Abstract:
A heating apparatus ( 10 ) for heating materials used in dental treatment is provided. The heating apparatus ( 10 ) comprises a heating compartment ( 33 ) with a heating element ( 35 ) for heating air inside the heating compartment ( 33 ), at least one socket for receiving and holding at least a part of the materials used in dental treatment inside the heating compartment ( 33 ), and an airflow generator ( 32, 34 ) for generating an airflow in the heating compartment ( 33 ).

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates to a heating apparatus for heating materials used in dental treatment. The heating apparatus comprises a heating compartment with a heating element for heating air inside the heating compartment and at least one socket for receiving and holding at least a part of the materials used in dental treatment inside the heating compartment. 
       BACKGROUND OF THE INVENTION 
       [0002]    In root canal treatment, a patient&#39;s root canal is first emptied and cleaned and then filled with an obturator. The obturator is often made of gutta-percha. Gutta-percha is a thermoplastic natural non-elastic latex. Before pressing the thermoplastic obturator into the emptied and cleaned root canal, it is heated to a suitable temperature for softening the obturator material. For this purpose, dedicated heating apparatuses are on the market. Other materials used in the dental treatment are also heated before being used in the dental treatment, such as, for example, composite for filling a tooth, or a liquid which is used for rinsing a tooth, or rinsing a root canal. 
         [0003]    An example of such a heating apparatus is the Thermaprep Plus Oven made by Dentsply. This oven comprises a heating chamber for heating thermoplastic obturators placed therein. Before using the obturator for filling a root canal, it is placed in an obturator holder and let down into the heating chamber. The heating time for the thermoplastic obturator varies from 25 to 45 seconds, depending on the obturator size and the used thermoplastic material. When at the right temperature, the obturator can be removed from the holder and placed inside the patient&#39;s root canal. 
         [0004]    One of the disadvantages of this known heating apparatus is that the dentist has to wait quite a long time before the obturator is at the right temperature for being inserted into the root canal. This problem is only partly solved by providing a second obturator holder and a corresponding second heating chamber. When a first thermoplastic obturator is inside the first heating chamber, the dentist may already place a second obturator in the second obturator holder. By alternately using the two heating chambers, the efficiency of the whole heating process is slightly improved. However, it still takes between 20 and 45 seconds to bring the thermoplastic material to the desired temperature. 
       OBJECT OF THE INVENTION 
       [0005]    It is an object of the invention to provide a heating apparatus that is more efficient in use. Most importantly, a heating apparatus is desired which is able to decrease the amount of time needed for bringing the obturator to the desired temperature. 
       SUMMARY OF THE INVENTION 
       [0006]    According to a first aspect of the invention, this object is achieved by providing a heating apparatus for heating materials used in dental treatment. The heating apparatus comprises a heating compartment with a heating element for heating air inside the heating compartment, at least one socket for receiving and holding at least a part of the materials used in dental treatment inside the heating compartment, and an airflow generator for generating an airflow in the heating compartment. 
         [0007]    The flow of hot air inside the heating compartment greatly reduces the amount of time needed for bringing the materials used in dental treatment to the desired temperature. With the heating apparatus according to the invention, the heating of the materials may take less than 5 seconds. Additionally, the air flow results in a more uniform temperature distribution inside the heating compartment. The more uniform temperature distribution improves the possibility to control the exact temperature of the materials. Examples of materials used in dental treatment are filling composite for filling a tooth, an ampoule with a dental rinsing liquid, or, for example, a thermoplastic obturator used for filling a dental root canal. 
         [0008]    In a preferred embodiment, the airflow generator is a fan, coupled to a motor for driving the fan, for providing a vortex within the heating compartment. Experiments and simulations have shown that a hot air vortex with a speed of, e.g., 5 m/s, may increase the heat transfer factor with a factor 10. 
