Abstract:
A portable dental prophylaxis and bleaching system is provided for simultaneous tooth polishing and bleaching. It includes an oscillatory driving handpiece, a dental angle with a disposable rubber cup assembly, a dual-component dispenser, and a disposable mouthpiece. The battery-powered handpiece transforms a continuous rotation through a driving cam into a rotary oscillation which is then transferred through the attached dental angle to the rubber cup with an obtuse angle at its distal output end. The dispenser is operated manually to correctly apportion and mix the dual treatment materials into the rubber cup. In order to provide longer shelf life and effective bleaching action, the treatment materials are maintained at optimal pH values in separate compartments within the dispenser before use. The disposable mouthpiece is shaped for easy access to the user&#39;s teeth while protecting the gum surfaces. The system can be used both in dental clinics and at home.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]      
         [0000]    
       
         
               
             
               
               
               
               
             
           
               
                   
               
               
                 U.S. Patent Documents 
               
             
          
           
               
                 Patent 
                   
                   
                 Current U.S. 
               
               
                 Number 
                 Published Date 
                 Inventors 
                 Class 
               
               
                   
               
               
                 7,762,813 
                 Jul. 27, 2010 
                 Seals et al 
                 433/124; 433/125 
               
               
                 7,601,002 
                 Oct. 13, 2009 
                 Milanovich 
                 433/215 
               
               
                   
                   
                 et al 
               
               
                 7,255,559 
                 Aug. 14, 2007 
                 Shen et al 
                 433/125; 433/118; 
               
               
                   
                   
                   
                 433/166 
               
               
                 7,160,111 
                 Jan. 9, 2007 
                 Baughman 
                 433/216; 433/140; 
               
               
                   
                   
                   
                 433/29; 600/242 
               
               
                 7,156,659 
                 Jan. 2, 2007 
                 Pernot 
                 433/144; 433/133 
               
               
                 7,153,133 
                 Dec. 26, 2006 
                 Chia et al 
                 433/125 
               
               
                 6,916,176 
                 Jul. 12, 2005 
                 Schatz et al 
                 433/126; 403/320 
               
               
                 6,294,155 
                 Sep. 25, 2001 
                 Thomas et al 
                 424/49; 423/339 
               
               
                 6,247,931 
                 Jun. 19, 2001 
                 Postal et al 
                 433/118; 433/122; 
               
               
                   
                   
                   
                 433/125 
               
               
                 6,174,516 
                 Jan. 16, 2001 
                 Curtis et al 
                 424/53; 424/613; 
               
               
                   
                   
                   
                 424/616 
               
               
                 6,168,433 
                 Jan. 2, 2001 
                 Hamlin 
                 433/125 
               
               
                 5,928,628 
                 Jul. 27, 1999 
                 Pellico 
                 424/49; 424/53 
               
               
                 5,902,107 
                 May 11, 1999 
                 Lowell 
                 433/130; 433/112; 
               
               
                   
                   
                   
                 433/125 
               
               
                 5,749,728 
                 May 12, 1998 
                 Bailey 
                 433/125; 433/126 
               
               
                 5,571,012 
                 Nov. 5, 1996 
                 Witherby 
                 433/125; 433/126; 
               
               
                   
                   
                 et al 
                 433/133 
               
               
                 5,531,599 
                 Jul. 1, 1996 
                 Bailey 
                 433/125; 433/126; 
               
               
                   
                   
                   
                 464/181 
               
               
                 5,503,555 
                 Apr. 2, 1996 
                 Bailey 
                 433/126; 433/125 
               
               
                 5,433,605 
                 Jul. 18, 1995 
                 Strobl 
                 433/112; 433/125; 
               
               
                   
                   
                   
                 433/126; 433/130 
               
               
                 5,423,679 
                 Jun. 13, 1995 
                 Bailey 
                 433/125; 433/126 
               
               
                 5,374,189 
                 Dec. 20, 1994 
                 Mendoza 
                 433/125; 433/132 
               
               
                 5,328,369 
                 Jul. 12, 1994 
                 Bailey 
                 433/125; 433/126 
               
               
                 5,139,421 
                 Aug. 18, 1992 
                 Verderber 
                 433/31; 433/30 
               
               
                 5,074,788 
                 Dec. 24, 1991 
                 Nakanishi 
                 433/115; 433/129 
               
               
                 4,681,540 
                 Jul. 21, 1987 
                 Landgraf 
                 433/126; 422/131; 
               
               
                   
                   
                 et al 
                 422/29; 433/131 
               
               
                 4,648,838 
                 Mar. 10, 1987 
                 Schlachter 
                 433/29; 433/126; 
               
               
                   
                   
                   
                 433/80 
               
               
                 4,460,337 
                 Jul. 17, 1984 
                 Landgraf 
                 433/29 
               
               
                   
                   
                 et al 
               
               
                 4,382,790 
                 May 10, 1983 
                 Loge et al 
                 433/126 
               
               
                 2010/0035205 
                 Feb. 11, 2010 
                 Wang et al 
                 433/133 
               
               
                 2006/0127844 
                 Jun. 15, 2006 
                 Michaelian 
                 433/125; 433/84 
               
