Patent Publication Number: US-3878608-A

Title: Removable denture connection

Description:
United States Patent [191 Gil-Castillo [451 Apr. 22, 1975 REMOVABLE DENTURE CONNECTION Arturo Gil-Castillo, San Jose de Ocoa. Dominican Republic [22] Filed: Oct. 1, 1973 21 Appl. No.: 402,285  
 Related U.S. Application Data [63] Continuation-in-part of Scr. Nos, 246,064. April 20, I972. Pat. No. 3.762.049, and Ser. No. 301.352, Oct. 27, i972, Pat. No. 3.8l8,594.  
 [76] Inventor:  
 Primary Examiner-Robert Peshock Altorney. Agent, or Firm-Mason, Mason &amp; Albright [57] ABSTRACT A removable artificial tooth (or teeth) and gum prosthesis is attached to a pier tooth crown by means of a tapered tongue and groove connection. A spring in the tongue part of the connection is adapted to bear against depression in the wall of the groove or socket receiving the tongue part to form a dedent type connection. The spring includes a shank which extends away from the tongue portion in the direction of the gum into the gum prosthesis where it is embedded and at about a 45 angle relative to the face of the tongue.  
 The inner part of the spring which engages the depression in the wall of the socket extends substantially in the direction of the gum and bears resiliently against the depression. Alternatively, a tube in the tongue part may receive the inner part of the spring which is resiliently restrained therein by a deformation proximate a gullet or slit near its end or within a curved portion in a curved tube. Further, a stop means may be formed in the channel of the tongue part proximate to its face which contacts the socket wall whereby deformation of the spring is necessary for its removal from the tube portion of the tongue part. In a still further embodiment for use in posterior bridges wherein the piers are longer and the intermaxilliary space is reduced, an obtuse angle spring may be utilized to advantage. As a yet further alternative, the spring may have three primary parts, the first of which extends from the direction of the gum at a 45 angle in a channel within the tongue part to its face which contacts the socket wall. a second spring part extends approximately parallel to the &#39;face of the tongue part away from the gum and engages a depression in the wall portion of the socket. and a third part extends at a 45 angle away from the gum and tongue face into a further channel of the tongue part. The channels for the latter spring are formed in part by backing plate which is, at least originally, in approximately the shape of a truncated triangle with the truncated portion adjacent and to the rear of the second spring part so that the second spring part can resiliently move towards the truncated part. Such plate is soldered in place and a portion is thereafter removed whereby it defines in part the channels for the first and third spring parts.  
 11 Claims, 21 Drawing Figures Pi&#39;JENTEE APR 22 i975 SHEU 1 0F 4 FIG. 2  
 FIG. 1  
 FIG. 3  
 PATENIED 3 878 608 SHZU 2 0F 4 46 FIG 7 FIG. 8 43 FIG. 9 FIG. I]  
 FIG. 12  
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 FIGZO RELATED APPLICATIONS This is a continuation-in-part application of application Ser. No. 246,064 filed Apr. 20, 1972-, and now U.S. Pat. No. 3,762,049 issued Oct. 2, 1973, and application Ser. No. 301,352 filed Oct. 27, 1972, and now US. Pat. No. 3,818,594 issued June 25, 1974.  
 BACKGROUND OF THE INVENTION The invention relates to a removable denture connection and particularly to the type wherein the denture is removably held in place by a tongue and groove connection, the groove or socket extending from a crown of a pier tooth and the tongue being generally T-shapedas seen from above and tapering.  
  It has been a practice for a yieldable interlock between the tongue and groove, that a spring of one type or another is provided for the tongue which bears against the adjacent surface of the groove which receives the tongue which may or may not have a corresponding depression.  
  As is well known, dental bridges are generally anchored between two natural teeth or to a single tooth. Various devices and techniques exist to establishremovable bridges in the mouth so that they will function to masticate food and at the same time be removable for cleaning and other purposes. One type is a tongue and groove connection wherein the groove is disposed at one side of a crown over an existing tooth and the tongue fits in the groove so that the bridge can be removed by lifting&#39;s&#39;ame in a direction away from the underlying gum. -With such connections it is not uncommon topr&#39;o vide&#39;,usually in the tongue or socket portion, a spring which-may be received in a corresponding recess in the wall of the groove so that a dedent type of connection is created. Such connections have, however, presented several problems. One is that the spring may prove too strong or weak for its purpose whereby either the denture is not easily removable or it will become dislodged in use. A definite need thus exists and has existed for many years for a bridge connection which will offer permanent stability for denture bridges and wherein the spring tension may be adjusted without undue difficulty so that the denture may be manually removed by the wearer.  
