Description:
This invention relates to a dental tool and more particularly to such a tool involving the utilization of sonic energy to massage gum tissue.
In furthering dental hygiene, it is highly desirable to regularly massage the gum structure primarily to provide stimulation to such structure and also to loosen and remove dirt between the gums and the teeth. To further these ends, certain vibratory dental instruments have been developed, including, for example, pulsing jets, and the electric toothbrush. These devices, however, do not couple sonic energy to the gum tissue as efficiently as would be desired, this in view of several factors such as the lack of efficient impedance matching of the vibratory generator to the gums, and the failure ro provide optimum utilization of the available energy. In these prior art devices, the applicator typically vibrates relative to the gums, and does not to any great degree transfer sonic energy to the gums such as to cause vibration thereof.
The device of this invention provides a significant improvement over prior art gum massaging instruments by generating sonic energy in a gyratory vibration mode in a resonant vibration system which includes an elastic stem or wand and the gum tissue itself. Such energy may be further impedance matched to the gum tissue by means of a soft resilient applicator which is coupled to the wand at an optimum impedance point in the standing wave vibration pattern set up therealong. The use of a resonant elastic vibration system enables the optimum utilization of the available power in that the vibrational output can be developed in a most efficient manner.
It is therefore the principal object of this invention to facilitate and improve the capability for massaging and cleaning gum tissue.
Other objects of this invention will become apparent as the description proceeds in connection with the accompanying drawings, of which:
FIG. 1 is a perspective view of one embodiment of the device of the invention;
FIG. 2 is a cross-sectional view taken along the plane indicated by 2-2 in FIG. 1;
FIG. 3 is a cross-sectional view illustrating the applicator and rotor member of the embodiment of FIG. 1;
FIG. 4 is a cross-sectional view indicating an alternative form of rotor member which may be utilized in the device of the invention;
FIG. 5 is a cross-sectional view illustrating another alternative rotor member which may be utilized in the invention;
FIG. 6 is an elevational view illustrating an alternative applicator member which may be utilized in the device of the invention; and
FIG. 7 is an elevational view illustrating another alternative applicator member which may be utilized.
It has been found most helpful in analyzing the device of this invention to analogize the acoustically vibrating circuit utilized to an equivalent electrical circuit. This sort of approach to analysis is well known to those skilled in the art and is described, for example, in Chapter 2 of "Sonics" by Hueter and Bolt, published in 1955 by John Wiley and Sons. In making such an analogy, force F is equated with electrical voltage E, velocity of vibration uis equated with electrical current imechanical compliance C m is equated with electrical capacitance C e , mass M is equated with electrical inductance L, mechanical resistance (friction) R m is equated with electrical resistance R and mechanical impedance Z m is equated with electrical impedance Z e .
Thus it can be shown that if a member is elastically vibrated by means of an acoustical sinusoidal force F o sin ω t (ωbeing equal to 2π times the frequency of vibration), that
Where ωM is equal to 1/ωC m , a resonant condition exists, and the effective mechanical impedance Z m is equal to the mechanical resistance R m , the reactive impedance components ωM and 1/ωC m canceling each other out. Under such a resonant condition, velocity of vibration uis at a maximum, power factor is unity, and energy is more efficiently delivered to a load to which the resonant system may be coupled.
It is important to note the significance of the attainment of high acoustical "Q" in the resonant system being driven, to increase the efficiency of the vibration thereof and to provide a maximum amount of power. As for an equivalent electrical circuit, the "Q" of an acoustically vibrating circuit is defined as the sharpness of resonance thereof and is indicative of the ratio of the energy stored in each vibration cycle to the energy used in each such cycle. "Q" is mathematically equated to the ratio between ωM and R m . Thus, the effective "Q" of the vibrating circuit can be maximized to make for highly efficient, high-amplitude vibration by minimizing the effect of friction in the circuit and/or maximizing the effect of mass in such circuit.
In considering the significance of the parameters described in connection with equation (1), it should be kept in mind that the total effective resistance, mass, and compliance in the acoustically vibrating circuit are represented in the equation and that these parameters may be distributed throughout the system rather than being lumped in any one component or portion thereof.
It is also to be noted that orbiting-mass oscillators are utilized in the implementation of the invention that automatically adjust their output frequency and phase to maintain resonance with changes in the characteristics of the load. Thus, in the face of changes in the effective mass and compliance presented by the load with changes in the conditions of the work material as it is sonically excited, the system automatically is maintained in optimum resonant operation by virtue of the "lock-in" characteristic of applicant's unique orbiting-mass oscillators. Furthermore, in this connection, the orbiting-mass oscillator automatically changes not only its frequency but its phase angle and therefore its power factor with changes in the resistive impedance load, to assure optimum efficiency of operation at all times.
