Abstract:
The present invention relates to an apparatus for providing specifically metered doses of at least two flowable dental materials in desired ratios to one another. In particular, the present invention allows for controlled metering and dispensing of two or more flowable dental substances which when subsequently mixed form a dental bonding composition, dental adhesive, dental cement, or other dental restorative or preparative materials. Specifically, one embodiment of the present invention utilizes a multi-rack system as well as a drive spring action to provide a substantial mechanical advantage to the user such that a relatively long throw of the dispensing button creates a relatively short, metered distance of movement of the multiple racks and corresponding pistons in the each lumen of a cartridge containing the component of the desired dental composition, allowing for small, metered doses of each flowable dental component to be dispensed from the apparatus in the proper proportions.

Description:
BACKGROUND 
       [0001]    Useful dental compositions include compositions resulting from the admixture of two or more components. For example, self-curing and/or self-priming dental adhesives and cements often comprise two or more components, one of which initiates the curing or hardening process when brought into contact with the other component(s). Some dental compositions are also presented in multi-component form to minimize or avoid long-term storage stability concerns otherwise present if all the components were present and in contact with one another in a single container. Such components of such multi-component dental compositions are also preferably combined with one another in certain ranges or ratios to one another to yield optimal results. Examples of multi-part dental compositions include dental bonding adhesives such as those represented by U.S. Pat. No. 5,348,988 to Suh et. al, and other dental adhesive and cement compositions well-known in the art. Multi-component dental restorative systems that include a colorant in one or more of its components may also require a separation of such components until admixing in metered amounts, depending on the nature of the colorant(s) and reactivity with the other compounds and/or the curing system employed in the restorative system. 
         [0002]    In practice, such multi-part dental compositions are mixed immediately prior to their use in order to prevent biological or chemical contamination and to preclude the mixed composition from curing or degrading before it is applied to the target surface. However, mixing of these dental compositions is often done in small quantities, and should ideally be metered with great precision to ensure that the mixed composition contains the proper proportion of the multiple components. Mixing the small volumes of these materials called for in dental restorations at the proper ratio is difficult in a clinical setting. In many cases, these dental compositions are mixed while the practitioner or technician is manipulating the target surface, or while the dental technician is at least partially occupied with attending to a patient. Metering small volumes of these two or more component systems while manipulating the restoration site in a patient&#39;s mouth can be difficult, particularly in light of the time constraints established by the curing of the materials used. Therefore, a system for providing metered doses of a plurality of flowable dental materials in desired small volumes and at specific ratios in a system easily manipulated by the dental practitioner would be greatly appreciated in the art. 
         [0003]    Previous attempts have been made to provide metered dosage of two-part adhesive systems, such as dual lumen syringes and similar devices. However, the expense of multi-component dental compositions, as well as the small range for error that is required to achieve the ideal mixture of the multiple components renders many of these previous systems unwieldy and impractical in laboratory and clinical dental settings. For example, a two lumen syringe might meter two components in appropriate proportions if the plunger is pushed squarely, but if the user pushes with greater force on either side of the plunger, the proportion of the components will likely vary. Further, such systems do not meter out the total volume of the combined components, which can lead to waste or improper proportion if the combined components must be further mixed with another component in a particular proportion. Typically, such prior art systems are single use dispensers, requiring the clinician to discard the entire system once the contents of one or more lumen are exhausted, and require the purchase of an entirely new system to replace or vary the applied dental composition. Therefore, a dispenser that readily meters out a prescribed total volume of components in a consistent proportion would be greatly appreciated, particularly if such a system comprises a replaceable cartridge or refillable lumens. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0004]      FIG. 1   a  is a top perspective view of a dental composition dispenser according to one embodiment of the present invention. 
           [0005]      FIG. 1   b  is a top perspective view of a dental composition dispenser with the cap removed according to one embodiment of the present invention. 
           [0006]      FIG. 2  is an exploded perspective view of a dental composition dispenser according to one embodiment of the present invention with the cap portion removed and cartridge removed from the dispenser. 
           [0007]      FIG. 3   a  is a top plan view of the dental composition dispenser of  FIG. 1  according to one embodiment of the present invention. 
