US 3473226 A
Description (OCR text may contain errors)
Oct. 21, 1969 s. A. ARLERS ET AL. 3,4 73,226
DENTIST'S WEDGE 2 Sheets-Sheet 1 Filed March 22, 1968 FIG! FIG.
Oct. 21, 1969 s. A. ARLERS ET AL 3,
DENTIST'S WEDGE Filed March 22, 1968 2 Sheets-Sheet 2 US. Cl. 32-64 7 Claims ABSTRACT OF THE DISCLOSURE A dentists wedge is designed as an elongated body having a cross section essentially like an isosceles triangle, in which the base is considerably shorter than the two legs. The edges between the base surface and the adjoining side surfaces are convex and the ridge formed by the adjoining side surfaces is likewise convex.
Background of the invention When filling a tooth, not only one-sided or doublesided cavities in the molar and premolar parts but also in the front, it is necessary to utilize matrix ribbons which, by means of wedges, are forced against the tooth to be repaired. The idea is to prevent leakage of saliva into the cavity and filling material away therefrom, respectively. An excess of filling material may cause parodontit and secondary caries will soon appear.
It has been proposed to utilize wedges of wood or synthetic resin. These wedges have been comparatively short, i.e. the wedge angle is great. In this manner only a small part of the wedge will find contact with the teeth when forced into the space therebetween. The wedges usually have rectangular or triangular cross section, and in the latter case the sides are equilateral. Such a wedge will lack stability as it is easily twisted. Wooden wedges have been made of hard and of soft material. A hardwood wedge may deform the matrix ribbon and easily works free of the space between the teeth. A wedge made of soft wood, such as used in matches, will itself be deformed when forced into the space. Wooden wedges may also be cut from a block to fit the actual need. This is a time consuming job and when utilizing a hard wood the final shaping must be done by grinding. It is evident that manually prepared wedges of this type are far from sterile.
Summary of the invention A correctly shaped wedge shall fulfil the following stipulations.
(1) The cross section of the wedge shall fit the shape of the space between the teeth.
(2) The base surface of the wedge shall preferably be located below the cavity to be filled.
(3) The wedge shall, along its total length, be so designed that it will be safely retained in the space.
(4) The wedge shall be made of a material which is hard to deform and does not swell when coming into contact with saliva.
(5) The material used must be of a kind which has a certain degree of softness and adaptability, but nevertheless has a satisfactory separation action.
(6) The wedge must be so designed that an implement for instance tweezers, will obtain a good grip thereof for application as well as for removal.
(7) The wedge must be able to stand sterilization and preferably be so arranged that it may be removed from a stand without contamination of other wedges.
The object of the invention is to design a wedge which fulfils the demands above stated and it is characterized nited States Patent 0 in the cross section having the shape of an isosceles triangle, in which the base is considerably shorter than the legs and in which the longitudinal edges between the base surface and the adjoining side surfaces are convex in relation to the longitudinal axis of the base surface.
The breadth of the wedge will thus slowly increase in the direction away from the point and finally decrease again, which makes it possible to securely retain the wedge. The maximum breadth of the wedge is utilized to apply a pressure against the portion where a leakage of filling material is to be expected. By designing the cross section as a isosceles triangle with a comparatively short base the Wedge will obtain such a height that it will not yield to twisting.
Brief description of the drawings FIGURE 1 shows on an enlarged scale a view, as seen from above of three teeth, of which the middle one is surrounded by a matrix ribbon. To the right of the tooth this is forced into contact with the tooth by means of a wedge of known design, whereas a wedge according to the invention is utilized to the left of the tooth.
FIGURE 2 shows a section along line II-II of FIG- URE 1.
FIGURE 3 shows a wedge according to the invention on an enlarged scale.
FIGURE 4 shows an elevation of the wedge in FIG- URE 3.
FIGURES 5-9 are sections along lines VV, VI-VI, VII-VII, VIIIVIII and DC-IX, respectively, in FIG- URE 4.
FIGURE 10 shows a number of wedges formed integral with a disc, and
FIGURE 11 shows a support stand for a number of wedge carrying discs according to FIGURE 10.
Description of the preferred embodiment The novel wedge has a cross-section shaped like a isosceles triangle in which a base line b corresponds to a plane base surface 1 of the wedge. This base surface is arranged essentially at right angles to an end surface 3 of the wedge being remote from a point 2 thereof. Joint 4 between the two side surfaces corresponding to legs a and c of the triangle forms a ridge, the breadth of which successively increases from the point 2 towards the end surface. The ridge is furthermore designed to follow a convex line the greatest height of which measured from the base surface is located closer to the end surface 3 than to the point 2. Preferably, the maximum height is located at about one third or one fourth of the length measured from the end surface. Edges 5 and 6 formed between the base surface 1 and the side surfaces corresponding to the legs a and 0, respectively, are furthermore slightly convex in relation to the longitudinal axis of the base surface. The maximum convexity of the edges are preferably located in the portion of the wedge, where the maximum height of the ridge is to be found. The convexity of the edges of the base surface is preferably so chosen, that part of the base surface will obtain an essentially constant breadth, with the end of the base surface close to the point having a lesser breadth that the portion having essentially constant breadth. This portion covers about one fourth of the total length of the wedge and is preferably located at about the middle portion of the wedge. The convex lines form parts of arcs, the relation of the radius of the ridge 4 in relation to that of the edges 5 and 6 being 1:3.
