Abstract
The system relates to a device and method for ultrasonic whitening of teeth through cavitation. The device and method provide functions to consistently whiten dental surfaces. Ultrasound is generated and coupled through a removable mouthpiece into a coupling fluid in which teeth and gums are at least partially submerged. Several different embodiments for the system, including variations in the mouthpiece, coupling components, and ultrasonic energy components are disclosed.
Claims
1. A device for whitening dental tissue, the device comprising: a mouthpiece being insertable into a mouth of a user and having at least three sides, with one or more volumes that are partially circumscribed by the sides of the mouthpiece; and an ultrasound generator removably attached to the mouthpiece that when attached couples ultrasound into the volumes through the sides of the mouthpiece.
2. The device in claim 1 that further includes a coupling fluid at least partially filling the volumes, and where the coupling fluid includes a whitening agent.
3. The device in claim 2, wherein the coupling fluid comprises water.
4. The device in claim 2, wherein the coupling fluid comprises glycerin.
5. The device in claim 2, wherein the coupling fluid comprises propylene glycol.
6. The device in claim 2, wherein the coupling fluid comprises calcium hydroxide.
7. The device in claim 2, wherein the coupling fluid comprises carbapol.
8. The device in claim 2, wherein the whitening agent is at least one of hydrogen peroxide and carbamide peroxide.
9. The device in claim 2, further comprising a fluid temperature controller that controls the temperature of the coupling fluid in the range of 70-100 F. and is thermosensitively responsive to said coupling fluid.
10. The device in claim 2, wherein the coupling fluid includes a stabilizing agent.
11. The device in claim 10, wherein the stabilizing agent is selected from a group consisting of gelling agent, thixotropic additives, and gum.
12. The device according to claim 1, further comprising a handle attached to the ultrasound generator, such that the handle allows the user to hold onto the device.
13. The device in claim 1, wherein the ultrasound generator further includes at least one piezoelectric transducer.
14. The device of claim 13, wherein the piezoelectric transducer is comprised of a piezoelectric stack immediately coupled to a horn-type transducer.
15. The device of claim 14, wherein said horn-type transducer joins with connectors to metal inserts in the mouthpiece.
16. The device in claim 1, wherein the ultrasound generator is operationally responsive to at least one drive signal and is driven about a frequency provided by the drive signal.
17. The device in claim 16, wherein the ultrasound generator further comprises more than one ultrasonic transducer, each transducer being independently operationally responsive to different drive signals.
18. The device in claim 17, wherein at least one first ultrasonic transducer is driven about a first frequency and at least one second ultrasonic transducer is driven about a second frequency that is out of phase with the first frequency.
19. The device in claim 18, wherein the drive signals provide for intermittent operation of the ultrasonic transducers.
20. The device in claim 1, wherein the mouthpiece comprises an acoustic impedance matching device.
21. The device in claim 20, wherein the acoustic impedance matching device is comprised of a material selected from a group consisting of: graphite, metal, and dielectric material.
22. A device for whitening dental tissue, the device comprising: an ultrasound generator for generating ultrasound, said ultrasound generator comprising: one or more piezoelectric transducers that oscillate to generate ultrasound; and one or more electrical connections connected to the one or more piezoelectric transducers, a mouthpiece attachable to the ultrasonic generator, said mouthpiece comprising: at least three sides being of a material having an acoustic impedance; and one or more volumes partially circumscribed by the at least three sides, such that when the mouthpiece is inserted in a mouth of a user one or more teeth are fit into said one or more volumes, a coupling fluid including a whitening agent and having an acoustic impedance that is about that of the material of the at least three sides of the mouthpiece; said coupling fluid at least partially filling the one or more volumes of the mouthpiece; and an ultrasonic controller that produces one or more drive signals that are communicated through the one or more electrical connections to the one or more piezoelectric transducers and independently drive the one or more piezoelectric transducers.
