Patent Publication Number: US-2021177251-A1

Title: Film Clamping Element

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to European patent application No. 19215633.9 filed on Dec. 12, 2019, the disclosure of which is incorporated herein by reference in its entirety. 
     TECHNICAL FIELD 
     The invention relates to a film clamping element. 
     BACKGROUND 
     Film clamping elements of this type have been known for a long time. By way of example, reference is made to WO 03/51185 A1, US2020188060A, and U.S. Pat. No. 10,292,788, both US publications which are hereby incorporated by reference in their entirety. Film clamping elements of this type are to ensure free access to the mouth of the patient. For this purpose, a film is provided which is disposed ovally or in the shape of a circular ring and which extends between two rings which are referred to as lip ring and vestibular ring. The film may also be mounted slidably on one of the rings. 
     In any case, it is elastic and, in this respect, adjusts to the course of the lips of the patient and covers the lips at the same time. 
     Both the lip ring and the vestibular ring are comparatively stiff compared to the film element. Thus, they stretch the film element between them, whereby the film element automatically widens the mouth of the patient. 
     The anatomic situation of the oral cavity and in particular of the vestibule and the lip area differ from one another significantly usually with regard to different patients. The elasticity of the film element is to account for this situation in the known solutions. In this case, the film extends from the vestibule of the patient over the constriction at the lips to the outside, wherein a comparatively large lip ring is to improve distribution of the occurring forces. 
     Particularly in the interior of the mouth, that is to say in the region of the vestibular ring, the tension introduced is frequently perceived as uncomfortable by the patient as the vestibular ring is frequently supported on the jaw bone of the patient. 
     Thus, it has become known from EP 3 160 381 A1 to produce a pretension corset which accounts for the frenulum and thus reduces the introduced tension. 
     This represents considerable improvement compared to the original solution, but is basically still worthy of improvement. 
     A further problem of the film clamping elements used up to now is the pressure which is exerted on the lips and which differs quite considerably from patient to patient. 
     On the one hand, this pressure depends on the size of the two rings compared to the mouth opening of the patient, but on the other hand of course on the materials used. 
     Too great a pressure in particular on the jaw bones and the frenula is perceived as uncomfortable. On the other hand, the stretching function of the film clamping element depends considerably on the force acting radially towards the outside. 
     Thus, film clamping elements are typically kept in stock in several sizes to carry out adjustment to different anatomies of different patients. 
     As the film needs to be extremely elastic, a material suitable for this purpose such as an elastomer or soft silicone is frequently used. 
     SUMMARY 
     In contrast, the invention is based on the task of providing a film clamping element according to the claims, which allows for improved acceptance. 
     This task is inventively solved by the claims. Advantageous developments may be taken from the subclaims. 
     The inventive film clamping element is inventively characterized by a special elastic band which extends circularly around the film or along the film, namely in the region between the two rings, and which draws the film radially towards the inside thereat. Even though the elastic band should actually counteract the preventive function or else the function of pulling away of the film clamping element per se, in the inserted state the elastic band comes to rest either in the transition zone between the outside and the inside of the lip or on the inside of the lip. 
     In this way, it causes a tensile force on the vestibular ring and draws this ring away from the alveolar ridge and the labial frenula. In this respect, now the vestibular ring is in parallel contact with a site of the soft tissue of lips and cheeks which is not very sensitive to pressure in comparison. 
     That the elastic band extends slightly more along the vestibular ring than along the lip ring, is also because of their size ratio; typically, the diameter of the lip ring is, for instance, 10 or 20% larger than that of the vestibular ring. 
     Wearing comfort is improved considerably with the inventive film clamping element. The film is drawn towards the inside such that the vestibular ring is more prominent in the mouth which facilitates insertion of the film clamping element. The pressure on the jaw bone is smaller such that pain reactions are reduced which in the past have led to the vestibular ring being removed from the mouth of the patient and the upcoming operation being continued without auxiliary means. 
     Preferably, the inventive elastic band is mounted floatingly on the film. Preferably, it is fixed with one, further preferably with two attachments. The attachments extend from the vestibular ring along the film but in such a way that the elastic band is spaced apart from the vestibular ring also at this site. 
     The elastic band is elastic to such an extent that it may be pulled over a part of the vestibular ring. Either, a circular elastic band is provided, or two elastic bands are provided which complement one another to form a circle. In that case, every elastic band may be pulled over the associated part of the vestibular ring. 