           [0008]      FIG. 3   b  is a side plan view of the dental composition dispenser of  FIG. 1  according to one embodiment of the present invention. 
           [0009]      FIG. 3   c  is a bottom plan view of the dental composition dispenser of  FIG. 1  according to one embodiment of the present invention. 
           [0010]      FIG. 4  is an exploded perspective view of a dental composition dispenser according to one embodiment of the present invention. 
           [0011]      FIG. 4   a  is an exploded perspective view of a dental composition dispenser according to one embodiment of the present invention. 
           [0012]      FIG. 5   a  is a side plan view of the chamber of a dental composition dispenser and cartridge with the cartridge removed according to one embodiment of the present invention. 
           [0013]      FIG. 5   b  is a side plan view of the chamber of a dental composition dispenser with a cartridge partially inserted, according to one embodiment of the present invention. 
           [0014]      FIG. 5   c  is a side plan view of the chamber of a dental composition dispenser with a cartridge fully inserted, according to one embodiment of the present invention. 
           [0015]      FIG. 5   d  is a partial side plan view of the chamber of a dental composition dispenser showing a close-up of the fully inserted cartridge of  FIG. 5   c , according to one embodiment of the present invention. 
           [0016]      FIGS. 6   a  and  6   b  show a side plan view of the operation of an inner mechanical system of a dispenser according to one aspect of the present invention. 
           [0017]      FIGS. 6   c  and  6   d  show a side plan view of the operation of the mechanical system of a dispenser according to one aspect of the present invention. 
           [0018]      FIG. 6   e  is a side plan view of the operation of the mechanical system of a dispenser according to one aspect of the present invention representing action of the drive spring and pawl spring with respect to the rack system according to one embodiment of the present invention. 
           [0019]      FIG. 7  is a side plan view of a chamber, a cartridge, and cartridge ejector system of a dental composition dispenser according to one embodiment of the present invention. 
       
    
    
     DESCRIPTION 
       [0020]    According to one aspect of the present invention, a reusable hand-held dispenser  5  as shown in  FIGS. 1   a  and  1   b ,  2 ,  3   a - 3   c    4  and  4   a  comprises a body  10 , inner mechanical systems  20 , and replaceable cartridges  30  which may be engaged for dispensing fluids therein. In addition, dispenser  5  may comprise a dispensing button  40 , a cartridge eject button  50 , and a cap  60 . 
         [0021]    Turning now to  FIGS. 1 through 3 , according to one embodiment of the present invention, body  10  comprises a top shell  11 , a bottom shell  12 , and a chamber  13 . The top shell  11  and bottom shell  12  encloses the inner mechanical systems  20  (shown in  FIG. 4 ), and the chamber  13  receives the cartridges  30  and aligns the cartridges  30  with the inner mechanical systems  20  to allow properly metered dosing when the mechanical systems  20  is activated. As shown in  FIG. 4 , mechanical systems  20  comprise a rack system  21  having a plurality of racks  22 , the racks  22  having teeth  23  (as shown in  FIGS. 6-8 ) registered against one another, a drive spring  25 , a pawl spring  26 , and rack return springs  27 . According to one aspect of the present invention, either all or a portion of the non-spring components of dispenser  5  may be created from injection molded compositions well known in the art that are chemically compatible with commonly used dental disinfecting solutions and the dental materials being dispensed. Other compatible materials may be used, such as glass, metals, and hard plastics. Further, it will be appreciated that spring components may comprise conventional spring materials for rack return springs  27 , ejector return spring  51 , button return spring  42 , and the materials for drive spring  25 , pawl spring  26 , cartridge ejector spring  46 , and retainer spring  28  components may comprise elastic materials or metallic materials with an elastic equivalent, including but not limited to high tensile strength steel, heat treated spring steel, or  17 - 7  grade steel. 
         [0022]    It will be appreciated that several embodiments of the present invention, and that the following exemplary embodiments are presented as nonlimiting. For example, turning to  FIGS. 1-4   a , it will be appreciated that body  10  may comprise an upper shell  11  and a lower shell  12  as disclosed above, and shown in  FIG. 3 , and that mechanical systems  20  are substantially enclosed therein once upper shell  11  and lower shell  12  are fastened together, either through the use of solvents, interlocking parts, fusion (such as ultrasonic fusion or welding) of the two parts, fasteners, or other means known in the art. Further, according to one embodiment, it will be appreciated that rack return springs fit over the individual racks  22  of rack system  21 . 