               
                 2005/0050658 
                 Mar. 10, 2005 
                 Chan et al 
                 15/22.1; 433/29 
               
               
                 2003/0180688 
                 Sep. 25, 2003 
                 Vocaturo 
                 433/215; 433/80 
               
               
                   
                   
                 et al 
               
               
                 2001/0046477 
                 Nov. 29, 2001 
                 Wolfe 
                 424/53 
               
               
                   
               
             
          
         
       
     
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to dental cleaning and bleaching. The invention is a battery-powered dental tool that effectively cleans and at the same time bleaches teeth. It is an assembly that has a driving handpiece, a dental angle, and a disposable rubber cup. For longer shelf life and effective action during use, the present invention also has an apparatus that mixes two properly pH-valued materials at the moment they are dispensed. By applying the mixed prophy and bleaching materials on teeth, the movement of the rubber cup polishes and bleaches simultaneously. To optimally and quickly achieve clean and white teeth, the invention employs a mixture of materials with bleaching capability that is pH and temperature optimized for oral use. The present invention uses a handpiece to transfer the continuous rotation of an electric DC motor into a rotary oscillation through a specialized cam bar, so as to drive the dental angle with this same rotary oscillation. Moreover, a disposable mouthpiece is used during operation in order to protect gum surfaces from contact with the bleaching materials. 
       BACKGROUND OF THE INVENTION 
       [0003]    Conventionally, dental polishing with prophy paste and dental whitening with bleaching paste are done as two separate procedures in dental treatment. This sequential polishing and bleaching is time-consuming; therefore, a method of combining the two procedures is desirable. The background analysis can be separated into two parts: mechanical tool design and prophy/bleaching compound design. 
         [0004]    A. Mechanical Tool Design 
         [0005]    A conventional prophy angle is used to remove plaque and to polish the dentin surface of a tooth. A prophy cup is secured to the prophy angle and is rotated by a driving torque from a motor in a dental tool, such as a dental handpiece. A typical drive mechanism is a gear connection between a driving rotor gear and a driven rotor gear at a right angle. The rotation is thereby transferred from the driving dental tool to the prophy cup. 
         [0006]    This prophy method has several drawbacks. First, the gear connection between driving and driven rotors is costly to manufacture. As disposable inexpensive plastic parts, gears are quickly worn out which results in bad engagement and operating noise. Second, the gear connection between driving and driven rotors usually transfers continuous rotation which splatters the prophy paste during operation, as opposed to oscillatory rotation which reduces splattering. Third, the typical gearing between driving and driven rotors is not suitable for an obtuse angle connection. An obtuse angle makes users feel more comfortable because it allows the user to maintain a correct neutral wrist position. 
         [0007]    Previous patents have been published which describe improvements in the gear mechanism or methods to achieve operation at angles other than 90 degrees, such as U.S. Pat. 2006/0127844, U.S. Pat. Nos. 7,762,813, 7,255,559, 6,916,176, 6,247,931, 6,168,433, 5,902,107, 5,749,728, 5,571,012, 5,531,599, 5,503,555, 5,433,605, 5,423,679, 5,374,189, 5,328,369, 5,074,788, 4,681,540, 4,460,337 and 4,382,790. However, in the present market, the products from those patents exhibit cost weakness or noise problems, typically because of the complicated structure of the non-gear mechanism. 
         [0008]    U.S. Pat. No. 7,153,133 discloses a transmission assembly which uses multiple linkage shafts to connect a driving shaft and a head mount, both with multiple mounting holes. Each linkage shaft rotates and slides in the corresponding mounting holes in the driving shaft and the head mount. It solves several drawbacks of the gear-transfer prophy angles, but the small mounting holes on the driving shaft and head mount make the assembly time-consuming. Furthermore, because of the size limitation of the driving shaft and head mount, the torque arm of the linkage shafts is small, and the driving torque is reduced even more by the friction from the fast movement of the driving shaft and head mount pressing on the inner surfaces of the housing. 
         [0009]    B. Prophy/Bleaching Compound Design 
         [0010]    One conventional tooth whitening method is to place peroxide upon a patient&#39;s teeth. Carbamide is a compound that rapidly releases hydrogen peroxide. The oxidation-reduction reaction of peroxide bleaches the enamel of the teeth. A popular application of this method is to place a carbamide-bearing compound in a dental tray and apply the tray to the patient&#39;s teeth for a length of time ranging from minutes to overnight. 
         [0011]    This whitening method has several drawbacks. First, peroxide is an irritant. When peroxide comes into a long contact with the gums, it causes irritation or pain. Second, the mere placement of peroxide on the patient&#39;s teeth is not effective if the enamel rods of the teeth are closed. Only when they are open, can the enamel rods take up peroxide significantly. 