 SUMMARY OF THE INVENTION The dental bridge of my invention comprises a precision attachment wherein a crown is received over a pier tooth which includes a groove or female part to receive the tongue or male part also known as a socket. The tongue part has a tubular member which extends away from the face of the tongue at a slant of about 45 towards the location for receiving the gum into the adjoining bridge. This tubular member in turn carries a spring portion having a long pointed shank that is slidably received in the channel formed by the tubular member and extends from such tubular member into the adjoining bridge whereby both the shank of the spring and the tubular member are anchored within the tooth prosthesis. Alternatively, the tube may be closed at its end encased in the prosthesis and spring therein deformed to provide a resilient connection with the tube. On the other end, the shank of the spring extends through an opening&#39;in the face of the tongue member and a further but shorter portion of the spring extends towards the gum partly within a groove in the face of the tongue member and partly outwardly thereof. For posterior bridges wherein the piers are longer and the intermaxillary space is reduced, the shorter portion may extend away from the adjacent gum. When the tongue member together with the spring and the denture is received in the socket, the shorter portion of the spring resiliently bears against the wall of the socket. A recess or depression is provided in the socket wall so that when the denture is in its desired position, the outwardly extending portion of the spring bears in the depression and a dedent type connection is provided. The groove has a tapering form which closely fits within a tapered socket whereby an anatomic contour of a tooth may be provided in the crown. An arm extends from the portion which includes the tongue which assists in stabilizing the adjacent prosthesis and is provided for attachment to frames of the various types used for removable bridges. The spring is easily removable by the technician and can be replaced in a matter of minutes to provide the desired resilient connection between the prosthesis and the crown over the pier tooth. However, due to the fact that the shank of the spring is received frictionally within the prosthesis, it is not likely to be unintentionally dislodged bythe user. If desired, stop means may be formed in the channel of the tongue part whereby deformation of the spring is required for its removal from the channel. Moreover, the location of the spring contributes to the stability of the prosthesis and it is possible to use a single attachment of the type disclosed herein advantageously for certain types of prostheses. In a further embodiment which is more suitable fortongue and groove attachments wherein there is not an adjoining prostheses but it is desired to pro vide stability and an attachment for a frame part of a bridge, the tubular part or nipple extending away from the face of the groove is not provided but, nevertheless, a channel extends from the tongue face in which the same direction and from the same space. However, the groove which is provided in the channel which instead of extending towards the gum from the opening for the spring extends away from same to a further opening for a further channelwhich extends away from the face of the groove at an angle of about and about 90 relative to the first mentioned channel. The channels are made by initially forming a vertical groove which is generally triangular in section from the rear of a tongue part towards its face whereby an imaginary apex of the triangle would extend through the opening in the face of the tongue part. The channels are then defined by inserting into the vertical groove a plate having the same thickness as the groove, the plate having substantially the shape of a truncated triangular or, perhaps more accurately, a volcanic like cross-section. With a U-shaped member (or spring) previously inserted, to provide spacing for the channels the plate may be easily soldered in place and the rear portion ground flush against the rear of the tongue part. A U-shaped spring located in the channels so formed thus has arms in each of the channels and serves to function as with the previously described spring, to hold or establish removable bridges in the mouth. The spring has on both sides away from the front portion, slanted parts so that the action of insertion and removal of the spring may be obtained with increased facility while at the same time the dedent arrangement provides a strong connection between the crown over the pier tooth and the prosthesis.  
 The pressure for such a spring can be adjusted simply and quickly and there is no problem in replacing the spring which may be available in various strengths. Replacement is made in case of breakage or if the spring weakens with use.  