Briefly described, the device of the invention comprises a hollow elastic wand member in which an eccentric rotor member is contained. Means are provided for rotatably driving the rotor member at a frequency such as to cause resonant elastic vibration of a vibration system which includes the wand member. Attached to the wand member at a low impedance point in the standing wave vibration pattern established therealong is a resilient applicator member for acoustically coupling sonic energy from said wand member to gum tissue. The resonant frequency of vibration of the vibration system including the wand member, the applicator member and the gum tissue is chosen to be one at which gum tissue will naturally respond in an efficient manner.
Referring now to FIGS. 1--3, one embodiment of the device of the invention is illustrated. A hollow wand member 11 may be integrally formed with a hollow handle member 12. Wand member 11 is fabricated of an elastic material such as nylon. Contained within wand member 11 at one end thereof is an eccentric rotor member 14 which is coupled to electric drive motor 15 by means of elastic shaft 16, guide bearing 17 and drive shaft 18. Shafts 16 and 18 are fabricated of an elastic material such as nylon, the guide bearing 17 acting to center the shafts within hollow wand member 11. Power may be provided for electric motor 15 by means of battery 21, or if so desired, this motor may be of a type which is run off the AC power lines.
Removably attached to wand members 11 at one end thereof is flexible applicator member 23 which is made of a soft pliable material such as rubber. The applicator may be of a porous material such as foam rubber in which a cleaning solution could be impregnated. Applicator 23 has a pick 24 formed therein which is applied to the gum tissue 27 and can fit between the teeth 28 as shown in FIGS. 1 and 2.
Motor 15 is operated at a speed such as to cause resonant elastic vibration of the resonant vibrating system including wand member 11 applicator member 23 and the gum tissue 27. This vibration frequency is preferably a low frequency of the order of 20 cycles per second so as to provide optimum energy transfer to the gum tissue. The vibrational pattern generated by rotor 14 is circular or gyratory in mode, thus providing the application of both compressional and shear stress on the gum tissue for optimum impedance match by applicator member 23. It is to be noted that in view of the circular vibrational pattern of the energy provided to the applicator, its orientation relative to the gums and teeth is not critical. It is further to be noted that applicator member 23 is attached to elastic wand member 11 at the end thereof, which is a point of low impedance in the standing wave vibration pattern, i.e., near a velocity antinoble. This assures good impedance matching to the gum tissue through the resilient applicator 23.
Referring now to FIG. 4, an alternative form of eccentric rotor which may be utilized in the device of the invention is illustrated. This rotor, rather than having the semicircular form of the rotor FIG. 3, rather has an eccentrically located hollowed out portion 14aformed therein, the outside walls of the rotor having a diameter just slightly less than the inside diameter of wand member 11. It thus can be seen that in view of the mass unbalance of this rotor that the desired gyratory vibration of wand member 11 will be induced.
Referring now to FIG. 5, another embodiment of rotor 14 is illustrated. This particular embodiment involves a relatively small diameter cylindrical element which is driven by rolling around within the raceway formed by the inner walls 11aof wand member 11. This particular type of rotor has the advantage in that it provides a frequency stepdown in the vibration frequency from the rotation frequency of shaft 16, and is useful in obtaining the desired low frequency vibrational output in conjunction with a somewhat higher speed motor.
Applicator member 23 preferably is made so that it is readily detachable from wand member 11 so that it can readily be replaced for applicator members exchanged for use by different persons. Applicator member 23 thus is preferably made so that it can be stretched to fit over the end of the wand in a hold tight relationship therewith. The end of wand member 11 is preferably roughened to provide friction to aid in holding the applicator member thereto.
Referring now to FIG. 6, another type of applicator member which may be utilized with the device of the invention is illustrated. This applicator, as for the applicator just described is of a flexible soft material which can be stretched to fit the end of wand member 11. However, rather than having a single pick member, it includes a plurality of pointed pick sections 30 for working between the teeth.
Referring now to FIG. 7, still another applicator member which may be utilized in the device of the invention is illustrated. This applicator member is also of flexible soft material which can be stretched on the end of wand member 11, and includes a plurality of concentric ridges sections 32 as the working elements.
The device of the invention thus provides a highly efficient gum massaging instrument which utilizes resonant sonic energy coupled to the gum tissue to implement the massaging action.