         [0012]    One method of facilitating the opening the enamel rods during bleaching is acid etching. When an acid of sufficient concentration is applied to the teeth, the chemical action of the acid serves to open the enamel rods of the teeth. However, this method is potentially harmful to the gums and is also time consuming. Another method involves the use of a pre-mixed carbamide and dental abrasive agent mixture. Such a mixture is applied to the teeth and is then burnished onto the teeth. The dental abrasive agent in the prophy paste serves to abrade the teeth, accomplishing three objectives: 1) it opens the enamel rods to facilitate their uptake of the peroxide; 2) it removes stains from the tooth enamel through a mechanical scrubbing action; and 3) it polishes the tooth enamel through a mechanical buffing action. To decrease tooth sensitivity during bleaching, fluoride can be included in the dental abrasive agent. However, a disadvantage of this method is that it delivers weakened carbamide to the teeth, resulting is less effective whitening. In addition, most readily and economically available carbamides are highly unstable, losing much of their oxygen (thus being reduced) when exposed to air and when mixed with other ingredients such as prophylaxis paste for an extended period of time. Therefore, the effectiveness of pre-mixed peroxide as a tooth whitener is limited. 
         [0013]    To overcome these drawbacks, previous patents have been published. However, those patents either use pre-mixed compounds and other less effective approaches such as U.S. Pat. 2005/0050658, U.S. Pat. Nos. 7,601,002, 6,294,155, 6,174,516, 5,928,628, or do not provide a cost-effective instant mixing method during usage, such as 2001/0046477. 
         [0014]    U.S. Pat. Nos. 4,648,838 and 5,139,421 etc. use a light to warm up the bleaching materials to achieve an effective bleaching activation. However, the lights in those patents are stationary and are applied simultaneously to multiple teeth so that the user must remain still during the treatment. The structure of the lights is also complicated and costly. 
         [0015]    US patent 2003/0180688 and U.S. Pat. No. 7,160,111 etc. use a mouthpiece to protect the gum surfaces from the bleaching materials on the teeth. However, with the mouthpiece of those patents, the user cannot simply leave the mouth open in a proper attitude without manual adjustment. 
       BRIEF SUMMARY OF THE INVENTION 
       [0016]    There are seven major aspects of this invention that address the drawbacks of current technology. 
         [0017]    The first aspect is the rotary oscillation of the dental angle. Rotary oscillations reduce paste splatter during operation. In the invention, a continuous rotation of the motor output shaft is converted into a back-and-forth swinging action and then to a rotary oscillation through a rotary oscillation driving cam with a specially designed cam curvilinear slot. The cam curvilinear slot achieves an even swinging movement with a nearly equal time for both the rightward and leftward parts of this movement. Moreover, the cam curve results in a momentary pause in the back-and-forth swinging action at the point where it changes swinging direction so that the impulse from the motor shaft to the driving cam is reduced, thereby increasing the working life of the motor shaft and the driving cam. 
         [0018]    The back-and-forth swinging movement is transferred as a rotary oscillation to a dental angle from the rotary oscillation driving cam via a rack-and-pinion gear connected to a drive shaft and thence through a slot-rod matching construction at the handpiece output end. The matched slot-to-rod connection is achieved, at the time of assembly, by inserting the bent driving rods into the corresponding slots on the conic nose end of the driving shaft. To avoid any possible mismatch between slots and rods, the diameter of the slots is gradually and smoothly enlarged at the conic nose end. 
         [0019]    The second aspect is the transfer of the rotary oscillation through an obtuse angle using two rotors connected by multiple bent driving rods within the dental angle. This rotary oscillation is further transferred from the handpiece output end to a disposable rubber cup assembly which is firmly attached to the output end of the dental angle. The bent driving rods can be easily pressed into the mounting slots on the in-line rotor and the angled rotor thereby avoiding the time-consuming process of inserting the rods through end holes of these slots. During operation the bent driving rods dynamically touch the inner cylindrical surface of the dental angle housing as a bearing mechanism to reduce the friction between the rotors and the inner cylindrical surfaces of the housing. Moreover, the axes of the input-end and output-end are engaged at an obtuse angle so that the teeth prophylaxis and bleaching operation can be done more comfortably. This is because an obtuse angle bend in the body of the angle allows the user to maintain a neutral wrist position. 
         [0020]    A third aspect is that the disposable rubber cup and rotor-cup adapter are pre-assembled or molded as a single entity which can be easily snapped onto and removed from the output end of the dental angle body. This means that the dental angle main body can be used repeatedly to reduce cost as a personal device at home. 
         [0021]    A fourth aspect is that the dental angle housing consists of a housing body and a housing head cap. The housing head cap has a circular ring at the lower end. The housing body has a bent output end with an obtuse angle so that the upper end of the head cap matches the bent end of the housing body and snaps on to form an obtuse dental angle. The integral circular wall at the input end of the housing body and the circular ring of the housing head cap tightly holds the bent driving rods to the rotors during operation to reduce noise and wear. 
