 mm. The length of the fissure 120
may also be from about 0.75 mm to about 1.25 mm.
[0039] Thus, an important distinction between the present invention
and the prior art is the difference in size and shape of the
measuring electrode tip 130. Thus, the present measuring probe 130
is smaller in diameter and more appropriately tapered so that it
can reach more deeply into pits and fissures (and other poorly
accessible sites). The dimensions of the probe tip 130 enable
contact with fluid present more deeply within the enamel and dentin
beneath the enamel (or cementum) at breached sites. Such fluid is
almost always present but not in sufficient quantities and close
enough to the enamel surface after drying to be reached
consistently with the electrodes used in the prior art for making
accurate electrical conductance or resistance measurements, and
particularly without the need for an external electrical conducting
means between measuring tip and tooth.
[0040] Turning to FIGS. 2A-2D, if there is electrical continuity
between the tip of the measuring electrode and fluid 220 within an
early enamel lesion, then there is no need to apply a conducting
fluid or medium between electrode and lesion as has been required
in the methods put forth in the prior art. However, if the probe
tip does not reach fluid 220 after drying the tooth surface with
blown air, then the result is an open circuit. Probes 250 that do
not penetrate sufficiently, easily result in some air remaining
between probe tip 250 and fluid 220 within the lesion as seen in
FIG. 2C. This does not happen when probe tips 260 are smaller, and
more appropriately shaped and positioned as in FIG. 2D. This is
because air is non-conducting and if sufficient air is left after
air drying, then there will be no current flow. The result is a
zero electrical conductance reading (i.e. a false negative), which
is also the reading obtained when there is no caries lesion present
(i.e. a true negative). Inadequate surface drying can be a
significant problem, because excess surface moisture will yield a
reading suggesting lesion presence (i.e. a false positive) when
such is not the case.
[0041] As noted above, use of a rubber dam to isolate a tooth from
its generally wet, oral surroundings will make achievement of the
necessary drying conditions certain. By this means, there is no
saliva at the measurement site contiguous with saliva or other
conducting fluid in the mouth. With rubber dam use, one has
complete tooth isolation and can freely employ a conductive means,
such as saline or a paste such as toothpaste. These will readily
ensure electrical continuity between measuring probe and fluid
within the caries lesion (Williams et al, 1978). However, in the
absence of a rubber dam a conductive means such as toothpaste may
have constituents that cannot be dried and collateral conductance
cannot be avoided. However, as pointed out above, use of a rubber
dam as a saliva barrier device results in a very slow examination
process and hence is not clinically practical, except perhaps in
limited caries diagnostic situations.
[0042] Previous investigators have dipped the measuring end of the
measuring probe into a patient's saliva, or another conducting
fluid, paste, or salt solution such as saline just before probe
placement followed by air drying (Williams et al, 1978). This has
proven difficult to do rapidly and consistently while ensuring
probe and caries lesion electrical connection without lateral
saliva conductance. From such attempts, it became clear that drying
to avoid lateral oral electrical conductance was too difficult to
achieve consistently, repetitively and within a short period of
time such as a few seconds. It is important to be able to probe
each tooth within such a time period in vivo. Otherwise, the
procedure (especially if multiple tooth examination is desired) can
take too long and becomes impractical.
[0043] Lussi et al (1995) like Ricketts et al (1995) above used a
shield for drying around the measuring site and measuring tip with
some success, while others tried to achieve reproducibility simply
by applying a constant flow of air for a fixed period of time.
However, the former reduces probe access capability and rapid
probing to identify sites of conductance. The latter standardized
drying procedure has proven to be less suitable and reliable for
clinical investigation or clinical practice than is desirable.
[0044] In contrast to conventional measuring electrodes, the
present invention utilizes electrodes with a shape and dimensions
that enable suitable placement and penetration of the measuring
probe into pit and fissure sites as seen in FIG. 2D. This method
enables the measuring electrode 260 to be placed into a pit or
fissure wherein (i) deep lying dentinal fluid is difficult or
impossible to displace during air drying and (ii) coronal seepage
of pulpal/dentinal fluid (because of hydrostatic and capillary
pressures that exist within dentinal tubules; Brannstrom, 1967),
was sufficient to ensure access by a more effective penetrating
electrode, even after significant drying of the tooth surface
around the measuring site. When breaching occurs, dentinal tubules
are exposed and tubules become open to the oral environment. As a
consequence, coronal measurement of dentinal fluid conductance,
both electrical and hydraulic, can be more readily accomplished
(Brannstrom, et al, 1966 and 1967). Air drying may reduce
superficial fluid within a breached site, but coronal seepage from
the depths of breached sites can spontaneously make up for such
fluid deficiency.
[0045] As a protective layer, root cementum behaves like enamel but
its breaching differs from enamel in that cementum is thinner and
generally more porous and very hard to keep dry.