  Other adaptabilities&#39;and capabilities will.appear as the description progresses, reference being had to the accompanying drawings, in which:  
 BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows in perspective the crown over a pier tooth with the tooth prosthesis attached thereto by a connection in accordance with the invention;  
  FIG. 2 is a plan view which shows the crown of FIG. 1 together with the tongue member without the prosthesis connected thereto;  
  FIG. 3 is a side view of the crown and tongue member shown in FIG. 2;  
  FIG. 4 is an elevational detail view of the tongue member;  
  FIG. 5 is a cross-sectional view of the connection of the invention between the crown and prosthesis;  
  FIG. 6 is a front view showing the tongue member connected to the prosthesis;  
  FIG. 7 is a perspective front view of the crown showing the socket and indentation for the spring in the wall portion of the socket;  
  FIG. 8 is a plan view of a further embodiment of the invention wherein a tongue member is received in a crown;  
  FIG. 9 is a front view of a tongue member shown in FIG. 8;  
  FIG. 10 is a side elevational view of the tongue member shown in FIGS. 8 and 9;  
  FIG. 11 is a front perspective view of the crown of the further embodiment showing the indentation in the wall portion of the socket;  
  FIG. 12 is a cross-sectional view of the tongue member shown in FIGS. 8 10;  
  FIG. 13 is an enlarged detail view of the spring seen in the cross-sectional view of FIG. 12;  
  FIG. 14 is a cross-sectional view of an alternative connection in accordance with the invention between the crown and the prosthesis;  
  FIG. 15 is a detailed view of the spring seen in the cross-sectional view of FIG. 14;  
 - FIG. 16 is a detailed view of an alternative embodiment of the spring shown in FIGS. 14 and 15;  
  FIG. 17 is a cross-sectional view of a further alternative connection in accordance with the invention between the crown and prosthesis;  
  FIG. 18 is an enlarged perspective view of the spring shown in FIG. 17;  
  FIG. 19 is a cross-sectional view of a still further alternative connection in accordance with the invention between a pier crown and prosthesis; and  
  FIG. 20 is a cross-sectional view of a yet further embodiment of the invention showing the connection between the crown and prosthesis.  
 DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, it will be noted that a crown 14 receives a tongue part 15 of the tongue member 16 which includes an arm 17 for attachment by soldering or other suitable means to a frame of a denture bridge. The prosthesis 20 comprises an artificial tooth 21 and a saddlepart 22 which forms a base for the artificial tooth and is made of plastic, a precious metal or other material to encase tooth 21 and to prevent injury from contact with the gums of the user. The plastic or other material is conventional and used in a conventional manner to anchor the artificial tooth as well as protect the gums of the user.  
  As may be seen in FIGS. 2 5, tongue member 16 includes the tubular member or nipple 24 which extends at an angle of 45 to 75 relative to and away from face 25 of tongue part 15. Nipple 24 includes a cylindrical channel designated 26 which receives a spring 27 comprised of a shank body or first spring portion 30 which includes a. neck portion 30a which can be flat or cylindrical and a head or second spring portion 31 which extends partly in a groove 34 leading from an opening 32 of channel 26 and generally in the direction of the underlying gum. It is to be noted that second spring portion 31 extends slightly outwardly of groove 34 whereby it may be resiliently received against an indentation 35 which is about 0.2 millimeters deep at its lower end in the rear wall portion 36 of socket 37 in crown 14 whereby a dedent arrangement is provided. It-will be further noted that the first spring part 30 is sharpened on its extreme end and together with nipple 24 is embedded in saddle part 22. Although spring 27 can be easily removed from the prosthesis 20 when same is removed from the mouth, by the proper dental instruments, the frictional engagement of the pointed first spring portion 30 within the saddle part 22 prevents its accidental dislodgement when the prosthesis 20 is removed by the user. It will also be noted that the tongue part 15 is tapered both as seen from face 25 (FIG. 6) and the side (FIG. 4) and itis to be appreciated that the socket 37 is similarly tapered so that tongue part 15 is, when in position in socket 37, in full engagement therewith and thus firmly secured and anchored to crown 14. The connection is thus practically unbreakable and offers a permanent stability in upper as well as lower bridge dentures. Due to the construction, friction or wear on the attachment is almost nonexistent. The prosthesis 20 is removed from crown 14 by moving same in a direction away from the gum parallel to the engagement of face 25 with the wall portion 36. The second spring part 31 then in deformed inwardly and, as previously indicated, it is important that a spring of suitable tension be chosen so that the prosthesis 20 is properly secured without being unduly difficult to remove. It will be seen that the end 33 of the spring portion 31 is ground at a bias whereby when tongue part 15 is inserted in socket 37, biased end 33 is moved inward by its contact with wall portion 36 and it thus does not tend to dig into the top of the crown 14.  