     In fact, it is possible to attach the elastic band to any desired positions on the film element. The fixings may be realized for instance by means of two points between the film and the elastic band. However, it has proven to be particularly favorable to have two attachments opposite one another starting from the vestibular ring, and to attach them thereat by means of a welding spot on the film, for instance at a distance of approximately 1 cm from the vestibular ring. 
     In an advantageous configuration, it is provided that the attachment is connected or has been connected with the film element at a connection site spaced apart from the vestibular ring. 
     However, it is also possible to attach the elastic band only to a part of the circle of the film, in which case the inventive effect takes place partially. 
     In an advantageous configuration, it is provided that in the state pulled over the vestibular ring the elastic band(s) pull(s) the film element further radially towards the inside at the connection sites spaced apart further from the attachments than at the attachments adjacent to the vestibular ring. 
     In an advantageous configuration, it is provided that the elastic band(s) comprise approximately (that is to say +/−30%) the same thickness as the attachment, but whose width is twice to ten times the width of each elastic band, in particular approximately three times the width. 
     In an advantageous configuration, it is provided that that two elastic bands each are supported on the same attachment spaced apart from one another in the tangential direction of the rings by few mm, and extend therefrom to the opposite attachment. 
     In an advantageous configuration of the invention, it is provided that the elastic bands extend between the attachments in the state where they are not pulled over in a limp fashion or minimally tensioned, that is to say with considerably less than 10% of their maximum tension force. 
     In a further advantageous configuration of the invention, it is provided that the elastic bands and the attachments are integral to one another and/or consist of the same material. 
     At least the majority of the elastic band extends preferably radially outside of the film. Preferably, it may be pulled over a part of the vestibular ring and may be used to tension the film radially towards the inside. It is connected to the film and/or the vestibular ring and/or the lip ring at least at one, preferably at least two connection sites. 
     The thickness and width of the elastic band may be adapted to the requirements to a large extent. For instance, it may have a circular, oval, square or rectangular cross-section or any other desired cross-section. 
     In case of a flat cross-section, that is to say a cross-section in which the thickness is smaller than the width, it clings to the film particularly easily. 
     Preferably, it lies flat against the outside of the film, namely particularly over considerably more than half of the ring extension of the film. 
     Its distance to the vestibular ring is smaller, for instance 1 mm to 15 mm, preferably at the position or positions at which it is connected with the film or a ring, and larger, up to half the distance between the rings or even more, at positions spaced apart therefrom, that is to say at positions which extend laterally when it is positioned at the mouth. 
     The elastic band may be pulled over the ring during production and may be delivered like this. Alternatively, it is also possible to ask the customer to pull it over the ring. 
     It is also possible to use a commercially available rubber band, for instance having a rectangular or square cross-section, and to connect it with the film and/or a ring at least at one position, preferably at the frenulum, and to cause it to extend all around the film. 
     The elastic band reduces the diameter of the film at the position at which it extends and gathers it. 
     In a further configuration it is provided to cause the cross-section and thus the tension force of the elastic band(s) to change over its/their course, and thus to simulate the anatomy of the lips: 
     For instance, in the lateral region, the tension force may be set to be larger, and smaller at the top and at the bottom. 
     In that case, the film is gathered more strongly laterally than at the top and at the bottom. This results in a flat-oval cross-section of the initially circular film clamping element, at least in the region of the film. 
     A precondition for this is to connect the elastic band with the film at several positions, in particular also laterally. 
     It is also possible to cause several elastic bands to extend all around the film next to one another in the side view. They may have the same elasticity and tension force, but if necessary also different tension forces. 
     For instance, an elastic band positioned in the middle may have the largest tension force, and the elastic bands extending between the elastic band positioned in the middle and one ring each have a smaller tension force each. 
     Preferably, the film is pretensioned automatically to have the shape of a lip or a shape similar to a lip, for instance by means of the above-mentioned multiple arrangement of elastic bands. 
     It is also possible to use a film material or a film-like material for the configuration of the elastic band(s). Such a band may have a thickness of between 0.05 and 1 mm and a width of between 3 and 8 mm. 0.3 mm*5 mm are preferred. 
     The band may also be laminated onto the film such that the connection runs around the entire circumference of the film, and the band is connected securely with the film. 
     It is also possible to configure the film as a layered film with several layers. In that case, one layer can form the elastic band, preferably in the shape of a ring, approximately centrally between the rings or slightly shifted towards the vestibular ring. 
     The elastic band may also be configured as a thickening of the film extending centrally between the rings. The thickening may be continuous or may have knobs and produces the inventive constriction due to its larger tension force. 