[0046] FIG. 3A is a schematic perspective view of a hand-held
measuring probe 300. Specifically, a hand-held measuring probe 300
consists of three parts, an electrically insulated handle portion
330, an insulating tightening knurl 320 and an easily replaceable,
removable, substantially right angle shaped, measuring probe
attachment or probe tip 310 (see FIGS. 3A and 4). The probe tip 310
may be made from a metal such as stainless steel, which is very
strong, flexible, and able to withstand the physical manipulation
and stresses involved. The measuring probe attachment 310 is
preferably right angle shaped to make it easier to line up the
probe tip for direct insertion into a tooth site of interest. Other
angulations are also possible but are less desirable. The part of
the removable measuring tip 310 that is inserted into the
tightening knurl 320 may range from 20.0 to 40.0 mm in length. In
some embodiments, the part of the removable measuring tip 310 that
is inserted into the tightening knurl 320 and/or handle 330 is
approximately 30 mm in length. Furthermore, this portion may range
from 1.0 to 2.0 mm in diameter. In some embodiments, the portion is
1.5 mm in diameter. The distance from the bend to the tip may range
from 6.0 to 9.0 mm. In some embodiments, the distance is 7.5 mm.
The diameter after the bend before tapering to a sharply pointed
cone may be in the range of 0.2 to 0.4 mm. In some embodiments, the
diameter after the bend is 0.3 mm. As seen in FIG. 4A, the tip
needs to include a taper to achieve a sharp point. In a suitable
embodiment, the taper to the sharp point falls in the range between
5.degree. and 30.degree.. A taper to a sharp point at an angle of
10.degree. is preferable. This results in the length of the taper
being 1.8 mm as illustrated in FIG. 4B. In some embodiments, the
length of the taper may be between 1.6 and 2.0 mm. The shape and
sharp tip enables maximum penetration of the measuring probe into
pit and fissure sites to where it is easier to have fluid
consistently present as described in FIG. 2. In some embodiments,
the tip has a diameter of 0.04 to 0.06 mm with a preference of 0.03
to 0.05 mm.
[0047] An easily attached and removable tip that is disposable is
highly desirable for ease of use and to ensure no contamination.
The probe part may be made from a metal of sufficient strength and
flexibility to enable shaping to a fine measuring tip and to be
capable of of re-use if desired. Orthodontic stainless steel wire
that has proven suitable for this purpose has been identified as
304V (Rocky Mountain Orthodontics, Denver, Colorado). It has the
chemical formula: Carbon 0.066%, Manganese 1.26%, Phosphorus
0.018%, Sulfur 0.001%, Chromium 18.59%, Nickel 8.80%, Molybdenum
0.15%, Nitrogen 0.025%, Copper 0.25%,Cobalt 0.15%, with Iron making
up the balance. This wire material and its probe tips are easy to
sterilize with minimal effect on their physical and electrical
properties. For commercial reasons, because the probe electrodes
are simple and can be made inexpensively, they may be made
disposable. If so, attachment to the handle of the measuring
electrode can be by a knurl means or by spring tension contact
between extension and coiling of the rigid part of the electrode
tip 310 which is inserted into the handle 320, where it makes
electrical contact.
[0048] Referring to FIG. 3B, a removable electrode tip 325 is shown
mounted on probe 300. Tip 325 includes a tapered tip housing 322
with an opening 324 at the distal end and a snap fit or threaded
portion at the proximal end 326. Electrode tip 310, having a
co-axial stiffening sheath 340 passes through opening 324 of
housing 322 and is secured therein, and terminates in coiled spring
section 350.
[0049] Probe 300 terminates in an electrode end having a tip anchor
342 with an electrical contact 344 protruding therethrough. In
operation, tip 325 is mounted to probe 300 by securing the snap-fit
or threaded portion of tip housing 322 to anchor 342. At the same
time, coiled spring section 350 is compressed onto and brought into
electrical contact with electrical contact 344.
[0050] Use of an indicator electrode with the penetrating electrode
tip just described, eliminates the need for a fluid applied orally
as a conducting means. In prior approaches to measuring
conductivity, the electrode dimensions and shape required
application of a fluid to ensure electrical contact with dentinal
fluid. The present approach simplifies the invention considerably
by eliminating this requirement and most importantly, it enables
the user of the device to make measurements much more rapidly and
accurately than previously possible.
[0051] Drying of any saliva on the tooth surface to eliminate
surface electrical conductance is usually accomplished with a brief
5 to 10 second blast of dry air from a dental air syringe. This
easily dries most occlusal surfaces and the entrances to pits and
fissures under measurement but it has little or no effect on the
fluid sitting more deeply (and not readily reachable by the blown
air) within the pit or fissure lesions being measured. Coating the
measuring electrode with a conducting fluid such as saline by
dipping the tip into such a fluid has been used to facilitate
conductivity with electrodes greater in dimensions than those
disclosed herein (Williams et al, 1978). But some air is commonly
left in the process and a reading of zero results, whether there is
a lesion present or not.
[0052] In essence, with conventional electrodes, accessibility is
largely limited to pit and fissure entrances as seen in FIG. 2C.