  Referring now to FIGS. 8 13, a further embodiment of the invention is shown whereby, as seen in FIG. 8, a crown 40 receives a tongue member 41 which includes a tongue part 42 received in a socket 43. Also, an arm 44 utilized for connection to frame parts of the bridge is included in tongue member 41. A roughly U- shape spring 45 extends from a groove 46 as shown best in FIG. 12. The tongue part 42 is tapered and received in the socket 43 with the same snug fit as described for the first mentioned embodiment. At the rear of the be noted that spring 45 includes a first spring portion 50, a second spring portion 51 and a third spring portion 52. Spring portions 50 and 52 are optionally provided with gullets 50a and 52a respectively which govern the resilience of spring 45. The spring portion 51 includes three parts. The central part of portion 51 as seen in FIG. 13 is designated by reference number 54 and, when in position as shown in FIG. 12 in tongue member 41, it is parallel to the face 47 of tongue part 42. At either side of central part 54, slanted parts 55 and 55a are provided. The central part 54 extends slightly outwardly from face 47 and when in position as shown in FIG. 8, bears in and against depression 48 which, like indentation 35, is about 0.2 mm in depth. The slanted parts 55 and 55a are inclined in the direction of face 47 so that the outer surfaces are practically parallel thereto and, in any event, do not extend beyond face 47 where they joint portions 50 and 52. These parts 55 and 55a thus facilitate the insertion and removal of tongue part 42 into socket 43. From FIG. 12, it will be noted that the first spring portion 50 is received in a first channel 56 and the third spring portion 52 is received in a second channel 57. The channels 56 and 57 and the groove 46 are formed by first making a slot in the rear of tongue part 41 and thereafter soldering therein a plate 60 which, as seen in FIG. 12, has a profile which is roughly a truncated triangle or similar to the profile of a volcano whereby the groove 46 is formed by the truncated portion 61 of plate 60. The sides of the triangle are spaced so as to form channels 56 and 57 for receipt of spring 45 and plate 60 is soldered in place to become, in effect, a part of tongue member 41. The portion of plate 60 shown in dotted lines in FIG. 12 is ground away so as to give the tongue member 41 a smooth contour. In this embodiment, only a small center groove 46 is required in tongue member 41. In practice, spring 51 can be replaced in a matter of minutes and, as with the previous embodiment, the resilience of the particular spring 45 depends upon the firmness desired for the connection between tongue member 41 and crown 40 as provided by the dedent arrangement of spring part 51 being received in depression 48, as well as precision fit which otherwise exists between tongue part 42 and socket 43. If desired, socket 43 can be manufactured in a separate part 40a, as seen in the perspective view, FIG. 8A, and subsequently soldered to a bridge or crown pier by a dental technician whereby a crown such as crown 40 may be obtained.  
  In FIG. 14 an alternative embodiment of the connection between the crown l4 and the prosthesis is shown. The same reference numerals have been utilized for parts similar to those shown in FIGS. 1 7, including artificial tooth 21, saddle part 22, face of tongue part 15, opening 32, groove 34, indentation 35, and rear wall portion 36 of socket 37. However, in lieu of nipple 24, a tube 24a is provided which receives a spring 27a that includes a shank body or first spring portion 38 having a neck portion 38a and, near its end and away from face 25, a gullet 38b. Spring 27a also includes a second spring portion 31 which is structurally the same as shown in the first mentioned embodiment. Spring portion 31 extends partly into groove 34 from opening 32 of tube 24a and, also, generally in the direction of the adjacent or underlying gum. As with the prior embodiment, it will be noted that the second spring portion 31 extends slightly outwardly of groove 34 whereby it may be resiliently received against indentation 35 in rear wall portion 36 of socket 37 included in crown 14 whereby a dedent arrangement is provided.  