         [0009]    In an embodiment, the fan is arranged in the heating compartment such that it can rotate around a rotation axis. The fan comprises at least two blades which extend in a radial direction away from the rotation axis. In a further embodiment, at least a portion of the blades are shaped such that an imaginary line following a surface of the blades forms an angle with the rotation axis to create, within the vortex, an airflow in a direction of the rotation axis. If the blades do not form an angle with the rotation axis, the fan only creates a vortex which rotates around the rotation axis. This may result in temperature differences within the vortex. If at least a part of the blades of the fan are tilted with respect to the rotation axis, the blades also move air of the heating chamber in an upwards and/or downwards direction. Thus, within the vortex, air starts also to circulate in a first and second direction, being opposite directions, and the first and second direction are substantially parallel to the rotation axis. Consequently, temperature differences within the vortex are reduced. In an optional embodiment, the angle between the imaginary line and the rotation axis is in between 5 and 85 degrees. In another embodiment, the angle is in between 5 and 45 degrees. In a further embodiment, the angle is in between 10 and 40 degrees. 
         [0010]    For further improving the temperature control, one or more temperature sensors may be provided in the heating compartment. When coupling the temperature sensor(s) to the heating element, a temperature control loop can be established. 
         [0011]    In a preferred embodiment, the heating apparatus further comprises a rechargeable battery unit for powering the heating element and the motor, the heating apparatus being adapted to be placed on a separate charger for charging the rechargeable battery unit. An important advantage of this embodiment is that the heating apparatus can be used close to the patient, without needing a nearby wall outlet or an extension cord. Only the charger needs to be connected to a wall outlet. The rechargeable battery unit is charged when placed on the charger. When the heating apparatus is needed, it is taken from the charger and placed close to the patient. The heated materials, such as obturators, are taken from the heating apparatus and directly used for the dental treatment, such as the insertion of the obturator into the appropriate root canal. The risks of an obturator cooling too much before insertion and of falling on the floor during the transport from the heating apparatus to the patient are reduced. 
         [0012]    After inserting the obturator into the root canal, the obturator handle still extends from the tooth. This obturator handle may be cut off using pliers or the dentist&#39;s drill. However, the obturator handle is preferably burned away by a heated tool tip of a dedicated cutting device. In a further embodiment of the heating device according to the invention, also a cutting device is provided. The cutting device comprises a cutting tip for burning the obturator handle from the obturator. The heating device further comprises an electric tool heater circuit and a slot for holding the cutting device in such a way that, when the cutting device is provided in the slot, an electrical contact on the cutting device is connected to the electric tool heating circuit for heating a cutting tip of the cutting device. The electric tool heater circuit is preferably also powered by the rechargeable battery unit described above. 
         [0013]    These and other aspects of the invention are apparent from and will be elucidated with reference to the embodiments described hereinafter. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    In the drawings: 
           [0015]      FIG. 1  shows a side view of a heating device according to the invention, 
           [0016]      FIG. 2  shows a top view of the heating device of  FIG. 1 , 
           [0017]      FIG. 3  schematically shows a cross section of the heating device of  FIG. 1 , 
           [0018]      FIG. 4  shows a close up of the cutting device, placed in a dedicated slot of the heating device, and 
           [0019]      FIG. 5  shows a close up of the heating compartment. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0020]      FIG. 1  shows a side view of a heating device  10  according to the invention. The heating device  10  is capable of heating thermoplastic obturators  15  to be used for filling root canals. When a user, probably a dentist, wants to heat an obturator  15 , he takes the obturator handle  16  of the obturator  15  between his fingers and hangs the obturator in a socket provided for holding the obturator  15  (see also  FIGS. 2 and 3 ). The thermoplastic obturator material is then heated to the correct temperature. A temperature control knob  13  may be provided for controlling the temperature inside the heating compartment of the heating device  10 . It is to be noted that the embodiments of the invention are not limited to heating obturators only. In other embodiment, the heating device  110  is also suitable for heating other material for use in dental treatment, such as filling composite for filling a tooth and a small ampoule with a rinsing liquid. 
         [0021]    In this embodiment, the heating device  10  is powered by an internal battery pack, but it may also be powered by a 220V/110V wall outlet. The internal battery pack is preferably rechargeable. A charger  11  is provided for recharging the battery pack when the heating device  10  is placed on it. The charging of the battery pack may be realized via direct electrical connections or via inductive charging. The charger  11  is connected to a wall outlet via a power cord  12 . The main advantage of using a charger  11  and a separate heating device  10  is that the wireless heating device  10  can be placed close to the patient when the obturators  15  are needed. The heated obturators  15  do not have to be transported over large distances before being inserted into a root canal. The risk of heated obturators  15  falling on the floor or cooling too much before being used is thereby reduced. No power cords hinder the freedom of movement of the heating device  10  or of people moving through the area close to the heating device  10 . The charger  11  can be placed close to a wall outlet. When the heating device  10  is not in use, it is placed on the charger  11  and the battery pack is recharged. 
