METHOD AND APPARATUS FOR TEMPERATURE CONTROL OF DENTAL MATERIALS, PARTICULARLY MATERIALS FOR DENTAL IMPRESSIONS

D e s c r i p t i o n

The present invention relates to a method of controlling the temperature of dental materials, in particular materials for dental impressions.

The invention also relates to an apparatus for temperature control of dental materials capable of carrying into effect the above mentioned method.

The present invention applies to the dental-treatment and dental-technology sector, and in particular it is suitable for use in preparing materials designed to make imprint moulds or dental impressions, such as the thermochromic silicone two-component compositions, to be mixed together immediately before use.

It is known that dental impressions are usually taken by application of said two-component compositions into the patients' buccal cavity where they set, i.e. become hard, until taking a shape matching that of the corresponding dental arches.

Usually the setting process starts, by addition cross- linking or condensation, immediately after mixing of the two components, i.e. base and catalyst, constituting the material used.

The reaction rate and consequently the setting rate of the compositions greatly varies in connection with the temperature of the latter before mixing.

In particular, it is known that even relatively moderate temperature variations greatly affect the setting rates (15°C more or 15°C less give rise to a reduction or an acceleration of 100%) , the working and setting times of the mixture.

In order to control the reaction rate during the working time and setting time of the two-component compositions to be prepared, although in an approximate and imprecise manner, the usual procedure involves heating or cooling of said compositions by disposing them either in hot or room temperature environments or in cold environments such as the refrigerators. Obviously, cooling or heating of the above mentioned compositions cause an unforeseeable slowing down or acceleration of the setting reaction because they strictly depend on imprecise adjustments that in turn are likely to suffer from unforeseeable variations.

The Applicant has found that, although dental impressions and moulds can be obtained through use of the present techniques, these techniques can be improved under different points of view, mainly in relation to control of the application rate or the work and setting rate of the materials used, as well as to regulation of the composition temperatures before preparation of said compositions.

In particular, the impossibility or difficulty in cooling or heating the required compositions in a precise manner for preparation of the material for dental impressions, as well as the difficulty in maintaining said temperatures constant (due to seasonal climatic or geographic conditions) , give rise, in terms of setting reaction, to unexpected setting rates that

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are sometimes hardly foreseeable. Consequently, during these operations a continuous control of the setting state of the material inside the patients' buccal cavity is required in order to perceive achievement of the desired solid state.

Under this situation, the technical task underlying the present invention is to propose a method and an apparatus for the ideal and susceptible-of- personalisation temperature regulation of dental materials, in particular materials for dental impressions, capable of substantially eliminating the drawbacks of the known art.

Within the scope of this technical task, it is an important aim of the invention to propose a method and a device enabling selective heating or cooling of one or more dental materials necessary for taking dental impressions in relation to the desired reference temperature.

It is a further technical aim of the invention to ensure constant maintenance of the temperature imparted to the dental material during the thermoregulation step.

The technical task mentioned and the aims specified are substantially achieved by a method and an apparatus for temperature control of dental materials, particularly materials for dental impressions, as described and set out in one or more of the appended claims.

Description of a preferred but not exclusive embodiment of a method and an apparatus for temperature control of dental materials, particularly materials for dental

impressions in accordance with the invention is given hereinafter by way of non-limiting example and illustrated in the accompanying drawings, in which:

- Fig. 1 is a perspective view of an apparatus for temperature control of dental materials, particularly materials for dental impressions, in accordance with the present invention;

- Fig. 2 is a diagrammatic view in section of the apparatus seen in the preceding figure; - Fig. 3 is an elevation view of the apparatus shown in the preceding figures.

With reference to the drawings, an apparatus for temperature control of dental materials, particularly materials for dental impressions in accordance with the invention has been generally identified with reference numeral 1.

As viewed from the accompanying figures, apparatus 1 on the whole comprises a structure 2 preferably having a box-shaped conformation made of plastic or similar material at least externally.

Just as a mere indication, structure 2 shall have a height of about 290 mm, a depth of about 260 mm and a width of about 265 mm so that it is of reduced bulkiness and can be easily carried.

