PATENT ABSTRACT
The present invention relates to an external capsule for holding fluid material suitable for preserving medical device, in particular a dental implant, wherein the external capsule is formed of cyclic olefin copolymer.

PATENT DESCRIPTION
FIELD OF THE INVENTION  
       [0001]     The present invention provides for an external capsule for holding fluid material suitable for preserving a medical device or the like, wherein the external capsule has a main body formed of cyclic olefin copolymer (COC). Furthermore, the present invention also provides for a package with an external capsule for preserving a dental implant or the like of the type described in U.S. Pat. No. 6,261,097 which was assigned to the assignee of the present invention and the full content of which is herewith incorporated by reference.  
       BACKGROUND ART  
       [0002]     Medical devices such as dental implants may require for a better and long-term preservation to be stored in a fluid.  
         [0003]     To ensure a proper functioning of medical devices, they need to be protected from undergoing changes during the storage.  
         [0004]     The primary package with the external capsule wherein the medical devices are stored should then contain a fluid, whose composition, characteristics and quantity should be kept constant for a long period of time.  
         [0005]     Also the environmental condition (e.g. high humidity or dryness) should not alter the properties of the stored fluid and thus of the device immersed in said fluid, so as to ensure the same preservation standard all over the world.  
       SUMMARY OF THE INVENTION  
       [0006]     It is therefore an object of the present invention to provide fox an external capsule for holding fluid material suitable for preserving a medical device such as a dental implant, wherein the external capsule is formed of a material which ensures a good long time storage and which is not influenced by environmental condition.  
         [0007]     Another object of the present invention is to provide for a package with an external capsule for preserving a dental implant in a fluid, such that to ensure a good long time storage and avoid influence by environmental condition.  
         [0008]     The above object as well as further objects which will become apparent hereinafter are achieved by an external capsule as defined in independent claim  1  and by a package for preserving a medical device or the like as defined in independent claims  2  through  4 . Further advantageous aspects of the invention are set forth in the dependent claims. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]     The foregoing and other objects, features, and advantages of the invention, as well as presently preferred embodiments thereof, will become more apparent from a reading of the following description, in connection with the accompanying drawings in which:  
         [0010]      FIG. 1  is a generic package with an external capsule as shown in the prior art according to U.S. Pat. No. 6,261,097; and  
         [0011]      FIG. 2  is a plot which shows a relative comparison of the oxygen and water vapor permeability of various components of a package including an external capsule, a cap etc. formed with various materials. 
     
    
     DESCRIPTION OF THE INVENTION  
       [0012]     With reference to  FIG. 1  there is shown a generic package with an external capsule and an ampule for a dental implant as known from U.S. Pat. No. 6,261,097.  
         [0013]     According to U.S. Pat. No. 6,261,097 there is provided, as shown in prior art  FIG. 1 , an implant  1  and a holding element  100  with an extension element  121  releasably associated with the implant  1 . In the assembled state, an ampoule  200 , with the implant  1  held therein by the holding element  100 , is inserted into an external capsule  300 . The external capsule  300  comprises a hollow cylinder  310 , the base  311  of which is closed, and a screw-on closure cap  320 . On the inside of the cylinder  310 , parallel to and at a distance from the base  311 , there is a support shoulder  313 , which is intended to act as an axial stop for the first planar base side on a fixing part  210  of the inserted ampoule  200 . In this case, the support shoulder  313  comprises four webs which are offset through 90 DEG in each case. The closure cap  320  points towards a stand part  220  of the ampoule  200 . At most in the region of the clearance between the second planar base side on the stand part  220  and the closure cap  320 , the ampoule  200  can move on the axis M and otherwise lies in a stable position in the external capsule  300  in the event of vibrations.  
         [0014]     The implant  1  is held by a holding element  100  with a screw  101  and a sleeve part  102 . An externally threaded part  131  of the screw  101 , which projects through the sleeve part  102 , engages in an internally threaded bore  14  on the implant  1 , while a mating shoulder  161  of a shoulder part  160  of the sleeve part  102  rests on an implant shoulder. A fixing part  110  of the holding element  100  is latched into the fixing part  210  of an ampoule  200 , i.e. the cylindrical section  116  of the holding element  100  is clamped in a laterally open indent  212  in the ampoule  200  and is surrounded laterally by the two jaws  215 ,  216 . The annular shoulders of the holding element  100  bear against the fixing part  210  on both sides. In this way, the implant  1  is held in line with the center axis M inside the ampoule  200  without coming into contact with the ampoule  200 .  
