US 3360860 A
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Description (OCR text may contain errors)
Jan. 2, 1968 J. H. ROLAND 3,360,860
APPARATUS FOR PREPARING IMPRESSIONS OF THE MANDIBULAR DENTITION Filed Sept. 23, 1965 INVENTOR JOHN H. ROLAND BYM-fl W ATTORNEY United States Patent 3,360,860 APPARATUS FOR PREPARING IMPRESSIONS OF THE MANDIBULAR DENTITION John H. Roland, 1435 Rockland St., Reading, Pa. 19604 Filed Sept. 23, 1963, Ser. No. 310,544 6 Claims. (Cl. 32-17) This invention relates to improved means for preparing models of the mandibular dentition and, more particularly, to improvements in lower dental impression trays.
In preparing dentures, an initial impression is cast of the patients dentition by using a settable material such as alginate. The alginate is carried in a dental impression tray which, when positioned in the patients mouth, enables an accurate impression of the patients dentition to be made in the alignate. After the alginate has set, the tray is removed from the mouth and a model of the patients dentition is made by pouring model material, such as plaster of Paris or artificial stone, into the alginate impression. This model, in turn, is then used in the preparation of the finished denture.
In preparing the model from the alginate impression, it is first necessary to form a retaining wall or flange around the impression in order to retain the plaster. Common practice in the preparation of such a model is to build by hand a clay or wax flange around the sides of the impression tray. Alternately, a band of metal or other flexible material may be used to circumscribe the impression. This is generally referred to as boxing. Once the impression has been boxed and filled with plaster, the impression is held on a vibrator to facilitate uniform distribution of the model material throughout the impression and remove any bubbles or voids.
As an alternative method of preparing the model, only a small amount of the model material is placed in the impression. It is placed on a vibrator and is then inverted onto a glass plate having a mound of model material. By pressing the tray into the model material, the entire impression is filled. This alternative method avoids the necessity of boxing the alignate impression, as the excess plaster may be scraped away from the periphery of the impres- SlOIl.
In either of the above two methods, difliculties are encountered with respect to the lower dental impression tray due to the fact that this tray necessarily carries an opening for resting the tongue when the impression tray is positioned in the patients mouth. This opening is called the lingual opening and is defined by the lingual flange of the lower impression tray. This lingual flange generally conforms to the shape of the tongue and is therefore approximately hyperbolic.
In the first method of making the plaster model, the lingual opening will become filled with model material unless suitable steps are taken to fill the lingual opening, as with modeling clay. If this is not done, the lingual opening will be filled with model material, and it is necessary to chip or cut this away after the model has been formed. This can be time consuming Work, and also makes it diflicult to obtain a smooth surface adjacent the lingual opening.
In the second instance, when the lower impression tray is inverted onto a mound of model material, the plaster will be forced into the lingual opening and again require removal as above. While it is possible to remove this excess material from the lingual opening before it has fully set up, thus avoiding the problem of chipping it away, this must be accomplished at the appropriate time and requires surveillance of the model material throughout the setting-up operation.
Accordingly, it is an object of this invention to provide a lower dental impression tray that will prevent model material from entering the lingual opening when the impression tray is filled with model material.
Another object of this invention is to provide methods and means whereby the alternative steps of plugging the lingual opening of the lower impression tray or removing excess model material therefrom are avoided in the preparation of models of the mandibular dentition.
Briefly, the objects of this invention are achieved by providing a groove or slotted rib around the top edge of the lingual flange. (When the terms top and bottom of the impression tray are used herein, such references refer to the impression tray when positioned for pouring a model. Accordingly, when the impression tray is in the patients mouth, the top of the tray will actually be lowermost.)
The slotted or grooved portion of the lingual flange is adapted to receive a flat plate, preferably made of a thin, but not readily deformable, metal or plastic, and the shape of such insert is such as to conform with and close the lingual opening of the upper portion of the lingual flange. By making such provision, the insert prevents model material from entering the lingual opening when model material is poured into the impression.
The invention will further be described in greater detail with reference to the attached drawing which forms a part of this specification.
The figure is a perspective and somewhat schematic view of the device of this invention, including a boxing device, an impression tray, and an insert for the lingual opening.
