Impression tray for dental prosthesis

(54) Impression tray for dental prosthesis.

(57) The invention relates to an impression tray for taking the impression of the teeth and jaws of a patient with an impression material such as alginate for the production of dental prostheses, this door -print consisting of a handle and a horseshoe-shape d body and having an approximate section of a "U", in this body being formed a multitude of perforations.

This impression tray is characterized in that it comprises, in combination, support elements 22, 23, 35, 36 for the practitioner's fingers disposed at a certain height from the top ** 11 of the body 3 while keeping the perforations 14, 15 ... I located in the support zones 20, 21 and of the holding elements 60 of the impression material when the impression is removed from the patient's mouth and covering the ends 6, 7 of the two branches 4, 5 of the body 3.

The invention relates to the dental industry.

FR 2 561 908 (7d) Applicant (s): FLECHER Michèle, born DELABAYS. FR.

(72) Inventor (s): Michèle Flecher.

(73) Holder (s):

(© Agent (s): Cabinet Lepage and Aubertin.

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Sale of booklets at IMPRIMERlE NATIONALE, 27, rue de la Convention - 75732 PARIS CEDEX 15

- 1 The inven tion relates to an impression tray for taking the impression of the teeth and jaws of a patient with an impression material such as alginate for the production of dental prostheses, this impression tray being composed of a handle and a horseshoe-shaped body and having an approximate section of a U, in this body being practiced a multitude of perforations.

There are already known impression trays composed of a handle and a body as mentioned above. The size of these impression trays depends on the patient's mouth. During the impression taking, the practitioner fills the inside of the impression tray with impression material such as alginate or the like. Then, after positioning the impression tray in the patient's mouth, the practitioner exerts a balanced pressure on the top of the impression tray, this pressure being exerted using the fingers applying horizontally with their ends. and, in particular using the index and middle fingers. After a period of time during which the impression material hardens, the practitioner removes the impression tray. However, it is known that significant deformations are frequently found either at the premolars or at the molars. These two kinds of teeth have very specific characteristics. Their shapes, often globular towards their surfaces and their constrictions, at the level of the collars, make them very retentive. In addition, there are also very retentive parts on the gingival level due to the shape of the jaws due to the presence of very developed roots. However, a good impression is only possible when the retention in the perforations of the impression tray is sufficient to ensure sufficient resistance when removing the impression from the patient's mouth. This retention must allow the compensation of the natural retention of the teeth and jaws.

However, known impression trays have several disadvantages. Indeed, because the practitioner presses with his fingers on the top of the impression tray, he plugs the perforations at the location of the fingers. However, due to the existence of the retention / traction force ratios, it is essential that the perforations reserved for this purpose in the impression trays can fully fulfill the role for which they are intended. It is certain that the plugging of a part of the perforations weakens the retention and, as a result, the resistance ratios between the retention of the impression tray and that of the teeth and jaws are nonexistent or lessened at this level. The impression material

- 2 takes off when the impression is removed, which gives inaccuracies in this area when casting the impression with plaster.

A second area is located at the posterior level and at the end of the impression tray. On the ends from two branches, the impression tray is not perforated and no longer has retention to hold the impression material. The detachment of the latter becomes very easy when the impression is removed.

These sources of error with their repercussions often oblige the practitioner to redo work or spend considerable time on the patient to make grindings due to significant overbites due to these imperfections of the impression.

The object of the present invention is to remedy these drawbacks and proposes to provide means for the impression tray to keep the retention / traction force ratios, on the one hand, while keeping all the perforations free and, on the other hand part, by ensuring the maintenance of the impression material during the removal of the impression, these means can be applied not only when making a new impression tray but can also be adapted to all existing impression trays on the market.

To this end, the invention relates to an impression tray for taking the impression of the teeth and jaws of a patient with an impression material such as alginate for the production of dental prostheses, this impression tray being composed of a mancbeet of a body in the shape of a horseshoe and having an approximate section of a U, in this body being formed a multitude of perforations characterized in that it comprises, in combination, support elements for the practitioner's fingers disposed at a certain height from the top of the body while keeping the perforations located in the support zones free and elements for holding the impression material during of the insertion of the impression from the patient's mouth and covering the ends of the two branches of the body.

