Abstract:
A sterilization cassette and a sterilization method for sterilizing, storing, and dispensing dental instruments. The sterilization cassette includes a mounting bar and a locking bar for dental pliers of various types, a removable instrument tray, and a case with a front side which opens and hinges in two places, allowing the cassette to be arranged in horizontal and vertical configurations.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to a cassette and tray system wherein cassettes of varying sizes are used to hold collections of orthodontic or dental tools for use in the sterilization process. 
     2. Background Information 
     While the human mouth is hardly a sterile environment, there is a need to protect patients from the transmission of infectious diseases from one patient to another through the use of contaminated orthodontic or dental tools. Gone are the days when the orthodontist or dentist merely washed his hand tools between use on patients. Such organizations as the American Dental Association, American Association of Orthodontics, the Federal Occupational Safety and Health Administration and the Center for Disease Control are all actively working to set standards and guidelines to insure the safety of the patients as well as the orthodontists, dentists, and their assistants. 
     At the present time, there are three standardized methods of sterilizing dental and orthodontic hand tools. In each of the three, the hand tools are first dropped into a tank containing water and perhaps solvents, and ultrasound is applied to agitate the fluid to wash and remove the debris remaining on the hand tools from their last use. The tools are left somewhat damp then dried and heated in some manner to a temperature sufficient to destroy any microorganisms or viruses on the hand tools. The three primary methods of doing this are the use of dry heat, heat wherein the hand tools are heated to a temperature of at least 365° Fahrenheit for six minutes, or the use of steam under pressure in an autoclave system. The time to sterilize, using a steam autoclave system, depends on heat and pressure and whether the instruments are wrapped or not. A common wrapped cycle is 270° at 27 psi for fifteen minutes. An unwrapped cycle at the same temperature and pressure would be for three minutes. In some sterilization processes, chemicals are applied to the hand tools as an intermediate step between the ultrasonic bath and the heating. A third method of sterilization is a chemical clave wherein a heated, controlled atmosphere of various gases is used to heat the hand tools held within sealed sterile paper bags. 
     The problem is that orthodontists and dentists with busy professional practices will see many patients in any given work day, indeed it is not unusual for an orthodontist to see in excess of 100 patients per day. A lot of hand tools are used each day, and they are generally collected throughout the day and recycled, in bulk, through the sterilization process. In a busy orthodontics practice, it is not unusual to have one assistant dedicated solely to collecting hand tools and sterilizing them on a full time basis. 
     In the typical prior art orthodontic or dental practice, once the tools have been resterilized, they are simply returned to the work station and placed where they are readily available for reuse. However, this is a source of contamination. If, for example, a dentist is working on a patient&#39;s teeth and calls to his assistant for a new and different tool, and the assistant reaches into the drawer to retrieve the tool wearing a latex glove that has been contaminated with the body fluids of the patient, the assistant can transfer those contaminants to other, unused tools which were previously sterilized. Inevitably, conditions arise where contaminated hands are used to retrieve tools from the drawers. 
     Accordingly, what is needed is a cassette system wherein cassettes can be preloaded with standard sets of tools for use in either orthodontic or dental practices, and kept together as a set throughout the sterilization process. What is also needed is a means of collecting the cassettes into convenient packages where they can be batch fed through the ultrasonic bath and heat applications, and remain in a sterile condition when they are returned as a set to the work station. Another need is for a sterilization cassette in which dental pliers and dental instruments can be carried through the sterilization process in a sterilization cassette which secures dental pliers in place during the sterilization process. The sterilization cassette also needs to be usable as a storage container, and be convertible into a dispensing device which dispenses the dental pliers and dental instruments from either a horizontal or a vertical position. Additionally, this cassette collection system must require a minimum amount of counter space at the vicinity of the dental chair, either on the bracket table or the work side unit, and finally, the cassettes must be configured such that they remain stable and flat on the countertop surface when opened so that they do not fall off the table onto the floor, or worse yet, the patient. 
     Additional objects, advantages and novel features of the invention will be set forth in part in the description as follows, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims. 
     SUMMARY OF THE INVENTION 
     These objects are achieved through use of a transfer rack and a plurality of cassette systems. The transfer rack is formed of side walls, a back wall, and a bottom wall which are all interconnected to form a rigid transfer rack. The tray is provided with a plurality of shelves for holding cassettes which are inserted through the front of the transfer rack. The walls and shelves of the transfer rack are provided with a plurality of holes or slots through which fluids and debris cleaned during the ultrasonic cleaning portion of the sterilization process may readily pass. 
     The transfer rack is also provided with two flanges which are attached to the top of the side walls. The transfer rack is dimensionally sized to a preselected dimension as to provide for interchangeability of cassettes as is later described. 
