Abstract:
A delivery system for supplying a single dose quantity of a two-component dental restorative material includes a dispenser which contains first and second components of the dental restorative material. The first and second components are stored in separate chambers which are sealed with a closure. To dispense the dental restorative material, a tip is installed to an end of the dispenser to move the closure to an open position, whereafter plungers may be depressed into the chambers to dispense the single dose of dental restorative material through the tip. The tip may be provided with a static mixer to mix the components as it is dispensed.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to a dental material delivery system, and more particularly to a delivery system for dispensing a single dose of a two-component dental restorative material.  
         BACKGROUND OF THE INVENTION  
         [0002]    Dental restoratives, such as crowns and bridges, are commonly used to address various dental problems such as restoring a damaged tooth to its original shape, strengthening a tooth, or simply improving the cosmetic appearance of a tooth. In the process of fitting a dental restorative to a patient&#39;s tooth, a dentist will typically take x-rays and impressions of the patient&#39;s dental anatomy, shape the subject tooth by either grinding away portions of the tooth or building up a damaged tooth, obtain an impression of the tooth, and prepare a crown or bridge to be placed over the shaped tooth (or teeth). Often “permanent” restoratives are prepared in a laboratory which is separate from the dentist&#39;s office and, therefore, a temporary dental restorative must be fitted to the shaped tooth in the dental office, to be worn by the patient until the permanent crown or bridge is ready.  
           [0003]    Temporary crowns and bridges are typically prepared by a dentist in his office and may be worn by the patient for a period of approximately one week to ten days, or even as long as approximately three to six months. The materials used for temporary crowns and bridges are typically provided in powder/liquid form or paste/paste form and comprise a base material and a catalyst material which causes the base material to harden when the two materials are combined. Advantageously, the temporary crown and bridge materials permit dentists to create temporary dental restoratives with good physical properties in the office at the time the subject tooth is shaped.  
           [0004]    To create a temporary dental restorative using a powder/liquid system, a dentist will generally dispense the base and catalyst components in a specific ratio by using a measuring device such as cup or scale. The contents are combined and mixed with a spatula in a mixing well or on a mixing pad until homogeneous. The mixture is transferred to a premade impression or a plastic matrix. Then the impression or matrix with the material is immediately applied to the area of the shaped teeth in a patient&#39;s mouth. The material is molded by pressing the impression or plastic matrix. The impression or plastic matrix is removed from the patient&#39;s mouth before the material is hardened. The temporary restorative is then separated from the impression or plastic matrix.  
           [0005]    For paste/paste systems, materials for forming temporary crowns and bridges have historically been provided in bulk via cartridges having two chambers whereby each component is stored in a separate chamber. The pastes are extruded from their respective cartridge chambers and are automatically mixed through a static mixer in predetermined volume ratios into a premade impression or a plastic matrix. Because the chemistry of the paste/paste components is fairly complicated, the resulting volumetric ratios are rather high, such as 4:1, 5:1, 10:1, and even 20:1. Most commercially available temporary crown and bridge materials are packaged in cartridges having a quantity of the materials sufficient for making several temporary restoratives. For example, a 50 ml cartridge can generally produce approximately 35 single crowns or 20 three-unit bridges.  
           [0006]    Bulk dispensing systems presently used for providing temporary dental restorative materials have various drawbacks. Because the components are provided in large quantities, all of the material may not be used before the expiration of the product&#39;s recommended shelf life, thereby resulting in wasted material. Material is also frequently wasted during the process of dispensing the individual components, in different ratios, to a well for mixing because it is often difficult to judge the quantity of material which will be required to create an individual restorative. Another drawback to the current bulk dispensing systems is that it is impossible to sterilize the cartridges between patient use, therefore creating a cross contamination situation which is less than ideal.  