         [0023]    Further, according to one embodiment, button system  40  lies substantially within body  10  when assembled, such that wedge portion  41  moves in a substantially forward and backward motion within body  10  as a user depresses an exposed external portion of button system  40 . The internal and external functional aspects of the button are optionally molded as one piece, but may be provided by separate parts. Button return spring  42  and button return rod  43  (see  FIGS. 4 and 4   a ) interact with button system  40  and interior portions of body  10  such that when button system  40  is depressed, button return spring  42  is compressed. Button return rod  43  fits within button return spring  42 , and button return spring  42  exerts a force upon button system  40  when button return spring  42  is compressed. Button return spring  42  biases the button rearward (away from cartridge  30 ) with respect to body  10 . Button return rod  43  is operable to align button return spring  42 , but it will be appreciated that other means for aligning button return spring may be used. Further, in one embodiment, drive spring  25  and pawl spring  26  (see  FIG. 4   a ) are anchored to an interior portion of body  10 , optionally on the interior of lower shell  12 . In one embodiment, pressure pad  29  (see  FIG. 4   a ) may be positioned in lower shell  12  at a position that will cause pressure pad  29  to engage rack return springs  27  and prevent rack return springs from interfering with drive spring  25  and pawl spring  26 . 
         [0024]    Additionally, according to one embodiment, ejector  45  is seated within lower shell  12  such that button  50  protrudes through an opening in lower shell  12  as shown in  FIGS. 3   c ,  4  and  4   a . Ejector  45  is operable to move in a forward and backward direction as further disclosed below. 
         [0025]    It will be appreciated that the dispenser  5  will likely come in contact with various disinfectants used in the dental field, of which some may be caustic or likely to erode or oxidize certain materials. Therefore, according to certain embodiments of the present application, materials that are resistant to corrosion or breakdown by oxidative materials may be preferred. For example, stainless steel or corrosion resistant materials may be used for the spring components or other components of the dispenser, or a paint or polymer coating applied to such materials to inhibit or prevent corrosion of susceptible surfaces. 
         [0026]    In one embodiment of the present invention, the operation of which is shown in  FIGS. 4 ,  4   a ,  6   c , and  6   d , drive spring  25  engages a first tooth  23 ′ on a first rack  22  and a corresponding first tooth  23 ′ on a second rack  22 , with both racks being of substantially identical tooth construction. Pawl spring  26  engages a second tooth  24 ′ on both racks a selected distance behind the teeth  23 ′ engaged by drive spring  25 . As shown in  FIGS. 6   c - 6   d , as button  40  is depressed and drive spring  25  advances rack system  21  either one or a plurality of teeth, pawl spring  26  engages a second tooth  24 ″ on a first rack  22  and a corresponding second tooth  24 ″ on a second rack  22 . It will be appreciated that drive spring  25  may have a curved end as shown in  FIGS. 6   a - 6   d , or may have a straight tip for interacting with teeth  23  as shown in  FIG. 6   e . As shown in the sequences in  FIGS. 6   c  and  6   d , and in the overlay representation in  FIG. 6   e , when at rest, pawl spring  26  resists the pressure from rack return springs  27 , adapted to fit over each rack  22  of rack system  21  to urge rack system  21  away from cartridge  30  until activation of dispensing button system  40 . Rack return spring  27  is compressed between end of rack  22   b  and pressure pad  29 . Optionally, if pressure pad  29  is not utilized, rack return spring  27  may be compressed between end of rack system  22   b  and a fixed point on body  10 , preferably on a portion provided on lower shell  12 . When a user depresses dispensing button system  40 , a wedge portion  41  of button system  40  moves toward cartridge  30  and depresses the top of drive spring  25 , changing the geometry of drive spring  25  as shown in  FIGS. 6   c ,  6   d , and  6   e , thereby causing the front portion of drive spring  25  to move against tooth  23 ′, and pushing both the first and second racks  22  to advance the distance between a first tooth  23 ′ and the next tooth  23 ″ on the rack system  21 . As racks  22  advance, end  22   a  of rack  22  engages and advances piston  31  into lumen  32  of cartridge  30  and causes a precise amount of component of dental composition material  38  to be dispensed out of opposite end  34  of lumen  32 . Simultaneously, as the rack  22  is advanced, tooth  24 ′ moves under pawl spring  26  such that tooth  24 ″ is now engaged by pawl spring  26 . Upon release of button  40 , wedge portion  41  retreats