Abstract:
A dental strainer unit includes a plastic strainer, a plastic strainer cap, and a transparent, non-rigid plastic housing. The strainer unit can be cost-effectively manufactured and easily disassembled and cleaned. The strainer cap can be manufactured in a variety of sizes to permit different aspirator devices to be attached thereto, and the housing can be snap-fit over the enlarged head of a saliva ejector valve. The dental strainer unit can be used in a modularized dental aspiration system.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to aspirator apparatus, and more particularly relates to aspirator apparatus of the vacuum-operated type. In its most immediate sense, the invention relates to dental aspiration devices such as are used to aspirate body fluids and solids from a patient&#39;s mouth, and to methods for using such devices. 
     Dental procedures can cause solid matter (e.g. bone chips, tooth particles, tissue fragments, pieces of amalgam etc.) to enter fluids (e.g. saliva, blood, and cooling water) that are present in the patient&#39;s mouth. The solid matter is removed from the mouth to prevent the patient from swallowing or aspirating it, and removal of the solid matter necessarily entails removal of the fluids as well. When such fluids are withdrawn from the patient&#39;s mouth (as by a vacuum-powered saliva ejector or a high-speed saliva aspirator) this solid matter can cause difficulties for the dentist and even for the patient. One such difficulty is that the solid matter can clog the vacuum system. Another such difficulty is that the solid matter can build up upon the inside surfaces of the vacuum lines, thereby forming a base for the growth of biofilm that in turn promotes the growth of bacteria. For these reasons, it is known to provide a strainer unit behind the ejector or aspirator. The strainer unit separates the solid matter from the body fluids, protecting the vacuum system and making it more difficult for a biofilm to build up. Conventionally, the ejector or aspirator is disposable, but the strainer unit is not. 
     Existing strainer units have a number of disadvantages. First, existing FDA regulations do not require that strainer units be sterile; they need only be clean. And, even if a particular dentist is motivated to sterilize a strainer unit before connecting it to the vacuum system, existing strainer units can neither be easily emptied nor easily cleaned and sterilized. Hence, a strainer unit used during a dental procedure on a patient will likely be unsterile at the beginning of the procedure. In the worst case, the strainer unit will contain solid matter and/or body fluids from a prior patient. This poses the danger that bodily substances from a dental procedure performed earlier in a day may cross-contaminate (as by backflowing fluid into the patient&#39;s mouth) a patient undergoing a dental procedure later on that day. Second, existing strainer units are not versatile. (The saliva ejector shown in U.S. Pat. No. 3,890,712 is an example of such a non-versatile device.) They are designed to work only with a particular type of saliva ejector or aspirator, and cannot easily be used with another type. Third, existing strainer units are relatively expensive. (The Osseous Coagulum Trap now being sold through Quality Aspirators, Duncanville Tex., is an example of an expensive strainer unit.) Hence, if a dentist is motivated to use a sterile strainer unit for each patient, the dentist must make a considerable investment in strainer units and must incur increased operating expenses to clean and to sterilize them. 
     It would be advantageous to provide an improved strainer unit that would overcome these disadvantages. 
     Existing saliva ejectors and high-speed saliva aspirators also have disadvantages. One conventional saliva ejector, which has a strainer tip at its distal end, can become painfully embedded in the soft tissue of the patient&#39;s mouth. This is because the patient&#39;s flesh can seal off the holes in the strainer tip. When this happens, the vacuum to the saliva ejector causes the strainer tip and the patient&#39;s flesh to be tightly urged against each other. Similarly, a conventional high-speed saliva aspirator can likewise become wedged against the patient&#39;s flesh and cause damage to the tissue. 
     Finally, although conventional saliva ejectors, saliva extractors and similar dental tools are supplied in a “clean” state, they necessarily become less clean when contacted by the hand of the dentist or dental hygienist. 
     It would be advantageous to provide a saliva ejector and a saliva extractor, and a method for using such dental tools, that would overcome these disadvantages. 
