Patent Description:
More specifically, the invention relates to an apparatus for thermoforming movable dental apparatuses in which at least one moulding support is present suitable to house a dental arch, a mounting support suitable to house a thermoformable sheet, a heating position in which a heating device for heating the thermoformable sheet is present housed in the relative mounting support and a moulding position in which there is a moulding device suitable to realize together with the moulding support and mounting support a moulding chamber in which the impression and the thermoformable sheet previously heated in the heating position are located and in which a vacuum/overpressure is created to execute the thermoforming of said thermoformable sheet (F).

Movable dental apparatuses, in particular mouth guards and aligners, are functional apparatuses to be applied to the dental arch to correct specific positioning defects. In particular, the aligners are manufactured with CAM-CAD (Computer-aided manufacturing/Computer-aided design) technology: starting from the plaster impression of the patient's dental arch and then proceeding with a 3D scan of the same in order to digitize the geometry and obtain virtual 3D models. Subsequently, through the use of CAD software, the corrective stages of the malocclusion and the physical models of the arches for each of the corrective stages are reproduced. Based on these physical models, a series of aligners necessary to satisfy the intended treatment is moulded. In fact, the treatment with invisible aligners is based on the sequential use of aligners, realized with transparent thermoplastic material and characterized by appropriate geometry. A certain number of aligners must therefore be made for each patient.

The aligners are made of a thermoformable material such as polypropylene (PP), polycarbonate (PC), polyethylene terephthalate glycol (PETG) or thermoplastic polyurethane (TPU), by means of a thermoforming apparatus.

An apparatus for thermoforming dental aligners conventionally comprises a moulding support on which the dental arch is rested, a mounting support in which the thermoformable disc is housed, a heating head in which the thermoformable disc is heated to soften and a moulding moulding head in which a moulding chamber is created in which the dental arch and the softened disc superimposed thereon are located and in which a vacuum or overpressure is created to cause the disc to copy the shape of the impression.

Still conventionally, these apparatuses comprise a single working head in which the heating station and the moulding station are present and a mounting support which contains the thermoformable disc is manually fed first to the heating station and then moved, again manually, to the moulding station, in which the dental arch to be copied is arranged, also in this case manually.

Also known are so-called automatic devices in which the soft disc is moved from the heating station to the moulding station automatically.

Apparatuses as outlined above are, for example, those covered by European patent <CIT> and German patent <CIT>.

In the operation of this type of machine, the high operator time required is a very significant limitation since, as previously highlighted, each individual treatment requires the production of a multiplicity of aligners. In fact, the analysis of the required operator time showed that the operator must always remain close to the machine to reload the disc and dental arch when the cycle is finished. The type with automatic movement is more advantageous because it does not require the intermediate operation of the operator to move the heated disc from the heating zone to the moulding zone. The operator time for each aligner produced is estimated at approximately <NUM> seconds of machine operation in the manual type, to which are added approximately <NUM> seconds of loading and unloading the disc and dental arch. The operator time for the automatic type is comparable to the previous one if the machine must continuously produce a number of aligners. In fact, by producing one aligner at a time, despite being automated from heating to moulding, the operator must still load one set at a time at the end of a cycle.

Apparatuses capable of producing multiple aligners at the same time are also known, thus reducing the operator time required to make a number of aligners. This category includes apparatuses having a single moulding head of increased size in which more than one dental impression may be housed at the same time and a moulding disc of increased size. In this type of apparatus the operator times are obviously reduced and however the aligners produced with this type of apparatus are judged of poor quality because the presence of several dental impressions (up to <NUM>) on which a single thermoformable material disc is thermoformed results in an incorrect stretching of the disc heated on the impression and therefore in an inadequate quality of the final product.

Finally, apparatuses are also known comprising a plurality of heating heads and as many moulding heads for simultaneously thermoforming a plurality of aligners. An apparatus of this type is described for example in <CIT> which provides a vacuum plate to which are associated a plurality of supports suitable to house dental impressions arranged in succession. The thermoformable material in the form of a continuous strip is fed to extend over the plate over which there is a heating head with a plurality of heating elements movable over the plate between a waiting position and a heating position. When the thermoformable material is lying on the plate, a plurality of aligners can be made simultaneously. However, also in this apparatus there is a single thermoformable sheet, thus it has the same limits as the system with enlarged head previously described.

Another limit of all the apparatuses highlighted above is related to the heating step. In most of the apparatuses the heating step is timed. This often results in a not optimal heating of the moulding disc mainly due to possible small differences in the thickness thereof or to the use of thermoformable materials of different composition.

From <CIT> the possibility of measuring the temperature reached by the thermoformable disc by means of an infrared sensor is also known. However, this involves the heating term being defined based on the achievement of a certain temperature. The infrared sensor has on the one hand a high cost, and also performs a reading that is not always precise both because the thermoformable disc has high radial thermal gradients and because this measurement can be influenced by the presence of the heating element present above.

