US 3399457 A
Description (OCR text may contain errors)
Sept. 3, 1968 H. c. HAGMAN 3,399,457
DENTAL BITE RIM OR IMPRESSION TRAY I Filed Feb. 19, 1964 INVENTOR. HARRY 6'. HAGMAN BYMSW flTTORNE-Yf United States Patent 3,399,457 DENTAL BITE RIM OR IMPRESSIQN TRAY Harry C. Hagrnan, 1111 Nicollet Ave., Minneapolis, Minn. 55403 Filed Feb. 19, 1964, Ser. No. 345,982 11 Claims. (Cl. 3219) This invention relates to a bite rim, bite block or impression tray depending upon its particular use in dentistry. Bite rims are made of various formable plastic materials. They are widely used for establishing relationships of the human jaws, one to the other. The formable plastic materials heretofore used have been largely composed of wax or wax-like molding or modeling compositions, or thermo-plastic materials as a base with wax applied to the biting surface. In some cases a fluid liner which later stiffens is applied to the tissue side of the base. As is well know, the bite rim is inserted into the mouth of the patient and he bites down upon it to form appropriate impressions in the bite rim registering a positional relationship of the mandible to the maxillae, in order that models or casts may be set in these depressions and mounted in a matrix type of machine which is designed to function like the human jaw.
The present invention has as its principal object the provision of a new and improved bite rim or bite block or impression tray formed from a rigid, non-toxic, finegrain, foamed resinous material which has the property of being readily deformed under ordinary jaw pressure and maintaining its deformed shape.
Other objects of the invention will become apparent as the description proceeds.
To the accomplishment of the foregoing and related ends, this invention then comprises the features hereinafter fully described and particularly pointed out in the claims, the following description setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principles of the invention may be employed.
The invention is illustrated by the accompanying drawings in which the same numerals refer to corresponding parts and in which:
FIGURE 1 is a perspective view of a preferred form of the bite rim or bite block according to the present invention, shown in inverted position;
FIGURE 2 is a top plan of the bite rim of FIGURE 1;
FIGURE 3 is a transverse section on the line 33 of FIGURE 2 and in the direction of the arrows;
FIGURE 4 is a perspective view of a slightly modified form of the bite rim according to the present invention shown after the impression therein of a cavity conforming to a portion of the mouth and jaw structure;
FIGURE 5 is a transverse section similar to that of FIGURE 3 but through the bite rim of FIGURE 4;
FIGURE 6 is a transverse section similar to FIGURE 3 through a further modified form of bite rim provided with an exterior protective coating;
FIGURE 7 is a perspective view of impression tray according to the present invention; and
FIGURE 8 is a transverse section through the center of the impression tray of FIGURE 7.
Referring to the drawings, the bite rim or bite block or impression tray according to the present invention, as shown and indicated generally at 10, is comprised of a unitary U-shaped or horseshoe-shaped block of rigid synthetic resinous foam. The block may be of any size and shape adapted to fit in the mouth between the jaws. The
bite rim 10 is relatively thick and fiat. It may be solid or, as shown, it may be comprised of a central semi-circular arcuate portion 11 and a pair of slightly diverging relatively short spaced apart straight portions 12 extending outwardly from the central portion. The extremities 13 of the straight sections 12 may be rounded. The central portion 11 of the bite rim is generally rectangular in cross section (with the sharp edges removed), as best shown in FIGURE 3, and preferably the width of the bite rim is about equal to its thickness.
In order to facilitate easier and more comfortable insertion of the bite rim into the mouth of a patient, the lower surfaces of the extremities of the straight portions 12 are desirably beveled or chamfered at an angle between about and 60 and desirably at about a angle sloping from about the mid-portion of the straight section toward the tip of the rounded extremity 13. The beveled surface 14 desirably extends about half to of the thickness of the bite rim. The bite rim is of an overall size and curvature adapted to fit easily between the upper and lower jaw members of a human skull. The tapered end portions facilitate comfortable fit of the bite rim in the angles adjacent the jaw pivots. While this is desirable, it is not essential with the bite rim of the present invention because the bite rim is easily deformed to fit. To permit the dentist or technician to properly position the bite rim in the patients month an integral projection 15 may be provided extending from the forward edge of the block to serve as a handle.
