The present invention relates generally to the field of periodontal tools, and more particularly to electro-physical periodontal tools used to evaluate gingival and osseous tissues.
The human periodontal ligament (PDL) is a group of connective tissue fibers that attaches a tooth to the alveolar bone and provides nutritive, proprioceptive, and reparative functions. In particular, the PDL is composed of collagenous fibers and a gelatinous ground substance including cells and neurovascular tissue. Biomechanically, the ligament demonstrates nonlinear viscoelasticity. Patient outcomes associated with dental treatments are strongly influenced by the mechanical support of the PDL. Therefore, testing the health of the PDL is increasingly important during routine examinations. Functional masticatory forces are relevant in prosthodonictics and periodontics, whereas low, continuous forces are typically applied in orthodontic treatments. Finite element (FE) analyses that have simulated clinical experiments of dental implants, operative dentistry, prosthodontics, and orthodontics may be limited by their use of relatively simple (linear elastic) material properties of the PDL. Studies using quasi-linear viscoelastic theory have been performed to quantify the non-linear, time-dependent PDL stress-strain behavior. An example study is described in “Quasi-Linear Viscoelastic Behavior of the Human Periodontal Ligament” (2002) by Toms, Dakin, Lemons and Eberhardt.
The interface between a tooth and the surrounding gingival tissue is a dynamic structure. The gingival tissue forms a crevice surrounding the tooth, similar to a miniature, fluid-filled moat, wherein food debris, endogenous and exogenous cells, and chemicals float. The depth of this crevice, known as a sulcus, is in a constant state of flux due to microbial invasion and subsequent immune response. Located at the depth of the sulcus is the epithelial attachment, consisting of approximately 1 mm-2 mm of junctional epithelium and another 1 mm-2 mm of gingival fiber attachment, comprising the approximately 2 mm-4 mm of biologic width naturally found in the oral cavity. The sulcus is literally the area of separation between the surrounding epithelium and the surface of the encompassed tooth.
The normal sulcular depth is three millimeters or less. Through much investigation and research, it has been determined that sulcular depths of three millimeters or less are readily self-cleansable with a properly used toothbrush or the supplemental use of other oral hygiene aids. When the sulcular depth is chronically in excess of three millimeters, regular home care is unable to properly cleanse the full depth of the sulcus, allowing food debris and microbes to accumulate. This poses a danger to the periodontal ligament (PDL) fibers that attach the gingiva to the tooth. If accumulated microbes remain undisturbed in a sulcus for an extended period of time, they will penetrate and ultimately destroy the delicate soft tissue and periodontal attachment fibers. If left untreated, this process may lead to a deepening of the sulcus, recession, destruction of the periodontium, and tooth loss.
A gingival pocket presents when the marginal gingiva experiences an edematous reaction, whether due to localized irritation and subsequent inflammation, systemic issues, or drug induced gingival hyperplasia. Regardless of the etiology, when gingival hyperplasia occurs, greater than normal (the measurement in a pre-pathological state) periodontal probing measurements can be read, creating the illusion that periodontal pockets have developed. This phenomena is also referred to as a false pocket or “pseudopocket”. The epithelial attachment does not migrate, but simply remains at the same attachment level found in health. The only anatomical landmark experiencing migration is the gingival margin in a coronal direction.
In a gingival pocket, no destruction of the connective tissue fibers (gingival fibers) or alveolar bone occurs. This early sign of disease in the mouth is completely reversible when the etiology of the edematous reaction is eliminated and frequently occurs without the need for dental surgical therapy. However, in certain situations, a gingivectomy is necessary to reduce the gingival pocket depths to a healthy 1-3 mm.
Tools used to evaluate and characterize periodontal human tissue are useful in maintaining the health of an individual. And, monitoring disease and pathology can greatly affect the mechanical properties of human tissue because if weaknesses are detected early enough, the individual can initiate corrective action. Periodontal-specific probes currently available measure pocket/sulcus depth. The more advanced of these available probes find the pocket/sulcus depth automatically using a mechanical means to ensure a semi-standard force is applied. These probes do not, however, characterize the tissue as a material continuum and instead only characterize the tissue in its geometry.
It is to the provision of meeting these and other needs that the present invention is primarily directed.
In example embodiments, the present invention provides a periodontal probe that measures periodontal health by interpreting a resistive force applied to a probe in contact with a defined region of gum tissue.
In one aspect, the present invention relates to a material characterization apparatus including a probe for applying a force to a defined section of biologic tissue. The apparatus further includes a sensor to record the force applied onto the biologic tissue by the probe and a data transmission interface to transmit the recorded force to a data processor.
In another aspect, the invention relates to a material characterization apparatus including a predictably flexible probe for applying a uni-directional force to a defined section of biologic tissue. The apparatus also includes a sensor secured to the flexible probe. And, the sensor records strain data generated by the flexible probe upon application of the uni-directional force to the biologic tissue. The apparatus further includes an interface in electronic communication with the sensor. The communication interface sends the strain data to a data processor.