Hence, an oral source of electrical conducting fluid, whether it is
saliva or an extra-oral occlusal additive, becomes necessary. This
makes it hard to achieve reproducibility, especially in the short
period of time needed in order for the process to be practical. In
contrast, the present invention needs no conductance adjuvant.
[0053] Electrical Conductance Measurement
[0054] In order to detect caries lesions, electrical conductance
may be measured. In some embodiments, a measuring instrument
features: (i) a battery powered DC current source that supplies
current as needed, (ii) a digital .mu.A meter to measure current,
(iii) a digital voltmeter to measure voltage (if desired), (iv) a
circuit board that enables several functions that facilitate the
taking of rapid, stable and reproducible conductance readings, (v)
a reference electrode placed distant from the measuring site so
that it does not interfere physically with measurements at
dentition sites of interest and (vi) an electrically insulated
measuring indicator probe, with a handpiece (e.g. #XHP1, Ellman
International, Oceanside, N.Y. 11572) and a replaceable measuring
tip.
[0055] The 9 volt battery that powers the circuitry of the instant
device may produce an unregulated current source limited to an
output of 10 .mu.A. It provides an open circuit output of 9 volts
and 0 .mu.A. These values correspond to the situation where the
probe is not in contact with a tooth site under measurement or is
in contact with a tooth site under measurement when the enamel is
intact (i.e. with no demineralization). In contrast, if the enamel
(or cementum) is breached, as occurs when sufficient caries
demineralization has developed and the breach is filled with
dentinal or oral fluid, electrical conductance occurs. When the
electrical circuit is closed, the current rises to a value greater
than zero. This occurs when there is a lesion and the rise in
current is proportional to the magnitude of the lesion. Decrease in
potential and resistance also occurs, as can be seen from Tables 1
and 2 below. In some embodiments, no external electrical current is
applied in order to ensure patient safety.
TABLE-US-00001 TABLE 1 Table relating the Ohm's Law variables:
conductance (I) to resistance (R), and electrical potential (V)
when the battery voltage is 8.61 volts. R (OHMS) V (VOLTS) I (MICRO
AMPS) R = V/I Open 8.61 0.00 0.0 22.0M 8.30 0.37 22.0M 15.0M 8.27
0.55 15.0M 10.0M 8.24 0.81 10.1M 6.8M 8.21 1.19 6.9M 4.7M 8.15 1.70
4.8M 2.7M 8.04 2.87 2.8M 1.8M 7.95 4.16 1.9M 1.0M 7.65 6.92 1.1M
800.0K 7.55 8.30 909.0K 600.0K 6.61 9.35 706.0K 400.0K 4.82 9.54
505.0K 200.0K 2.93 9.72 301.0K 100.0K 1.98 9.82 201.0K 80.0K 1.79
9.84 181.0K 60.0K 1.59 9.86 161.0K 40.0K 1.40 9.88 141.0K 20.0K
1.20 9.91 121.0K 10.0K 1.10 9.92 110.0K 8.0K 1.08 9.92 108.0K 6.0K
1.06 9.92 106.0K 4.0K 1.04 9.92 104.0K 2.0K 1.02 9.92 102.0K 1.0K
1.01 9.92 101.0K 0.0K 1.00 9.92 100.0K
Measurements showing that, as the electrical conductance increases,
the voltage and the resistance both decrease. This pattern is
reflective of increase in severity of dental caries. The calculated
values of circuit resistance closely match the resistance (R)
column, R.sub.1+Rs (100,000+1000 Ohms).
TABLE-US-00002 TABLE 2 Table relating the Ohm's Law variables:
conductance (I) to resistance (R) and electrical potential (V) when
the battery voltage is 6.37 volts. R (OHMS) V (VOLTS) I (MICRO
AMPS) R = V/I Open 6.37 0.00 0.0 22.0M 6.34 0.28 22.6M 15.0M 6.33
0.42 15.0M 10.0M 6.30 0.63 10.0M 6.8M 6.28 0.91 6.9M 4.7M 6.24 1.30
4.8M 2.7M 6.15 2.19 2.8M 1.8M 6.06 3.18 1.9M 1.0M 5.89 5.31 1.1M
800.0K 5.78 6.37 907.0K 600.0K 5.62 7.95 706.0K 400.0K 4.82 9.54
505.0K 200.0K 2.93 9.73 301.0K 100.0K 1.98 9.83 201.0K 80.0K 1.79
9.84 181.0K 60.0K 1.59 9.86 161.0K 40.0K 1.40 9.87 141.0K 20.0K
1.20 9.90 121.0K 10.0K 1.10 9.90 111.0K 8.0K 1.08 9.91 108.0K 6.0K
1.07 9.92 107.0K 4.0K 1.05 9.93 105.0K 2.0K 1.03 9.93 103.0K 1.0K
1.02 9.93 102.0K 0.0K 1.00 9.93 100.0K
Measurements showing that when the electrical conductance
increases, the voltage and the resistance both decrease. This
pattern is reflective of increase in severity of dental caries. The
calculated values of circuit resistance closely matches the
resistance (R) column, R.sub.1+Rs (100,000+1000 Ohms). Moreover,
completion of the circuit when any reading is made may be linked to
a maximum current flow of 10 .mu.A. As seen in Table 3, most early
lesion readings are below 4 .mu.A:
TABLE-US-00003 TABLE 3 Electrical Conductance and Demineralization
Scores of Test Teeth Current Demineralization Tooth # (.mu.A) score
32 1.9 2 15 3.0 4 2 3.0 4 15 2.0 3 2 3.0 4 2 3.0 3 1 3.0 3 32 2.0 2
19 1.0 1 1 2.0 2 16 0.3 0 19 1.0 2 15 2.0 2 30 3.0 3 18 3.0 2 19
3.0 3 19 1.0 1 31 3.0 4 15 13 1 32 0.8 1 1 1.3 1 16 1.7 1 30 0.9 1
1 1.5 1 31 2.7 2 19 1.9 2 Number 26 Mean = 2.16 .+-. 0.55 Mean =
2.11 .+-. 0.67 of teeth
[0056] Circuit Description
[0057] In a similar examination of non-carious teeth (see Example 2
below), electrical conductance readings showed a mean value of 0.0
.mu.A and mean demineralization scores were zero.