     The sterilization cassette for dental pliers and dental instruments is a generally rectangular case. It has a back side, a front side, a left side, a right side, a top side, and a bottom side. The case opens by the front side hinging forward. To the front side, which hinges forward, is attached the top side, and portions of the left and right side. At least one of the sides of the sterilization cassette contains perforations which allow for the passage of sterilization gases through the cassette. 
     A plier mounting bar is attached to the left side and the right side, and extends through the cassette from these sides. Dental pliers are placed on the plier mounting bar. The plier mounting bar is divided into two or more dividers, which provide each dental plier a discreet position on the plier mounting bar. A plier locking bar is provided which attaches to the front side. When the front side swings to its closed position, the plier locking bar presses against the dental pliers on the plier mounting bar, and holds them in place. One or more removable instruments trays is also provided. Other dental instruments can be placed in the instrument tray for passage through the sterilization process. The sterilization cassette is configured so that it may serve as a storage container for the dental pliers or dental instruments, and it also may be used as a dispensing tray which is positionable in either a horizontal or vertical position, for dispensing these tools when a dentist works with a patient. 
     In another version of the invention, the metal case opens by two hinges which are located on the front side. The first and second hinge on the front side divide the front side into a bottom front side, a mid front side, and a top front side. The top front side is attached to the first hinge. The top side is also attached to the top front side, and part of the left and right side is also attached to the top front side. The second hinge divides the mid front side from the top front side, and allows further opening of the front side to make the dental pliers and dental instruments accessible. 
     Another aspect of the invention is a method of sterilizing, storing, and dispensing dental pliers and dental instruments. This method involves the steps of providing one of the sterilization cassettes previously described, and placing dental pliers on the plier mounting bar. The pliers are placed between plier mounting bar dividers, and dental instruments are also placed in one of the removable metal instruments trays. The next step is closing the sterilization cassette, so that the plier locking bar presses down on the dental pliers and holds them firmly in place on the plier mounting bar. The cassette may be placed in a transfer rack, or may be placed in an ultrasound cleaning chamber without a transfer rack. After a period of time in the ultrasonic cleaning chamber, the cassette is removed from the ultrasonic cleaning chamber, and the fluid from the ultrasonic cleaning chamber is drained from the cassette, without opening the cassette. At this point, the cassette may optionally be placed inside a membrane which is permeable to sterilization gases but is impermeable to microbes. The sterilization cassette is then placed in a sterilization chamber. The sterilization chamber can be any of the conventionally available sterilization chambers, which utilize heat, steam, chemical vapors, pressure, or combinations of any of these. After sterilization is complete, the sterilization cassette is removed from the sterilization chamber and allowed to cool to ambient temperature. The sterilization cassette is then used as the storage container of the dental pliers and dental instruments, and may be placed in an appropriate storage shelf or housing. When the dental tools within the sterilization chamber are needed for use, the sterilization cassette can be placed in either the vertical or horizontal position, the front side may be opened, and dental pliers and dental instruments may be dispensed. 
     The cassettes are also provided with color coded markers fixed to the end walls and plier mounting bar so that the kits of dental tools that are contained within each cassette and the individual dental tools can be readily identified. 
     Still other objects and advantages of the present invention will become readily apparent to those skilled in this art from the following detailed description wherein I have shown and described only the preferred embodiment of the invention, simply by way of illustration of the best mode contemplated by carrying out my invention. As will be realized, the invention is capable of modification in various obvious respects all without departing from the invention. Accordingly, the drawings and description of the preferred embodiment are to be regarded as illustrative in nature, and not as restrictive. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective representational view of the sterilization cassette configured for dispensing tools in a vertical position. 
     FIG. 2 is a perspective representational view of the sterilization cassette configured for dispensing tools in a vertical position, with the hinging front cover and top arranged to form a storage area. 
     FIG. 3 is a side view of the sterilization cassette configured for horizontal dispensing or loading of tools. 
     FIG. 4 is a side view of the sterilization cassette in a horizontal configuration, with the opening front cover and top side arranged to form a storage compartment on the sterilization cassette. 
     FIG. 5 is a perspective representational view of the sterilization cassette showing the cassette almost closed. 
     FIG. 6 is a view of the transfer rack of the sterilization method. 
     FIG. 7 is a front view of a number of sterilization cassettes mounted on a transfer rack placed in a sterilization chamber, with one of the sterilization cassettes wrapped in a membrane. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     While the invention is susceptible of various modifications and alternative constructions, certain illustrated embodiments thereof have been shown in the drawings and will be described below in detail. It should be understood, however, that there is no intention to limit the invention to the specific form disclosed, but, on the contrary, the invention is to cover all modifications, alternative constructions, and equivalents falling within the spirit and scope of the invention as defined in the claims. 
