US 3724076 A
A device for forcing or expressing dental cavity filling materials into tooth cavities wherein the materials are incompatible with metals or will objectionably adhere thereto and wherein those portions of the device are not contacted by the dental filling materials desirably are of metal, and those portions which are located within the filling materials and from which said materials are forced or expressed into the cavities, are of plastic or similar substances unaffected by the dental filling materials; the device including structure simplifying the charging thereof with the filling materials and also being constructed to utilize as much of said filling materials as possible without waste due to the expense of said filling materials.
Description (OCR text may contain errors)
Q United States Patent 1 [111 3,724,076 Schmitz [4 1 Apr. 3, 1973 54 DENTAL CEMENT GUN Primary ExaminerRobert Peshock [7 51 Inventor. 32:22am L. Schmltz, San Marmo, Attorney Anan D Mockabee  Assignee: Vac-O-Cast, San Marino, Calif.  ABSTRACT  Filed: Apr. 5, 1971 A device for forcing or expressingdental cavity filling materials into tooth cavities wherein the materials are  Appl 130343 incompatible with metals or will objectionably adhere thereto and wherein those portions of the device are 52 US. Cl ..32/60 not contacted by the dental filling materials desirably 511 lm. Cl ..A6lc 5/04 are of metal, and Pmtim which are located 58 Field of Search ..32/60- 222/376 413 327- withi" filling maeials and mm which said l28/272 materials are forced or expressed into the cavities, are of plastic or similar substances unaffected by the  References Cited dental filling materials; the device including structure simplifying the charging thereof with the filling materi- UNITED STATES PATENTS als and also being constructed to utilize as much of said filling materials as possible without waste due to Newman the expense of said materials 833,044 10/1906 Goodhugh ..32/60 2,903,794 9/1959 Carfagni ..32/60 3 Claims, 5 Drawing Figures PATENTEDAPR3 I975 3,724,076
INVENTOR W/A/AM 4.507014/7 Z DENTAL CEMENT GUN This invention relates to a device for use in filling dental cavities.
There have been developed dental filling materials or cements which are quick setting so that a tooth can be filled and the cement polished within a very shor time, for example, within minutes from the time the tooth is filled. This greatly speeds up the filling procedure, and in many cases, obviates the need for a return visit to the dentist for final polishing of the filling.
Heretofore, the various methods for filling tooth cavities with quick setting cements and other filling materials have failed to provide for delivery of the filling materials to the tooth cavity in a quick and simple fashion. These other methods are too time consuming considering the rapid chemical reactions resulting in quick setting of the cements, or the methods are too messy for efficient operation in and out of the oral cavity. Much delay and expense results from cleaning up the instruments as well as the dental structures under treatment.
Many of the newer filling materials, which have rather recently appeared and are still appearing on the market today, are of an extremely thick consistency when mixed, and it is imperative to place the filling material so that it completely fills the tooth cavity, to prevent air voids upon set, and also to be able to effect this procedure with precise control at all times. Air voids entrapped in fillings adjacent tooth cavity walls tend to weaken the finished filling and lessen support for the remaining tooth structure. Prevention of future decay in and aroundthe filling material is predicated upon close adaption of the filling material to the shape of the cavity walls of the tooth structure.
If the filling material is mixed properly on the mixing slab, no air should be incorporated in the material. It follows therefore, that a device used for placing the filling material in the tooth cavity should be charged with the material in a manner which not only prevents air from accompanying the charge, but allows for the I expulsion of any air which might be pushed ahead of the filling material during this charging procedure.
The present invention contemplates the use of a device including an expressing plunger and a guide therefor, whichin many respects is similar to a conventional amalgam gun. This plunger and guide assembly can and preferably should be of metal. The guide for the plunger is adapted to have connected thereon a cylinder assembly in which is a piston engageable by the plunger, the cylinder assembly having an outlet of dimensioned size which can be inserted in a tooth cavity for the discharge of dental filling material which previously has been loaded into the cylinder assembly. The cylinder assembly and piston are of a suitable material, such as a plastic having low frictional drag, and the fit between the cylinder assembly and the metallic plunger guide and between the piston and the cylinder assembly, being such that the plunger can exert all necessary forces against the piston to express or extrude the dental filling material, during which operation the dental filling material is kept out of contact with the metal of either the plunger or its guide.
The device is such that the cylinder assembly and piston can be conveniently made from a molded plastic with such economy that they can be single use elements, making it more economical to disposed of the FIG. 1 is a perspective view of an embodiment of the invention;
FIG. 2 is an enlarged longitudinal sectional view taken approximately on the line 22 of FIG. 1;
FIG. 3 is an enlarged detail, in perspective, of the end of the plunger guide and a portion of the cylinder assembly illustrating the manner in which the cylinder assembly is charged;
FIG. 4 is a composite perspective view of a portion of the cylinder assembly and a piston;
FIG. 5 is a perspective view of another piston illustratirig a different length from that of FIG. 4 and consequently, a different filling material charge capacity for the cylinder assembly.