In particular, structure 2 comprises a base portion 2a having at least one cavity 3 (Fig. 3) open at the top and a cover 2b having at least one corresponding seat 4 too (Fig. 3) . Cover 2b is hinged on the base portion 2a and is movable between a closed position at which it abuts against the base portion 2a (Figs. 1 and 3) to close the cavity 3 of the base portion 2a and prevent

access thereto, and an open position (not shown) at which cover 2b is lifted and cavity 3 of the base portion 2a is accessible from the outside to enable introduction of at least one dental material for taking dental impressions.

Structure 2 internally defines, through cavity 3 of the base portion 2a and seat 4 of cover 2b, a thermoregulation environment 5 designed to house at least one container 6, 7, 8 or similar casing provided with the dental material, such as chromatic silicone two-component compositions or similar setting materials .

Advantageously, both the base portion 2a and cover 2b have walls provided with one layer of thermally insulating material 9 (Fig. 2) , such as foamed polyurethane or similar material for heat insulation, capable of insulating the thermoregulation environment 5 from the surrounding atmosphere when cover 2b is in its closed position. In other words, still with reference to Fig. 2, the thermally insulating material 9 is interposed between the thermoregulation environment 5 and an outer cap 10 defining the box- shaped conformation of structure 2.

By way of example only, cavity 3 will be able to simultaneously house two 50-ml cartridges 8 with related tip and two 380-ml cartridges 6, 7 with related tip.

As shown in Fig. 2, apparatus 1 comprises thermoregulation means 11 operatively associated with the base portion 2a of structure 2 for temperature regulation of the dental material placed inside the

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thermoregulation environment 5.

Advantageously, the thermoregulation means 11 comprises at least one Peltier cell 12 that can be electrically connected by means of one or more conductors (not shown as known) to a power supply. The Peltier cell 12 (and generally a pack consisting of a plurality of said cells) can be activated between a first condition at which it heats the dental material present inside the thermoregulation environment 5, and a second condition at which it cools this dental material, so that the same device can selectively allow heating or cooling of the internal environment 5.

In particular, activation of the Peltier cell 12 between the first and second conditions is obtained by passage of a direct-current flow through one or more conductive elements (not shown in the figures) of the Peltier cell itself, in a predetermined sense or direction. Depending on the flow direction, at least one surface of the Peltier cell 12 is heated (first condition) and the opposed surface is cooled (second condition) . In this manner, the Peltier cell 12 heats or cools the thermoregulation environment 5 depending on the sense of passage of the current bringing said environment from a starting temperature corresponding to the room temperature, to a predetermined reference temperature, higher or lower than the starting temperature. Advantageously the reference temperature is determined in relation to the desired setting rate for the dental material during application of same into the buccal cavity of a patient.

In order to uniformly ensure the same temperature in all parts of the thermoregulation environment 5,

apparatus 1 is provided with at least one ventilation device 13 operatively associated with a surface of the Peltier cell 12 facing environment 5, to cause circulation of a fluid (air) present inside the thermoregulation environment 5. In this case air heating or cooling takes place by means of the Peltier cell 12 by conduction in ^' such a manner that the thermoregulation environment 5 is in turn heated or cooled.

As shown in Fig. 2, the ventilation device 13 comprises at least one fan 13a positioned close to the Peltier cell 12. Fan 13a is drivable in rotation to determine circulation of air within the thermoregulation environment 5. In this manner the heated or cooled air travels within environment 5 thus surrounding and at least partly, but preferably fully, impinging on containers 6, 1 , 8 provided with the respective dental materials .

As shown in Fig. 2, apparatus 1 is further provided with a heat dispersion device 14 operatively associated with the Peltier cell 12 on the opposite side from the ventilation device 13.

In particular, the heat dispersion device 14 comprises at least one dispersion fan 15 disposed close to the Peltier cell 12 on the opposite side from fan 13a of the ventilation device 13.

As shown in Fig. 2, the dispersion fan 15 is operatively disposed in a communication channel 16 between the thermoregulation environment 5 and a vent chamber 17 formed inside the base portion 2a of ^' structure 2. The dispersion fan 15 is drivable in

rotation to generate a continuous air stream from the Peltier system 12 to the vent chamber 17, through the communication channel 16.