[0058] As seen in FIG. 5, during caries probing, the present device
is essentially an open circuit instrument. The circuit is closed
when there is fluid traversing the lesion site and the fluid makes
contact with a measuring electrode with or without a conducting aid
such as a paste or saliva. The circuit may include a pathway of
current flow from a patient's forearm, back of neck or cheek
through his or her body to the patient's tooth being measured. This
circuit completion may be achieved via the indicator and reference
electrodes with a .mu.A meter and/or voltmeter measuring unit in
between. A suitable reference is an EKG type of silver/silver
chloride electrode (Silver Mae Trade plus Tab, Cardiology Shop,
Berlin, Mass. 0150) attached to the ventral surface of the forearm.
A lip hook can also be used but is not desirable because it hinders
application of the measuring electrode by the dentist or other
healthcare worker.
[0059] As can be appreciated from FIG. 5, the present device may be
powered by two batteries. The first battery powers a .mu.A meter
and if included, a voltmeter. The current source output voltage is
unregulated (9 volts down to 1 volt) and the current output as
indicated above is limited to 10 .mu.A. A second battery may power
the current source circuitry and the control and monitoring
circuits (see above). This battery may have a voltage in the range
6.3 to 9.0 volts. At a voltage below 6.3 volts, the battery should
be replaced. In some embodiments, determination of battery life may
include turning on a battery test switch. The first battery may be
similarly replaced when the meter displays a low battery
condition.
[0060] A small load indicates the presence of a cavity at an early
stage of development; it is associated with a high resistance (e.g.
22 megohms). The lesion being evaluated in such a situation will
draw a small amount of current and show a small decrease in the
voltage. Should the load be higher, (e.g. one reflected by a
resistance between 100,000 and 600,000 ohms), the current flow will
be greater; decrease in voltage will become larger and a more
advanced cavity is indicated. Should the load be still higher,
resistance will be very low (e.g. between 1,000 and 100,000 ohms).
The current will rise and reach close to the maximum current of 10
.mu.A; correspondingly, the voltage will drop to 1 volt and a more
advanced cavity would be indicated.
[0061] Additional components in the completed meter circuit may
include a resistor (R1), a resistance shunt (Rs) and the .mu.A
meter. R1 is calculated by the formula R1=V/A where V is voltage
and A is current in amperes. Design is such that the current source
output voltage will drop no lower than 1 volt. This occurs when the
reference electrode and the dental probe are intentionally shorted
(no patient in the circuit) as is done as a systems test, when
carrying out pre-testing as described below. The maximum current
source output in this situation is 10 .mu.A and R1=1 volt/10
microamps=100,000 ohms (see Tables 1 and 2).
[0062] The Rs shunt may be set to 1,000 ohms for a 200 .mu.A
digital panel meter with a 200 my range (full scale). In that case,
Rs=Vm/Im=200 mv/200 .mu.A=1,000 ohms.
[0063] The completed circuit meter readings in the instant device
for various resistance values placed between the reference
electrode and the instant device probe, simulates dental caries
conditions and the results are shown in Tables 1 and 2. The
calculated resistance values will include the circuit resistors,
R1+Rs, as stated above; these values are shown in the R=V/I column
in Tables 1 and 2.
[0064] The voltage and current measurements with the present device
(Tables 1 and 2) both show a pattern that is directly related to
dental caries presence. The magnitude of the cavity is related to
the magnitude of the current, the voltage decrease and the
combination of both the voltage and current changes. The battery
voltage range differences are in Table 1 (8.61V) and Table 2
(6.37V); they yield an insignificant difference in circuit
resistance plus a micro-ampere difference ranging from 0 at 80K
ohms to a maximum of 1.61 .mu.A at 1 megohm.