  For the purpose of restraining spring 27a in tube 24a, spring 27a is provided with gullet 38b, which is manually deformed slightly by the dentist or dental technician in its narrow portion proximate gullet 38b thereby providing spring portion 38 with a slight bend or resilient deviation. With such deformity or resilient deviation proximate gullet 38b, spring 27a is resiliently restrained within the tube 24a whereby although it may be removed by proper dental instruments, the accidental dislodgement of spring 27a when prosthesis 20 is removed by the user and&#39;is brushed does not occur. An alternative arrangement is shown in the embodiment in FIG. 16 where a spring 27b having a shank portion 39 and a neck portion 39a includes, in lieu of the gullet 38b shown in FIG. 15, a slit 39b. The bifurcated portion of spring 27b, so formed adjacent slit 39b may be deformed by a dentist or dental technician to provide a resilient deviation in this portion of spring 27b for resiliently restraining it within tube portion 24a, again to provide against accidental dislodgement of the spring 27b when prosthesis 20 is removed by the user.  
  In either of the spring embodiments, FIG. 15 or FIG. 16, the deformity to the spring can be as little as one one-thousandths of an inch or even less whereby only with a certain amount of force is it entered into tube 24a. This, it has been found, is sufficient to retain the spring in a definite position.  
  Embodiments shown in FIGS. 14 16 are commercially advantageous because the spring can be replaced and the resilience of the connection adjusted in less than five minutes as a practical matter. In addition, there is no problem with acrylic material trespassing into the tube 24a which is closed at its end.  
  The angle between the spring portion 38 and face 25 of tongue part 15 is normally between 40 and 80; the most commonly used angles are between and 55. However, with isolated piers, an angle of higher than 80 may be utilized as an alternative to the structure shown in FIGS. 8- 13 such structure being specially designed for such cases because it is short and can be extracted without disturbance from the opposite wall.  
 Preferably, tube 24a should measure about 15 gauge and should be no more than 7 to 10 millimeters in length. Otherwise, it would be difficult for the collocation of adjacent teeth to provide the best articulation. Slit 39b shown in FIG. 16 is preferably 1% 2 mm in length.  
  A still further embodiment of the connection between crown 14 and prosthesis 20 is shown in FIG. 17. The-same reference numerals have been applied for parts similar to those shown in FIGS. 1 7 as in FIG. 14. The primary distinction in this embodiment is that in lieu of a straight open tube 24, a curved flattened tube 24b receives a spring 27c which is curved as shown in perspective in FIG. 18 and has in its shank portion 30b a rectangular cross-section. However, the spring portion 31 of spring 270 is similar to that shown in the embodiments of FIGS. 1 7 and 14 16. In addition, the width of spring portion 31 is somewhat less than that of shank 30b. The construction shown in FIGS. 17 and 18 offer essentially the same advantages as the other embodiments. But, the spring 30b is somewhat shorter, measuring only about 7 mm in length, and its curve permits more space for the articulation of the tooth or teeth which are replaced. As with the previous embodiments, the pressure of the spring is simply and quickly adjustable and no problem exists in replacing the spring which may be available in different strengths. The spring is practically unbreakable and offers a permanent stability for both upper and lower bridges.  
  The anchoring of the spring does not result in a click type action. There is a uniform pressure and, when correctly positioned, a bridge held in place in accordance with the invention does not move and no friction or wear occurs on the attachment.  
  Referring to FIG. 19, again the same reference numerals have been applied for parts similar to those shown in FIGS. 1 7 and 17. The important distinction between this embodiment and that shown in FIG. 14 may be found in the configuration of the spring 272 and in the opening 32c. The spring 27e consists of a shank portion 300, a bowed neck portion 38c and a spring portion 310 which extends outwardly of groove 34 and is resiliently received against indentation 35. It will be noted that the opening 32c is so configured to provide a stop member 32c which functions to prevent withdrawal of spring 27e from tube 240 unless same is accomplished by intentional deforming the neck portion 38c in a downward direction from that seen in FIG. 19. This construction permits the user to withdraw the prosthesis for cleaning purposes with little likelihood of spring 27e being dislodged. This spring functions well and the angle of the tube portion 240 relative to the face of the tongue part is preferably in the range of 40 to 55. The embodiment disclosed in reference of FIG. 19 may be utilized in any case with the exception of where the pier is a long, thin and isolated.  