     In accordance with the invention, a modularized aspiration system is provided. One component of the system is an all-plastic strainer unit. This strainer unit has three parts: a plastic strainer, a plastic strainer cap, and a plastic housing. The strainer has an open inlet end and an outlet end and a multiplicity of openings sized to permit fluids to pass out of the strainer and to retain solids within the strainer. The retainer cap is attached to the strainer and covers its inlet end, and has an inlet port where an aspirator device (such as a saliva ejector or a high-speed saliva aspirator) can be attached. The housing has an inlet end and an outlet end. The inlet end is shaped to receive the strainer so that the inlet end of the strainer faces the inlet end of the housing and the outlet end of the strainer faces the outlet end of the housing. The outlet end has an outlet port sized to fit onto a distal end of a conventional vacuum valve. 
     In preferred embodiments, the strainer unit is a dental strainer unit, the vacuum valve is a saliva ejector valve, the openings are sized to permit saliva, blood, and water to pass out of the strainer, and the strainer cap and strainer are removably secured within the housing. This makes it possible to adapt the strainer unit for attachment to almost any saliva removal device by mounting the strainer unit with a cap having an appropriately-sized male or female element. This also makes it possible to manufacture the strainer unit economically, since the number of parts required is small; the same strainer and housing can be used in all instances and only the cap (which is a comparatively small and inexpensive part) need be made in a variety of sizes. 
     Advantageously, and in preferred embodiments, the housing is transparent and non-rigid; transparency allows the dentist or dental hygienist to know if the strainer is becoming overfull, and non-rigidity allows the strainer unit to be positively snap-fit over the enlarged head of a conventional saliva ejector valve (and to thereby positively notify the dentist or hygienist that the attachment between the valve and the housing is proper). To make the strainer unit more generally useful, it is possible to provide an elongated adaptor having one end with the shape of a saliva ejector valve head and the other end shaped to mate with a high-volume valve. The preferred embodiment of a strainer unit in accordance with the invention forms the basis for a versatile modular system and can be used to connect virtually any type of saliva removal device with any conventional vacuum source. Further advantageously, and in preferred embodiments, the strainer is generally frustum-shaped, with its inlet end at the base of the frustum. 
     Further advantageously, in accordance with the invention an improved saliva ejector and an improved high-speed saliva aspirator are provided. In a flexible saliva ejector in accordance with the invention, a protective flange is provided adjacent to, and spaced apart from, the strainer tip that is conventionally provided. This prevents the patient&#39;s flesh from blocking all the holes through which fluids are removed from the patient&#39;s mouth, and thereby prevents the saliva ejector and the patient&#39;s flesh from being tightly and painfully urged together by the vacuum. In a saliva extractor in accordance with the invention, a protective flexible tip is secured at the distal end. This cushions the patient&#39;s flesh at the point where it is contacted by the distal end of the saliva extractor, making it less likely that the distal end of the extractor will injure the patient. 
     In preferred embodiments, a saliva ejector and a saliva extractor in accordance with the invention are pleated, as with locking bellows. This makes it easier for the device to maintain the shape desired without the use of stiffening wire in the wall of the device. 