     When viewed in the transverse view, the profile of the film gets closer to the lip profile by means of the elastic band and its position, which also considerably facilitates introduction of the film clamping element into the oral cavity. 
     In this respect, a special advantage is provided in that insertability of the film clamping element with the inventive elastic band which causes the film to constrict is improved considerably. 
     According to the invention it is preferred that the elastic band may be pulled over a part of the vestibular ring. Alternatively, it may also be pulled over the lip ring or over a part of this ring. It is connected preferably at two attachments with the respective ring, but considerably more elastic compared thereto. In the relaxed state it is shorter than the circumference of the ring. However, due to its elasticity it may be pulled or moved over its outer circumference readily. 
     In order to activate the elastic band, it is lifted without further ado, for instance using one or two fingers, and pulled over the respective part of the vestibular ring. This process may also take place at the factory and supported by machines. 
     In an advantageous configuration two elastic bands are provided which extend between opposite positions of the vestibular ring like limp tendons in the relaxed state. The film clamping element is produced in this form. 
     Two attachments extend from opposite positions of the vestibular ring towards one another, and every attachment ends in two ends of an elastic band, at the support base. 
     Preferably, it is provided that the connection site is between the vestibular ring and the support base. 
     Preferably, it is provided that the protrusion edge of the vestibular ring comprises a padding which is recessed at the tangential connection sites of the attachments. 
     In an advantageous configuration it is provided that the attachments are turned over and affixed to the film, for instance by laser welding, ultrasound welding, gluing or sewing or another joining process, approximately  0 . 5 cm to  12 mm away from the vestibular ring. In this way, the elastic band or elastic bands are tensioned. Still, the tension in the elastic band is so small that the respective elastic band cannot tear in no case. 
     For activation, the right elastic band is now turned or pulled over the right part of the vestibular ring and the left elastic band is turned or pulled over the left part. 
     Now, both elastic bands together form a circle which rests against the film from the outside and pretensions it radially towards the inside. Pretensioning takes place at a small distance from the vestibular ring, for instance at a distance of  1 cm, wherein the distance from the vestibular ring increases with increasing distance from the attachment, such that the elastic band slides towards the center between lip ring and vestibular ring thereat, that is to say into the position lowest in energy. 
     The film element, which has been pre-assembled limply, is pretensioned by the elastic band radially towards the inside at that position. On the other hand, it forms soft loops as there is excess material due to the smaller diameter now. 
     By the way, these loops have a damping effect and are downright comfortable on the sensitive skin of the lips as they are extremely elastic. 
     In an advantageous configuration of the invention, it is provided that the film has one attachment each at at least two positions opposite from one another. 
     In a further advantageous configuration of the invention, it is provided that the film and the elastic bands have an E-modulus which is smaller compared to that of the rings by 80 to 99%. 
     In a further advantageous configuration of the invention, it is provided that the attachment extends away from the vestibular ring along the film element, and guides and supports the elastic band(s) at its distal end. 
     In a further advantageous configuration of the invention, it is provided that the attachment extends over a fractional part of the distance between the lip ring and the vestibular ring, in particular over less than 60% and particularly preferably over 10 to 45% and more preferably over approximately 30%. 
     In a further advantageous configuration of the invention, it is provided that the attachment comprises approximately three times the width of each elastic band. 
     In a further advantageous configuration of the invention, it is provided that the elastic bands comprise a non-destructive elasticity of at least twice their initial length, particularly preferably ten times to 50 times. 
     In a further advantageous configuration of the invention, it is provided that the elastic bands contract the film element radially towards the inside by 10 to 30% of its diameter, and in particular produce padding folds in the film element. 
     In a further advantageous configuration of the invention, it is provided that an elastic band may be tensioned radially towards the inside and is connected or may be connected with the film or a ring at at least two connection sites. 
     According to a further aspect of the invention, a film clamping element, in particular for dental treatments, is provided comprising the lip ring and the vestibular ring between which and possibly beyond which the film extends. The film and also the rings are elastically deformable. The film is turned over at the vestibular ring or the lip ring. In this connection, the film is fixedly connected with both rings or with at least one of the two rings. The effect of the inventive elastic band takes effect only by this fixed connection. It extends at the end of the turned-over film along the film spaced apart from both rings and extending in the region therebetween. Said elastic band is used to tension the film radially towards the inside at a position between the rings. Surprisingly, this improves the wearing comfort considerably. 