23. A method for whitening dental tissue, the method comprising: inserting a mouthpiece, having one or more volumes partially circumscribed by one or more sides of the mouthpiece, into a mouth of a user such that one or more teeth of the user fit within the said one or more volumes, filling the volumes partially with a coupling fluid with the coupling fluid including a whitening agent, controlling the temperature of the coupling fluid within a desired temperature range of 80-90 F., controlling the generation of ultrasound; wherein controlling the generation of ultrasound, comprises: providing at least one drive signal; said at least one drive signal comprising at least one frequency, generating ultrasound with an ultrasound generating means; wherein generating ultrasound comprises: oscillating at least one piezoelectric transducer at said at least one frequency in response to the at least one drive signal; and coupling the ultrasound through the one or more side of the mouthpiece into the coupling fluid such that ultrasound is directed toward buccal, lingual, and occlusal surfaces of the mouth, wherein coupling the ultrasound comprises: matching an acoustic impedance of the one or more piezoelectric transducers.
Description
BRIEF DESCRIPTION OF THE FIGURES
[0043] These and other features, aspects and advantages of the present disclosure will become better understood with regard to the following description, appended claims, and accompanying drawings where:
[0044] FIG. 1 depicts a schematic of a version of a device for whitening and/or cleaning teeth and a mouth.
[0045] FIG. 2 depicts a schematic of a version of a device for whitening and/or cleaning teeth and a mouth.
[0046] FIG. 3 depicts a schematic of a version of an ultrasound generator and mouthpiece.
[0047] FIG. 4 depicts a schematic of a version of an ultrasound generator and mouthpiece.
[0048] FIG. 5 depicts a schematic of a version of an ultrasound generator and mouthpiece.
[0049] FIG. 6 depicts a schematic of another version of a device for whitening and/or cleaning teeth.
[0050] FIG. 7 depicts a schematic of another version of a device for whitening and/or cleaning teeth.
[0051] FIG. 8 depicts a pictorial view of a custom mouthpiece that has contours that parallel a mouth of a specific user.
[0052] FIG. 9 depicts a schematic showing ultrasound being coupled through one or more sides of a mouthpiece.
[0053] FIG. 10 depicts a schematic showing ultrasound being coupled through one or more sides of a mouthpiece.
[0054] FIG. 11 depicts a schematic showing ultrasound being coupled through one or more sides of a mouthpiece.
[0055] FIG. 12 depicts a schematic showing ultrasound being coupled through one or more sides of a mouthpiece.
[0056] FIG. 13 depicts graphs of ultrasonic parameters.
[0057] FIG. 14 depicts graphs of ultrasonic parameters.
[0058] FIG. 15 depicts graphs of ultrasonic parameters.
[0059] FIG. 16 depicts graphs of ultrasonic parameters.
[0060] FIG. 17 depicts graphs of ultrasonic parameters.
[0061] FIG. 18 depicts a flow chart of a controller of ultrasound generation.
[0062] FIG. 19 depicts a table with exemplary ranges of ultrasonic parameters.
[0063] FIG. 20 depicts a schematic of a version of a device for whitening and/or cleaning teeth and a mouth, which includes a horn-type transducer
[0064] FIG. 21 depicts a schematic-cross section of a version of a device for whitening and/or cleaning teeth and a mouth, which includes a horn-type transducer
[0065] FIG. 22 depicts a version of a device which includes a waveguide
DETAILED DESCRIPTION
[0066] Referring to FIG. 1, a version of the present disclosure, a device for whitening and/or cleaning a mouth of a user, is shown with: a mouth 10. Herein, the terms cleaning and whitening may be used interchangeably. Herein, the term dental tissues may refer to any of the hard dental tissues of enamel, dentin and cementum. The version illustrated in FIG. 1 is shown having a handle 12 that is attached to an ultrasound generator 14. The handle 12 allows the user to hold onto the device when it is inserted within the user's mouth 10. While an elongated, tubular-type handle is shown, differently shaped handles may also be used, with any such handle preferably housing the electronic components described below. Surrounding the ultrasound generator 14 is a mouthpiece 16. The mouthpiece 16 is removable from the ultrasound generator 14.