           [0007]    Dispensing from bulk powder/liquid systems is also relatively time consuming, requiring a dentist or other personnel to retrieve the containers in which the individual components are stored, unseal the containers, measure out quantities of each component in the required ratio, reseal the containers, and then return the containers to storage. The hand spatulation and mixing technique has a disadvantage in that it introduces numerous air bubbles into the mixed pastes. The entrapped air bubbles in the hardened material are detrimental to physical strength and lead to sites for bacterial colonies, fracture sites, and discoloration. Furthermore, it is very difficult to measure out the proper small quantities needed to mix the components in a desired mixing ratio using this technique.  
           [0008]    Dispensing pastes from bulk cartridge delivery systems in different volume ratios requires dentists to have delivery systems for use with these ratios, or to change out the plungers used with their current system whenever they need to dispense the temporary restorative material. In addition, a dentist or other personnel needs to remove a cap or a used static mixer from the cartridge before attaching a new static mixer prior to each use. Furthermore, the bulk cartridge delivery systems require more storage space and disinfecting between patent uses.  
           [0009]    There is thus a need for a delivery system which is capable of providing a single dose of a two-component dental restorative material which overcomes drawbacks of the prior art such as those discussed above and which is susceptive of use with two-component restorative materials requiring different volumetric ratios for the base and catalyst components.  
         SUMMARY OF THE INVENTION  
         [0010]    The delivery system of the present invention provides a convenient means of dispensing two component dental restorative materials in a single-dose quantity. In one aspect of the invention, the system includes first and second components of the dental restorative material which has been formulated for dispensing in a 1:1 ratio.  
           [0011]    In one aspect of the invention, a dispenser has a dispenser body incorporating first and second adjacent chambers which are sized to contain single dose amounts of the first and second components. First and second plungers are disposed in the respective chambers and are movable therein to dispense the respective first and second components through dispensing orifices associated with the chambers. The chambers are each individually sealed by a movable closure provided adjacent the dispensing orifice of the respective chambers. Each closure may be moved from an orifice-sealing position to an orifice-unsealing position to unseal its respectively associated orifice, whereby the first and second components may be dispensed from the chambers via the unsealed orifices to a dispensing tip located proximate the orifices for application to a desired target.  
           [0012]    The dispensing tip may further include a static mixer which mixes the two components as they are being dispensed. In another aspect of the invention, the dispensing tip is a separate component which is only attached to the dispenser structure defining the chambers, in fluid communication with the orifices, immediately prior to the point in time when it is desired to unseal the chamber orifices. Attachment of the dispensing tip is operative to move the closures to their respective orifice-unsealing positions, thereby enabling the restorative components to be expelled from the chambers, via their respective unsealed orifices, into the dispensing tip.  
           [0013]    In another aspect of the invention, a method of providing a single dose of a two-component dental restorative includes the steps of providing a dispenser having first and second chambers sized to contain single-dose amounts of first and second components of the dental restorative, a closure for sealing the chambers, plungers for dispensing the components from the chambers, and a dispensing tip; loading the first chamber of the dispenser with the first component of the dental restorative; loading the second chamber of the dispenser with the second component of the dental restorative; and sealing the chambers with a closure.  
           [0014]    In yet another aspect of the present invention, a method of dispensing a single dose of a two-component dental restorative includes providing a single dose of dental restorative as described above, moving the closure to permit the first and second components of the temporary dental restorative to be dispensed from the first and second chambers, attaching the dispensing tip, and moving the plungers to dispense the first and second components from the dispensing tip. The features and objectives of the present invention will become more readily apparent from the following Detailed Description taken in conjunction with the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]    The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with a general description of the invention given above, and the detailed description given below, serve to explain the invention.  
         [0016]    [0016]FIG. 1 is an exploded perspective view of an exemplary dispenser of the present invention;  
         [0017]    [0017]FIG. 2 is a partial cross-sectional view of the dispenser of FIG. 1 taken along lines  2 - 2 ;  
         [0018]    [0018]FIG. 3 is a cross-sectional view of the dispenser of FIG. 1 depicting the dispenser tip being attached; and  
         [0019]    [0019]FIG. 4 is a cross-sectional view similar to FIG. 3 depicting the dispenser tip fully attached.  