The end surafce 3 of the wedge is continued as an elongated part 7 designed as a mounting or handle to be used when the wedge is brought into working position or removed therefrom, respectively. This part 7 has a cross section the dimensions of which are larger than 3 those of the adjacent part of the wedge, with the cross section of the part being mainly rectangular at this end. The free end of the mounting part extending about halfway the length thereof has a cross-section shaped as an inverted T where the horizontal flanges are coplanar with the base surface 1.
A number of wedges are formed integral with a disc 9, with the point of each wedge being attached to the periphery of the disc in such a manner that a wedge may be easily torn ofi? from the disc. This is provided with a central aperture adapted to be fitted on a support stand comprising a base plate 12 and a stanchion 13, and the latter has such a length that several discs may be fitted thereon. In order to prevent turning of the discs in relation to the stanchion when a wedge is to be torn off, each disc is provided with a slot 14 which cooperates with a corresponding key 15 of the stanchion.
The wedges and the discs are made of a synthetic resin of suitable nature for instance a semi-soft styrene resin which may be utilized to bring about a certain separation of the teeth when applied with force. Preferably, the wedges are manufactured with different breadths at the base surface to fit varying sizes of inter-tooth spaces. Three different sizes will usually be sufiicient, with each size being made on its own disc, possibly in different colors and the stand is designed to carry at least one disc of every size.
FIGURES 1 and 2 show a common situation when wedging a cervical matrix ribbon. To the right side of the tooth to be repaired, and which is surrounded by a matrix ribbon 16, a wedge 17 of known design (US. patent specification 2,867,905) is introduced in the intertooth space. This wedge 17 has straight sides, which cannot be brought into contact with the bulging sides of the tooth. In this way an interstice is formed between the ribbon and the tooth which is open downwards and thus permits entrance of saliva or extrusion of filling material. Such excess of material (vide the arrow in FIGURE 2) will form pockets between the tooth and the gums, which forms nests for bacteria and increases the risk of secondary caries and parodontit.
To the left of the middle tooth in FIGURES l and 2 a wedge according to the invention is shown. It is evident that the cross section of the wedge completely harmonizes with the shape of the inter-tooth shape. The base surface rests against the gums and the side surfaces of the Wedge abut the matrix ribbons 16 and the juxtaposed tooth, respectively. The ribbon will, due to the action of the wedge, be maintained in a proper position and is given a shape which conforms with the desired contour of the tooth. The entrance of saliva is furthermore prevented, which simplifies the application of filling material.
As the breadth of the wedge according to the invention slowly increases in the direction away from the point and thereafter diminishes somewhat, the maximum breadth of the wedge may be utilized for exerting pressure just at the point where a leakage of filling material may be expected. This point is not always located furthermost in the mesial or distal, but depends on the caries situation. The wedge may furthermore be used in connection to the restricted mesial surfaces at 4+4, Where fittings usually are difficult to make.
The wedge has sufiicient height to prevent twisting and the length thereof is not larger than necessary to permit an easy application without displacement of the lock for the matrix ribbon, which would cause discomfort to the patient.
What We claim is:
1. A dentists wedge comprising an elongated solid body having a cross section essentially similar to an isosceles triangle, in which the base is considerably shorter than the legs, the improvement comprising that the longitudinal edges between the base surface and the side surfaces are convex in relation to the longitudinal axis of the base surface and the breadth of the base surface at the end of the wedge remote from the point being less than the breadth at the mid portion of the wedge.
2. The dentists wedge according to claim 1 in which the convexity is so chosen, that part of the middle portion of the base surface will obtain an essentially constant breadth.
3. The dentists wedge according to claim 1 in which the convexity is so chosen that part of the base surface will obtain an essentially constant breadth corresponding to about one fourth of the length of the wedge, the portion extending from about halfway the length thereof, away from the point.
4. The dentists wedge according to claim 1 in which the joint between the two side surfaces being opposite to the base surface is rounded and designed as a convex ridge, the breadth of the rounded ridge portion successively increasing away from the point.
5. The dentists wedge according to claim 1 in which the joint between the two side surfaces being opposite to the base surfaces is designed as a convex ridge, the greatest height of the rounded ridge being located closer to the end of the Wedge remote from the point than to the point itself.
6. The dentists wedge according to claim 1 in which the joint between the two side surfaces being opposite to the base surface is designed as a convex ridge, the convexity of the ridge being considerably greater than the convexity of the two edges.
7. The dentists wedge according to claim 1 in which the end surface of the wedge remote from the tip merges into an extended portion formed integral with the wedge and shaped to form a handle, the cross section of the handle close to the wedge body being larger than the cross section thereof and of essentially rectangular configuration, and the cross section of the handle portion at the free end thereof, extending about halfway the length of the handle portion, being designed as an inverted T, where the horizontal flanges are coplanar with the base surface of the wedge.
References Cited UNITED STATES PATENTS 2,782,503 2/1957 Thompson 3263 3,193,094 7/1965 Schulsted 32-64 XR ROBERT PESHOCK, Primary Examiner