     Some of the preferred embodiments of the invention are shown in FIGS. 1 through 7. Referring to FIG. 1, there is shown a sterilization cassette  10 . Sterilization cassette  10  includes a generally rectangular case  12  which is preferably made of metal such as stainless steel. Other materials which are suitable to withstand the ultrasonic cleaning and sterilization process would also be acceptable to use in case  12 , such as other metals, plastics, ceramics, or other materials. Case  12  includes a left side  14 , a right side  16 , a back side  18 , a front side  20 , a top side  22 , and a bottom side  24 . In the preferred embodiment of the invention shown in FIG. 1, each of these sides have perforations  26 , which allow the passage of hot air, steam, ultrasonic cleaning fluid, and sterilization chemical vapors into and out of the sterilization cassette  10 . 
     The case  12  includes a plier mounting bar  28  which extends from right side  16  to left side  14 . Plier mounting bar  28  would typically be a metal bar covered by Teflon® cylinders  30 . The Teflon® cylinders  30  would preferably be color coded to allow fast identification of dental pliers, and accurate replacement in the rack after use. The Teflon® cylinders  30  are separated by metal disks  32 , which form individual positions for dental pliers  34 . Dental pliers  34  can include a number of plier-like instruments, and specifically include hard wire cutters, bird&#39;s beak pliers, three-prong pliers, ligature cutters, adjustment pliers, Weingart pliers, hemostats, and other plier-like dental hand tools. An instrument tray  36  is also provided, and other small dental instruments  38  are placed in instrument tray  36 . Dental instruments  38  can include a number of instruments such as mirrors, picks, scrapers, files, scalpels, and other small hand tools. The Teflon® cylinders  30  and the metal disks  32 , form plier mounting positions. 
     The sterilization cassette  10  also includes a plier locking bar  40  which is attached to front side  20  of case  12 . Plier locking bar  40  is a bar which extends from a first bracket  42  to a second bracket  44 , each of which is attached to front side  20 . Plier locking bar  40  would typically be a metal bar which is covered by a Teflon® covering. In a preferred embodiment of the invention, case  12  includes a first hinge  46  and a second hinge  48 . In this embodiment of the invention, first hinge  46  and second hinge  48  are piano hinges and divide front side  20  into three portions. These portions are best seen in FIG.  5 . First hinge  46  divides front cover  20  into a top front side  50  and a mid front side  52 . Second hinge  48  divides front cover  20  into another side, a bottom front side  54 . 
     Referring again to FIG. 1, sterilization cassette  10  further includes plier handle divider  56 . Sterilization cassette  10  also includes a tool slot  58 , into which larger tools such as hemostats or forceps may be placed for sterilization. 
     By utilizing the double hinge configuration of sterilization cassette  10 , sterilization cassette  10  may be configured in a number of ways to suit the needs of the user. FIG. 1 shows sterilization cassette  10  arranged in a vertical configuration, so that dental pliers  34  or dental instruments  38  may be removed or replaced in their positions in a horizontal configuration. 
     FIG. 2 shows sterilization cassette  10  in a vertical configuration, with front side  20  folded into a configuration which provides a tray below the tools of the open cassette. FIG. 3 shows the sterilization cassette  10  in horizontal configuration, and in this configuration, tools would be presented to the practitioner in a horizontal rather than a vertical format. In the horizontal configuration, the front side  20  can also be folded to various configurations. One configuration is shown in FIG. 3, and another configuration of front side  20  is shown in FIG.  4 . 
     FIG. 5 shows the sterilization cassette  10  in an almost closed configuration, in which top front side  50  is open only slightly. 
     FIG. 6 shows a transfer rack  60 . This particular transfer rack is configured with four trays, and the number of trays would vary according to the size of the sterilization oven. A typical sterilization oven is shown in FIG. 7, and includes a transfer rack  60  with four sterilization cassettes  10 . In FIG. 7, one of the sterilization cassettes  10  is shown wrapped in a membrane  64 . One option for sterilizing instruments in the sterilization cassettes  10  is to cover the sterilization cassettes  10  with a membrane  64  which allows the passage of gases, which is stable in the heat in the sterilization chamber, and which is impermeable to microbes. A membrane  64  could be folded around a sterilization cassette  10 , much like the wrapping of a gift. The membrane  64  could also be in the form of a bag with a sealable closure. The oven shown in FIG. 4 is similar to a popular type of sterilization oven such as the Dentronix 5000. There are a number of configurations of sterilization cassettes, some of them with polygonal chambers, and transfer rack  60  can be adapted for different sizes and configurations of sterilization ovens  62 . FIG. 7 shows sterilization oven  62  with the oven door  66  open. 
     While there is shown and described the present preferred embodiment of the invention, it is to be distinctly understood that this invention is not limited thereto but may be variously embodied to practice within the scope of the following claims. 
     From the foregoing description, it will be apparent that various changes may be made without departing from the spirit and scope of the invention as defined by the following claims.