Other documents in the art are exemplified by <CIT> and <CIT>.

The object of the present invention is to propose an apparatus for the thermoforming of dental aligners capable of exceeding the limits of the prior art highlighted above, in particular with regard to the operator time necessary to realize an entire set of aligners.

Another object of the present invention is to propose an apparatus for the thermoforming of dental aligners that has a high productivity, both by virtue of the reduced operator times, and for a drastic reduction of the moulding time.

Another object of the present invention is to propose an apparatus for thermoforming aligners in which the heating head is optimized in particular to ensure that the thermoformable disc is optimally heated.

The above objects are achieved by an apparatus for the thermoforming of dental aligners as provided in claim <NUM>.

Conventionally, an apparatus for the thermoforming of dental aligners, comprises a support structure suitable to house a plurality of moulding supports each suitable to house at least one dental arch, a mounting support suitable to house a thermoformable sheet and a relative retaining ring element, a heating device for heating a thermoformable sheet housed in said mounting support and a moulding device suitable to realize together with said moulding support and mounting support a moulding chamber, said moulding device being suitable to realize a vacuum/overpressure in said moulding chamber for executing the thermoforming of said thermoformable sheet, said mounting support being movable at least between a heating position in which it is associated with said heating device and a moulding position in which it is associated with said moulding device.

According to a characteristic aspect of the present invention, to each of said moulding supports of the apparatus are associated a relative mounting support and retaining ring element in an operating module, a plurality of operating modules being arranged at an angle equidistant on a rotary table of said support structure, said rotary table being operated in rotation in discrete steps to bring each of said operating modules in succession, first at said heating position and subsequently at said moulding position.

By virtue of the presence of a plurality of operating modules mounted on a rotary table, the apparatus of the invention allows to simultaneously load a plurality of sets for realizing as many dental impressions, thus allowing the operator to not man the apparatus for the entire processing period until all the aligners have been made.

Advantageously, the heating device comprises at least one contactless sensor arranged to detect a certain amount of deformation of said thermoformable sheet as a result of the softening to which it is subject due to the heating, a control unit of said apparatus being configured to determine the interruption of a heating step in said heating position as a function of the information received from said contactless sensor.

The contactless sensor detects the extent of deformation undergone by the thermoformable disc as a result of its softening and thus allows to directly determine when the degree of softening achieved is ideal for the subsequent moulding operation.

These and other advantages associated with the apparatus for the thermoforming of dental aligners of the present invention will moreover be more easily understood by means of the illustration of a non-limiting embodiment, as described below with the aid of the attached drawings, in which:.

With reference to <FIG> and <FIG>, an apparatus for thermoforming dental aligners according to the present invention is indicated as a whole with <NUM>, which comprises a support structure, <NUM>, provided with feet, <NUM>, on which a rotary table, <NUM>, centrally hinged to the support structure <NUM> and operated in rotation with respect to its vertical barycentral axis by means of a gear motor, <NUM>, housed on the support structure <NUM> near the rotation axis of the table <NUM> and electronically controlled.

On the rotary table <NUM> are arranged at an angle equidistant from each other a plurality of operating modules, <NUM>, which in this embodiment are ten in number.

With reference to <FIG>, each operating module <NUM> comprises: a moulding support, <NUM>, permanently anchored to the rotary table <NUM> and arranged to receive at least one dental arch, I; a vertical slide, <NUM> to which a mounting support, <NUM> is slidably associated; a return element, <NUM> consisting in this embodiment of a spring, suitable to push the mounting support <NUM> upwards; and a locking/unlocking mechanism , <NUM>, which keeps the mounting support <NUM> locked in a lowered moulding position, PA, when the latter is pushed downwards and which selectively releases it to allow it to return to a raised position, PS. In alternative embodiments, the reference element may be of a magnetic type and the locking/unlocking mechanism <NUM> may not be present in this case.

With reference in particular to <FIG>, the mounting support <NUM>, movable above the moulding support <NUM>, is suitable to house a thermoformable disc, F, and a retaining ring, <NUM>, which keeps the disc F in position once inserted into the mounting support <NUM>.

Referring to <FIG>, <FIG> and <FIG>, at a position which each operating group <NUM> can assume following the rotation of the rotary table <NUM>, called the heating position, PR, a heating device <NUM> is mounted. The heating device <NUM> provides a heating head, <NUM>, mounted above the raised position PS of the mounting support <NUM>, by means of a column, <NUM>, stably associated with the support structure <NUM>. An arm, <NUM>, arranged at an adjustable height along the column <NUM>, carries a contactless sensor, <NUM>, arranged below the mounting support <NUM> near the latter. The contactless sensor <NUM> is advantageously a horizontally arranged optical sensor for measuring the vertical deformation of the heated thermoformable disc F. In fact, as schematically shown in <FIG>, following the heating, the disc F softens moulding, due to the force of gravity, a sort of bubble extending downwards with respect to the relative initial lying plane. When the bubble reaches the height at which the sensor <NUM> is positioned, it is detected by the sensor and consequently a control unit of the apparatus interrupts the heating step.