[0065] The values for R=V/I, calculated using Ohm's Law, are shown
in Tables 1 and 2. The calculated values for circuit resistance
closely match the Ohms column and the R=V/I calculated resistance
column; this includes R.sub.1 (100K)+Rs (1K) for both battery
voltage levels.
[0066] Voltage Regulation
[0067] The present device may use a 9 volt unregulated, 10 .mu.A
current limited power supply. The use of an unregulated supply
allows the voltage to drop (e.g. 9 volts to 1 volt) as the load is
increased. If desired, this allows voltage data to be recorded in
addition to current data.
[0068] A constant voltage regulated supply limited to 10 .mu.A
output may also be used. The difference is that, as the load is
increased, the voltage holds constant at 9 volts and the current
still rises (e.g. 0 to 10 .mu.A). The current data available are
recordable and values are directly related to the magnitude of the
caries lesions.
[0069] In essence, the important aspect of the instant device is
the development of (i) a specialized measuring probe, (ii) a method
of measuring electrical conductance that includes use of the
conductivity of a patient's body and the supplying of a current
source limited to 10 .mu.A of current and (iii) a method of being
able to rapidly probe for active sites and record conductance
rapidly and accurately. As indicated above, measurement is one that
either involves no conduction (i.e. open circuit) when there is no
caries, or one that does involve conduction (i.e. closed circuit)
when there is caries present.
[0070] Processor and Storage
[0071] In some embodiments, the probe is coupled to a processor and
a storage medium. Any suitable processor can be used, including a
combination of individual processors. Any suitable storage medium
can be used. Storage media may include volatile, nonvolatile,
removable, and non-removable media implemented in any method or
technology for storage of information, such as computer readable
instructions, data structures, program modules, or other data.
Examples of storage media include RAM, ROM, EEPROM, flash memory or
other memory technology, CD-ROM, digital versatile disks (DVD) or
other optical storage, magnetic cassettes, magnetic tape, magnetic
disk storage or other magnetic storage devices, or any other medium
which can be used to store the desired information and which can be
accessed by a computing device or other processor. Methods of
communication between components of the arrangements described
herein can include both wired and wireless (e.g. acoustic
radio-frequency, optical, or infrared) communications methods. By
way of example, wired communications can use items such as twisted
pair, coaxial cable, fiber optics, wave guides, and other wired
media and wireless communications can use methods such as those
above.
[0072] In at least some embodiments, the processor is coupled to a
storage medium and sends data to the storage medium for storage or
further calculations. In some embodiments, the storage medium may
be portable, such as a compact disk. The storage medium may
automatically record or log data sent to it by the processor. In
some embodiments, the storage medium stores patient data in a log
including, for example, patient name, date of visit, number of
caries detected and/or location of caries.
[0073] The processor may also be coupled to an indicator. The
indicator may be configured on either a probe or as part of the
processor. In at least some embodiments, when a caries lesion is
detected, one or more signals may be emitted. In another
embodiment, a signal may be emitted when electrical conductivity is
first detected. Many different types of signals may be emitted from
the indicator including, for example, at least one auditory signal,
at least one visual signal, at least one tactile signal, at least
one olfactory signal, a telemetry signal to another device, or the
like or combinations thereof. For example, an emitted signal may
include one or more beeps, chirps, squeaks, chimes, rings, the
activation or de-activation of one or more lights or light-emitting
diodes one or more times, a message may be displayed on one or more
displays, one or more vibrations or tactile pulses, the emission of
one or more peculiar odors, and the like or combinations thereof.
The indicator may be activated for any set period of time. In some
embodiments, the indicator is activated for at least a period of 3
to 5 seconds, so that the dentist or dental care provider such as a
hygienist can verify or record the presence of the caries.
[0074] As discussed, the processor may be coupled to an indicator
in the form of a message or emitted signal. Alternatively, the
indicator may be in the form of a graphical representation of the
teeth. As the probe is moved over the teeth, the area may be mapped
onto a graphical representation, showing possible caries. Such a
graphical representation may be helpful in identifying possible
problematic areas for the attending dentist or dental care
provider.
[0075] Device Operation.
[0076] FIG. 6 is a schematic front view of the front end of a
caries measuring instrument. Operation of the device may be as
follows: (i) The instrument is turned on by moving switch S1 to the
ON position; the .mu.A meter will read 0.00. If a low battery
condition is displayed, the meter battery needs to be replaced;
(ii) Switch S2 is moved to the BATTERY TEST position; the current
source battery needs to be replaced if the test light does not
illuminate; (iii) Switch S2 is moved to the ON position and (iv)
the probe and reference electrode, which are connected to the
device by jacks, are used to test whether the circuits are
functioning properly. The output of the current source supplies 9
volts at 0 .mu.A in the open circuit state and a maximum of 1 volt
and 10 .mu.A in the shorted closed circuit condition, i.e. when
reference and probe electrodes are in contact with each other.