         [0022]      FIG. 2  shows a top view of the heating device  10  of  FIG. 1 . In this view, you can see the obturator handle  16  of an obturator  15  hanging in one of the five obturator sockets  17 . The heating device  10  may have any number of obturator sockets  17 , but it is practical to provide at least two or three obturator sockets  17  to make it possible to heat multiple obturators  15  simultaneously. Often, more than one obturator  15  is needed for treating one patient. The obturator sockets  17  may be provided in an exchangeable obturator interface  14 . When the obturator interface  14  is exchangeable, it is possible to provide different obturator interfaces  14  for different types of obturators, which may have different dimensions. In a preferred embodiment, the obturator interface  14  is recognized by the heating device  10 , e.g. mechanically or electronically, and one or more obturator specific device settings are controlled automatically. 
         [0023]    When the obturator interface  14  is removable, it is also easier to clean the heating compartment (see  FIG. 3 ). Cleaning of the heating compartment may be needed when, e.g., obturator parts fall through the obturator sockets  17  into the heating compartment. Cleaning may even be easier when larger parts of the top surface are removable. If the heating device  10  is used to heat other materials used in dental treatment, the obturator interface  14  may have a slightly different shape such that the other materials may be well supported and may be easily inserted into a heating compartment of the heating device  10 . In a further embodiment, the obturator interface  14  may have differently shaped sockets  17  which are arranged to receive different materials to be used in the dental treatment, such that the different materials may be heated simultaneously. 
         [0024]    The obturator  15  may be inserted into the obturator socket  17  directly from or via a larger opening  18  and a tapered canal leading towards the obturator socket  17 . Next to this larger opening  18 , a slot  19  for holding and, optionally, heating a cutting device is provided. The use of the cutting device is further elucidated below, with reference to  FIG. 4 . A heater ready indicator may be provided for indicating when the device  10  is ready for heating the cutting device. 
         [0025]    Various indicators  21  may be provided, e.g., for indicating a power level of the battery, a temperature inside the heating compartment or how long an obturator has to be kept in the device until it is ready for use. A power button  22  may be provided for turning the device on or off. The power button  22  may light up, when the heating device  10  is connected to the charger  11 . 
         [0026]      FIG. 3  schematically shows a cross section of the heating device  10  of  FIGS. 1 and 2 . In addition to the features already described above, this view shows the heating compartment  33 , a fan  32 , a temperature sensor  36 , a cutting device  30 , the rechargeable battery pack  37 , a charger connector  38   a,    38   b,  a power adapter  39  and some other features that will be discussed below. 
         [0027]    The heating element  35  produces heat for warming the air inside the heating compartment  33 . The walls of the heating compartment  33  are preferably air-tight and made of a heat insulating material to make it easier to control the temperature inside the heating compartment  33  and to save energy. According to the invention, a fan  32  is provided for providing a vortex inside the heating compartment  33 . The vortex of heated air inside the heating compartment  33  greatly reduces the amount of time needed for bringing the thermoplastic material of the obturator  15  to the desired temperature. As a result, the heating of the obturator material may take less than 5 seconds. Experiments and simulations have shown that a hot air vortex with a speed of, e.g., 5 m/s, may increase the heat transfer factor with a factor ten. Higher vortex speeds may lead to even better results. Additionally, the vortex results in a more uniform temperature distribution inside the heating compartment  33 . The more uniform temperature distribution improves the possibility to control the exact temperature of the obturator material. A temperature sensor  36  may be placed in the heating compartment  33  for improving the temperature control. The temperature sensor  36  may be coupled to the heating element and/or the motor  34  of the fan  32  via electronic circuitry for establishing a control loop and keeping the air inside the heating compartment  33  stable and within the preferred temperature range. 