         [0022]    A fifth aspect is a dual-component dispenser that proportionally mixes the prophy and bleaching compound immediately before tooth cleaning The dispenser comprises a central tube and an outer shell that are co-axial with the dispenser housing, a double piston with a central circular cross-section and a surrounding annular cross-section, a matched platform at the tail, and a disposable cap at the dispending end. High pH prophy paste and low pH bleaching paste are stored in the tube and shell, respectively during storage and transport. The dimensions of the central tube and shell have the proper volumetric proportion so that the compounds from the two compartments can be easily mixed to reach the correct pH value for use. In addition, the end cap serves both to seal the dispenser and as a mixing container after the pastes are dispensed. This invention allows long-term storage of bleaching compound at low pH, increasing the pH just at the moment of cleaning and bleaching. The higher pH opens the enamel rods at the surface of the teeth, resulting in a better bleaching effect. 
         [0023]    A sixth aspect of the invention is a disposable mouthpiece for protecting gum surfaces during bleaching. The mouthpiece has a closed, curved edge that pushes the lips apart to expose the frontal teeth. The edges of the mouthpiece abut the edges of the roots of the teeth. The mouthpiece has a wedge-shaped positioning bite tab at both sides so that when the user bites down, the mouthpiece remains stationary within the mouth and the upper and lower lips are held open comfortably in a proper orientation. 
         [0024]    A seventh aspect of the invention is a light bulb, such as an emitting diode (LED), mounted at a proper location on the handpiece housing so that the emitted light is focused directly onto the area near the rubber cup of the dental angle during operation. The light radiation heats up the bleaching material to speed up the bleaching action while providing illumination. 
         [0025]    Other details and features of the invention will pointed out hereinafter. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]    The invention will be further described in conjunction with the attached drawings: 
           [0027]      FIG. 1  shows the major subassemblies and the mouthpiece of the tooth prophylaxis and bleaching system. The subassemblies are the battery-powered handpiece, the dental angle, the rubber cup, and the paste dispenser. The mouthpiece is a one-piece component. 
           [0028]      FIG. 2  is a cross-sectional view of the battery-powered driving handpiece with the dental angle and rubber cup assembled. 
           [0029]      FIG. 3  shows the battery-powered driving handpiece of  FIG. 2 . 
           [0030]      FIG. 4  is an axial cross-sectional view (a) and a longitudinal cross-section view (b) of the mechanism which transforms continuous rotation to oscillating rotation inside the handpiece housing. 
           [0031]      FIG. 5  is a set of axial cross-sectional views showing the four quadrants of the cam movement as driven by the motor shaft, which illustrates how the cam transfers continuous circular rotation (clockwise, as viewed) of the motor shaft to a back-and-forth swinging movement—(a) extruded off-axis post starting into the first quadrant, (b) off-axis post starting into the second quadrant, (c) off-axis post starting into the third quadrant and (d) off-axis post starting into the fourth quadrant. 
           [0032]      FIG. 6  is a cross-sectional view showing the output side of the rotary oscillation driving cam; how the rack-and-pinion gearing connection transfers the back-and-forth swinging movement of the cam to an oscillating rotation of the driving shaft. 
           [0033]      FIG. 7  is a perspective view of the driving shaft which, when assembled, is located at the output end of the handpiece. 
           [0034]      FIG. 8  shows the nose end of the driving shaft of  FIG. 7  with two representative cross-sectional views at the nose and the body. 
           [0035]      FIG. 9  is a cross-sectional view of the dental angle housing with the bent driving rods, the in-line rotor, the angled rotor, and the rotor-cup-adapter all assembled. It also shows the rubber cup assembled as well as the handpiece driving shaft inserted. 
           [0036]      FIG. 10  is similar to  FIG. 9  but without the rubber cup assembly and the handpiece driving shaft. 
           [0037]      FIG. 11  is a perspective view of the bent rod driving mechanism. 
           [0038]      FIG. 12  is a front cross-sectional view and corresponding longitudinal cross-sectional view of both the in-line rotor and the angled rotor showing the placement of the bent driving rods in the rotors. 
           [0039]      FIG. 13  shows cross-sectional views of the angled rotor and the rotor-cup adapter with the rubber cup attached. 
           [0040]      FIG. 14  is a perspective view of the angled rotor and the matching rotor-cup adapter. 
           [0041]      FIG. 15  is a perspective view of the dental angle housing with the hollow housing body and the housing head cap assembled. 
           [0042]      FIG. 16  shows a perspective view of the hollow housing body of the dental angle housing, similar to that of  FIG. 15 , but without the housing head cap. 
           [0043]      FIG. 17  is a perspective view of the housing head cap of the dental angle housing. 
           [0044]      FIG. 18  is a perspective view (partially cross-sectional) of the two-component paste dispenser. 
           [0045]      FIG. 19  shows an axial cross-sectional view, on the left, and a longitudinal cross-section view, on the right, of the central tube of the two-component paste dispenser of  FIG. 18 . 
           [0046]      FIG. 20  shows axial and longitudinal cross-section views of the double piston of the two-component paste dispenser of  FIG. 18 . 