[0067] FIG. 2 shows a cross-section of the device in FIG. 1. Within the handle 12; a battery 18, an ultrasonic controller 20, and one or more electrical connections 22 are housed. The battery 18 provides a source of electrical power, powering the ultrasonic controller 20 and the ultrasound generator 14. One or more drive signals are provided by the ultrasonic controller 20 by way of the one or more electrical connections 22 to the ultrasound generator 14. The ultrasound generator operates, generating ultrasound, in response to these one or more drive signals. The ultrasonic controller 20 therefore controls the generation of ultrasound. The cross-section in FIG. 2 shows at least three sides that make up an upper half of the mouthpiece. An upper buccal side 24, an upper lingual side 26, and an upper occlusal side 28 together partially circumscribe an upper mouthpiece volume 30. Inserting the mouthpiece into the mouth of the user results in teeth belonging to an upper arch 32 being positioned within the upper mouthpiece volume 30, such that: Upper buccal surfaces 36 are adjacent the upper buccal side of the mouthpiece 24. Upper lingual surfaces 38 are adjacent the upper lingual side of the mouthpiece 26. And, Upper occlusal surfaces 40 are adjacent the upper occlusal side of the mouthpiece 28. A lower half of the mouthpiece is illustrated in FIG. 2 as being a mirror image of the upper half of the mouthpiece. A lower arch 34 of the user will therefore fit within a lower mouthpiece volume during insertion. Ultrasound generated by the ultrasound generator is coupled through one or more of the sides of the mouthpiece and into the upper and lower mouthpiece volumes.
[0068] FIGS. 3-5 shows an exploded view of a version of the present disclosure. In the version of the present disclosure shown in FIG. 3, the ultrasound generator comprises a multitude of ultrasonic transducers, which are located such that during insertion of the device they are within the mouth of the user. An upper half of the ultrasound generator may comprise: one or more upper buccal ultrasonic transducers 42, upper lingual ultrasonic transducers 44, and upper occlusal ultrasonic transducers 46. A lower half of the ultrasound generator is illustrated in FIG. 3 as being a mirror image of the upper half of the ultrasound generator. The ultrasonic transducers generate ultrasound by producing a series of pressure changes in an ultrasonic medium. The pressure changes are typically generated through a small change in volume of the ultrasonic medium. The small changes in volume of the ultrasonic medium are the result of a change in at least one dimension of the ultrasonic transducer. The size of the change in at least one dimension of the ultrasonic transducer relates to an amplitude of the pressure changes and an amplitude of the generated ultrasound. The ultrasonic transducers being driven by one or more drive signals oscillate in said dimension at a frequency that is above 20 KHz and below 10 MHz. The ultrasonic transducers may be piezoelectric transducers. Piezoelectric transducers that are lead-free are advantageously selected for use in applications within the mouth. PIC700 ultrasonic transducer material from PI Ceramic GmbH of Lindenstrasse, Germany is lead-free and comprises bismuth-sodium-titanate. Of course, other suitable transducer materials may also be used. The ultrasonic transducers shown in FIG. 3 are shown as disks being defined by a diameter and a thickness.