     Still further advantageously, in accordance with the invention a new method of operating a hand-operated dental instrument (such as a high volume valve or a saliva ejector valve) is provided. In accordance with this method, a dental tool (such as a saliva ejector or a high-speed saliva aspirator in accordance with the invention, with or without a strainer unit in accordance with the invention) is packaged within a pouch, advantageously a conventional sterilizing pouch. If the dentist so desires, he can sterilize the tool and the strainer unit inside the pouch before using them. One end of the pouch is then opened to permit the instrument to be introduced into the pouch and connected with the tool. Then, the other end of the pouch is opened so the tool can be pushed out of the pouch and used in a dental operation. The tool is pushed out until the instrument is sheathed within the pouch, where it can be operated through the pouch without being physically touched by the dentist or dental hygienist. In this way 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be better understood with reference to the following illustrative and non-limiting drawings, in which: 
     FIG. 1A shows a conventional saliva ejector; 
     FIG. 1B shows a saliva ejector in accordance with a first preferred embodiment of the invention; 
     FIG. 1C shows a saliva ejector in accordance with a second preferred embodiment of the invention; 
     FIG. 1D shows conventional high-speed saliva aspirator; 
     FIG. 1E shows a high-speed saliva aspirator in accordance with a first embodiment of the invention; 
     FIG. 1F shows a high-speed saliva aspirator in accordance with a second embodiment of the invention; 
     FIG. 2 is an exploded view of a preferred embodiment of a strainer unit in accordance with the invention; 
     FIG. 3A shows how a preferred embodiment of a saliva ejector in accordance with the invention can be mounted to a strainer unit in accordance with the preferred embodiment of the invention; 
     FIG. 3B shows how a preferred embodiment of a high-speed saliva aspirator in accordance with the invention can be mounted to a strainer unit in accordance with the preferred embodiment of the invention; 
     FIG. 3C shows how another type of saliva ejector can be mounted to a strainer unit in accordance with the preferred embodiment of the invention; 
     FIG. 4A shows how a strainer unit in accordance with the invention may be attached between a saliva ejector and a saliva ejector valve; 
     FIG. 4B shows how a strainer unit in accordance with the invention may be attached between a high-speed saliva aspirator and a high-volume valve using an adaptor; and 
     FIGS. 5A-5D show a method of operating a dental tool in accordance with the preferred embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     The same elements are always indicated by the same reference numbers in all the Figures. The Figures are not necessarily to scale and dimensions of certain parts may be exaggerated for clarity. Corresponding elements of different embodiments have the same reference number, but are distinguished by the use of primes. 
     FIG. 1A shows a conventional saliva ejector generally indicated by reference number  2 . This has a flexible tube  4  of transparent or opaque plastic. A bendable wire  6  is embedded in the tube  4 ; this keeps the tube  4  in the position into which it is bent. 
     The ejector  2  has a strainer tip  8  at its distal end. The strainer tip  8  has a plurality of radially extending slots  10  that permit body fluids and small solid objects (bone, tooth debris, tissue, dental amalgam etc.) to be withdrawn through the tube  4  via a vacuum. 
     If the strainer tip  8  is introduced into a small recess in the patient&#39;s mouth (not shown) while the vacuum is turned on, the patient&#39;s flesh (not shown) can block off some the slots  10  at the same time. This causes the tip  10  and the patient&#39;s flesh to press tightly against each other, and can be painful. 
     A saliva ejector  2 ′ in accordance with the preferred embodiment of the invention as illustrated in FIG. 1B has the same tube  4 , wire  6 , and strainer tip  8  with slots  10 . However, a protective flange  12  is located adjacent to the tip  8  but spaced apart from it by a relatively small distance. Advantageously but not necessarily, the flange  12  is made of the same material as the tip  8 , is molded integrally with it, and is molded so that the gap  14  between the flange  12  and the tip  8  is of constant width, but this is not required. 
     Because the flange  12  is spaced apart from the tip  8  by a relatively small distance, it is unlikely that a flap of the patient&#39;s flesh can be interposed between the tip  8  and the flange  12 . For this reason, any slot(s)  10  that are located in the region of the flange  12  will likely always remain unblocked, so that the tip  10  and the flange  12  never become tightly wedged against the patient&#39;s flesh. 
     In accordance with the preferred embodiment of a saliva ejector  2 ′, the flange  12  is diametrically opposed to the wire  6 . The location of the flange  12  therefore identifies the location of the wire  4  within the tube. This permits the dentist or dental hygienist to bend the tube  4  so that the wire  6  is on the outside, even if the tube  4  is made of opaque material. 