     
    
     DETAILED DESCRIPTION  
       [0020]    Referring to FIGS.  1 - 4 , there is shown an exemplary dispenser  10  for dispensing a single dose of a two component temporary dental restorative material according to the present invention. The dispenser  10  includes a dispenser body  12 , an actuator  14 , a closure  16 , and a dispenser tip  18 . With reference to FIGS. 1 and 3, the dispenser body  12  includes first and second cylindrically-shaped chambers  20 ,  22  defined by sidewalls  24 ,  26  and sized to contain the first and second components  28 ,  30  of the temporary dental restorative material. The first and second chambers  20 ,  22  are positioned adjacent one another and have dispensing orifices  32 ,  34  disposed at first ends  36 ,  38  of the chambers  20 ,  22  and openings  40 ,  42  at second ends  44 ,  46  of the chambers  20 ,  22  opposite the first ends  36 ,  38 . The openings  40 ,  42  are sized to receive the actuator  14  which may thereafter be depressed into the chambers  20 ,  22  to dispense the first and second components  28 ,  30  of the temporary dental restorative material through the first and second orifices  32 ,  34 , respectively.  
         [0021]    The actuator  14  includes first and second plungers  50 ,  52  which may be received into the first and second chambers  20 ,  22 , respectively, through their respective openings  40 ,  42 . Each plunger  50 ,  52  includes a piston  20   54  which may be disposed within the respective chambers  20 ,  22  and is constructed to slidably seal against the sidewalls  24 ,  26  of the respective chambers  20 ,  22 . The plungers  50 ,  52  further include elongated plunger rods  56 ,  58  which are configured to extend from the respective chambers  20 ,  22  through the openings  40 ,  42  whereby the pistons  54  may be urged along the  25  respective chambers  20 ,  22  to dispense the respective dental restorative components  28 ,  30  as the respective plunger rods  56 ,  58  are depressed. In the exemplary embodiment shown, the first and second plungers  50 ,  52  are connected at their distal ends, opposite the pistons  54 , by a thumb pad  60 , whereby the pistons  54  may be advanced in unison along the chambers  20 ,  22  to dispense the first and second components  28 ,  30  simultaneously. The dispenser body  12  may further include one or more outwardly extending flanges  62  to provide a convenient means to grasp the dispenser  10  and to facilitate depressing the plungers  50 ,  52  of the actuator  14  into the chambers  20 , 22  to dispense the components  28 ,  30 .  
         [0022]    The dispenser  10  further includes a closure  16  which may be installed to the dispenser body  12  to seal the first and second orifices  32 ,  34 . Advantageously, the closure  16  prevents premature dispensing of the temporary dental restorative components  28 ,  30  and protects the components  28 ,  30  from contaminants prior to use. In the exemplary embodiment shown, the closure  16  includes a disc-shaped base  70  having first and second projections  72 ,  74  extending from one side of the base  70 . Sealing members  76 ,  78  are formed on the distal ends of the projections  72 ,  74  opposite the base  70  and are configured to sealingly engage the first and second orifices to thereby seal the first and second chambers  20 ,  22  when the closure  16  is attached to the dispenser body  12  adjacent the first and second orifices  32 ,  34  in a first position, as depicted in FIGS. 2 and 3. The closure  16  further includes slot-shaped passages  80 ,  82  formed between the sealing members  76 ,  78  and the base  70 . These passages  80 ,  82  provide a path for the components  28 ,  30  to flow through the orifices  32 ,  34  when the closure  16  is moved from the first position to a second position, as depicted in FIG. 4, where the sealing members  76 , 78  of the closure  16  are moved into the first and second chambers  20 ,  22 , generally in a direction toward the first and second openings  40 ,  42 . Accordingly, the dispenser  10  may be placed into a condition for dispensing the first and second components  28 ,  30  by moving the closure  16  from the first position to the second position.  