[0077] To carry out the testing, readings may be made by first
having the system in its open position and to then test if reading
range is at its maximum. For the latter, the probe tip is placed in
contact with the reference electrode so that the circuit is
shorted. This activates an auditory component (a beeper) in the
measuring unit for a period of time that indicates to the operator
that he or she has made electrical contact. In some embodiments,
the auditory component is activated for 1, 2, 3, 4, 5 or 10
seconds. When the beeping of the auditory component stops, the
electrode is removed from contact with the measuring site. At the
end of the beep, a five second numerical hold circuit is triggered
which results in the display of no more than 10 .mu.A on the .mu.A
meter and no less than 1 volt on the voltmeter. The reading may
hold for five seconds to allow time for reading recording; the
meters then return to zero .mu.A and full battery voltage. The
system is now ready for successive intermittent probing for hidden
dental caries lesions with the indicator electrode. Sliding probing
can also be done where the probe is run along fissures and a beep
or beeping will locate early hidden caries lesions. An immediate
intermittent probe thereafter will confirm lesion presence and its
magnitude.
[0078] To enable device portability, batteries may be used. This
eliminates the need for patient isolation techniques, power cords
and reduces cost. A line powered or battery eliminator can also be
constructed. The use of line power or a battery eliminator
transformer requires a power cord and the addition of patient
isolation techniques. The voltages supplied to and by the circuitry
in the meter are set and will not vary like a battery can, as it
gradually discharges during use. Circuit operation of the current
source is the same.
[0079] These features will allow the same data from all such
meters. If eliminating the need to manually record data is desired,
a method may be introduced to record the data in a memory or print
the data instead.
[0080] The details of the device are provided in the Examples given
below which are provided as an illustration of the invention only
and therefore should not be construed to limit the scope of the
present invention.
Example 1
[0081] An apparatus was assembled to simulate the in vivo condition
to show that fluid can move coronally through the apical foramen of
a tooth (from underlying tissue fluid) and then through the pulp
and thereafter through the dentine to fill any breached or partly
breached (porous) enamel spaces. In doing so, the nature of the
electrical conductance circuit involved is demonstrated along with
its open and closed nature during measurements.
[0082] The apparatus is also of considerable use for the testing
beforehand of probe tips for their suitability for use in the
measuring instrument. It is also of use for training health care
providers before proceeding to work on patients.
[0083] The device consists of a Petri dish (9 cm diameter) without
its lid, covered with a rubber or cardboard sheet (15 cm
square.times.2 mm thick) with a hole in the center for a tooth to
be placed in an upright position ready for probing and electrical
testing (cf. rubber dam used in vivo). Another hole in the sheet is
used to accommodate a reference electrode as above. Still another
hole is cut to enable addition or removal of saliva, serum or other
fluids, as desired or appropriate.
[0084] The sheet is supported by a 15 cm.times.7 mm thick wooden
frame placed over the Petri dish. Thirty ml of 0.9% (w/v) NaCl
solution (i.e. saline) is added to the Petri dish and the roots of
each tooth undergoing measurement is pressed through the hole in
the center of the rubber sheet until the apical portion of the root
is immersed about 2 to 3 mm into the saline in the Petri dish. The
saline enters the pulp chamber through the root canal or canals of
the tooth being tested. It then passes from the pulp and through
the dentinal tubules to reach the pits, fissures or fossae under
test. If any covering enamel is not intact (i.e. porous or
breached), then current will be detected and measured.
[0085] The reference electrode utilized in making conductance
determinations consists of a convenient length of platinum wire
placed into the saline solution in the Petri dish and is connected
to an insulated wire leading to the measuring instrument. The
indicator electrode and its replaceable measuring tips may be
similar to those described above with reference to FIGS. 3 and
4.
Example 2
[0086] In a set of experiments to compare sound and carious teeth
and confirm such to be the case by biopsy, electrical current at 6
to 8 occlusal surface sites per tooth were measured in 26
non-cavitated carious and in 13 freshly erupted (and hence, clearly
non-cavitated and non-carious) teeth. At each site, readings were
made in triplicate. Each time beforehand, the tooth was dried by
air-blowing for 5 to 10 seconds prior to the taking of
measurements. The crown of each tooth was then sectioned
transversely with tooth slices cut progressively from the occlusal
to the cemento-enamel junction area. This gave slices that were
each 630 .mu.m thick. In a re-constructed sectioned tooth, slices
would be spaced 150 .mu.m apart due to the thickness of the diamond
blade in a low speed saw (Isomet 11-1180, Buehlar, Evanston, Ill.)
used for the slicing. Each horizontal section was photographed in
color and examined visually for demineralization, which indicated
extent of lesion progression and was scored on a scale of 0-4.
[0087] Electrical conductance ranged between 0.3 and 3 .mu.A in the
occlusal sites in the 26 carious teeth measured as seen in Table 3
and was zero in all of the occlusal sites measured in the 13
non-carious controls as seen in Table 4. The teeth identified in
Tables 3 and 4 are numbered in accordance with the Universal System
of Tooth Numbering. The right maxillary third molar is designated
"1" and the count increases to the left. The left mandibular third
molar is designated "17" and the count increases to the right along
the bottom teeth.