         [0028]    The fan  32  is driven by a motor  34  which is powered by the rechargeable battery  37 . The rechargeable battery  37  is charged when the heating device  10  is placed on the charger  11  and the charge connectors  38   a,    38   b  couple the battery  37  to a power outlet, optionally via a power adapter  39 . The charge connectors  38   a,    38   b  may make an electrical connection or power may be transferred from the charger  11  to the heating device  10  inductively. It is to be noted that, instead of a fan  32  drive by a motor  34 , other known ways of producing airflows may be used. 
         [0029]    An electronic circuit board  41  is provided for comprising the electronic circuits that control the operation of the device  10 . Most or all electronic parts described above are powered by the battery  37  via the electronic circuit board  41 . The exchangeable obturator interface  14  comprises a chip  40  for identifying the type of obturators  15  that are going to be used. Depending on the type of obturators  15  to be expected, some of the operational parameters, such as the temperature inside the heat compartment  33  or the rotational speed of the fan  32 , may be automatically adjusted. 
         [0030]    A cutting device  30  for cutting the obturator handles  16  from the obturators  15  after insertion of the obturator into the patient&#39;s root canal is provided in a slot  19  provided for this purpose.  FIG. 4  shows a close up of the cutting device  30  and the dedicated slot  19 . The cutting device  30  comprises a heating tip  31  for burning the obturator handle  16  from the inserted obturator  15 . A button  43  is provided for switching on and off an internal heating element of the cutting device  30 . When inserted in the corresponding slot  19  of the heating device  10 , electrical contacts  41  on the surface of the cutting device  30  close circuit a heating circuit  42  of the heating device  10 . A heater ready indicator  45  may be provided in the heating device  10  to indicate when the heating tip  31  is warm enough to be used for cutting off an obturator handle  16 . A condensator or rechargeable battery  44  may be provided in the cutting device  30  for keeping the heating tip  31  at the right temperature, when the electrical contacts  41  are not in contact with the heating circuit  42 . 
         [0031]      FIG. 5  shows a close up of the heating compartment. As discussed above, the heating compartment  33  comprises a heating element  35 , a temperature sensor  36 , a fan  32 , and may comprise, in use, the obturator(s)  15  which are attached to the obturator handle  16 . At a bottom of the heating compartment  33  is provided a fan  108  which rotates, in use, around rotation axis  106 . The fan  108  is mechanically connected to the motor  34  which drives, in use, the fan  108 . The fan  108  comprises at least two blades. In  FIG. 5  three blades  104 ,  110 ,  112  are shown. A side surface of blade  112  is shown, which means that blade  112  extends, in the presented position of the fan  108 , from the rotation axis  106  in a direction perpendicular to a plane of the drawing of  FIG. 5 . It is seen that blade  112  is tilted with respect to the rotation axis  106 . This means that, when an imaginary line  102  follows a surface of the blade  112 , the imaginary line forms an angle α with the rotation axis  106 . In  FIG. 5  the whole blade  112  is tilted and, in other embodiments, only a portion of the blade  112  is tilted. The other blades  104 ,  110  are also tilted in a similar way. The result of the tilted blades  104 ,  110 ,  112  is that the air flow in the heating compartment does not only follow the direction of the vortex (which is a direction around the rotation axis  106 ), but that the air also flows in a direction parallel to the rotation axis  106 . In  FIG. 5  air flows  101  are drawn which are created by the fan  108 . The exact direction of air flows  101  depends on the direction in which the fan  108  rotates. At least it may be expected that in a portion of the heating compartment  33  the air flows in an upwards direction (which means: following the rotation axis in a first direction), and that in another portion of the heating compartment  33  the air flows in a downwards direction (which means: following the rotation axis in a second direction which is opposite the first direction). Because of the air flows  101  in a direction following the rotation axis  106 , the temperature within the heating compartment  33  is more homogeneously distributed. In an optional embodiment, the angle α between the imaginary line and the rotation axis is in between 5 and 85 degrees. In another embodiment, the angle α is in between 5 and 45 degrees. In a further embodiment, the angle α is in between 10 and 40 degrees. By selecting a specific angle α, in combination with a specific rotational speed, a speed of the air flows  101  may be influenced. 
         [0032]    It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verb “comprise” and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article “a” or “an” preceding an element does not exclude the presence of a plurality of such elements. The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the device claim enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.