Referring to <FIG>, <FIG> and <FIG>, at a further position that each operating group <NUM> can assume following the rotation of the rotary table <NUM>, called the moulding position, PF, a moulding device <NUM> is mounted.

The moulding device <NUM> comprises a cylinder, <NUM>, with a piston, <NUM>, which actuated downwards presses on the retaining ring <NUM> bringing the mounting support <NUM> in its lowered position in abutment on the moulding support <NUM>. In this configuration, the moulding support <NUM>, the mounting support <NUM> and the piston <NUM> define a sealed moulding chamber <NUM>. According to known methods, at least one inlet pipe <NUM> is provided for bringing a fluid to the moulding chamber so as to put pressure on the latter so that during a moulding time the disc F is pushed to copy the shape of the dental arch I. In the advantageous embodiment illustrated in <FIG>, the moulding device <NUM> comprises an outlet pipe, <NUM>, communicating with the moulding chamber <NUM> to allow the expulsion of gas from said moulding chamber <NUM>. The outlet pipe <NUM> is arranged to remain at least partially open during the application of the moulding pressure, so that during the application of said moulding pressure there is a gas circulation from the inlet pipe <NUM> to the moulding chamber (<NUM>) and then to the outlet pipe <NUM> to be expelled outside the moulding device. This makes it possible to significantly reduce the moulding time and therefore increase the productivity of the apparatus since the gas circulation in the moulding chamber <NUM> allows a high heat removal and therefore a much faster cooling of the thermoformable material. The outlet pipe <NUM> is obviously calibrated in size to allow the flow of gas without causing significant pressure losses in the moulding chamber <NUM>. Alternatively, the pipe <NUM> may be opened with a certain delay with respect to the closure of the moulding chamber <NUM> and the realization of the overpressure therein.

The moulding device <NUM> is mounted on a self-supporting structure, <NUM>, associated with the support structure <NUM> and which provides a striker element, <NUM>, arranged below in contact with said rotary table <NUM> during the downward pressure operation of the piston <NUM> so that the pressure exerted by said piston <NUM> is supported by said striker element <NUM> instead of by the rotary table <NUM>. In fact, as indicated by the arrows in <FIG>, when the piston <NUM> is lowered to bring the mounting support <NUM> into the lowered position PA, the self-supporting structure <NUM> is raised by bringing the striker element <NUM> in abutment under the rotary table <NUM>. Thereby, the relevant applied forces of the piston <NUM> and the pressure present in the moulding chamber <NUM> (about <NUM> - <NUM>), are not supported by the rotary table <NUM>, which could suffer damage to the relative bearings through which it is mounted on the support structure <NUM>, but by the striker element <NUM>.

From the foregoing description, the operating mode of an apparatus according to the present invention is readily understandable. The automatic movement for discrete angular steps of the rotary table <NUM> brings the operating modules <NUM> in succession first at the heating position PR and then at the moulding position PF. The moulding of the disc F present in an operating module <NUM> and the heating of the disc F present in the angularly subsequent operating module <NUM> therefore take place simultaneously without dead times. The movement of the rotary table <NUM>, the activation and deactivation of the heating device <NUM> and the activation and deactivation of the moulding device <NUM> are automated and controlled by a programmable control unit.

Claim 1:
Apparatus (<NUM>) for thermoforming dental aligners, said apparatus (<NUM>) comprising a support structure (<NUM>) which houses a plurality of moulding supports (<NUM>) each one suitable to house at least one dental arch (I), a plurality of mounting supports (<NUM>) each with a relative retaining ring element (<NUM>) suitable to house and retain a thermoformable sheet (F), a heating device (<NUM>) for heating a thermoformable sheet (F) adapted to be housed in said mounting support (<NUM>) and a moulding device (<NUM>) suitable to realize together with said moulding support (<NUM>) and mounting support (<NUM>) a moulding chamber (<NUM>), said moulding device (<NUM>) being suitable to create a vacuum/overpressure in said moulding chamber (<NUM>) to execute the thermoforming of said thermoformable sheet (F), said mounting support (<NUM>) being mobile at least between a heating position (PR) in which it is associated with said heating device (<NUM>) and a moulding position (PF) in which it is associated with said moulding device (<NUM>), said apparatus (<NUM>) being characterised in that each of said moulding supports (<NUM>) is associated with a relative one of said mounting supports (<NUM>) and a relative one of said annular retaining elements (<NUM>) in an operating module (<NUM>), a plurality of operating modules (<NUM>) being placed at an angle equidistant on a rotary table (<NUM>) of said support structure (<NUM>), said rotary table (<NUM>) being operated in rotation in discrete steps to bring each of said operating modules (<NUM>) in succession, first at said heating position (PR) and then at said moulding position (PF)