In still another aspect, the invention relates to a material characterization apparatus including a force-application member that physically reacts to a resistive force generated by the surface upon which a force is applied. The apparatus also includes a sensor that records data describing the physical reaction of the force-application member. And, the apparatus includes a data transmitter that digitally transmits the data recorded by the sensor to a remote receiver.
In still another aspect, the invention relates to a system for characterizing material including a contact member for applying a force to a defined section of material and a sensor to record the force applied onto the material by the contact member. The system also includes a data communicator to communicate the recorded force and a data receiver to receive the communicated recorded force.
In still another aspect, the invention relates to a method for characterizing material including applying a force to a material with a contact member comprising predictable flexibility and recording a material resistive force with a sensor in flexible communication with respect to the contact member. The method also includes communicating the recorded resistive force through a data communicator.
In still another aspect, the invention relates to an apparatus for material characterization including a contact member for applying a force to a defined section of material and a sensor to record the force applied onto the material by the contact member. The apparatus also includes a displacement instrument secured with respect to the contact member. This displacement member recognizes the physical displacement of the contact member with respect to a fixed geometry secured within the defined section of material to be characterized.
These and other aspects, features and advantages of the invention will be understood with reference to the drawing figures and detailed description herein, and will be realized by means of the various elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following brief description of the drawings and detailed description of the invention are exemplary and explanatory of preferred embodiments of the invention, and are not restrictive of the invention, as claimed.
The present invention may be understood more readily by reference to the following detailed description of the invention taken in connection with the accompanying drawing figures, which form a part of this disclosure. It is to be understood that this invention is not limited to the specific devices, methods, conditions or parameters described and/or shown herein, and that the terminology used herein is for the purpose of describing particular embodiments by way of example only and is not intended to be limiting of the claimed invention. Any and all patents and other publications identified in this specification are incorporated by reference as though fully set forth herein.
Also, as used in the specification including the appended claims, the singular forms “a,” “an,” and “the” include the plural, and reference to a particular numerical value includes at least that particular value, unless the context clearly dictates otherwise. Ranges may be expressed herein as from “about” or “approximately” one particular value and/or to “about” or “approximately” another particular value. When such a range is expressed, another embodiment includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms another embodiment.
In one example embodiment, the present invention is an apparatus for material characterization used to consistently measure pocket/sulcus depth and characterize tissue as a material continuum. The apparatus can also enable a user to determine adequate mechanical characterization of material, for example soft-tissue integration onto, and nearby, a fixed geometry, for example a tooth, dental implant or dental prosthesis. This is of particular importance because a true sulcus or cemento-enamel junction does not form with respect to a dental prosthesis. And, data obtained from the apparatus preferably allows for continual, accurate monitoring of oral tissue health by a user. Additionally, the apparatus can be used to characterize a variety of materials which have structural preferences.
In example embodiments, the apparatus characterizes gingival and osseous tissues in-vivo via electro-physical means. For example, in one embodiment, the apparatus includes a sensor that responds to stress or strain produced by probing tissue materials. In such embodiments, the apparatus determines and returns quantitative and qualitative mechanical response data to the user using a wireless device for data communication, through a data communicator, from the apparatus and a wireless receiver for data acquisition, graphic display and interpretation. Alternatively, the response data can be returned to the user using a wired device. Optionally, the apparatus can return the response data to the user in real time. And, the apparatus can provide data suitable for deriving output, for example viscoelastic mechanical response curves, energy absorbed and/or peak applied-force values with in-vivo human tissue.
Preferably, the apparatus is capable of being submerged within a sterilizing solvent without sustaining damage to electrical components. This ability ensures that all surfaces open to blood-borne pathogens can be thoroughly cleaned and/or sterilized. Alternatively and/or additionally, the apparatus can also be autoclavable to ensure that levels of cleanliness equivalent to standard periodontal probing tools are maintained and the necessity for disposable systems attached directly to a probe handle tip is reduced.
With reference now to the drawing figures, wherein like reference numbers represent corresponding parts throughout the several views, FIGS. 1 and 2A-2D show an example embodiment of the apparatus contact member 10. The depicted contact member includes a probe tip 12, a base 16 and an intermediate flexure bridge 14. The probe tip 12 is preferably constructed of a substantially rigid material that will not easily flex, such as, but not limited to, injection-molded plastic. Alternative embodiments can include contstruction of titanium, stainless steel or other metal, ceramic or polymeric materials. This probe can be disposable after use or can be re-used with sufficient sterilization. The base 16 is also preferably constructed of a substantially rigid material, such as, but not limited to, injection molded plastic. The flexure bridge 14 can be constructed of injection molded plastic, however, as described further below, in example embodiments, the bridge is capable of flexing in a predictable uni-axial direction, for example laterally and vertically and more preferably uni-axially. Optionally, the probe tip 12 can additionally be marked to indicate depth during use, and can also be marked and/or anodized to indicate intended range of application force.