TABLE-US-00004 TABLE 4 Electrical current and Demineralization
Scores of Control Teeth Current Demineralization Tooth # (.mu.A)
score 1 0.0 0 15 0.0 0 32 0.0 0 32 0.0 0 32 0.0 0 17 0.0 0 16 0.0 0
19 0.0 0 16 0.0 0 3 0.0 0 32 0.0 0 16 0.0 0 31 0.0 0 Number 13 Mean
= 0.0 Mean = 0 of teeth
[0088] Visual examination of the horizontal sections of the carious
group of teeth showed a mean demineralization score of 2.11.+-.0.67
(S.D.) (see Table 3 above) on a 0-4 scale as described below in
Table 5. Their mean electrical conductance value (see Table 3) was
2.16.+-.0.55 (S.D.) .mu.A. In contrast, the control group of teeth
showed a mean electrical conductance of 0.0 .mu.A (Table 4) and no
mineral loss was visible in these sections. Their mean
demineralization score was 0. The difference in the electrical
current values between the two groups was highly significant by the
Student t test as was the difference in their demineralization
values (p<0.001).
Example 3
[0089] The occlusal surfaces of forty extracted permanent molars
were each first measured with the measuring device to detect
presence of caries lesions and to then confirm their presence by
tooth biopsy as in Example 2 above. This group of teeth showed
electrical current values between 0 and 4 .mu.A. Occlusal sites
were selected in each slice and electrical conductance was measured
in each location in triplicate. The teeth were then biopsied by
sectioning as in Example 2 and visually examined and scored for
demineralization from color photographs thereof. Electrical current
was plotted against demineralization scores (FIG. 7). Correlation
between electrical conductance and detection by biopsy was very
high (r=0.914; p<0.001).
Example 4
[0090] Batteries lose voltage with use. Such discharge may affect
the stability of instrument readings. To test for this possibility,
a 100K resistor was introduced into the instant device between the
probes of the measurement instrument. This adds to RI and Rs a
value of 101,000 ohms. In Table 1, with a battery voltage of 8.61
volts, the instrument reads 1.98 volts and 9.82 .mu.A. Using Ohms
Law, R=V/I, this works out to 201,000 ohms. Table 2 shows similar
measurements when the battery voltage is 6.37 volts. Connecting the
same 100K resistor between the probes of the present device results
in meter readings of 1.98 volts and 9.83 .mu.A. This also
calculates out to 201,000 ohms.
[0091] In comparing Tables 1 and 2, the differences in the
calculated values of column R=V/I are insignificant. A review of
the .mu.A column shows a difference of 0 .mu.A at 80,000 ohms, and
a maximum difference of 1.6 .mu.A at 1,000,000 ohms. This
difference in .mu.A may be insignificant in determining the
magnitude of caries lesions. Thus, the accuracy of the measuring
device in detecting dental caries has been demonstrated. Thus,
readings are not affected as the 9 volt battery power source loses
some of its charge.
Example 5
[0092] A 14-month study was carried out to compare detection in
vivo of occlusal caries lesions in the occlusal surfaces of the
first permanent molars of Venezuelan children by electrical
conductance and by visual-tactile means. Two hundred children, 9 to
11 years of age, from Unidad Educativa Baute in Venezuela
participated in this investigation. Of the 200 children accepted,
119 remained at the end of this investigation and these are the
basis of the data analysis. The visual-tactile and electrical
conductance methods were both used to detect carious lesions at
baseline and after 14 months. The occlusal surface examinations
were done by two examiners. One performed the visual-tactile
examination using artificial light, probe and dental mirror; the
other utilized the caries detection device of the present
invention. Both examiners were standardized beforehand for their
respective methods. Visual-tactile examination used a DMFS scoring
procedure based on the criteria shown in Table 5:
TABLE-US-00005 TABLE 5 The recording criteria used in the
visuo-tactile examination method. 1a: Change in enamel surface
translucency or 2: Filled tooth surface opacity that is distinctly
visible after air drying 1b: Opacity distinctly visible while
surface is 3: Extracted tooth still wet. surface 1c: Localized
enamel breakdown where 4: No or slight change in the enamel is
opaque or discolored. enamel translucency (sound) 1d: Cavitated
enamel 5: Unerupted surface DMFS scoring: 1a, b or c is scored D
1/2; 1d is scored D1; 2 is scored Filled; 3 is scored Missing; and
4 is scored Sound.