In the drawing there is shown a gun made up of a barrel 6, plunger rod 8, plunger guide tube 10 and flexible plunger 12. This gun is indicated in its entirety by the numeral 14 and is termed a gun because of its similarity to the conventional amalgam gun above mentioned as being known and used in the dental profession.
The plunger rod 8 has a stop ring 16 thereon in a cavity 18 in the barrel 6. Also, in the cavity 18 is a compression spring 20 which bears against the stop ring 16 on the plunger rod 8 at its rear end, and at its forward end, bears against the inner end of the guide tube 10. Guide tube 10 is shown soldered into a flanged sleeve 22 which in turn is threaded into the forward end of the barrel 6, as shown in FIG. 2.
The forward end of the plunger rod 8 is reduced at 24 and on the reduction is the inner end of the flexible plunger 12. As illustrated, the plunger guide 10 is preferably curved to facilitate manipulation thereof by the dentist in the tooth filling operation and the plunger 12 is flexible, being made of a coiled wire. The plunger 12 is threaded on the reduced end 24 of the plunger rod 8.
At the outer portion of the outer end of the plunger guide 10, but spaced inwardly from said outer end, are external threads 26. Then from the threaded portion 26 to the outer end, the plunger guide tip 28 is of less diameter than the threaded portion 26.
Threaded onto the threaded portion 26 of the plunger guide is an outer cylinder element 30 having a thickened internally threaded inner end 32. The thickened end or band 32 may desirably have projections 34 thereon somewhat similar to those of a caste]- lated nut to facilitate gripping of the end portion 32 when it is threaded on and removed from the tip of the plunger guide 10.
The outer cylinder portion 30 has an outer end terminating in a reduced diameter discharge tip 36, the inner end of the tip 36 being defined by a cylinder end wall 38 which is directed inwardly and forwardly and may be frusto-conical or concave-convex.
Removably located within the outer cylinder member 30 is an inner sleeve 40, said sleeve being of an outer diameter to closely fit the inner diameter of the outer cylinder member 30 and of a length to reach from the cylinder outer end wall 38 to a point against the internally threaded portion of the inner end 32 of the outer cylinder member. The inner diameter of the sleeve 40 is such as to closely fit the tip 28 at the outer end of the plunger guide 10. It is preferred that the sleeve 40 be insertible on the plunger guide tip 28 readily with the fingers, but that it be retained thereon by friction during a charging operation to be described below.
Removably received within the cylinder assembly sleeve 40 is a piston 42 which preferably is provided with tapered ends 44. A similar piston 46 is shown in FIG. 5, the latter being longer and taking up more of the space in the sleeve 40 when assembled, as shown in FIG. 2.
The projecting end of the plunger rod 8, as shown in FIG. 2, is provided with threads 48 for receiving an internally threaded knob 50, the latter being locked longitudinally on the threaded portion 48 of the plunger rod by means of a lock nut 52. The longitudinal positioning of the knob 50 and lock nut 52 on the plunger rod 8, and the spacing of the lock nut from the end face 54 of the barrel 6, determines the stroke of the plunger rod 8. This stroke is such that the plunger 12 will move the piston 42 from the position shown in FIG. 2 to a point where the forward end of said piston will engage the inside of the forwardly and inwardly directed end wall 38 of the outer cylinder element 30. When a longer piston, such as piston 46, is used in place of piston 42 to reduce the volume of the cylinder assembly which can be charged with dental filling material, the lock nut 52 and knob 50 can be adjusted to the right as viewed in FIG. 2 to reduce the stroke of the plunger rod 8 and plunger 12 to the equivalent possiblemotion of the piston 46 in the cylinder assembly.
FIG. 3 illustrates the manner in which the device is charged or filled with dental filling material. Many of the modern quick setting filling cements are epoxy-like materials requiring the mixing of two substances immediately before use. In FIG. 3 there is shown a slab 56 on which is a quantity of stirred dental filling material 58. It is introduced into the inner sleeve 40 of the cylinder assembly after a piston, such as piston 42, has slipped into the sleeve and the sleeve then pressed up on the reduced diameter tip 28 of the plunger guide where it is frictionally held. The dentist or his assistant then rapidly presses the lower end of the sleeve 40 into the dental filling material 58 until the sleeve is filled with said material from its lower end to the lower end of the piston 42, and the upper end of the piston 42 is pushed up into engagement with the end of the plunger guide tip 28 and the end of the plunger 12, the plunger and plunger rod being then in the position shown in FIG. 2. During the filling operation air is exhausted from between the filling material and the lower end of the piston 42 to a vent 60 in the side of the sleeve 40.
The illustrated pistons 42 and 46 of different lengths are provided so that the sleeve 40, and as a result the entire cylinder assembly, can be charged with different quantities of dental filling material. This is highly advisable for the reason that the modern quick setting dental cements are quite expensive and it is desirable to use no more than approximately the amount necessary to complete the filling of the dental cavity. Also for the reason the ends of the piston are shaped to conform to the cylinder end wall 38 so that approximately all of the dental filling material is expressed from the cylinder assembly and utilized for the cavity except the quite small amount which is left in the tip 36 of considerably reduced diameter.