           [0047]      FIG. 21  is a perspective view of the mouthpiece. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0048]      FIG. 1  shows the system components of the tooth prophylaxis and bleaching system  10  which consists of a battery-powered driving handpiece  20 , a dental angle  30 , a rubber cup and rotor-cup adapter  40 , a dual-component paste dispenser  50 , and a protecting mouthpiece  60 . 
         [0049]      FIG. 2  shows a cross-sectional assembled view of the battery-powered driving handpiece  20  including the dental angle  30  with the rubber cup assembly  40 . 
         [0050]      FIG. 3  shows the parts inside of the handpiece  20 : a battery chamber  22 , a direct current (DC) electric motor  23  with an output rotating shaft  26 , an on-off switch  213 , a driving cam  24  with a rack and pinion connection to a driving shaft  29  which transfers the output of the cam to the dental angle, a driving shaft positioner  28  whose central hole holds the driving shaft  29  axially, an light bulb  25 , and a basic housing  21  with a housing output cap  211  and a housing battery cap  212  to enclose all the parts. 
         [0051]      FIG. 4  shows the transformation mechanism inside the handpiece  20  in an axial cross-sectional view (a) and a longitudinal cross-sectional view (b). The mechanism transforms a continuous rotation into an oscillating rotation via a cam setup. The motor shaft disk  261  of the electric motor  23  rotationally drives the cam  24  via the extruded off-axis post  262 . The driving cam  24  is swung around the cam pivot post  271  which is fixed on the extruded cam pivot on housing  27  of the handpiece basic housing  21 . The cam rack  241  is molded with the driving cam  24  as an entity, so that when the driving cam  24  swings, the cam rack  241  swings with it. Hence a back-and-forth swinging movement is transformed into an oscillating movement of the driving shaft  29  as the cam rack teeth  242  repeatedly pass over the driving shaft pinion  291 . 
         [0052]    There are two stages of motion transfer: 1) continuous rotation to swinging, 2) swinging to oscillating rotation. The continuous rotation of the motor shaft  26  and the oscillating rotation of the driving shaft  29  are coaxial along the central axis of the handpiece basic housing  21 , but the back-and-forth swinging movement of the driving cam  24  rotates around the cam pivot post  271  which is located on the inner wall of the housing. 
         [0053]      FIG. 5  shows the first stage: motor to cam. The power input comes from the electric motor  23 . The output is the driving cam  24  that has a center of rotation about the cam pivot post  271  secured to the inner wall of the cylindrical handpiece basic housing  21 . The motor shaft  26  has a motor shaft disk  261  firmly connected to the axle of the motor  23  (refer to  FIG. 4 ) that rotates concentrically. The motor shaft disk  261  has an extruded off-axis post  262  that inserts into a cam curvilinear slot  240  in the driving cam  24 . The continuous rotation of the off-axis post  262  about the axis of the motor shaft  26  forces the driving cam  24  to be swung back and forth. This swinging movement can be understood by considering the four quadrants of a motor shaft&#39;s revolution. First quadrant as shown on  FIG. 5(   a ): the cam curvilinear slot  240  on the driving cam  24  is contoured such that when the off-axis post  262  moves clockwise a quarter of a circle (starting from the top), it pushes the right side  245  of the cam curvilinear slot  240  so that the driving cam  24  is swung to the right side around the cam pivot post  271 . Second quadrant as shown on  FIG. 5(   b ): the off-axis post  262  continues to move clockwise down along the contour of the cam curvilinear slot  240  which causes the cam  24  to experience a short pause in its motion, after which the off-axis post  262  contacts the left side  246  of the cam curvilinear slot  240  so that the driving cam  24  changes direction and begins to swing to the left side. Third quadrant as shown on  FIG. 5(   c ): the off-axis post  262  moves from the bottom upward another quarter of circle, continuously pushing the driving cam  24  and swinging it to the left side around the cam pivot post  271 . Fourth quadrant as shown on  FIG. 5(   d ): the off-axis post  262  continues clockwise up another quarter of a circle and returns to the top of the curve, which causes the cam  24  to experience a short pause, after which the off-axis post  262  contacts the right side  245  of the cam curvilinear slot  240  so that the driving cam  24  changes direction again and starts to swing to the right side, finishing a cycle. This back-and-forth swinging movement of the driving cam  24  around the cam pivot post  271  is repeated once per revolution of the electric motor  23 . The specialized cam curvilinear slot  240  of the driving cam  24  in this invention achieves an approximately even swinging movement with approximately equal amounts of time spent moving right and left. It improves upon the weakness of the conventional straight slot cam that causes the rightward swing to take much longer than the leftward swing (assuming clockwise rotation, as drawn). 
         [0054]    If the motor shaft  26  rotates in the counter-clockwise direction, the roughly even swinging movement, with the pauses at the extremes of the cam motion, is achieved similarly except that all the rotating directions are opposite to those described above. With this design, balanced swinging movement with pauses at the extremes is achieved independent of the rotation direction of the electric motor  23 . 