         [0023]    The dispenser  10  further includes a dispenser tip  18  which may be attached to the dispenser body  12  adjacent the first and second orifices  32 ,  34 . In the exemplary embodiment shown, the dispenser tip  18  includes an elongate, cylindrically-shaped nozzle  84  having a nozzle outlet  86  through which the combined first and second components  28 ,  30  may be dispensed to a desired target area. The dispenser tip  18  further includes a cylindrically-shaped protrusion  88  at an end of the dispenser tip  18  opposite the nozzle  84 . The protrusion  88  is sized to be received within a corresponding cylindrically-shaped extension  90  of the dispenser body  12 , located adjacent the first and second orifices  32 ,  34 . Advantageously, the protrusion  88  on the dispenser tip  18  and the extension  90  on the dispenser body  12  help to align and secure the dispenser tip  18  to the dispenser body  12  so that the first and second components  28 ,  30  flowing from the first and second orifices  32 ,  34  may be received into the dispenser tip  18  and dispensed through the nozzle  84 .  
         [0024]    The dispenser tip  18  may further include one or more hasps  92  provided on a flange  94  of the dispenser tip  18  and extending adjacent the cylindrical protrusion  88 . The hasps  92  are configured to engage corresponding tabs  96  provided on an outer surface  98  of the cylindrical extension  90  on the dispenser body  12  whereby the hasps  92  may engage the tabs  96  in an interlocking relationship to secure the dispenser tip  18  to the dispenser body  12 .  
         [0025]    Advantageously, the cylindrical protrusion  88  on the dispenser tip  18  may be configured to engage the closure  16  as the dispenser tip  18  is installed onto the dispenser body  12  whereby the closure  16  is moved from the first, sealing position to the second position as the dispenser tip  18  is attached to the dispenser body  12 . In this manner, the dispenser  10  is placed in condition to dispense the first and second components  28 ,  30  of the temporary dental restorative material when the dispenser tip  18  is attached to the dispenser body  12 . Accordingly, after the dispenser tip  18  has been attached to the body  12 , the first and second plungers  50 ,  52  of the actuator  14  may be urged into the first and second chambers  20 ,  22  to dispense the first and second components  28 ,  30  of the dental restorative material through the first and second orifices  32 ,  34  and through the dispenser tip  18 . In one exemplary embodiment, the dispenser tip  18  may further include a mixing element  100  provided within the nozzle  84  and having a series of vanes  102  which are configured to mix the first and second components  28 ,  30  prior to dispensing from the nozzle outlet  86 .  
         [0026]    In another exemplary embodiment, the first and second components  28 ,  30  of the dental restorative material comprise a base and catalyst as described in U.S. Pat. No. 5,977,199 to Xie, assigned to the assignee of the present invention and hereby incorporated by reference in its entirety. According to this embodiment, the first component  28  is a catalyst paste comprising at least one polymerizable acrylic monomer, at least one polymerization initiator, at least one polymerization inhibitor, and filler. The second component  30  is a base paste comprising at least one polymerizable acrylic monomer, at least one polymerization accelerator, at least one polymerization inhibitor, and filler. Advantageously, the temporary dental restorative material may be provided in a 1:1 ratio for convenient dispensing in a single-dose quantity by the dispenser  10 . While the exemplary embodiment described above depicts a dispenser  10  which is configured to dispense components  28 ,  30  of a temporary dental restorative material in a single-dose quantity and having a volumetric ratio of approximately 1:1, it will be understood that the dispenser  10  could be configured to accommodate other volumetric ratios by modifying the length or cross-sectional dimensions of one of the chambers  20 ,  22  with respect to the other chamber. Accordingly, the dispenser  10  described above may easily be configured to accommodate volumetric ratios of approximately 4:1, 5:1, 10:1 or 20:1, or even greater.  