backwards away from cartridge  30 , allowing drive spring  25  to disengage from tooth  23 ′, and consequently to engage tooth  23 ″ and further allowing drive spring  25  and pawl spring  26  to reassume their respective geometries shown in  FIG. 6   c , but with their respective ends now engaging teeth  23 ″ and  24 ″ on rack  22 . As the rack system  21  advances, pawl spring  26  constrains the rack  22  in its forward achieved position and holds the rack  22  in position to be reengaged upon the next depression of button system  40 . In this manner, pawl spring  26  in conjunction with rack return spring  27  further serve as an anti-hysteresis device, as rack return springs  27  cause pawl spring  26  to be in constant contact with the tooth such that rack system  21  cannot move backward when pawl spring  26  is engaged. 
         [0027]    As can be seen in  FIG. 6   e , the distance traveled by the wedge portion  41  of button system  40  (A to F) is substantially farther than that traveled by the rack system  21  (B′ to E′), allowing the user to depress the button  40  a reasonable distance while only causing the pistons  31  to travel a metered distance. In one embodiment, the movement of wedge portion  41  between areas C and D on the button system  41  causes the rack  22  to advance the distance between C′ and D′. It will be appreciated that in the exemplary embodiment of  FIG. 6   e , wedge portion  41  of button system  40  includes certain flat portions that do not cause depression of drive spring  25 . For example, movement of button system  40  in from reference point A to reference point B does not cause a change in geometry of drive spring  25 , and therefore does not cause advancement of rack  22 . However, travel of button system  40  from reference points B to E causes a change in the geometry of drive spring  25 , and causes advancement of rack  22  a distance from B′ to E′, causing a tooth  23  to progress forward under pawl spring  26 , such that pawl spring  26  is deflected upward as shown until the tooth passes under pawl spring  26 . 
         [0028]    Such a system allows rack  22  to travel a small metered distance compared to a substantially larger distance traveled by button system  40 , which results in a mechanical advantage to the user. For example, this mechanical advantage may be approximately 6:1, with the user depressing the button  40  six times as far as the rack  22  will travel in response. By way of nonlimiting example, the button  40  stroke may travel a combined distance of 0.400 inches while driving rack  22  a distance of only approximately 0.045 to 0.066 inches, thereby allowing a relatively small, precisely metered, total volume of each component of the dental composition to be dispensed. By way of nonlimiting example, depression of button  40  could cause advancement of the rack  22  a distance of a plurality of teeth with each depression by changing the geometry of drive spring  25  to adjust the metered amount of dental composition to be dispensed, or such dispensed amount could be metered by changing the distance between teeth  23 , or by a combination of those methods. Thus, mechanical system  20  may be modified to create a multitude of different mechanical advantages and distances traveled and the dispensed amount of the dental composition for each depression of the button system  40 . Further, it will be appreciated that, rather than utilizing a flexible pawl spring  26  that deflects upward as rack  22  is advanced, a fixed notch or pawl may be utilized, and the rack  22  may move downward as a tooth  23  progresses across the fixed notch or pawl, only to have the rack  22  move back up once the apex of tooth  23  has passed under fixed notch or pawl. 
         [0029]    According to yet another embodiment of the present application,  FIGS. 6   a - 6   b  demonstrates an optional feature for ensuring that the end of rack  22   a  engages piston  31  upon the first depression of button system  40 . Optionally, end of rack  22   a  may be sized and shaped in many variations, including stepped, chamfered, substantially flat, curved, or other shapes adapted to engage pistons  31  in a manner that maintains racks  22  in a substantially central alignment with respect to pistons  31 . Specifically, rack system  21  is optionally sized such that upon the first depression of button system  40  after insertion of new cartridge  30  into chamber  13 , the back of rack system  22  is engaged by button system  40 , causing rack system  22  to advance a substantial distance, and ensuring that each front end of each rack  22  engages each piston  31 . It will be appreciated that this initial advance will likely result in some of the components of dental composition  28  to be ejected from the front of cartridge  30 , and such first advance ensures that each additional depression of button system  40  (as described in the previous paragraphs) results in a dispensing of a metered amount of the components of dental composition  28 . 