         [0055]      FIG. 6  shows the second stage of motion transfer: driving cam  24  to driving shaft  29 . The input is the driving cam  24  and the output is the driving shaft  29 . The back-and-forth swinging movement is transferred to the driving shaft  29  by a rack-and-pinion gearing connection. The torque source is the cam rack  241  which is located at the top of the driving cam  24  (with the teeth on the inner edge). The cam rack  241  is combined with the driving cam  24  to form a single entity. The driving shaft  29  has a circular driving shaft pinion  291  at its input end that matches the cam rack  241  on the driving cam  24 . The central axis of the driving shaft  29  lies along the central axis of the handpiece  20 . Hence the swinging movement of the driving cam  24  is transferred to a matched rotary oscillation of the driving shaft  29 .  FIG. 6(   a ) shows the location of the cam  24  when it is swung to the extreme right of its motion around the cam pivot post  271 . From the location of the cam  24  in  FIG. 6(   a ) to the location of the cam  24  in  FIG. 6(   b ), the driving shaft  29  rotates clockwise around its axis by an angle of almost 180 degrees. The driving shaft&#39;s other end connects to the dental angle  30  via a matched slot and rod connection structure described below. 
         [0056]      FIG. 7  shows a perspective view the driving shaft  29  of the driving handpiece  20 . The circular driving shaft pinion  291  is attached to the driving shaft  29  at the input end of the driving shaft body  292 . The driving shaft pinion  291  matches the cam rack teeth  242  on the driving cam  24  (refer to  FIG. 6 ). After assembled, the driving shaft positioner  28  (refer to  FIG. 3 ) positions the driving shaft body  292  axially by its central hole. A conic driving shaft nose  293  is located at the output end of the driving shaft body  292 . 
         [0057]      FIG. 8  shows a detailed perspective view of the conic driving shaft nose  293  of the driving shaft  29  shown in  FIG. 7  with its cross-sectional views cut at locations A-A and B-B. The driving shaft nose  293  loosely fits into the input end of the housing  34  of the dental angle  30  when assembled. The number of driving shaft slots  2921  on the cylindrical surface of the driving shaft body  292  is matched to the number of the bent driving rods  31  of the dental angle  30 . The diameter of the shaft nose end  2931  is smaller than the diameter of the driving shaft body  292 . The driving shaft nose  2931  has a conic shape so that the front end  2931  is easily insertable into the dental angle  30 . During the insertion of the dental angle  30  into the driving handerpiece  20 , the shaft nose slope  2932  guides the driving rods  31  into the driving shaft slots  2921 . 
         [0058]      FIG. 9  shows a cross-sectional view of the dental angle housing with the bent driving rods  31 , the in-line rotor  32 , the angled rotor  33 , and the rotor-cup adapter  41  inside, as well as with the rubber cup  42  assembled and the handpiece driving shaft  29  inserted. After assembly, the dental angle housing, which consists of the main hollow housing  34  and the angled housing head  35 , keeps the bent driving rods  31 , the in-line rotor  32 , and the angled rotor  33  together as an integral piece. The rotary oscillation is transmitted from the in-line rotor  32 , via the bent driving rods  31 , to the angled rotor  33 , and then to the assembled or molded cup assembly  40  of the rotor-cup adapter  41  and the rotor-cup  42 . 
         [0059]      FIG. 10  is similar to  FIG. 9  but without the assembled or molded cup assembly  40  of the rotor-cup adapter  41 , the rubber-cup  42 , and the handpiece driving shaft  29 . There exists an in-line rotor flange  321  near the in-line rotor conic head  322  of the in-line rotor  32 , and another angled rotor flange  331  near the output end of the angled rotor  33 . The in-line rotor flange  321  maintains the axial position of the in-line rotor  32  through contact with the positioning step  340  in the inner tube of the main hollow housing  34 . Similarly, referring to  FIG. 16  and  FIG. 17 , the angled rotor flange  331  maintains the axial position of the angled rotor  33  through contact with the bottom step  344  on the angled outlet  342  of the main hollow housing body  34  and through contact with the angled housing step  350  on the angled housing head cap  35 . The conic head  322  of the in-line rotor  32  and the conic head  332  of the angled rotor  33  contact each other when the components are assembled inside the dental angle housing  3435 , which is also necessary to maintain the axial position of the rotors  32  and  33 . 
         [0060]      FIG. 11  is a perspective view of the bent rod driving mechanism: the in-line rotor  32  is located in the inlet tube  341  of the hollow housing body  34  (refer to  FIG. 16 ). The in-line rotor  32  has several axial mounting slots  323  which are equally distributed around the cylindrical surface of the in-line rotor  32 . The angled rotor  33 , with matching axial mounting slots  333 , is located in the angled outlet section  342  of the housing body  34  (refer to  FIG. 16 ). A number of bent driving rods  31  (preferably three), of constant diameter and bent at a right or obtuse angle, are positioned with the straight driving segment  311  of each rod contacting the inner wall of the inlet tube  341  of the hollow housing body  34  and the straight driven segment  312  of each rod contacting the inner surface of the outlet wall  351  of the housing head cap  35  (refer to  FIG. 17 ). Each driving rod  31  fits correspondingly inside each mounting slot  323  or  333  of the in-line and angled rotors. The driving rods  31  rotate along the inner surfaces of the dental angle housing  3435  (refer to  FIG. 15 ). 