[0069] FIG. 4 shows a version of the mouthpiece. The mouthpiece shown in FIG. 4 is one piece, having an upper half 48 and a lower half 50. The mouthpiece may alternatively be comprised of two separate and distinct elements or, an upper portion and a lower portion. The mouthpiece 16 approximately matches the acoustic impedance of the ultrasound generator 14 and a coupling fluid that at least partially fills the one or more volumes of the mouthpiece 30. The mouthpiece may comprise: rubber, silicone, PVC, foam, or any elastomeric polymer. The coupling fluid may include but are not limited to one or more of the following ultrasonic mediums: water, glycerin, propylene glycol, calcium hydroxide, carbapol, one or more stabilizing agents, one or more solvents, one or more flavor additives, or one or more surfactants. Stabilizing agents act to increase the viscosity of the coupling fluid. An increased viscosity allows the coupling fluid to be handled and applied more easily as a paste or gel into the one or more volumes of the mouthpiece. Suitable stabilizing agents include but are not limited to: gelling agents, thixotropic additives, and gums. The presence of solvents in the coupling fluid would act to chemically break down biofilm and/or inhibit bacteria on the dental surfaces. Suitable solvents may include but are not limited to: Alcohol, chlorhexidine gluconate, cetylpyridinium chloride hexetidine, benzoic acid, methyl salicylate, triclosan, benzalkonium chloride, methylparaben, hydrogen peroxide, domiphen bromide, fluoride, enzymes, calcium, essential oils, such as: phenol, thymol, eugenol, eucalyptol, menthol. Flavor additives may be used in the coupling fluid to improve the taste and appeal for using the device. Suitable flavor additives include but are not limited to: sorbitol, sucralose, stevia, sodium saccharin and xylitol, which additionally acts to inhibit acid causing bacteria. The presence of surfactants in the coupling fluid acts to lower the surface tension of the fluid and increases ultrasonic cavitation. Suitable surfactants include but are limited to: detergents, wetting agents, emulsifiers, and dispersants. Microbubbles or, ultrasound contrast mediums, such as: SonoVue, Optison or Levovist, may also be added to the coupling fluid.
[0070] An embodiment of the present device may also be directed to the process of tooth whitening. One embodiment of the present device may be used with whitening agents, where one or more of the coupling fluid, solvents, or surfactants contain a percentage of peroxide, where hydrogen peroxide and carbamide peroxide are preferred. The device's ultrasonic features may be used with whitening agents, using similar or different operating parameters as are used for ultrasonic cleaning processes that do not include whitening agents. Preferably, for tooth whitening purposes, a tooth-whitening agent containing peroxide, preferably hydrogen peroxide or carbamide peroxide, is included as percentage of the coupling fluid.
[0071] FIG. 5 shows version of the present disclosure illustrated in FIG. 3 with the mouthpiece 16 attached to the ultrasound generator 14. With the mouthpiece attached to the ultrasound generator 14 and the volumes 30 filled with coupling fluid 52, the generated ultrasound is coupled through the buccal 24, lingual 26, and occlusal 28 sides of the mouthpiece into the coupling fluid 52.
[0072] Ultrasound when introduced into the coupling fluid at sufficient levels produces cavitation. Cavitation occurs when pressure waves, produced by ultrasound, generate low pressure regions within the coupling fluid forming a multitude of vapor bubbles. When the pressure waves are inverted the vapor bubbles collapse as the formally low pressure regions experience high pressure. The collapse of these vapor bubbles creates localized temperatures that have been measured as high as 5000K and localized pressures that have been measured as high as 1000 atm. These high localized temperatures and pressures that exist only momentarily remove particulate from dental tissue that is adjacent to the cavitation. Providing cavitation adjacent to teeth and gum surfaces within the mouth breaks up and removes plaque.
[0073] The efficiency of ultrasonic cleaning is a function of the temperature of the coupling fluid. An elevated temperature allows cavitation to be achieved at low pressures regions that have slightly higher pressures than when the coupling fluid is at lower temperatures. This therefore, causes low pressure regions to form more cavitation. For an intraoral application the temperature must be limited in order to prevent dental tissue damage. It is therefore ideal that the temperature of the coupling fluid be controlled at an elevated temperature, in order to maximize cavitation, that is below a threshold level that would cause discomfort or damage to the user. Some versions of the present disclosure may include a fluid temperature controller that is thermosensitively responsive to the temperature of the coupling fluid. Such that, the temperature of the coupling fluid is sensed and the coupling fluid is heated or cooled in order to maintain a coupling fluid temperature within a desired temperature range. The sensing of the coupling fluid temperature may be done thermostatically or through thermoelectric means, such as a thermistor or thermocouple. The fluid temperature controller determines a heating or cooling load required to maintain the coupling fluid temperature within the desired coupling fluid temperature range. Determination of the heating or cooling loads may be achieved through P.I.D., or other equivalent control logic algorithms, by the temperature controller. The heating load may be provided for by controlled heating of the coupling fluid through electric resistance heating, heat generated through oscillation of ultrasonic transducers, or through a thermoelectric heat pump. The cooling load may be provided for by controlled cooling of the coupling fluid through a thermoelectric heat pump, or other equivalent means. Controlled cooling of the coupling fluid additionally reduces the risk of overheating and damaging the dental tissue of the user. The desired temperature range is typically within 70-100 F. and is preferably held within a smaller range that is elevated, but still comfortable to the user, such as 80-90 F.