     FIG. 1C shows a second preferred embodiment of a saliva ejector  2 ″. The saliva ejector  2 ″ has the same tube  4 , tip  8  and flange  12  as the second preferred embodiment, but there is no wire in the tube  4  and the tube  4  is pleated with thin, flexible pleats  14 . The pleats are formed as locking bellows. (Such pleats  14  are known by themselves; they are similar in nature to the pleats provided in plastic beverage straws.) By using pleats  14  formed as locking bellows, the saliva ejector  2 ″ maintains its desired shape in use, and a stiffening wire (such as  6 ) is not required. 
     FIG. 1D shows a conventional high-speed saliva aspirator generally indicated by reference number  16 . This has an elongated rigid plastic tube  18  that tapers down from a larger proximal end  20  to a smaller distal end  22 . Such an aspirator  16  can injure or cause pain to the patient (not shown) if the distal end  22  is occluded by the patient&#39;s flesh while the vacuum is on. 
     To reduce the likelihood that such injury or pain will result, a first preferred embodiment of a high-speed saliva aspirator  24  in accordance with the invention (see FIG. 1E) has a protective flexible tip  26  attached around its distal end. Advantageously although not necessarily, the tip  26  is a solid drop of an elastomeric polymer and has a small port  28  through which the patient&#39;s body fluids may be withdrawn. For visibility, the tip  26  is colored to contrast with the color of the patient&#39;s flesh. 
     A second preferred embodiment of a high-speed saliva aspirator  30  in accordance with the invention (see FIG. 1F) has pleats  14 ′ intermediate its ends. The pleats  14 ′, like the pleats  14 , are formed as locking bellows. These make it possible for the dentist or dental hygienist to put the aspirator  30  in a more convenient shape. 
     A preferred embodiment of an all-plastic strainer unit generally indicated by reference number  50  is shown in FIG.  2 . The strainer unit  50  has a plastic strainer generally indicated by reference number  52 . The strainer  52  is advantageously but not necessarily a unitary part made of polyethylene or styrene; these materials are easy to mold and can be sterilized. The strainer  52  is generally frustum-shaped; it is open at its base  54  (which is the input end) and may be open or closed at its apex  56 . A short tubular collar  58  is provided at the base  54 , and ribs  60  extend radially inwardly into the strainer  52  between the collar  58  and the apex  56 . A multiplicity of openings  62  are provided; in this example the openings  62  are rectangular and extend in parallel arrays between adjacent ribs  60 , but this is not required and any other suitable pattern could be used instead. The openings  62  are sized to permit body fluids (e.g. saliva and blood) to pass out of the interior of the strainer  52  while retaining solid matter (not shown) inside it. 
     A strainer cap generally indicated by reference number  64  fits into the collar  58 . The cap  64  is advantageously a unitary part likewise made of polyethylene or styrene, but this is not required. The outside portion  66  of the cap  64  is an annulus that supports an inside portion  68  and that has a central inlet port  70 . In this example, the inside portion  68  is formed of a plurality of radially-extending arms  72 , but this is merely for convenience; it could be formed otherwise. 
     The dimensions of the cap  64  are chosen so that the periphery of the inside portion  68  is a circle that is only slightly larger than the inside of the collar  58 . As will be seen below, this slightly expands the collar  58  so as to hold the cap  64  securely in the strainer  52  and to hold the strainer  52  within the housing  74  described below. The inlet port  70  is dimensioned to permit a saliva removal device (such as the above-described preferred embodiments of the saliva ejector  2  and  2 ″) to be attached to the cap  64  (as by insertion and friction-fitting therein) and to permit body fluids and foreign bodies to be drawn into the strainer  52 . As will be seen below, the cap  64  is an adaptor; different saliva removal devices are attached to the strainer unit  50  by using differently shaped caps  64 . 
     A housing  74  is a unitary piece that is advantageously transparent and made of any suitable elastomeric polymer that is transparent when cured. (Transparency allows the dentist or the dental hygienist to see if the strainer unit  50  is becoming overfull or is operating improperly; it is advantageous but not required. As used herein, “transparency” refers to the ability of a dentist or dental hygienist to generally determine the amount of material inside the housing  74 ; it is not necessary that the housing  74  be as clear as glass.) The housing  74  is generally cylindrical, but in this example the inlet end  76  is slightly larger than the outlet end  78 . 