         [0061]      FIG. 12  shows cross-sectional views with side views of the driving mechanism by bent driving rods  31  (shown in  FIG. 11  as a perspective view). On the cylindrical surface of the in-line rotor  32  and the angled rotor  33 , there are multiple (three preferred) mounting slots  323  and  333  that are equally distributed and parallel to the rotor axis. The cross-section of the mounting slots  323  and  333  is an arc between 180° and 240°. The diameter of the mounting slots  323  or  333  is slightly larger than the diameter of the driving rods  31 . When the rods  31  are pressed into the mounting slots  323  and  333 , they will fit loosely and slide freely inside the slots  323  and  333 . The bent driving rods  31  act as a bearing mechanism between the rotors  31  and  32  and the inner surface of the dental angle housing  3435  (refer to  FIG. 15 ), so that friction is reduced during operation. 
         [0062]    Each straight driving segment  311  of a driving rod  31  is radially secured by the inner cylindrical surface of the hollow housing body  34 . The straight driving segment  311  sits loosely in the mounting slot  323  of the in-line rotor  32  which itself is positioned by an axial inner tube step  340  of the hollow housing body  34 . The housing head cap  35  positions the angled rotor  33  and the bent segment of the driving rod  312 . The driving rods  31  here are radially secured by the inner cylindrical surface of the housing head cap  35 . The straight driven segment  332  of the driving rod  31  sits loosely in the mounting slot  333  of the angled rotor  33 . The angled rotor  33  is positioned by a positioning step  350  in the circular cap ring  354  of the housing head cap  35 . 
         [0063]    The in-line rotor  32  and the angled rotor  33  have conic heads  322  and  332  and rotor flanges  321  and  331 , respectively. The flanges  321  and  331  contact the inlet tube step  340  and angled housing step  350 , respectively, thereby preventing the rotors from separating. Similarly, the conic heads  322  and  332  touch each other, thereby maintaining the correct orientation and axial positioning of the rotors  32  and  33 . 
         [0064]      FIG. 13  shows cross-sectional views of the angled rotor  33  and the rubber cup subassembly  40 . The bottom side of the angled rotor  33  is snapped on to the top of the rotor-cup adapter  41 . The top end of the rubber cup  42  is pre-assembled or molded on to the bottom end of the rotor-cup adapter  41  to form a disposable, integral assembly  40 . The axis of rotation of the rotor-cup adapter  41  and the rubber cup  42  is aligned to the axis of the angled rotor  33 . The bottom end of the rubber cup  42  has a skirt opening to receive the mixed prophylaxis and bleaching compounds during operation. 
         [0065]    A perspective view of the angled rotor  33  and a different perspective view of the rotor-cup adapter  41  are shown in  FIG. 14 . The rotor-cup adapter  41  has two protruding ridges  412  that are aligned parallel to the diameter of the adapter base  411 . The two ridges  412  are split by a gap  413 . Each ridge  412  has a convex ribbed protrusion  414  on the outside of the vertical wall. The ridges  412  also have a thicker center to form a gapped cylindrical positioning drum  415 . A negatively matched slot, which forms the counterpart to the entire protruding ridge structure  412 , is located in the bottom side of angle rotor  33 . The cup assembly  40  (consisting of the rotor-cup adapter  41  and the rubber cup  42 ; refer to  FIG. 13 ) can therefore be easily pressed into and removed from the bottom end of the angled rotor  33 . 
         [0066]      FIG. 15  is a perspective view of the dental angle housing  3435 . The inner diameter of the input end of the hollow housing body  34  is just slightly larger than the outer diameter of the driving shaft  29  of the driving handpiece  20  for easy insertion during assembling the dental angle  30  to the handpiece  20 . The housing head cap  35  is locked on to the hollow housing body  34  by a snap-on lock button connection at the location  34 - 35  so that after assembly the upper curved buckle hole  353  of the housing head cap  35  matches the curved buckle button  343  of the hollow housing body  34  (refer to  FIG. 16 ). 
         [0067]      FIG. 16  is a detailed perspective view of the hollow housing body  34  of the dental angle housing  3435 . The housing body  34  comprises an inlet tube  341  and an angled outlet section  342 . The housing body bending angle between the axis of the inlet tube  341  and the angled outlet  342  matches the bending angle of the driving rods  31 . The angled outlet  342  has a pair of snap-on buckle buttons  343 , a bottom step  344 , and a vertical open area bounded by the matching wall edges  345 . The buckle buttons  343  match the corresponding buckle holes  353  in the housing head cap  35  (refer to the snap-on lock button connection location  34 - 35  in  FIG. 15 ). 
         [0068]      FIG. 17  is a detailed perspective view of the housing head cap  35  of the dental angle housing  3435 . The housing head cap  35  has a circular cap ring  354  at its bottom end. After assembly the outlet wall  351  forms a matched part of housing body to match the bending angle of the driving rods  31 . The housing head cap  35  has a pair of snap-on buckle holes  353  and a vertical open area bounded by the matching wall edges  355 . The buckle holes  353  match the corresponding parts on the housing body  34  when assembled (refer to the snap-on lock button connection location  34 - 35  in  FIG. 15 ). 
         [0069]    The assembly steps for the dental housing subassembly  30  are as follows. First, press the driving rods  31  into the corresponding mounting slots  323  and  333  on the rotors  32  and  33 . Second, insert the in-line rotor side of this rod and rotor pre-assembly into the hollow housing body  34 . Third, insert the angled rotor side of the pre-assembly into the housing head cap  35 , with the bottom end of the angled rotor  33  inside the circular cap ring  354  of the housing head cap  35 . Fourth, snap the housing head cap  35  on the housing body  34  to form the complete dental angle  30 . 