         [0015]     The Applicants of the present invention found that the control of the above mentioned parameters, namely the composition characteristics and quantity of the fluid may be achieved by an appropriate external capsule. In addition, the control can be improved by an appropriate overall package. Particularly relevant for this purpose is the selection of the material from which the external capsule and/or the package are made. In fact, in a device manufactured according to the principles of the present invention the liquid level could be kept constant over a period of 5 years.  
         [0016]     Specifically it has been found that in order to prevent evaporation of the fluid present in the external capsule or in the overall package, the material that constitutes said external capsule and/or the overall package should posses a low water or fluid vapor permeability and a low gas permeability.  
         [0017]     Glass generally offers an excellent low water vapor and low gas permeability. Furthermore, it is transparent, and thus allows the device to be seen by the user, this being an highly desirable characteristic. However, glass containers are not easy to be handled in that they are heavy and breakable.  
         [0018]     The conventional polymers used in the medical package field such as styrene butadiene copolymer (SBS), Poly(methyl methacrylate) (PMMA), polystyrene (PS) and polyester (PET) do not offer the desired low water vapor and gas permeability that allows a long term storage of the medical device.  
         [0019]     In view of the above there is then the need of new containers for medical devices to be stored in a fluid which offer the advantage of the glass container (low water vapor, low gas permeability, and transparency) without however being affected by the drawbacks of the containers made of glass. Moreover, there is the need to avoid the disadvantages of the conventional polymers.  
         [0020]     Accordingly, the Applicants have found that the external capsule is advantageously manufactured from cyclo-olefin copolymer (COC) or the like, which is a plastic material with an excellent impermeability to moisture (less than 5%, preferably less than 1% fluid loss per year) and good impermeability to gas, as shown in  FIG. 2 . At the same time COC is transparent and can be sterilized and has full medical device certification (FDA, CE). COC may also advantageously be used to manufacture the ampoule in view of its good hydrophobic properties (less than 0.01% fluid absorption in 24 hours at 23° C.), such that the overall shape of the ampoule does not change while immersed in a fluid.  
         [0021]     COC also combines excellent electrical properties with low density, high stiffness and strength therefore leading to a light, resistant overall package. Because of the chemical structure of the COC it emits no ions or heavy metals that could affect the stored fluid.  
         [0022]     Moreover, an improvement in the oxygen and fluid vapor impermeability can be achieved by coating the COC of the external capsule with a SiOx coat, as shown in  FIG. 2 .  
         [0023]     The cap of the present package may be advantageously manufactured from a polymer. High density polyethylene (HDPE) or low density polyethylene (LDPE) has proven to be particularly advantageous for caps. Also polypropylene (PP) was proven to perform in a satisfactory manner for certain application.  
         [0024]     Further, the cap can be replaced by a sealing barrier or used together with the sealing barrier, such that a particularly good impermeability is provided in conjunction with the external capsule made of COC. Preferably, the sealing barrier is embodied as an aluminum membrane closing the open end of the capsule. Nevertheless, titanium or polymer membranes can also be used.  
         [0025]     In addition, the combination of a COC capsule with a HDPE or LDPE cap and/or the sealing barrier provides for an excellent shelf life of the medical device stored therein, particularly if a storage fluid, such as an electrolyte or an aqueous solution, is used. The shelf life is further improved by the COC ampule which does not change its shape by soaking up with fluid.  
         [0026]     The overall package impermeability can be improved by including the package in a protective blister  FIG. 2 ).  
         [0027]     The foregoing description of the invention, including the preferred embodiments thereof, has been presented for the purpose of illustration and description. It is not intended to be exhaustive nor is it intended to limit the invention to the precise form disclosed. It will be apparent to those skilled in the art that the disclosed embodiments may be modified in light of the above teachings. In particular, a person skilled in the relevant art will readily understand that the external capsule/package and the ampoule are not limited to the use with dental implants. Rather the external capsule/package and the ampoule may by used in connection with other medical or non-medical devices providing the same handling and sterility maintenance advantages as described hereinbefore. Furthermore, the present invention is not limited to the package shown in present prior art  FIG. 1  according to U.S. Pat. No. 6,261,097 but may be used with any kind of similar packages, such as those according to the concurrently filed application with the title “Package for Preserving a Medical Device or the Like” (attorney docket 2771), the full content of which is also herewith incorporated by reference.  
         [0028]     The embodiments described are chosen to provide an illustration of principles of the invention and its practical application to enable thereby one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. Therefore, the foregoing description is to be considered exemplary, rather than limiting, and the true scope of the invention is that described in the following claims.  
         [0029]     Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included just for the sole purpose of increasing intelligibility of the claims and accordingly, such reference signs do not have any limiting effect on the scope of each element identified by way of example by such reference signs.