     In an advantageous configuration of this solution, it is provided that the elastic band is configured as a ring-shaped thickening of the film at its turned-over end and/or that the elastic band has a smaller diameter than the rings in its relaxed state. 
     According to a further aspect of the invention, a film clamping element, in particular for dental treatments, is provided comprising the lip ring and the vestibular ring, between which and possibly beyond which the film extends, wherein said film and also said rings are elastically deformable. The film is fixedly connected with both rings and at least one elastic band extends spaced apart from both rings and extending therebetween and substantially parallel thereto, in particular integrally therewith, said elastic band being able to tension the film radially towards the inside at a position between the rings. 
     In an advantageous configuration of this solution, it is provided that the elastic band is formed by realizing knobs which extend along the elastic band, in particular at regular distances to one another. 
     According to a further aspect of the invention, a film clamping element, in particular for dental treatments, is provided comprising the lip ring and the vestibular ring, between which and possibly beyond which the film extends, wherein said film and also said rings are elastically deformable. At least one elastic band extends radially on the outside of the film, wherein said elastic band can be pulled over a part of the vestibular ring and/or the lip ring and with which the film can be tensioned radially towards the inside. The elastic band may be connected or is connected with the film or a ring at at least one, preferably at least 2, connection sites. 
     It is preferable that a film clamping element for dental treatments is provided having a lip ring and a vestibular ring, between which and possible beyond which a film extends, wherein the film and the lip and vestibular rings are elastically deformable, wherein the film comprises one or more attachments at at least one position, starting from which one or more attachments, at least one elastic band extends which may be pulled over a part of the vestibular ring and/or the lip ring and with which the film may be tensioned radially towards the inside. 
     It is preferable that the one or more attachments include two attachments at at least two positions opposite one another, between which two attachments, at least one elastic band extends which may be pulled over a part of the vestibular ring and/or the lip ring and with which the film may be tensioned radially towards the inside. 
     It is preferable that the film and the at least one elastic band are more elastic than the rings and have an E-modulus which is smaller compared to an E-modulus of the rings by 80 to 99%. 
     It is preferable that the at least one elastic band comprises two elastic bands which may be tensioned such that they complement one another to form a circle. 
     It is preferable that each elastic band of the two elastic bands may be pulled over a part of the vestibular ring. 
     It is preferable that the attachment extends away from the vestibular ring, along the film element, and guides and supports the elastic band(s) at a support base spaced apart from the vestibular ring, at a distal end. 
     It is preferable that the one or more attachments is molded to the film element integrally, and/or consists of the same material, and wherein the one or more attachments extends over a fractional part of the distance between the lip ring and the vestibular ring. 
     It is preferable that the one or more attachments extends over an amount selected from less than 60% the distance between the lip ring and the vestibular ring, over 10-45% the distance between the lip ring and the vestibular ring, and over 30% of the distance between the lip ring and the vestibular ring. 
     It is preferable that the at least one elastic band comprises a flat or flat-oval cross-section with a width extending along the film element, and/or wherein in a state pulled over the vestibular ring, the at least one elastic band(s) extend(s) along the film element on an outside and pretension(s) the film element radially towards the inside. 
     It is preferable that the at least one elastic band comprises a non-destructive elasticity selected from more than 1.2 times an initial length and twice an initial length. 
     It is preferable that the at least one elastic band comprises a non-destructive elasticity of ten times to 50 times an initial length. 
     It is preferable that a protrusion edge extends away from the film element in extension thereof starting from the vestibular ring, and wherein the one or more attachments are attached to the protrusion edge. 
     It is preferable that, in the state pulled over the vestibular ring, the one or more elastic bands contract the film element radially towards the inside, by 10 to 30% of a diameter, and produce padding folds in the film element. 
     It is preferable that a film clamping element for dental treatments is provided having a lip ring and a vestibular ring, between which and possibly beyond which a film extends, wherein the film and the lip and vestibular rings are elastically deformable, wherein the film is turned over at the vestibular ring or the lip ring, wherein the film is fixedly connected with both the lip and vestibular rings and wherein at least one elastic band extends at the end of the turned-over film along the film spaced apart from both rings and extending in the region therebetween, said at least one elastic band being able to tension the film radially towards the inside at a position between the rings. 
     It is preferable that the elastic band is configured as a ring-shaped thickening of the film at a turned-over end and/or wherein the elastic band has a smaller diameter than the rings in a relaxed state. 