The bite rim according to the present invention, is formed from a lightweight rigid synthetic resinous foam material. The foam is formed with minute fine grain cells which are virtually imperceptible to the naked eye. The cells are preferably closed so that the bite rim is not absorptive of moisture and does not absorb saliva from the mouth of the patient. While rigid it must also be readily deformable under pressure and must have memory retention such that it remains dimensionally stable in its deformed shape and maintains the outline of the deformed cavities or impressions made by the jaw structure of the patient. These impressions are made by breakdown and compression of the cellular structure of the foamed resinous material. The foamed material must be nontoxic and, desirably, tasteless. Because of the practice of dentists to initially partially heat dental appliances and devices before inserting them into the mouths of patients, by passing them through a flame, the foam materials should also be either non-flammable or self-extinguishing.
Useful materials which possess all of these characteristics are urethane foams, also known as polyurethanes and isocyanates. As is well known, these materials are formed by the reaction of polyols such as hydroxyl-rich polyesters and polyethers with isocyanates. The reaction is carried out in the presence of a blowing agent which is in gaseous form at the reaction temperature and creates a cellular structure with an extremely low coefficient of thermal conductivity within the resinous reaction product. A typical blowing agent is one of a group of fiuorinated hydrocarbons which results in rigid urethane foams with virtually closed cells. Such foamed urethanes are commonly produced in slabs or sheets. The bite rims according to the present invention, may be cut or stamped from such slabs or sheets having thicknesses ranging between about A and 1 inches, although in most instances the thickness will range from about A and 1% inches. Alternatively, the bite rims may be formed 3 by foaming in place by pouring the reactant materials into an open cavity or mold having the desired shape.
One exemplary rigid polyurethane foam material which may be used in the practice of the present invention is sold under the brand-name Foamthane by Pittsburgh Corning Company. It is a rigid urethane foam material which is dimensionally stable, has a good compressive strength, is rot-proof, fungus-proof and vermin-proof, has an extremely low thermal conductivity (K factor), is unaffected by petroleum solvents, is odor free and nontoxic and is self-extinguishing. It has a fine grain cellular structure made up of extremely small cells which are imperceptible without magnification. The material in sheet form is rigid but is readily deformable by slight pressure and is easily deformed by the pressure which can be exerted by the jaw of a patient being fitted with dentures. Other exemplary rigid synthetic resinous foamed materials include cellulose acetate, ureaformaldehyde, polystyrene, butadiene-styrene and epoxies. These foamed synthetic resins may be used in the present invention when compounded to have the requisite properties.
In use, the bite rim is placed in the mouth of the patient between the upper and lower jaws in general alignment with the jaw bones and the patient bites down upon the rim. This causes an impression or cavity 16 to be formed in the opposite top and bottom surfaces of the bite rim, as shown in FIGURES 4 and 5. Because of the dimensional stability and retentive memory of the plastic foam material the impression 16 remains in the bite rim after the jaw pressure is relaxed and the bite rim is removed from the patients mouth. The foamed plastic bite rim enables the dentist to produce an accurate impression of the jaw structure with a maximum of ease and minimum of discomfort or distress to the patient.
The bite rim as shown in FIGURES 4 and 5 is provided with a modified form of handle member A. The handle 15A is formed from thin fiat rigid sheet material, such as metal, stiff cardboard, or the like. It has a penetrating portion 16A adapted to be inserted into the forward edge of the bite rim and a projecting portion 17 to permit manipulation of the bite rim in the mouth of a patient.
In a modified form of bite rim shown in section in FIGURE 6 and indicated generally at 10A, and otherwise conforming in structure to the bite rim already described, an optional, deformable retentive memory coating 18 encases the bite rim. Coating 18 may be formed from wax or other wax-like coating materials. It is relatively thin and functions primarily to prevent small fragments or particles of the plastic foam bite rim from becoming dislodged from the bite rim in the patients mouth as the bite rim is being manipulated during its insertion and removal from the patients mouth.
