1. Technical Field of the Invention
The present invention relates generally to the field of oral hygiene devices and, more specifically, to the field of oral hygiene devices such as toothbrushes that employ sonic and/or ultrasonic acoustic mechanisms.
2. Brief Description of the Related Art
Even the most effective existing power toothbrushes leave clinically significant plaque at tooth-to-tooth contact surfaces, at the gingival-tooth contact points, below the gingiva and beyond the direct reach of the bristles or other toothbrush components. Many oral hygiene devices employing sonic and/or ultrasonic mechanisms are known in the art. Previous attempts to take advantage of ultrasound acoustic energy in toothbrushes failed to exploit microbubble formation in dental fluid for purposes of facilitating plaque removal, or failed to consider microbubbles and macrobubbles as a potential impediment to ultrasound propagation beyond the bristle tips.
Some toothbrushes that employed ultrasound technology attempted to achieve the propagation of ultrasound waves from the base of the bristles either through the bristles themselves or through the bubbly dental fluid that fills the spaces between the bristles. For example, U.S. Pat. Nos. 5,138,733 and 5,546,624 to Bock disclose an ultrasonic toothbrush having a handle, a battery pack, an electronics driving module, a piezoelectric member, and a removable brush head. U.S. Pat. Nos. 5,247,716 and 5,369,831 to Bock disclose a removable brush head for an ultrasonic toothbrush having a plurality of bristle clusters, a substantially tubular body constructed of a flexible material, and tensioning means securing the brush head to the ultrasonic device, providing for the efficient transmission of ultrasonic frequency oscillations from the device via the brush head. Because conventional toothbrush bristles and bubbly dental fluid can reduce rather than facilitate the propagation of ultrasound waves, the toothbrushes disclosed in these references would not achieve efficient ultrasound wave propagation. Also, the ultrasound systems in prior art toothbrushes did not take advantage of the specific bubble structure within dental fluid.
U.S. Pat. No. 3,335,443 to Parisi discloses a brush that is coupled to an ultrasonic, vibratory handheld dental instrument that is capable of being oscillated at high sonic and ultrasonic frequencies. U.S. Pat. No. 4,071,956 to Andress discloses a device that is not a toothbrush, for removing dental plaque by ultrasonic oscillations.
U.S. Pat. No. 3,809,977 to Balamuth et al., which reissued as U.S. Pat. No. RE 28,752, discloses ultrasonic kits, ultrasonic motor constructions, and ultrasonic converter designs for use alone or in combination. The ultrasonic motor may be of piezoelectric material having a removable tip and is contained in a housing having an electrical contact means adapted to be plugged into an adapter that is connected to a converter. U.S. Pat. No. 3,840,932 and No. 3,941,424 to Balamuth et al. disclose an ultrasonic toothbrush applicator in a configuration to be ultrasonically oscillated to transmit mechanical oscillations from one end to a bristle element positioned at the other end.
U.S. Pat. No. 3,828,770 to Kuris et al. discloses a method for cleaning teeth employing bursts of ultrasonic mechanical oscillation at an applicator repeated at a sonic frequency to produce both ultrasonic and sonic vibratory motion during use.
U.S. Pat. No. 4,192,035 to Kuris discloses an apparatus comprising an elongated member formed of a piezoelectric member with a pair of contacting surfaces with a brush member adapted to be received within the mouth. A casing adapted into a handle is configured to receive the piezoelectric member. U.S. Pat. No. 4,333,197 to Kuris discloses an ultrasonic toothbrush that includes an elongated handle member in the form of a hollow housing having a low voltage coil and cooperating ferrite core that is driven at ultrasonic frequencies. A brush member is affixed to the core and is adhesively affixed to an impedance transfer device that is adhesively affixed to the core material. The impedance transfer device insures maximum transfer of ultrasonic energy from the core material to the brush.