[0074] Another version of the present disclosure is shown in FIGS. 7 and 8. The handle 12 is shown having a joint 54. The joint allows for the attitude of the handle relative the mouthpiece to be selected by the user. This allows the user to hold the handle at any number of angles relative the mouthpiece. The joint 54 shown in FIG. 7 is a ball and socket joint although any equivalent hinging mechanism may be used. FIG. 7 also, shows a version of the present disclosure that includes a mouthpiece with an upper portion 56 and a lower portion 58 that is separate and distinct from the upper portion. The upper arch of the user is fitted within the upper portion and the lower arch of the user is fitted within the lower portion. A version of the mouthpiece is also conceived of that includes only a single portion, which houses only one arch of the user at a time. This version of the disclosure has the single portion fitted over a first arch of the user. The device ultrasonically cleans the first arch. Then, the single portion is removed from the first arch and fitted over a second arch of the user. And, the device ultrasonically cleans the second arch. The version of the disclosure with the single portion mouthpiece roughly doubles the amount of time needed to clean the mouth, and halves the number of components in the device.
[0075] Referring to FIG. 8 a version of the present disclosure includes a custom mouthpiece. The custom mouthpiece is shown having an upper custom portion 60 and a lower custom portion 62. The custom mouthpiece has contours that parallel the dental surfaces of the user. The contours of the custom mouthpiece allow the custom mouthpiece to fit closely over the upper arch 32 and lower arch 34 of the user. Inserting the custom mouthpiece into the mouth of the user may form multiple volumes 30 that may partially circumscribe one or more individual teeth. The contours of the custom mouthpiece may form a gap 64 between dental surfaces and the mouthpiece. The gap 64 may be of uniform width. Selecting the size of the gap 64 may allow for optimum performance of ultrasonic cleaning. This is because the distance the ultrasound is transmitted in the coupling fluid prior to reaching the dental surfaces is a function of the gap. Minimizing the gap 64 will generally reduce the ultrasonic loses within the coupling fluid and unintended heating of the coupling fluid.
[0076] The contours of the custom mouthpiece are to be specially formed for a specific user. The specific user may have a scan or an impression taken of his mouth. The scan or the impression is then used to form the contours of the custom mouthpiece. Forming of the custom mouthpiece may be achieved from the scan of the mouth through additive manufacturing processes, such as: SLA or an equivalent 3-D printing/fabrication technology. A positive of the scan may be printed, through additive manufacturing, and used to generate a mold to form the custom mouthpiece with. Likewise the custom mouthpiece may be formed from a mold made from the impression of the mouth. The contours of the custom mouthpiece may also be formed by inserting a pliable mouthpiece into the mouth of the user and using the mouth of the user directly to form the contours.
[0077] FIG. 9 through 12 show the lower arch of the user with a version of the lower portion of the mouthpiece. FIG. 9 shows a cross-sectional view. A lower lingual side of the mouthpiece 66 rests on the bottom of the mouth. The distance in height of the lower lingual side is greater than the height of teeth in the arch. This difference in distance produces the gap 64 between the occlusal surfaces of the teeth and a lower occlusal side of the mouthpiece 68. The distance of the gap between sides of the mouthpiece and surfaces of the mouth of the user is a parameter that affects the distance that the ultrasound is transmitted through the coupling fluid to reach the surfaces of the mouth to be cleaned.