Advantageously, the heat dispersion device 14 comprises at least one heat sink 18, preferably of the close- blade type, disposed within the vent chamber 17 adjacent to the communication channel 16 and the dispersion fan 15, so that the air stream produced by the last-mentioned fan impinges on the heat sink 18 when it reaches the vent chamber 17.

Still with reference to Fig. 2, apparatus 1 is further provided with a vent fan 19 operatively placed within the vent chamber 17 to cause an air stream from the vent chamber 17 to the external atmosphere, in case of need.

Referring particularly to the preferential embodiment shown in Fig. 2, cavity 3 of the base portion 2a has at least two chambers 20, 21 in fluid communication by means of one or more connecting ducts 22 so that the air heated or cooled by the Peltier cell 12 and moved by fan 13a circulates ^" - ^' within the whole environment 5 without distinction. A first chamber 21 houses the Peltier system 12 and fan 13a, while ^" a second chamber 21, preferably bigger than the first chamber 20, is adapted to receive containers 6, 7 holding the dental material the temperature of which is to be regulated. Advantageously, the second chamber 21 has at least one auxiliary compartment 23 of reduced volume for housing further dental material ready for mixing. The auxiliary compartment 23 is separated from the rest of the second chamber 21 by a partition 24 provided with one or more communication ducts 25 to enable passage of the air

circulating within the thermoregulation environment 5.

Advantageously, the thermoregulation environment 5 has a coating 26 made of a thermally conductive material such as aluminium or the like, so as to possibly enable heat exchange by conduction between the conductive element 12a and the dental material placed in the thermoregulation environment 5.

The invention further relates to a method of controlling the temperature or dental materials, in particular materials for dental impressions.

The method firstly comprises introduction of at least one container 6, 7, 8 provided with dental material for taking dental impressions, into a thermoregulation environment 5 defined at the inside of apparatus 1.

Once the dental material, the temperature of which is wished to be controlled, is introduced into apparatus 1 by a suitable electronic control unit, a reference temperature is inputted to bring the thermoregulation environment 5 and dental material placed therein from a starting temperature corresponding to the room temperature, to the inputted temperature. Input of the reference temperature is carried out by entering, through an interface 3θy a temperature that can be both higher and lower than the room temperature so that the thermoregulation environment 5 is selectively heated or cooled relative to the surrounding atmosphere, depending on requirements.

Preferably, the reference temperature is determined and inputted to a given value in the range of 15°-30°C, for instance to a value of 20 ⁰ C; obviously the temperature

generated inside the environment will be included in a tolerance range centred on the inputted temperature (accuracy of temperature control +; 0.2 ⁰ C), in any case between a slightly higher and slightly lower value.

Advantageously, the heating or cooling steps are carried out inside the thermoregulation environment 5 itself. Heating or cooling of dental material is at least partly obtained by convection through heating or cooling of the air present in the thermoregulation environment 5.

In order to increase the heating or cooling action and carry out a uniform distribution of the desired temperature, air circulation is suitably caused. In this way said air impinges on the dental material and gives rise to heat exchange with the latter. Preferably, fluid circulation in the thermoregulation environment 5 is carried out continuously to keep the desired application temperature constant and uniform.

In detail, the dental-material heating or cooling step is performed using the Peltier system 12 that, depending on the direction of the electric current associated therewith heats or cools the thermoregulation environment 5.

The above mentioned temperature control has been conceived for use on chromatic silicone two-component materials, i.e. made up. of a base and a catalyst that, suitably mixed, react becoming conveniently set.

Initial introduction of the dental material into the thermoregulation environment 5 therefore consists in introducing both the bases and catalysts that are

submitted to the required heating or cooling operations to cause the desired setting rate.

Obviously, the apparatus and related method can be also employed for other materials in use in the dentist/odontologist ' s surgery that benefit from being at a controlled temperature.

The invention solves the problems found in the known art and achieves important advantages.

First of all, the method and apparatus of the present invention enable a precise temperature regulation of the dental materials for dental impressions. In particular, the object of the present invention allows, within the same thermoregulation environment, heating or cooling of dental materials relative to a room temperature depending on the desired setting rate during the step of taking impressions. The possibility of both controlling the temperature of said materials and keeping them to th,e inputted temperature allows the setting rates of the materials themselves to be regulated in a precise manner in the patients ' buccal cavities without a continuous control of the setting state being required.