In somewhat greater detail, there is shown in the figure a conventional tray for making impressions of the lower teeth and gums. The tray, generally designated 2, is comprised of a horizontally disposed, generally U shaped main portion 4, outside flange member 5, and inside flange (the lingual flange) member 6. Both flanges 5 and 6 are connected with the main portion 4. The composite structure is adapted to be positioned within a patients mouth and will generally conform to and enclose the mandibular dentition. The tray is ordinarily fabricated from a reticulated metal and, for ease in manipulation, a handle 8 is provided.
The opening defined by the lingual flange 6 is the lingual opening that is adapted to receive the patients tongue when the tray is inserted in the mouth. A plate 3, comprised of a thin metal or plastic, is adapted to be received in sealing frictional engagement with the slotted or grooved portion 7 adjacent the top of the lingual flange. For ease in inserting the plate 3 into the grooved portion 7, the plate may have beveled edge portions (not shown) where plate 3 contacts the grooved portion.
There is also shown in the drawing a strip of flexible metal 1 adapted to circumscribe the impression tray for boxing the tray. While this strip may be comprised of any readily deformable metal, it may also be made of a plastic material that is readily deformable and which will conform to the outside configuration of the impression tray.
In operation, the impression tray 2 is filled with a moldable material (not shown) such as alginate, and the tray is then inserted into the patients mouth and pressed down against the lower dentition. After a clear impression has been made in the alginate and time has been allowed for it to set up, the tray 2 is removed from the patients mouth. The reticular structure of the impression tray enables excess alginate to be squeezed out of the impression tray when the impression is being made.
After the tray has been removed from the patients mouth, the plate 3 is positioned in the grooved portion 7 of the lingual flange 6, thus sealing the lingual opening. A flexible strip'l is then-positioned circumferentially around the tray and held in such position by any suitable device, i.e., rubber bands.
Once the tray has been so boxed, model material such as plaster of Paris or artificial stone is poured into the alginate impression and the filled alginate impression is vibrated. Alternatively, as mentioned above, if the impression tray is not boxed, a small quantity of model material may be poured into the alginateim-pression, vibrated, and then inverted onto and pressed into a mound of model material.
In either of the above methods, it is readily apparent that the model material is prevented from entering the lingual opening due to the provision for plate 3. Thus, it is unnecessary to remove model material from the lingual opening, and a clean, smooth surface of the lingual opening results without further effort.
As an alternative to the above, it is to be understood that the grooved portion of the lingual flange 6 may be positioned instead about the engaging surfaces of plate 3. In this instance, the lingual flange would carry, instead of the grooved portion 7, a single raised portion or flange adapted to fit within the groove carried by the plate 3.
1. A lower dental impression tray for preparing models of the human mandibular dentition comprising a channel section adapted to conform to and encompass the mandibular dentition, characterized in that the upper portion of the innermost wall of said channel section supports in sealing relationship therewith a substantially fiat plate without any portion of said plate extending above a plane tangent to the upper edge of said innermost wall.
2. A lower dental impression tray according to claim 1, in which said channel section has a reticular structure.
3. A lower dental impression tray according to claim 1, in which the means for supporting said'flat plate in sealing relationship with said innermost wall is a groove carried by said wall adapted to receive in frictional engagement the contacting edges of said fiat plate.
4. A lower dental impression tray according to claim 1, in which said means for supporting said fiat plate in sealing relationship with said innermost wall is comprised of a flange section adjacent the upper portion of said innermost wall that is adapted to receive in frictional engagement a groove carried along the contacting edges of said plate.
5. A lower dental impression tray according to claim 3, in which the contacting edges of said flat plate are beveled.
6. In a lower impression tray a device for preventing model material from entering the opening formed by the lingual flange of said lower impression tray, said device comprising grooved means positioned around the circumference of the uppermost portion of the lingual flange and a flat, rigid plate whose outside dimensions substantially conform to the inside dimensions of said groove removably mounted in sealing relationship with said groove, thereby preventing entrance of model material into the lingual opening.
References Cited UNITED STATES PATENTS 1,834,980- 12/1931 Stealy 264-17 X FOREIGN PATENTS 320,820 10/1929 Great Britain.
RICHARD A. GAUDET, Primary Examiner.
R. E. MORGAN, Examiner.