The discharge tip 36 is preferably provided with a thin enough side wall so that it can be pressed more or less flat with the fingers, and the plastic material from which it is made is distortable enough so that it will temporarily retain its flattened condition to facilitate insertion of the tip 36 between adjacent teeth where the space is quite restricted.
The outer cylinder 30 fits onto the guide tube 10 and up against the shoulder provided by the thread 26 on the guide tube and the movable piston with its conical end fits the end of the flexible plunger 12 and filling material is kept from contact with any of the parts of the gun 14. The pistons, 42 or 46, being cone-shaped at both ends, can be inserted in the sleeve 40 of the cylinder assembly without requiring any attention to whether one end of the other of the piston is directed forwardly or rearwardly, since the conical ends will seat in the end of the flexible plunger and also will conform to and seat against the inner wall of the cylinder end 38.
It should be noted that the sleeve 40 and one of the pistons 42 or 46 inserted therein are slipped on the end 28 of the guide tube 10 before mixing of the filling material 58. Thus, two'of the three plastic parts, which are mounted on the gun, are assembled thereon prior to mixing, sothat when the sleeve 40 is charged or filled with filling material, it is only necessary to screw on the outer cylinder 30 and the dentist is ready to fill the dental cavity.
The filling material 58 acts as a piston during charging of the sleeve 40 and pushes air in the sleeve out of the vent hole 60, which always lies ahead or outwardly relative to a piston located in the sleeve 40. It should also be noted that the vent hole is placed midway between the ends of the sleeve 40 so that it does not matter which end of the sleeve 40 is slipped onto the end 28 of the guide tube 10, further facilitating assembly of the parts.
While in FIG. 2 I show the filling material 58 as a completely filling the space between the front end of the piston 46 and the cylinder end 38, a lesser amount of cavity filling material can be used when desired. Due to the rather high cost of the newer epoxy-type dental cavity filling materials, it is highly important to use no more than necessary. When a lesser amount is used, there of course is air between the mixed filling material and the end of the piston 46. When this condition occurs, air is removed when pressure is applied on the plunger rod 8 and plunger 10, causing the entrapped air to be forced between the piston 46 and the inner wall of the inner sleeve 40 and thence upwardly through the metallic parts of the gun. Since the piston 40 is movable in the sleeve 40, there of course is some minute clearance which permits the passage of such entrapped air but completely seals the piston against the inner wall of the sleeve 40 against any passage of the quite thick filling material 58.
The outer plastic cylinder 30 by means of its threaded connection with the end of the guide tube 10,
holds the inner sleeve 40 against the shoulder provided by the threads 26 on the guide tube, and prevents forward dislodgement of the cylinder assembly when pressure is exerted by the flexible plunger on the piston to extrude the filling material. The outer cylinder 30 also holds the sleeve in position by reason of the close fit between the outer end of the inner sleeve 40 and the funnel-shaped cylinder end 38, this close fit providing a quick efficient seal when the outer cylinder 30 is threaded upon the threads 26 and the and the inner sleeve 40 is compressed lengthwise between the shoulder provided by said threads 26 and the cylinder end 38.
It will of course be understood that various changes can be made in the form, details, arrangement and proportions of the various parts without departing from the spirit of the invention.
1. A dental cavity filling device for dispensing modern quick setting composite resin tooth filling materials including a reciprocating plunger rod and a guide therefor with a free end, wherein the improvement comprises:
an open ended inner sleeve with an inner diameter of such dimension so as to frictionally be retained on the plunger at the free end of said guide and said sleeve having a vent hole therein;
a piston slidably fitting the interior of the cylindrical open-ended liner; wherein said inner sleeve with said piston therein being chargeable with dental filling material by pressing said sleeve into said material; and
an outer cylinder having an outer end terminating in an integral reduced diameter discharge tip and an inner end with means detachably securing it to the guide after said inner sleeve is charged, said inner end being open so as to encompass the entire said inner sleeve, the outer cylinder by means of its connection to the guide holds the inner sleeve against forward dislodgement when pressure is exerted by the plunger rod on said piston.
2. The structure in claim 1, and the outer end of said outer cylinder having its inner wall tapered forwardly and inwardly to said discharge tip; and
said piston having both ends shaped to conform to the inner wall of the outer end of said outer cylinder.
3. The structure in claim 1, and the guide for said plunger having an outer end portion with a cylindrical shape;
inwardly from its extremity said guide, adjacent said outer end, having an enlarged threaded portion;
an outwardly facing shoulder forwardly of the threaded portion;
the inner end of said inner cylinder being frictionally held on said cylindrical shape of the outer end of said guide and butting said shoulder; and
said means detachably securing the inner end of the outer cylinder comprising internal threads engaging the enlarged threaded portion of said guide.