For this example, surfaces were scored carious if any of criteria
1a to 1d were met and sound if criterium 4 was met. The results of
such carious/sound scoring are shown in Tables 6 and 7, below:
TABLE-US-00006 TABLE 6 Number and percentage of occlusal surfaces
in first permanent molar teeth at baseline showing status according
to the (i) Electrical Conductance and (ii) Visual-Tactile methods
utilized. Detection methods Electrical Conductance Visual-Tactile
First Molar Teeth (6) (number) (number) in Quadrants 1-4 Sound
Carious Sound Carious 16 7 (5.9) 112 (94.1) 81 (68.1) 38 (31.9) 26
21 (17.6) 98 (82.4) 80 (67.2) 39 (32.8) 36 26 (21.8) 93 (78.2) 45
(37.8) 74 (62.2) 46 24 (20.2) 95 (79.8) 52 (43.7) 67 (56.3) Total
78 (16.4) 398 (83.6) 258 (54.2) 218 (45.8) Carious/sound ratio 5.10
0.84 Values in parentheses are expressed in percentages.
TABLE-US-00007 TABLE7 Number and percentage of occlusal surfaces in
first permanent molar teeth at 14 months showing status according
to the (i) Electrical Conductance and (ii) Visual-Tactile methods
utilized. Detection methods Electrical Conductance Visual-Tactile
First Molar Teeth (6) (number) (number) in Quadrants 1-4 Sound
Carious Sound Carious 16 4 (3.4) 115 (96.6) 68 (57.2) 51 (42.8) 26
4 (3.4) 115 (96.6) 63 (53.0 56 (47.0) 36 9 (7.6) 110 (92.4) 33
(27.7) 86 (72.3) 46 9 (7.6) 110 (92.4) 24 (20.2) 95 (79.8) Total 26
(5.5) 450 (94.5) 188 (39.5) 288 (60.5) Carious/sound ratio 17.30
1.53 Values in parentheses are expressed in percentages.
[0093] At baseline, the electrical conductance (EC) method detected
many more occlusal surfaces with caries lesions than was observed
with the visual-tactile procedure (see Table 6 and particularly the
carious/sound ratios shown therein; i.e. 5.10 by EC and 0.84 by
visual-tactile). This wide difference can be attributed to the wide
difference in their detection capabilities, namely that EC
examination is capable of detecting lesions at a much earlier stage
in their development than can be detected by visual-tactile means,
when many very early lesions are not yet visible by visual-tactile
examination. A second examination was done 14 months after baseline
to enable lesions to develop and thus become more readily
detectable by both methods. The results showed that caries
increased between baseline and 14 months by both methods (Tables 6
and 7 and see FIG. 11). From Tables 6 and 7, one can see that with
time (i.e. after 14 months) the higher ratio of carious to sound
surfaces is sustained as caries progresses with age (i.e. 17.30 by
EC and 1.53 by visual-tactile). FIG. 11 clearly shows the much
greater caries detection capability with EC measurement than with
the classical mirror and probe method, which is what should be
expected because of the much greater and earlier detection
capability by EC measured with the device of the present
invention.
[0094] Earlier detection by electrical conductance is particularly
valuable at the pre-cavity stage of caries development, because
there are major treatment consequences of early detection. Most
significant is that treatment can be achieved by simpler means,
namely re-mineralization procedures, whereas later detection by
visual-tactile means involves larger lesions (cavities) and use of
so-called drilling and filling restorative procedures.
Example 6
[0095] The size and shape of the removable measuring tips of the
device of the present invention are important features. The probe
tips are able to fit into caries-prone sites more readily than
heretofore. Probe tips ranging in tip sizes were tested and
compared to the probing ends of a range of explorer probes normally
used in conjunction with hand mirrors to probe for and locate
presence of early cavities.
[0096] Probing tips ranging from 0.12 to 0.73 mm in diameter at
their actual tips were examined for their ability to measure
electrical conductance in molar teeth using the apparatus described
in Example 1. Results are presented in FIG. 8. Tips with a diameter
ranging from 0.12 to 0.40 mm gave similar results. For tips with
diameters greater than 0.40 mm, electrical conductance values,
measured in .mu.A, dropped as would be expected because the tip
would not be able to penetrate and fit sufficiently into a pit,
fissure or fossa site.
[0097] Similar electrical conductance measurements were also made
for a range of commercially available dental explorers coupled to
the device of Example 1 (FIGS. 9 and 10). Their tip diameters were
larger in size than the described tip diameters proposed herein and
hence caries-prone site penetration can be expected to be less, as
in FIG. 9 and even less as in FIG. 10 These explorers are available
commercially and comprise a representative sample. Their tips are
larger and slightly more rounded at their tips than are the tips of
the present invention. Accordingly, the tips of the present
invention were more suitably shaped and finer than the commercial
explorer tips and thus could penetrate into occlusal sites more
readily. The results in FIG. 10 showed virtually no electrical
conductance which is consistent with penetration of the probes
being insufficient to give much current flow. FIG. 9 indicates some
penetration. Thus, the size of the prior art tips limited their
ability to penetrate sufficiently into caries prone sites and hence
meant unsatisfactory and less sensitive diagnostic capability. This
limitation also applies to tufted tips (i.e. bundle of tufts)
presently available. Such tufts cannot penetrate fissures deeply
and their behaviour is like that of the oversized electrodes in
FIGS. 8, 9 and 10. Also such a tufted electrode tip lacks the
rigidity that enables reproducable probe placement into a fissure
site.
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