     At the very end of the outlet end  78  is located a lip  81 . The interior surface of the inlet end  76  is advantageously a slightly enlarged tubular collar  80  that has the same width as the collar  58  but a slightly smaller diameter than the exterior diameter of the collar  58 . The lip  81  and the collar  80  serve to fix the cap  64  and the strainer  52  inside the housing  74  so they neither slip out of the housing  74  nor slide inside it. In use, the strainer  52  is inserted past the lip  81  into the housing  74  until the strainer  52  slides in as far as it can go. The slight oversize of the collar  58  relative to the collar  80  makes an interference fit inside the housing  74 . Then, the cap  64  is snapped in just below the lip  81 . In this position, the inside portion  68  of the cap  64  is pressed into the collar  58  and the cap  64  and the strainer  52  are locked in place inside the housing  74 . 
     FIGS. 3A,  3 B, and  3 C are exemplary illustrations showing how different saliva removal tools can be attached to the strainer unit  50  by using different caps  64 ,  64 ′, and  64 ″. FIG. 3A shows how the saliva ejector  2 ′ can be attached to the strainer unit  50  using a cap  64 . FIG. 3B shows how the high-speed saliva aspirator  30  can be attached to the strainer unit by using a different cap  64 ′, and FIG. 3C shows how another type of saliva ejector  3  can be attached to the strainer unit  50  using a different cap  64 ″. 
     At the extreme end of the outlet end  78  is an annular lip  82 . The lip  82  is dimensioned so that the outlet end  78  can be snap-fit over the enlarged head  84  of the distal end of a saliva ejector valve  86 . Alternatively, if the strainer unit  50  is to be connected to a high-volume valve  88  (FIG.  4 B), an adaptor generally indicated by reference number  90  can be used. The adaptor  90  has an enlarged end  92  that has the same shape as the head  84  of a saliva ejector valve and a smaller end  94  that is dimensioned to fit within a conventional high-volume valve  88 . Hence, if the strainer unit  50  is to be used with a saliva ejector  2  or  2 ′, the strainer unit  50  can be connected directly to a saliva ejector valve  88  (FIG.  4 A). If, alternatively, the strainer unit  50  is to be used with a high-speed saliva aspirator  16  or  24 , the strainer unit can be attached to a high-volume valve  86  via an adaptor  90  (FIG.  4 B). If a high-volume valve  86  becomes clogged, a high-speed saliva aspirator (e.g.  16  or  24 ) can be supplied with vacuum via a saliva ejector valve  88 ; likewise, if a saliva ejector valve  88  becomes clogged, a saliva ejector  2  or  2 ′ can be supplied with vacuum via a high-volume valve  86 . 
     The method illustrated in FIGS. 5A-5D is shown using a tool  100 , which generally indicates a saliva ejector  2 ′ in accordance with a preferred embodiment of the invention connected to a strainer unit  50  in accordance with a preferred embodiment of the invention. This is only exemplary, and any other dental tool can be used instead. 
     The tool  100 , in a clean or (optionally, and preferably) sterile state, is packaged inside a conventional sterilizing pouch  102 , with openable ends  104  and  106 . Initially, the end  104  is opened (FIG.  5 B), which permits a hand-operable dental instrument  108  (in this instance, the instrument  108  is a saliva ejector valve but this is not required) to be attached to the tool  100  (FIG.  5 C). Then, the end  106  is opened, permitting the pouch  102  to be slid down so as to expose the distal end of the tool  100  while covering the instrument  108  (FIG.  5 D). The tool  100  can be used in a dental operation while the instrument  108  is operated through the pouch, thereby preventing the tool from becoming unsterile as a result of contact with the hand  110  of the dentist or dental hygienist. 
     Although at least one preferred embodiment of the invention has been described above, this description is not limiting and is only exemplary.