Patent Application
20160278877
The delivery of streams of water and/or air into patients' mouths, sometimes carried out in support of another more complicated dental procedure, is an established part of current dental practice. When, as is typical, the temperature of the fluid being delivered is significantly below normal human body temperature, the patient experiences discomfort. In some cases, the discomfort may reach the level of pain, seriously impacting the patient's ability to tolerate whatever dental procedure is being performed.
Two main categories of systems have been developed that aim to deliver fluids to the mouth at temperatures closer to body temperature, but neither has met with widespread acceptance. In one category of fluid delivery systems, the approach has been to incorporate a heating element and associated controls into the hand-held unit—the “handset”—from which the fluid streams are directed into the mouth of the patient. The modified handset receives the fluids through a simple tubing assembly connected at the far end to a dental cart. Air and water ports at the cart connect in turn to convenient fluid sources, which normally supply those fluids at relatively cool or uncontrolled ambient temperatures. In the second category of fluid delivery systems, temperature control is carried out within dedicated fluid reservoirs, or in a preliminary manual-heating step before those reservoirs are filled. The reservoirs may be within or attached to a dental cart or tray, the temperature adjusted fluids then being fed through a tubing assembly from the cart or tray to reach a standard, unmodified handset.
One major disadvantage of the former category of systems is susceptibility to bacterial growth within the handset, as it is difficult to sterilize a handset that includes the electronics required to provide the controlled heating. A second disadvantage is simply the cost of replacing existing handsets with these heater-augmented versions. A third problem is the difficulty of transferring sufficient heat to the moving fluid within the limited volume of the handset without overheating the other parts of the unit, wasting energy and potentially making the handset uncomfortable or even unsafe to hold.
The main disadvantages of the latter reservoir-based category of systems are the increased space taken up by the reservoirs, and overheating and energy efficiency issues, because of the thermal losses suffered during the relatively long fluid passage from the reservoirs through the tubing and the handset to the mouth. Cases that depend on the water to be delivered being heated on a patient-by-patient basis, prior to filling a reservoir, clearly have an additional “time and trouble” disadvantage.
It is therefore desirable to provide an apparatus that can efficiently transfer heat to water and air and efficiently maintain each fluid at the desired temperature until it is as close as possible to reaching the patient. It would be particularly beneficial if this apparatus were compatible with the use of an unmodified dental handset, allowing standard sterilization procedures to be carried out as necessary. Ideally, the apparatus would also interface simply and smoothly with standard dental cart fixtures, incurring minimal additional cost.
The present invention includes an apparatus that delivers a temperature-controlled fluid to a dental handset. The apparatus comprises a tube assembly comprising an outer tube and a first inner tube. The first inner tube comprises a first input end configured to removably attach to a first source port of a system delivering a first fluid; a first output end configured to removably attach to a first input port in the dental handset; a heating element making good thermal contact with the first inner tube; and a first temperature sensor. The heating element and the first temperature sensor are configured to be operably connected to a temperature control unit such that the temperature control unit controls the heating element in response to a signal received from the temperature sensor.
In one aspect the tube assembly additionally comprises a second inner tube comprising a second input end configured to removably attach to a second source port of a system delivering a second fluid; and a second output end configured to removably attach to a second input port in the dental handset; wherein the heating element further makes good thermal contact with the second inner tube. In another aspect, the first fluid is water and the second fluid is air.
The manner in which the present invention provides its advantages can be more easily understood with reference to
Tube assembly 100 also includes heating element 170, running alongside first inner tube 120A for almost the entire length of that tube. While the figure shows an air gap between 120A and heating element 170 for visual clarity, in reality, there must be good thermal contact between heating element 170 and first inner tube 120A to achieve high thermal efficiency; this is typically achieved by minimizing the apace between them. In some embodiments, the material of the wall of tube 120A is chosen to have high thermal conductivity. Suitable choices include thermally conductive silicone rubber composites. Such materials have the additional advantages of mechanical flexibility and low cost.
In some embodiments, heating element 170 may be simply placed alongside the wall of tube 120A, running lengthwise as shown in the figure. In other embodiments, heating element 170 may be coiled around tube 120, so that it follows a helical path around 120A, into and out of the plane of the figure as well as extending from right to left as shown. In some embodiments, a thermally conductive material, such as a thermal grease compound, may be inserted between heating element 170 and tube 120A. Heating element 170 may be a simple resistive heater, delivering thermal energy to its environment—ultimately the fluid within first inner tube 120A—via I2R heating, where R is the electrical resistance characterizing the element and the current I is supplied by temperature control unit 190.
In many embodiments, almost the entire length of inner tube 120A is in direct thermal contact with heater element 170. In some embodiments, the length of heating element 170 is substantially equal to the length of inner tube 120A.