[0078] FIG. 10 shows ultrasound being coupled through the mouthpiece and being directed toward three different surfaces of the mouth; specifically a lower lingual surface, a lower occlusal surface, and a lower buccal surface. In a version of the present disclosure the ultrasonic transducers are independently controlled. In this case, the ultrasound directed at the three different surfaces may have different phases. For example, the ultrasound directed toward the lingual surface may be 180 out of phase of the ultrasound directed toward the buccal surface. And, the ultrasound directed toward the occlusal surface may be 90 out of phase of both the ultrasound directed toward the lingual surface and the ultrasound directed toward the buccal surface. The ultrasound directed toward the buccal surface is generally opposing the ultrasound directed toward the lingual surface. This will result in destructive interference and ultrasonic loses if they are of a same frequency and of a same phase. Having the ultrasound directed toward the lingual surface and the ultrasound directed toward the buccal surface 180 out of phase from one another results in constructive interference and greater ultrasound efficiencies. The ultrasound may be generated by one or more first ultrasonic transducers driven to oscillate at a first frequency and one or more second ultrasonic transducers driven to oscillate at a second frequency. The first frequency may be out of phase of the second frequency. The use of drive signals to independently drive ultrasonic transducers also allows ultrasound to be directed to less than all of the surfaces of the mouth at a time by oscillating the ultrasonic transducers intermittently.
[0079] FIG. 11 shows a schematic of a version of the present disclosure having ultrasound that is directed substantially toward one or more interproximal regions. Interproximal regions are some of the more difficult surfaces of the mouth to clean. Directing ultrasound toward interproximal regions results in cavitation occurring adjacent interproximal regions, or in between teeth. Directing the ultrasound may be achieved through positioning and orienting the ultrasonic transducers, or horns or waveguides to direct ultrasound to the desired surfaces.
[0080] FIG. 12 shows a cross-sectioned schematic view of a version of the present disclosure. One or more piezoelectric transducers 70 are mated to one or more horns 72. The use of the horn, or waveguide, magnifies the amplitude of the oscillations produced by the mating ultrasonic transducer. The horn 72 is mated to an acoustic impedance matching device 74. The acoustic impedance matching device may comprise: graphite, metal or a dielectric material. Ultrasound will reflect where it is being coupled between two mediums of different impedances. The acoustic impedance matching device matches the impedance of horn or ultrasonic transducer and the mouthpiece allowing for more efficient coupling into and through the mouthpiece.
[0081] The mouthpiece may be comprised of a number of materials comprising: rubber, silicone, PVC, elastomeric polymers and foam. The material of the mouthpiece is preferably compliant enough to form a seal around gums in the mouth. The seal prevents leaking of the coupling fluid. Acoustic impedance of the material is a function of the density of the material as well as the acoustic velocity of the material. The material for the mouthpiece ideally matches one or both of the ultrasonic generator or the coupling fluid, thus preventing reflections at a mouthpiece interface. The acoustic impedance matching device may be bonded to the mouthpiece and have an acoustic impedance that generally matches that of the ultrasound generated, ultrasonic transducer, piezoelectric transducer, or horn. And, the mouthpiece may have an acoustic impedance that generally matches that of the coupling fluid.
[0082] FIGS. 13 through 17 show graphs related to controlling and generating ultrasound. Ultrasonic transducers are oscillated at a frequency above 20 KHz to produce ultrasound. Typically ultrasonic transducers have a natural frequency or resonant frequency based upon their composition and dimensions that at which they oscillate most efficiently. Resulting from manufacturing dimension tolerances an individual ultrasonic transducer will likely have a natural frequency that is not exactly equal to its nominal natural frequency. The result is that the individual ultrasonic transducer will oscillate most efficiently at a frequency that is not equal to that of its nominal natural frequency. In a version of the present disclosure the ultrasound generator and ultrasonic transducers are operationally responsive to one or more drive signals being controlled by an ultrasonic controller. The ultrasonic controller thereby drives the ultrasonic transducers to oscillate at one or more frequencies. Sweeping the frequency the ultrasonic transducers oscillate about a center frequency that is about the same as the nominal natural frequency or a harmonic thereof ensures that the individual ultrasonic transducers are occasionally driven at its actual resonant frequency. The harmonic of the nominal natural frequency is generally defined as being of a frequency that is evenly divisible by a common denominator of the nominal natural frequency. A sweep range determines the variance in frequency that the ultrasonic transducers will oscillate at. FIG. 13 shows a normal distribution that shows frequency in the domain and time or probability in the range.