         [0030]    Referring now to  FIG. 4   a , according to one embodiment of the present application, the inner mechanical systems  20  further comprises a pressure pad  29 , which interfaces with chamber  13 , and which contains at least one opening to allow racks  22  to pass through pressure pad  29  while preventing rack return springs  27  from passing through the at least one opening of pressure pad  29 . Pressure pad  29  is preferably located in the rear portion of bottom shell  12  in such a manner that rack return spring  27  does not interfere with the operation of drive spring  25  or pawl spring  26 . Therefore, when button system  40  is depressed, rack return springs  27  oppose the forward movement of the rack system  21  due to rack return springs  27  pressing against both rack return pad  29  on one end, and rack system  21  on the other end. 
         [0031]    As discussed above, as rack system  21  advances toward cartridge  30 , the rack system  21  advances the pistons  31  within the lumens  32  of cartridge  30 , thereby displacing the components of dental material  38  out of ends  34  (see  FIG. 2 ). The lumens  32  of cartridge  30  may be sized to determine the amount of fluid displaced from each chamber of cartridge  30 , thereby regulating the ratio of a first fluid to a second fluid. Since the mechanical systems  20  provide for a substantially identical travel by the plurality of racks  22 , the ratio of the first fluid to the second fluid dispensed is determined by the lumen size of each chamber in the cartridge  30 . As shown in  FIG. 3   a , a first lumen  32   a  may be of a greater diameter of the second lumen  32   b , allowing for a ratio of metered fluid to be 3:1, or the lumens may be identical, allowing for a 1:1 dispensing, or varied according to the desired dispensing ratios of the dental compositions. A number of different ratios of the cross section area of the lumens may be created, allowing for varying dispensing ratios. Since each of the plurality of racks is advanced in identical travel distance, the ratio of the volume of a first fluid to a second fluid is a function of the cross section area of the lumen. 
         [0032]    It will be appreciated that according to one embodiment of the present application, the total metered volume of the dental composition is a function of the distance from a first tooth on a rack to a second tooth on a rack. Because depression of button system  40  causes wedge portion  41  to engage drive spring  25  to advance rack system from a first tooth to a second tooth, the volume of each component of the dental composition dispensed per depression of the button system  40  is equal to the surface area of the cross section of the lumen multiplied by the distance from the first tooth to the second tooth. Therefore, the metered amount of dental composition dispensed per depression of the button system  40  is a function of the distance between each tooth. A shorter distance between a first and second tooth results in a smaller volume of dental composition dispensed. Further, cartridge lumen size and distance between teeth  23  can readily be adapted to ensure a particular volume of dental composition is dispensed, thereby allowing a practitioner to easily dispense a specific amount of two different components of a dental composition in precise ratios to one another with the use of only one hand. 
         [0033]    Turning now to  FIGS. 5   a ,  5   b ,  5   c , and  5   d , cartridge  30  preferably engages cartridge retaining spring  28  to help seat cartridge  30  into cartridge retaining slot  12   a . Cartridge retaining spring  28  resists upward movement of cartridge  30  inside of chamber  13  as cartridge  30  rests in the cartridge retaining slot  12   a . However as shown generally in  FIG. 7 , when cartridge ejector button  50  is depressed, ejector  45  is advanced, causing cartridge  30  to become unseated from cartridge retaining slot  12   a  and allowing cartridge ejector spring  46  to propel cartridge  30  from chamber  13 . (See, for example,  FIG. 7 ) Further, as the ramp  47  on ejector  45  elevates cartridge  30 , drive spring  25  and pawl spring  26  are elevated to allow rack system  21  to be urged out of the lumens  32  of cartridge  30  and fully pulled to its starting position by rack return springs  27 . Optionally, cartridge  30  may be shaped to include a notch (not shown) in its rear portion for interfacing with a corresponding protruding portion in chamber  13  to prevent cartridge from being inadvertently removed when cap  60  is removed from chamber. Further, according to one embodiment, it will be appreciated that an ejector button return spring  55  (see  FIGS. 4 and 4   a ) is optionally used to return the ejector  45  and ejector button  50  (see  FIG. 3   c ) to its original position after it is depressed. 