The invention will be better understood by referring to the following description given by way of nonlimiting example and to the attached drawings in which:

- Figure 1 is a plan view of an impression tray according to the invention, provided with support elements according to a first embodiment.

- Figure 2 is a partial elevational view of the end of one of the branches of the body of the impression tray provided with the support elements according to the first embodiment.

- 3 - Figure 3 is a plan view of an impression tray according to the invention provided with support elements according to a second embodiment.

- Figure 4 is a partial elevational view of the end of one of the branches of the body of the impression tray provided with the support elements according to a second embodiment.

- Figure 5 is a plan view of the support elements according to the second embodiment.

- Figure 6 is a bottom view of these same elements.

- Figure 7 is a partial view from below of these elements.

- Figure 8 is a plan view of a support plate.

- Figure 9 is a plan view of a lateral fastening element of the support elements according to the second embodiment.

- Figure 10 is a plan view of an impression tray provided with an element for holding the impression material.

- Figure 11 is a partial elevational view of the end of one of the branches of the body of the impression tray provided with the holding element.

- Figure 12 is a plan view of the holding element.

- Figure 13 is an elevational view of this holding element.

We refer to Figures 1 and 2.

The impression tray 1 consists of a handle 2 making it easy to handle the impression tray 1 and of a body 3. The latter has, in plan view, the approximate shape of a horseshoe and consists of two branches 4, 5 flaring towards their free end 6, 7 and a curved connection wall 8 connecting the two branches 4, 5 together. The body 3 has a U-shaped section, the two wings 9 of which, 10 flare down. Both the top 11 and the wings 9, 10 of the body 3 have a multitude of perforations 12, 13, 14, 15, 16, 17 allowing the passage of the impression material such as alginate during the setting operation of the 'footprint. The material in question is placed on the internal faces 18 of the wings 9, 10 and on the internal face 19 of the top 11. When the impression of the teeth and jaws is taken in the mouth of a patient, the impression material passes through these perforations 12, 13, 14, 15,

16, 17. A good impression is only possible when the retention in said perforations 12 to 17 is sufficient to ensure sufficient resistance when leaving the impression from the patient's mouth. To cause the impression material to pass through the perforations 12 to 17, the practitioner exerts pressure on the top 11 of the body 3 of the impression tray

1. According to the invention, the impression tray 1 comprises in the

- 4 zone 20, 21 for supporting the fingers of the practitioner of the support elements 22, 23.

According to a first embodiment, these support elements 22, 23 consist of a metallic mass having an approximate shape of a pyramid whose tip 24 is secured to the top 11 of the body 3 of the impression tray 1. The top 25 of these elements 22, 23 is advantageously provided with grooves 26 to annihilate any sliding of the practitioner's fingers bearing on these elements 22, 23 to depress the impression tray 1 during the impression taking. Thus, the practitioner's fingers are not in direct contact with the top 11 of the impression tray 1 and do not obstruct the retention perforations 12 to 17. The tip 24 is tapered and is located between two perforations. The position of these two support elements 22, 23 must take into account, on the one hand, the size of the impression tray 1 which, in turn, depends on the dimensions of the patient's mouth, and, on the other hand, as a general rule, the practitioner uses the index and middle fingers either with the right hand or with the left hand. According to this embodiment, the support elements 22, 23 form a body with the impression tray 1 and are provided from the manufacture of said impression tray 1. Indeed, frequently, the latter is made of aluminum or plastic, which excludes the subsequent fixing of the support elements 22, 23 by welding and fixing by screwing is relatively empirical because there is a risk that the support elements 22 , 23 unscrew.

However, the subsequent contribution of the support elements 22, 23 is particularly desirable for all the impression trays already existing on the market. To this end, the invention provides a second embodiment represented by FIGS. 3 to 9.