[0083] FIG. 14 shows a graph of sweep range vs. time for a version of the present disclosure. It is beneficial to vary or modulate the sweep rate such that it is non-constant. This is because a constant sweep rate would produce a peak amplitude of ultrasound at the resonant point, and periodically generating a peak amplitude of ultrasound would potentially result in harmful resonance.
[0084] FIG. 15 is a graph showing the size of cavitation producing vapor bubbles. Different frequencies of ultrasound are better suited for cleaning particles of different sizes. Large particles are typically removed best with low ultrasound frequencies, which produce larger vapor bubbles. Smaller particles are typically removed best with higher ultrasound frequencies, which produce smaller vapor bubbles. As it can be seen the ultrasonic transducers may be oscillated about a harmonic of their natural frequency. Jumping the center frequency that the ultrasonic transducer is oscillating about from one harmonic to another allows for the ultrasound to produce cavitation from different sized vapor bubbles and may achieve efficiently the removal of different size particles. Jumping from one center frequency to another may be performed discretely.
[0085] Power of the generated ultrasound is controlled in versions of the present disclosure. An amplitude of the generated ultrasound is a parameter that may be varied to modulate the power of the ultrasound. The greater the amplitude of the ultrasound the more cavitation will occur in the coupling fluid. Another controllable parameter that affects the power of the generated ultrasound is an ultrasound pulse, shown in FIG. 16. Generating the ultrasound in pulses allows the ultrasound to generate less power while maintaining its level of cleaning efficiency. This is ideal for cleaning within the mouth as excessive ultrasound may damage tissue within the mouth. In a version of the present disclosure the ultrasound generator generates the ultrasound in pulses. FIG. 17 shows ultrasound that is generated in pulses having different duty cycles. Varying the duty cycle of the ultrasound provides for varied power levels and may be performed continuously or discretely. The duty cycle may be varied from 0-100%. A degassing step may be performed to remove gas bubbles from the coupling fluid. Typically degassing requires longer pulses, typically in the range 0.5-2 s and low duty cycle, typically in the range of 5-60%. The degassing step loosens gas bubbles from the coupling fluid with the ultrasound and then allows time a delay time in between ultrasonic generation for gas bubbles to escape the coupling fluid. Degassing the coupling fluid is advantageously performed prior to a cleaning step that involves generating ultrasound for cleaning through cavitation. This is because gas bubbles within the coupling fluid contribute to losses in ultrasound. A version of the present disclosure comprises a degassing step.
[0086] Ultrasound generation is performed with different parameters for cleaning. Ultrasound generated at frequencies below 500 KHz has a lower cavitation threshold and is better suited for cleaning through cavitation, for this reason less power is needed for cavitation to occur. When ultrasound is generated and the cavitation threshold is not reached acoustic streaming may occur. Acoustic streaming is the movement of the coupling fluid or the generation of standing waves. Acoustic streaming requires parameters other than those used for cleaning through cavitation. Generally higher frequency ultrasound in excess of 500 KHz, and preferably in excess of 1 MHz, is best suited for acoustic streaming as high ultrasound amplitudes may be employed without causing cavitation. Acoustic streaming will produce a flow within the coupling fluid. A flow within the coupling fluid is advantageously implemented in some versions of the present disclosure in order to dislodge and move debris from surfaces of the mouth.