         [0034]    According to yet another embodiment shown in  FIG. 7 , ejector  45  optionally comprises a ramp  47 , a drive spring disengaging portion  48 , and a pawl spring disengaging portion  49 , all of which act in combination to eject cartridge  30  from chamber  13  while allowing rack springs  27  to fully disengage pistons  31 , and return to its fully extended position to clear the lumens of cartridge  30 . Therefore, when ejector button  50  (see  FIG. 3 ) is pressed in a direction toward chamber  13 , ejector  45  is urged toward chamber  13 , thereby causing ramp  47  to disengage the cartridge  30  from its seated position in lower shell  12  by lifting engaging portion  33  of cartridge  30  to elevate cartridge  30  from retaining slot  12   a  of bottom shell  12  such that cartridge ejector spring  46  urges cartridge  30  away from slot  12   a  and out of chamber  13 . Simultaneously, as ejector button  50  was urged toward chamber  13 , drive spring disengaging portion  48  and pawl spring disengaging portion  49  are lifted away from teeth  23  of rack system  21  such that rack return springs  27  allow rack system  21  to return to its fully retracted position away from chamber  13 . 
         [0035]    Yet another aspect of one embodiment of the present application relates to a design of replaceable cartridge  30 . According to one embodiment, cartridge  30  comprises at least two lumens  32 . It will be appreciated that multiple lumens, including 3 or more lumens  32  may be employed, as required in view of the number of components that should be stored separately and dispensed together to achieve the desired dental composition. According to the exemplary embodiment, cartridge  30  comprises two lumens comprising a translucent, transparent, or opaque polymer, such as polyethylene, acrylic, or polycarbonate polymer. It will be appreciated that the selection of the polymer or other material (such as glass, hard plastics, etc.) that is used to construct the lumens, can vary with regard to its chemical compatibility with components of the dental composition  38  contained in the lumen, depending upon the dental compositions intended for use therein. The lumens may contain, for example, various components of multi-component dental adhesive systems, colorant systems, cement systems, or other dental restorative systems, such as the components included in ALLBOND 2®, DUOLINK®, RESINOMER®, and TYRIAN® (available from Bisco, Inc., Schaumburg, Ill.) systems, or may include any flowable multiple component dental compound, it being appreciated that adjustments may be required to achieve the required viscosity of the component for ease of dispensing from the dispenser. It will also be appreciated that the components of two component or multiple component dental systems that, upon admixing of the components, initiate curing or hardening, may be disposed in separate lumens  32  of cartridges  30  for metered dispensing admixing according to the present invention. Additionally, dental compositions that change colors upon admixing and/or subsequent curing or hardening can be employed in the separate lumens  32  and dispensed therefrom according to the present invention. It is well known that some dental compositions cure in the presence of certain radiation, and some components of a dental compositions may be sensitive to radiation in the wavelengths from 380 to 520 nm or other wavelengths of light operable to cure or degrade the particular dental composition, and therefore a translucent or opaque cartridge or lumen that is operable to block radiation, such as light, in those wavelengths would be preferable. In addition, use of a transparent material for chamber  13  in combination with a transparent or translucent polymer or other material for cartridge  30  allows a practitioner or lab technician to monitor the amount of dental composition left in the lumens of cartridge  30  so that the cartridge may be replaced at the appropriate time. 
         [0036]    Although several embodiments have been described in considerable detail above and in the accompanying figures and appendices herein, such description is offered as non-limiting examples of the present invention as many other versions of the present invention are possible. It is anticipated that a variety of modifications and changes will be apparent to those having ordinary skill in the art and that such modifications and changes are intended to be encompassed within the spirit and scope of the present invention as defined by any later appended claims. Further, additional embodiments of the present invention are anticipated.