     It is preferable that a film clamping element for dental treatments is provided having a lip ring and a vestibular ring, between which and possibly beyond which a film extends, wherein the film and the lip and vestibular rings are elastically deformable, wherein the film is fixedly connected with both the lip and vestibular rings and at least one elastic band extends at the end spaced apart from both rings and extending therebetween and substantially parallel thereto, integrally therewith, the elastic band configured to tension the film radially towards the inside at a position between the rings. 
     It is preferable that the elastic band is formed by realizing knobs which extend along the elastic band, at regular distances to one another. 
     It is preferable that a film clamping element for dental treatments is provided having a lip ring and a vestibular ring, between which and beyond which a film extends, wherein the film and lip and vestibular rings are elastically deformable, wherein at least one elastic band extends radially on the outside of the film, wherein the at least one elastic band is pulled over a part of the vestibular ring and/or the lip ring and with which the film is tensioned radially towards the inside and connected with the film or a ring at at least one connection site. 
     It is preferable that the at least one connection site includes two sites. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further advantages, details and features may be taken from the following description of several exemplary embodiments of the invention in conjunction with the drawings, in which: 
         FIG. 1  shows a perspective view of an inventive film clamping element in one embodiment; 
         FIG. 2  shows the film clamping element according to  FIG. 1  in the top view; 
         FIG. 3  shows the film clamping element according to  FIG. 1  but with an elastic band pulled over part of the vestibular ring; 
         FIG. 3 a    shows the film clamping element according to  FIG. 2  but with an elastic band pulled over part of the vestibular ring; 
         FIG. 4  shows an enlargement of a detail from  FIG. 3 ; 
         FIG. 5  shows a top view of a detail from  FIG. 3 ; 
         FIG. 6  shows a section of a detail of a further embodiment of the inventive film clamping element; 
         FIG. 7  shows a side view of a further embodiment of the inventive film clamping element; 
         FIG. 8  shows a side view of a further embodiment of the inventive film clamping element; 
         FIG. 9 a    shows a section through a further embodiment of the inventive film clamping element; and 
         FIG. 9 b    shows a perspective view of a further embodiment of the inventive film clamping element. 
     
    
    
     DETAILED DESCRIPTION 
     The film clamping element  10  illustrated in  FIG. 1  comprises a film  12  which extends between a lip ring  14  and a vestibular ring  16 . 
     Both rings are stiff but still elastically deformable. 
     The film extends practically in the shape of a ring or a jacket such that the interior both of the vestibular ring  16  and of the lip ring  14  is free from material. 
     In this exemplary embodiment, the lip ring  14  is slightly larger than the vestibular ring  16  in a way known per se. 
     At least one elastic band  20  extends transversely over the vestibular ring  16 . In the exemplary embodiment illustrated, a further elastic band  22  is provided which extends parallel to the elastic band  20 . 
     The bands  20  and  22  may also be spaced apart from one another considerably farther such that crescent-shaped constrictions are formed. 
     Both elastic bands are anchored at attachments  24  and  26  wherein every elastic band  20  and  22  extends between these two attachments  24  and  26 . 
     The attachments  24  and  26  are attached to the vestibular ring  16  for their part and additionally to the film  12  in the preferred exemplary embodiment illustrated. 
     Preferably, the elastic bands  20  and  22  are made of the same material as the film  12  and are highly elastic. 
     They are elastic to such an extent that it is possible without further ado to pull them over the respective adjacent part of the vestibular ring, that is to say the right elastic band  20  over the right part  28  and the left elastic band  22  over the left part  30  of the vestibular ring  16 . 
     When both bands  20  and  22  are pulled over the vestibular ring  16 , they substantially form a circle. 
     It is apparent from  FIG. 2  and  FIG. 3  how the attachments  24  and  26  are configured. Every attachment is attached to the vestibular ring like a flap in such a way that both attachments  24  and  26  are opposite one another. 
     Additionally, every attachment extends radially outside of the film  12 , partially beyond it. 
     The attachment  24  is connected with the film  12  at the position  36  by ultrasound welding, and the attachment  26  at the opposite position. 
     These two positions are spaced apart from the vestibular ring considerably. However, the attachment  24  or  26 , respectively, extends slightly beyond each considered position  36  as far as a support base  40  ( FIG. 4 ). This support base  40  is located at the distal end of the attachment  24  or  26 , respectively, and the elastic bands  20 ,  22  extend therefrom, namely divergent from one another ( FIG. 5 ). 
     At this position the elastic bands  20 ,  22  are turned over in the position according to  FIG. 2  and extend beyond the vestibular ring  16  over the open end of the film clamping element  10 . 