[0087] FIG. 18 shows a flow chart for an ultrasonic cleaning process as controlled by the ultrasonic controller in a version of the disclosure. Before initiating the ultrasonic cleaning process, the user fills the volumes of the mouthpiece with coupling fluid and inserts the mouthpiece in his mouth.
[0088] Once the cleaning process is initiated the fluid temperature controller ensures that the coupling fluid is within a desired temperature range for degassing. FIG. 19 shows a table that has preferential ranges for ultrasound parameters used during the cleaning process in a version of the present disclosure. FIG. 19 is not intended to be limiting the scope of the present disclosure. Once the coupling fluid is within a temperature range for degassing, a degas step is performed. The degas step removes air entrained in the coupling fluid by generating ultrasound in pulses with relatively low duty cycles.
[0089] Upon completion of the degas step, the fluid temperature controller controls the temperature of the coupling fluid to be within a desired temperature range for entire mouth cleaning. An entire mouth cleaning step is then performed. The entire mouth cleaning step is intended to provide ultrasound to every surface of the mouth simultaneously at a low enough power such that mouth tissue is not damaged. In some versions of the present disclosure ultrasound is directed toward interproximal regions of the mouth and ultrasound generation includes phase modulation.
[0090] Upon completion of the entire mouth cleaning step the fluid temperature controller controls the temperature of the coupling fluid to be within a desire temperature range for high power cleaning. A first high power cleaning step directs ultrasound, at high power levels, but only toward some surfaces of the mouth; for example the upper buccal and occlusal surfaces and the lower lingual surfaces. The ultrasound generator may comprise ultrasonic transducers that are driven independently by drive signals from the ultrasonic controller. Thus directing of ultrasound only toward some surfaces of the mouth by operating only some of the ultrasonic transducers.
[0091] Upon completion of the first high power cleaning step, a second high power cleaning step is initiated. The second high power cleaning step directs ultrasound only toward those surfaces of the mouth not having ultrasound directed toward them during the first high power cleaning step.
[0092] Upon completion of the second high power cleaning step the fluid temperature controller controls the temperature for the coupling fluid to be within a desired temperature range for rinsing. The desired temperature range for rinsing is typically low, because the goal of rinsing is to perform acoustic streaming, not cleaning through cavitation. A rinsing step is intended to rinse debris, which has been removed in previous cleaning steps from the mouth surfaces. Upon completion of the rinsing step, the user removes the mouthpiece from his mouth and the cleaning process is complete. For example, the process above and illustrated in FIG. 18 is provided for example and other processes are possible that include additional or fewer steps, or steps in a different order. For example, the rinsing step may be performed prior to the entire mouth cleaning step. Or, the first and second high power cleaning steps may be omitted.
[0093] FIG. 20 and FIG. 21 show a version of the present disclosure. Handle housing 10e contains components including component housing 106, piezoelectric stack 104, and horn transducer 102. The hollow tip of horn transducer 102 joins with tip 100 to connectors 112. Preferrably, tip 102 is of a tubular configuration to best transmit ultrasonic energy. Connectors 112 join with metal inserts 112 imbedded in mouthpiece 14.
[0094] FIG. 22 shows a version of the present disclosure. This embodiment uses a waveguide as shown, preferably made of brass. The waveguide is preferably surrounded by a combination of air and silicone rubber, formed in part with a plastic housing. Components for ultrasound energy generation and control, similar to other embodiments, are also contained in the plastic housing. The waveguide extends to join a mouthpiece as in the above embodiments, including a portion preferably made of plastic or metal that creates a boundary with the air/brass portion.
[0095] Although the present disclosure has been described in considerable detail with reference to certain preferred versions thereof, other versions are possible. For example, a means of filling the volumes with the coupling fluid, such as a pump may be incorporated. The ultrasonic transducers may be located partially or totally outside of the mouth and ultrasound is coupled to the mouthpiece through the use of a waveguide or horn. Mouthpieces may come in various sizes for children as well as adults. Therefore, in the spirit and scope of the appended claims should not be limited to the description of the preferred versions contained herein.