  The embodiment disclosed in FIG. 20 is intended only for posterior bridges where the piers are longer and the intermaxillary space is reduced. The spring 27d consists of a shank portion 30d, a narrowed portion 38d and a head or spring portion 31d. The indentation 35d in the rear wall portion 36 of the socket is disposed parallel to the longitudinal axis of the pier crown 14 near the center of the socket similar to the location of depression 48 in FIG. 11. The head portion 31d extends upwardly (or outwardly relative to the adjacent gum) as seen in FIG. 20 rather than downwardly (or inwardly) as shown in FIGS. 5, 14, 17 and 19. Thus, the angle between the tube portion 24d and the face 25d of the tongue part is preferably an obtuse angle in the range of 100 140 as measured counterclockwise as seen in FIG. 20.  
  It will be noted that tube portion 24d is substantially longer than tube portion 240. Both springs 276 and 27d are provided with gullets 38e and 38f respectively for resiliently retaining same within their tubes.  
  It is to be understood that the various materials utilized in construction of the embodiments described herein are those which are usual and conventional in dental practice and which do not react in any significant degree with normal substances to be found in the oral cavity. Thus, the invention may be utilized in combination with or as part of both custom made and commercial type attachments, three-fourths crown structures, veneer and full gold crowns.  
  Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:  
  1. In a removable denture, the combination of a socket member for attachment on a pier tooth and a tongue part attached to an artificial tooth prosthesis, said tongue part slideably received by said socket member whereby said prosthesis is received in its desired location with said tongue part engaging a wall portion in said socket member, said wall portion lying substantially in a plane extending transversely between the pier tooth and said prosthesis, a tube part in said tongue part which includes a tube portion, a spring member extending from said tube part resiliently bearing against said wall portion, said tongue part including a neck portion, said tube portion extending in one direction away from the surface of said tongue part engaging said wall portion through said neck portion and in the other direction opening through said tube part into said surface, a groove in said surface extending from said opening in a direction parallel to the longitudinal axis of said pier tooth, a spring having two portions, the first of said spring portions being a shank received in said tube portion and the second spring portion extending at an angle from said first spring portion and received at least in part in said groove for resiliently bearing against said wall portion when said tongue part is in said socket, said first spring portion being provided with a resilient deviation and said opening having proximate thereto in said tube part stop means adapted to bear against said deviation whereby said spring is restrained from withdrawal from said tube portion.  
  2. The structure in accordance with claim 1 wherein said first string portion defines a gullet near its end away from said second portion, a second resilient deviation being provided proximate said gullet for restraining said spring within said tube portion.  
  3. The structure in accordance with claim 1 wherein said resilient deviation comprises a bowed portion of said first spring portion.  
  4. Structure in accordance with claim 3 wherein said first spring portion is narrowed in configuration where it joins said second spring portion.  
  5. Structure in accordance with claim 1 wherein said tube portion is biased relative to said surface of said tongue part at an angle between 40 and 55 from the direction of the underlying gum.  
  6. Structure in accordance with claim 5 wherein said wall portion includes a depression adapted to receive said second spring portion.  
  7. Structure in accordance with claim 6 wherein said second spring portion extends in the direction of the adjacent gum.  
  8. In a removable denture, the combination of a socket member for attachment on a pier tooth and a tongue part attached to an artificial tooth prosthesis, said tongue part slideably received by said socket member whereby said prosthesis is received in its desired location with said tongue engaging a wall portion in said socket member, said wall portion lying substantially in a plane extending transversely between said pier tooth and said prosthesis, a spring member extending from said tongue part resiliently bearing against said wall portion, said tongue part having a neck portion and a tube portion which extends in one direction away from the surface of said tongue part engaging said wall portion into and through said neck portion and which in the opposite direction has an opening to said surface, a groove in said surface extending from said opening in a direction parallel to the longitudinal axis of said pier 9 10 tooth, a spring having two portions, the first of said said first spring portion defines a gullet near its end spring portions being a shank portion received in said away from said second portion, said resilient deviation tube portion and the second spring portion extending being proximate to said gullet. at an angle from said first spring portion in a direction 10. A structure in accordance with claim 8 wherein away from the adjacent gum, said second spring porsaid first spring portion has a narrowed neck where it tion being received at least in part in said groove for rejoins said second spring portion. siliently bearing against said wall portion when said 11. Structure in accordance with claim 8 wherein an tongue part is in said socket, said first spring portion obtuse angle is formed between said first tooth portion being provided with resilient deviation whereby it is reand said second tooth portion relative to the adjacent siliently restrained within said tube portion. 10 gum in the range of about 100 to 140.  
 9. A structure in accordance with claim 8 whereby