In the interests of safety and comfort as well as thermal efficiency and effectiveness in controlling fluid temperature, it is desirable that the material making up the wall of outer tube 110 be thermally insulating. One good choice for that material is a thermally insulating silicone rubber, which also has good mechanical flexibility and is of relatively low cost. In some embodiments, the space between inner tube 120A and outer tube 110 comprises air.
Tube assembly 100 also includes temperature sensor 180, which may be of any of a variety of well-known temperature sensor types; a simple thermocouple, for example, or a thermo-resistive or infrared sensor. In all cases, there must be good thermal contact between the sensor and the fluid of interest, either by direct physical contact with first inner tube 120A, or indirectly via a path of low thermal resistance. In the embodiment of
In some embodiments, the temperature control unit may adjust the drive to the heating element to reach and maintain a predetermined temperature value. In other embodiments, the objective may be to reach and maintain a temperature value within a predetermined temperature range. In one experimental example, the range is +/−5 deg F., but it is envisaged that in improved embodiments, the range will be narrower.
In some embodiments, more than one temperature sensor may be present within tube assembly 100, with the output signals from each being used either separately or in combination to feed into control unit 190 and correspondingly determine the output from control unit 190 that drives heating element 170. In some embodiments, one temperature sensor may be positioned close to the input end of first inner tube 120A to monitor the temperature of the fluid entering the tube, providing this information to temperature control unit 190 in addition to the temperature information provided by another temperature sensor, positioned close to the output end of the tube as shown in
In the embodiment of
As standard dental handsets generally convey two fluids—water and air—to the patient, some embodiments of the current invention accommodate the provision of two fluids by including an additional, second inner tube 120B within tube assembly 100, as shown in
In many embodiments, almost the entire length of inner tube 120B is in direct thermal contact with heater element 170. In some embodiments, the length of heating element 170 is substantially equal to the length of inner tube 120B.
In some embodiments, temperature sensor 180 is positioned between first and second inner tubes 120A and 120B, as shown in
One example of the apparatus of the current invention includes the choice of a conductive silicone rubber tube for the first and second inner tubes, and a conductive silicone rubber heating element integrated with one or both. Such an assembly provides good heat transfer in a mechanically flexible tubing assembly.
In some embodiments, tube assembly 100 may include a sheath lying within outer tube 110 and surrounding the combination of first and second inner tubes. The material of the sheath may be chosen to be thermally insulating, confining as much heat as possible to the region containing the fluids of interest, and maintaining outer tube 110 at close to room temperature. In some embodiments, the tube may be formed from a heat-shrinkable PVC tube, encapsulating the inner, fluid-conveying tubes. PVC is thermally insulating, and serves to keep the outer tube cool and easy to handle, as well as, of course, minimizing thermal losses to the environment. The result is a tubing assembly that looks and feels like the tubing assemblies of the prior art, while delivering temperature controlled fluids with higher efficiency and fewer concerns regarding bacterial growth than comparable systems of the prior art.
In some embodiments of the current invention, a tube assembly such as assembly 100 shown in
One major feature of the invention (in comparison to prior art approaches to fluid temperature control for dental applications) is apparent in the various embodiments described above and illustrated by the corresponding figures—the inclusion of heating and sensing components within the tubing assembly connecting the fluid source to the dental handset, rather than within the handset or the source. The interaction between the heating element and the fluid occurs over a long distance (typically between 1 m and 2 m) allowing efficient heat transfer to occur, and readily available, relatively low cost material choices for the tubing walls serve to keep manufacturing costs (and therefore costs to the purchaser) low while maintaining high thermal efficiency. Migrating from a prior art system that lacks thermal control to a system that incorporates the current invention can be as simple as replacing the standard tubing assembly, such as the one shown in
In addition to thermal efficiency, and the cost and convenience advantages mentioned above, limiting the heating element and the sensor to the tubing assembly, with waterproof seals positioned at each end of the assembly, means that the dental handset itself can be sterilized in the usual fashion between uses, without risk of any adverse effects on those heating and sensing components.
In this application, the term “configured to” is defined to mean that the structural element recited before the term has a size, shape, and in some cases, additional features that are structured by design such that the action recited after the term is inherently enabled. For example, stating that the first input end is “configured to removably attach to a first source port of a first system delivering a first fluid” is a compact way of saying that the first input end has the right size and shape and other structural features to allow it to be attached to and detached from a first source port of that type. The first end may be threaded, for example, such that it can screw into or onto a correspondingly threaded port of the source containing the fluid of interest, or it may plug into a port receptacle on that source.
In this application, the term “substantially” is defined to mean approximately, with a margin of +/−10%
The above-described embodiments should be considered as examples of the present invention, rather than as limiting the scope of the invention. Various modifications of the above-described embodiments of the present invention will become apparent to those skilled in the art from the foregoing description and accompanying drawings. Accordingly, the present invention is to be limited solely by the scope of the following claims.