Referring to these Figures 3 to 9. According to this embodiment, there is provided a movable assembly 27 adaptable to all existing impression trays. This mobile assembly 27 comprises an elastic element 28 composed of a central loop 29 and two branches 30, 31. Advantageously, this elastic element 28 is formed from a round wire of hardened nickel-chrome. The space 32 between the two branches 30, 31 is a function of the size of the impression tray and of the position of the support elements 35, 36. On the free ends 33, 34 of the two branches 30, 31 are fixed support elements 35, 36. As indicated above, when the practitioner puts the impression tray 1 filled with impression material in the mouth, he presses with the index and middle finger on the support elements 35, 36 for insertion in the mouth. The ends of these fingers are applied horizontally to said support elements 35, 36 to exert a balanced pressure. The length

- 5 of the index is different from that of the middle finger. This is why the two bearing elements 35, 36 are arranged at different distances 37, 38 from the central loop 29. The distances 37, 38 indicated in the figures apply to right-handers and they are reversed for left-handers.

Each support element 35, 36 having a practically rectangular shape has two truncated corners 39, 40. The cut 41 on the side of the tongue is larger than that 42 located on the side of the cheek. Indeed, it is important to leave this area clear to allow the tongue to move during the taking of the impression of the lower jaw. On the other hand, the cutout 42 on the side of the cheek is less important because there is no risk of injury at this level because the width of the fingers is greater than that of the support elements 35, 36. this fact, the fingers screen between the tray 1 and the cheek of the patient.

Preference is given for these support elements .35, 36 to an unalterable alloy such as chromium-cobalt-molybdenum. Indeed, this alloy must resist corrosion so as to present no danger when the support elements 35, 36 are in contact with the oral environment. The top 43 of these support elements has grooves 44.

The underside 45 of each support element 35, 36 is provided with bosses 46, 47 having a notch 48, 49 serving as a housing at the end 33, 34 of the two branches 30, 31 of the elastic element 28. The height 50 of these bosses 46, 47 makes it possible to obtain an empty space between the top 11 of the body 2 and the support elements 35, 36. The ends 51 of these bosses 46, 47 are tapered and do not obstruct the perforations 12 , 13.

Each support element 35, 36 has on its external edge 52, 53 an elastic element 54, 55 for holding the assembly 28. This elastic element 54, 55 serving as a connecting element between the mobile assembly 28 and the impression tray 1, consists of a loop 56 allowing its fixing on the top 43 of the support elements 35, 36, of a part formed in S 57 and of an end 58 perpendicular to the termination of the formed part in S 57. The latter acts as a clamping means due to its elasticity while the end 58 is engaged in one of the perforations 14 and 17 made in the wings 8, 9 of the tray 1. The location of the end 58 relative to the edge 59 of the support elements 35, 36 is very important, this to avoid a rocking movement of the latter. In addition, it prevents the elastic element 28 from resting on the top 11 of the impression tray 1. The particular shape given to the elastic elements

-6 ques 54, 55 allows easy movement of the end 58 depending on the location of the perforations 14 and 17 either in traction upwards or downwards, or towards the rear part.

In accordance with the invention, in order to obtain maximum retention, the free ends 6, 7 of the branches 4, 5 of the impression tray 1 are provided with a holding element 60.

For this purpose, reference is made to FIGS. 10 to 13.

This holding element 60 extending beyond the rear edge 61 of the body 3 of the impression tray 1 consists of an elastic element of oval shape.

The central turns 62 of the holding element 60 keep the impression material in contact with the impression tray 1 during the removal of the impression from the patient's mouth. The central turns 62 are arranged between two branches 63, 64 which intersect, giving the holding element 60 a pinching effect. The ends 65, 66 of these two branches 63, 64 are provided with hooks 67, 68 engaged from the inside towards the outside in the perforations 14 to 17 situated at the end 69, 70 of the wings 9, 10 of the body 3 .

Although the invention has been described in connection with a particular embodiment, it is understood that it is in no way limited thereto and that there can be made various modifications of shapes, materials and combinations of these various elements, without departing from the scope and spirit of the invention.