         [0070]    The snap-on locking mechanism of the housing body  34  and the angled cap  35  is achieved by two protruded snap-on buckle buttons  343  near the output end of the inlet tube  341  which match the corresponding snap-on buckle holes  353  near the top of the housing head cap  35 . The curved edge wall of the buckle button  343  is a circular arc slightly larger than 180 degrees. The corresponding curved edge wall of the buckle hole  353  has the same arc as the buckle button  343 . When the button  343  is snapped into the buckle hole  353 , the housing head cap  35  is firmly locked in the housing body  34 . The snap-on structure assures that the housing head cap  35  cannot be pulled off by any downward force that may be applied during operation or the cup assembly  40  removal. The circular cap ring  354  is firmly held to the angled outlet  342  at the output end of the hollow housing body  34 . Hence, when the bent driving rods  31  drive the angled rotor  33  to rotate along the angled rotor axis, the rods  31  will be held inside the cap ring  354  with minimum wobble, friction, and noise. 
         [0071]      FIG. 18  is a perspective view of the two-component paste dispenser  50 . The two components are installed within the central tube  53  and the dispenser housing  51 , respectively. A double dispenser piston  52  advances in the central tube  53  and the dispenser housing  51  simultaneously when pressed. The dispenser housing  51  has an open mixing output end  511  at the head of the housing cylinder  512  and an open input end  55  at the tail of the housing cylinder  512 . A disposable cover cap  54  seals the mixing output end  56  during storage and serves as a mixing container during use. A dispenser housing flange  513  is located near the open input end  55  of the housing cylinder  512 , serving as a finger-grip when the piston  52  is pressed forward. The disposable cover cap  54  consists of a cap cover head  541  which tightly seals the open mixing output end  511  and a cap cover skirt  542  which expends the opening of the cap cover head  541  to facilitate manipulation of the cap cover head  541  during usage. 
         [0072]    The central tube  53  divides the space of the dispenser housing  51  into a central reservoir  514 , which is defined as the volume inside the central tube  53 , and a surrounding shell reservoir  515 , which is defined as the volume outside the central tube  53  and inside the dispenser housing  51 . In one reservoir  514  or  515 , a bleaching peroxide agent with a low pH value is installed. In the other reservoir  515  or  514 , an abrasive cleaning prophylaxis agent with a high pH value is installed. Hence the bleaching agent can be stored longer before usage and acts more effectively during usage when proportionally mixed with the prophy agent to increase the pH value and then immediately applied on tooth surfaces. 
         [0073]      FIG. 19  shows two cross-sectional views of the dispenser central tube  53 . The dispenser central tube  53  consists of a straight tube  531  and tube wings  532  near the output end of the straight tube  531 . The location of the tube wings  532  should be matched to the conic mouth near the output end  56  (refer to  FIG. 18 ) so that the content from the reservoir  515  (refer to  FIG. 18 ) is pressed out easily through the slots between the tube wings  532 . 
         [0074]    Two cross-sectional views of the dispenser piston  52  are shown in  FIG. 20 . The double piston  52  consists of a central piston  521  of circular cross-section, a surrounding piston  522  of annular cross-section and a piston base at the tail of the piston  52 . The circular cross-section of the central piston  521  tightly matches the inner diameter of the central tube  53 , and the surrounding annular piston  522  tightly matches the surrounding ring-shaped section of the dispenser housing when the double piston is inserted into the open input end of the dispenser housing  51  (refer to  FIG. 18 ). The dispenser piston base  523 , the diameter of which is larger than the diameter of the outer diameter of the surrounding annular piston  522 , is used to press both of the central piston  521  and the annular piston  522  simultaneously into the dispenser housing  51  so as to squeeze a proper amount of both the prophy paste and bleaching paste out of the dispenser housing  51  through the open mixing output end  511 . The dispenser piston base  523  also is used for a vertical stand when the paste dispenser  50  is not in usage for convenience. 
         [0075]      FIG. 21  is a perspective view of the disposable mouthpiece  60 . The mouthpiece is oblong in shape. The upper and lower curved sections  61  and  62  engage the tooth and gum surfaces to expose the upper and lower frontal teeth when in use. They abut against the gum surfaces to prevent contact with the bleaching material. At the left and right ends of the upper and lower curved sections  61  and  62 , there are wedge-shaped positioning tabs  63 . When the user bites down on the tabs, the mouthpiece  60  remains stationary in the mouth with the upper and the lower lips held in a natural open state. 
         [0076]    The objectives of the invention are achieved as shown above. Although specific examples of the present invention and its application are set forth herein, they are not intended to be exhaustive or limiting of the invention. These illustrations and explanations are intended to acquaint others skilled in the art with the invention, its principles, and its practical applications, so that others skilled in the art may adapt and apply the invention in its numerous forms, as may best suit the requirements of a particular use.