As shown in FIGURES 7 and 8, the bite rim according to the present invention, indicated generally at 10B, may be formed with a relatively large and deep recess or channel 19 in one or both planar surfaces. Recess or channel 19 may be for-med either by cutting away portions of the foamed plastic or by application of deforming pressure it may then be filled with an impression material 20, such as colloid, plaster and rubber compounds, as are commonly used in dental ofiices for the taking of impressions. The impression tray thus formed may be used in full sections for bilateral impressions or in half sections for unilaterial impressions. For preparation of partial dentures or crowns the recess 19 need be formed only in that part of the bite rim adjacent to the affected area. As shown, the impression tray is adapted for forming an impression of the lower teeth or jaw. For forming impressions of the upper mouth structure the tray is formed from a solid semi-circular block of foamed resin of similar configuration in which no open space is present between the sides of the block.
It is apparent that many modifications and variations of this invention as hereinbefore set forth may be made 4 without departing from the spirit and scope thereof. The specific embodiments described are given by way of example only and the invention is limited only by the terms of the appended claims.
1. A one piece composite upper and lower dental bite rim comprising a single block of fine grain foamed synthetic resinous material of a size and shape adapted to fit in the mouth of a human between the jaws, said foamed synthetic resinous material being rigid, thermally stable, non-toxic, lightweight with a myriad of minute cells and easily deformable by jaw pressure alone at ambient temperatures with memory-retentive properties to stably maintain the dimensions of deformations produced there- 2. A bite rim according to claim 1 further characterized in that said bite rim is generally U-shaped having a central arcuate portion and a pair of straight spaced apart portions extending therefrom.
3. A bite rim according to claim 2 further characterized in that the lower surfaces of the extremities of said straight portions are sloped upwardly toward their ends to facilitate insertion in the mouth.
4. A bite rim according to claim 1 further characterized in that said synthetic resinous material is foamed polyurethane.
5. A bite rim according to claim 1 further characterized in that said synthetic resinous material is fire-proof.
6. A bite rim according to claim 1 further characterized by the provision of a recess formed in at least one surface of said block of foamed resinous material, said recess being filled with dental impression material whereby said bite =rim functions as an impression tray.
7. A bite rim according to claim 6 further characterized in that said recess is in the form of a U-shaped channel, said channel conforming generally in size and shape to the tooth supporting portions of the human jaw and filled with dental impression material.
8. A bite rim according to claim 1 further characterized in that said block of foamed resinous material is provided with a projecting handle element extending from the forward edge of said block to facilitate manipulation and alignment of the bite rim within the mouth.
9. A one piece composite upper and lower dental bite rim comprising a single U-shaped block of foamed polyurethane of a size and shape adapted to fit in the mouth of a human between his jaws, said block being relatively thick and flat and having a central arcuate portion with a pair of straight spaced apart portions extending therefrom, the lower surfaces of the extremities of said straight portions being sloped upwardly toward their ends to facilitate insertion in the mouth, said foamed polyurethane being rigid, thermally stable, non-toxic, self'extinguishing, tasteless, non-absorptive to moisture, lightweight, with a myriad of minute closed cells and easily deformable by jaw pressure alone at ambient temperatures with memory retentive properties to stably maintain the dimensions of deformations produced therein.
10. A dental bite rim comprising a U-shaped block of foamed polyurethane of a size and shape adapted to fit in the mouth of a human between his jaws, said block being relatively thick and flat and having a central arcuate portion with a pair of straight spaced apart portions extending therefrom, the lower surfaces of the extremities of said straight portions being sloped upwardly toward their ends to facilitate insertion in the month, said foamed polyurethane being rigid, non-toxic, self-extinguishing, tasteless, non-absorptive to moisture, lightweight, with a myriad of minute closed cells and easily deformable by pressure with memory retentive properties to stably maintain the dimensions of deformations produced therein, and said foamed polyurethane being encased in a thin smooth pressure deformable and memory retentive plastic coating.
11. A one-piece composite upper and lower dental References Cited bite rim comprising a single bloch of fine grain foamed UNITED STATES PATENTS synthetic resinous material of a sac and shape adapted to fit in the mouth of a human between the jaws, said 2,153,710 4/1939 Coble 32 19 foamed synthetic resinous material being rigid, non-toxic, 5 3,064,354 11/1962 P05 lightweight with a myriad of minute cells and easily FO GN PAT N S deformable by pressure with memory-retentive proper- 1,044,351 11/1958 Germany ties to stably maintain the dimensions of deformations produced therein, said synthetic resinous material being LOUIS M ANCENE Primary Examiner encased within a thin smooth pressure deformable and 10 memory-retentive plastic coating. C. R. WENTZEL, Assistant Exammer.