The example probe tip 12 depicted in
The end of the forward-extending member 24 opposite the material-contacting member 18 is secured to a ramp member 26. The ramp member 26 extends obliquely away from the forward-extending member 24 at an angle of inclintation of between about 110 and 130 degrees with respect to the forward-extending member. More preferably, the ramp member 26 extends at an angle of about 120 degrees with respect to the forward-extending member 24. The ramp member 26 has a generally circumferential outer surface. As shown in
In example embodiments, the intermediate flexure bridge 14 includes a planar member or panel 30 that is separated from the probe tip 12 by a wall or flange 28. The wall 28 can be vertically perpendicular to the length of planar member 30. The wall 28 can have a variety of shapes. As shown the wall 28 can have a hexagonal shape. The planar member 30 can have a rectangular shape that flexes vertically (with respect to the orientation of
The base 16 is secured to the flexure bridge 30 at an end opposite the wall 28. As shown, the base 16 generally includes the gripping region 32, an intermediate region 36 and a rear region 38. The gripping region 32 can have a variety of shapes, for example a hexagon. Preferably, the gripping region 32 has an outer surface shape that allows a user to grip with a gripping tool (e.g., wrench) and rotate the probe 10 for tightening purposes. As shown, in the example embodiment the gripping region 32 has a shape similar to the wall 28. The intermediate region 36 can include a threaded outer surface. And, as shown, the rear region 38 is cylindrical in shape. As seen in
As shown in
The second channel 57 extends the length of the intermediate region 54 of the handle 40. The second channel 57 can have an identical diameter to the first channel 48, or alternatively, the second channel 57 can have a greater or smaller diameter to the first channel 48.
As shown, the handle 40 includes an outer grip surface 52 that comprises raised concentric ridges. This grip surface 52 is located near the forward region 42 and behind the tapered surface 50.
As depicted in
A sensor measures the strain values imparted on the flexure bridge 30 resulting from the application of force on the tip 20. The sensor includes a dynamic electrical component adapted to flex with respect to the bridge 30. This dynamic electrical component can produce a variable electrical output and can be a strain gauge, a piezoelectric conductor and a transducer. A typical strain gage can measure strain in the linear direction either vertically or laterally. The sensor is preferably secured to the upper or lower surface of the planar member 30 of the flexure bridge 14. As shown in
A method of using an apparatus for material characterization according to an example embodiment of the present invention is shown in
The described can communicate via wired or wireless connection with a remote or onboard device capable of resolving electrical differences in resistance of the described strain gage and returning real strain values in real time. A typical value of electronic communication is 1000 Hz. The geometry of the described probe, in conjunction with measured strain values and material properties, is used to calculate the approximate force applied. A graph of the strain with respect to time is transformed into a plot of deformation with respect to time, and then integrated. The resulting unit for this measurement is Newton-seconds (i.e., an energetic measurement describing change in momentum). The real-time graph of strain gives an indication of tissue rupture and force ramping (i.e., evidence of contact with a hard surface, for example a bone), while the integrated result quantifies the energetic resources required to reach the hard surface. This quantification can be used to characterize the quality with which soft tissue is attached, in-vivo, to important surrounding structures. An example remote device is a computer that can record data, process or convert signals received to values relevant to the practitioner, display data graphically, compare measured values with target ranges or threshold values.
The displacement instrument 94 operates on the same wiring and physical principles of strain generation as the probe tip 12, but pivots off a stable feature on the top of the fixed geometry structure, which has proximal tissue being characterized. While the contact member 10 can sense depth to the point of first tissue contact by an algorithm that does not commence recording force data until a specific threshold has been met (i.e., that of a nominal contact force between probe tip and tissue), the displacement instrument 94 produces data that can include overall displacement and distinguish regions of displacement that involve tissue contact and those that do not. Monitoring of strain and displacement rates can notify the user when a hard surface has been contacted through a typical signal communication device (e.g., transmitter), and therefore, when all soft tissue has been displaced. The data, all recorded in real time, is sufficient for determining the basic viscoelastic response of the tissue in question. The algorithm used for the displacement instrument 94 optionally also accounts (to a reasonable degree) to the tremor susceptibility of a user's hand by deleting corresponding force/time data that is not in a uni-axial downward progression with respect to displacement.
Preferably, this displacement instrument 94 is used in-vivo and in a clinical setting, but can alternatively be operable as attached to a stable linear actuator through a periodontal force probe holster 92, and ready-set to quickly interface testing equipment such as a linear actuator manufactured by MTS Systems, Corporation.
The contact member 10 is shown in
τ=movement=Fapplied×l1=Frecorded×l2
While the invention has been described with reference to preferred and example embodiments, it will be understood by those skilled in the art that a variety of modifications, additions and deletions are within the scope of the invention, as defined by the following claims.