U.S. Pat. No. 4,991,249 and No. 5,150,492 to Suroff disclose an ultrasonic toothbrush having an exchangeable toothbrush member that is removably attached to an ultrasonic power member.
U.S. Pat. No. 5,311,632 to Center discloses a device for removing plaque from teeth comprising a toothbrush having a thick, cylindrical, hollow handle encompassing an electric motor that is actuable to cause rotation of an eccentrically mounted member and oscillation of the entire device and an ultrasonic transducer actuable to produce high frequency sound waves along the brush.
Japan Application No. P1996-358359, Pat. Laid Open 1998-165228, discloses a toothbrush utilizing ultrasonic waves in which an ultrasonic wave generator is provided in the handle of a manual or electrically powered toothbrush and an ultrasonic wave vibrator is mounted in the brush and wired to the wave generator.
Japan Application No. P2002-353110, Pat. Laid Open 2004-148079, discloses an ultrasonic toothbrush wherein ultrasonic oscillation is radiated from a piezoelectric vibrator arranged inside a brush head and transmitted to the teeth via a rubber projection group.
U.S. Pat. No. 6,203,320 to Williams et al. discloses an electrically operated toothbrush and method for cleaning teeth. The toothbrush includes a handle, a brush head connected to the handle having a plurality of hollow filament bristles, passageways through the handle and brush head for transporting fluid into and through the hollow filament bristles, an electrical energy source in the handle, and a vibratory element for imparting a pulsation to the fluid being transported.
U.S. Patent Publication No. 2003/0079305 to Takahata et al. discloses an electric toothbrush in which a brush body is simultaneously oscillated and reciprocated. The electric toothbrush comprises a casing main body, an arm extending above the casing main body, a brush body arranged in a top end of the arm, and an ultrasonic motor arranged in a top end inside of the arm for driving the brush body.
U.S. Pat. No. RE 35,712, which is a reissue of U.S. Pat. No. 5,343,883 to Murayama, discloses an electric device (i.e. a flosser) for removal of plaque from interproximal surfaces. The device employs sonic energy and dental floss secured between two tines of a flexible fork removably attached to a powered handle. The electric motor revolves at sonic frequencies to generate sonic energy that is transmitted to the flexible fork.
U.S. Pat. No. 6,619,957 to Mosch et al. discloses an ultrasonic scaler comprising a scaler tip, actuator material, a coil, a handpiece housing, and an air-driven electrical current generator. The actuator material, coil, and air-driven electrical current generator are all encompassed within the handpiece housing.
U.S. Pat. No. 6,190,167 to Sharp discloses an ultrasonic dental scaler for use with a dental scaler insert having a resonant frequency. The dental scaler insert is removably attached to a handpiece having an energizing coil coupled to a selectively tunable oscillator circuit to generate a control signal having an oscillation frequency for vibrating the dental scaler.
U.S. Pat. No. 4,731,019 to Martin discloses a dental instrument for scaling by ultrasonic operation. The instrument of the dental instrument has a distal end with a hook-like configuration with a conical pointed end and comprising abrasive particles, typically diamond particles.
U.S. Pat. No. 5,378,153 to Giuliani discloses a dental hygiene apparatus having a body portion and an extended resonator arm. The apparatus employs an electromagnet in its body that acts in combination with two permanent magnets to achieve an oscillating action about a torsion pin. The arm is driven such that the bristle-tips operate within ranges of amplitude and frequency to produce a bristle tip velocity greater than 1.5 meters per second to achieve cleansing beyond the tips of the bristles.
U.S. Patent Publication No. 2005/0091770 A1 discloses a toothbrush employing an acoustic waveguide that facilitates the transmission of acoustic energy into the dental fluid. The acoustic waveguide may be used in combination with a sonic component and/or an ultrasonic transducer. The disclosure of this publication is incorporated herein by reference in its entirety.
There remains a need in the art for devices that provide improved oral hygiene, and particularly that improve cleaning between the teeth and gums, at points of contact between the teeth, and beyond the direct action of the bristles.