         [0027]    In another exemplary embodiment, a method of providing a single dose of temporary dental restorative material includes the step of providing a single-dose dispenser  10  as described above, loading the first chamber  20  of the dispenser  10  with a first component  28  of the single dose of temporary dental restorative, loading the second chamber  22  with a second component  30  of the single dose of temporary dental restorative material, and sealing the first and second chambers  28 ,  30  with the closure  16 .  
         [0028]    In another aspect of the invention, a method of dispensing a single dose of temporary dental restorative material includes the steps of providing a temporary dental restorative according to the method described above and further moving the closure  16  from the first position to the second position to thereby permit the first and second components  28 ,  30  to be dispensed from the first and second orifices  32 ,  34 , attaching the dispenser tip  18  proximate the first and second orifices  32 ,  34 , and moving the first and second plungers  50 ,  52  to dispense the first and second components  28 ,  30  through the dispenser tip  18 .  
         [0029]    The following examples illustrate the embodiments of the present invention.  
       EXAMPLE 1  
       [0030]    [0030]                                                                                           Ingredient   Weight %                                    CATALYST PASTE                Ethoxylated bisphenol-A-dimethacrylate   55.88           Dibenzoyl peroxide   1.0           Butylated hydroxytoluene   0.12           Fumed silica   5.0           Barium glass, silanized   38.0            BASE PASTE                Bis-GMA   5.0           Urethane dimethacrylate   40.43           Dibutyl phthalate   10.0           Dihydroxyethyl-p-toluidine   4.4           Butylated hydroxytoluene   0.06           Fumed silica   4.0           Barium glass, silanized   36.0           Pigment   0.11                        
         [0031]    Both the catalyst paste and base paste were separately formed by mixing the ingredients in a planetary mixer. The catalyst paste and base paste were loaded into the separate chambers of a single-dose dispenser as described above. A static mixer equipped with 8 mixing elements was attached and then depressed to unseal the chambers. The catalyst and base pastes were extruded in a 1:1 volume ratio through the static mixer. The mixed paste has a gel time of 35 seconds and a set time of 2 minutes 54 seconds. The paste was directly applied into a premade matrix which was immediately placed on a prepared tooth. After about 1 minute 30 seconds, the matrix with the curing material was removed. The obtained crown was allowed to cure for an additional 2 minutes. After trimming and polishing a temporary crown was formed.  
       EXAMPLE 2  
       [0032]    [0032]                                                           BASE PASTE                Ingredient   Weight %                            Bis-GMA   5.0           Urethane dimethacrylate   42.83           Dibutyl phthalate   10.0           Dihydroxyethyl-p-toluidine   2.0           Butylated hydroxytoluene   0.06           Fumed silica   4.0           Barium glass, silanized   36.0           Pigment   0.11                        
         [0033]    The base paste was formed by mixing the ingredients in a planetary mixer. The catalyst paste from Example 1 and base paste were loaded into the separate chambers of a single-dose dispenser as described above. A static mixer equipped with 8 mixing elements was attached and then depressed to unseal the chambers. The catalyst and base pastes were extruded in a 1:1 volume ratio through the static mixer. The mixed paste has gel time of 1 minute 19 seconds and set time of 6 minutes 3 seconds. The paste was directly applied into a premade matrix which was immediately placed on a prepared tooth. After about 2 minutes, the matrix with the curing material was removed. The obtained crown was allowed to cure for an additional 5 minutes. After trimming and polishing a temporary crown was formed.  
         [0034]    While the present invention has been illustrated by the description of various embodiments thereof, and while the embodiments have been described in considerable detail, it is not intended to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. For example, while the invention has been described herein with respect to a two-component temporary dental restorative, it will be understood that two-component restoratives intended for longer, more permanent duration could be utilized as well.  
         [0035]    The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and methods and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the scope or spirit of Applicant&#39;s general inventive concept.