     However, it is possible to tension both elastic bands  20  and  22  and to pull them over the vestibular ring  16 . This state is illustrated in  FIG. 3 . In this state, the right elastic band  20  is pulled further to the right until it extends over the right part  28  of the vestibular ring  16 . It is released just behind this part such that it contracts again and assumes approximately the shape according to  FIG. 3 . 
     In this shape, the elastic band  20  tensions the film  12  radially towards the inside. The position at which this happens is determined by the length of the attachments  24 ,  26 , in particular by the position of the connection sites  36 . 
     At this position, the film  20  forms loops  50  which have an additional damping effect. 
     The elastic band  20  automatically slides into the position lowest in energy, that is to say into the position in which the tension between lip ring  14 , vestibular ring  16 , film  12  and elastic band  20  keeps its balance. 
     This position illustrated in  FIG. 3  is ideal for the best wearing comfort of the patient wherein reliable coverage of the mouth opening is provided nevertheless. 
     As a consequence of the comparison of  FIGS. 3 a    and  2 , the film  12  has a smaller inside diameter radially and is pre-tensioned radially towards the inside when the elastic band  20  is activated. 
     The position of the elastic band  20  apparent from  FIG. 3  is apparent in a detailed fashion from  FIG. 4 . The support base  40  is shifted slightly towards the lip ring  14  when viewed from the connection site  36  where the welding is made. 
     The elastic band  20  starts thereat and clings to the film  12  radially on the outside. 
     The length of the attachment  24  which defines the distance to the vestibular ring  16 , and also the location of the connection sites  36  determine an exact position. 
     Alternatively, it would also be possible to realize guidance of the elastic band  20  starting from the lip ring  14  using a correspondingly longer attachment  24 . 
       FIG. 5  illustrates the attachment  24  in the top view. The attachment  24  consists of the same material as the film  12  and the elastic bands  20  and  22 . The support base  40  enables almost a circular shape of the ring formed by the elastic bands  20  and  22 . 
     It is also apparent that the attachment  24  comprises approximately three times the width of the elastic bands  20  and  22 . The elastic bands  20  and  22  preferably comprise a flat-oval cross-section such that they can cling to the film  12  easily. 
       FIG. 6  shows a further embodiment of the invention. In case of this embodiment, the inventive elastic band  20  is integrated in the film  20 . In this respect, it extends along the film as an annular thickening thereof along the entire circumference of the ring. 
     The thickening  20  has a greater tension force than the film  12  as for the rest. As a consequence, the film comprises a constriction at the position of the thickening  20  which extends in a way kind to the lips, that is to say which is similar to the bent circular shape of the lips. 
     When viewed from the outside and in section, the film forms a concave concavity with the elastic band  20  which envelops the lip gently and at the same time ensures that the vestibular ring is pulled away from the jaw bone. 
     In the embodiment according to  FIG. 7 , the film  12  is stretched between the vestibular ring  16  and the lip ring  14 . In this embodiment, an elastic ring  20  is incorporated into the film  12  circumferentially. The elastic ring  20  extends approximately in the middle region between the vestibular ring  16  and the lip ring  14 . It is configured quasi as a thickening and preferably has a diamond-shaped cross-section as is apparent from the section illustrated in  FIG. 7 . 
     In this solution the elastic band  20  pulls the film  12  radially towards the inside. The pressure on the lips acting radially to the outside is reduced such that the wearing comfort of the film clamping element  10  is improved. 
     In the embodiment according to  FIG. 8 , the elastic band  20  is formed by a circumferential arrangement of knobs  52 . They effect a strengthening of material at this position such that there in turn the lips are relieved by radial inward pull of the elastic band  20 . 
     In the embodiment according to  FIG. 9 a    and  FIG. 9 b   , the film  12  is extended beyond the vestibular ring  16 . It ends in an elastic band  20  which is configured in the shape of a ring. 
     The film extension  54  produced in this way may be pulled over the vestibular ring  16  in turn. Then, the elastic band  20  at the end of the film extension  54  pushes the middle region between the vestibular ring  16  and the lip ring  14  radially towards the inside, which in turn leads to the desired relieve of the lips and thus improves wearing comfort. 
     The diameter of the opening  56  of the elastic band  20  may be adapted to the requirements to a large extent. When the elastic band  20  is configured to be stronger, the diameter of the opening  56  is reduced and thus also the diameter of the middle region of the film  12  as the film extension  54  including the elastic band  20  is pulled over the vestibular ring  16 . 
     While, here, the elastic band  20  is configured so that it can be pulled over, it is to be understood that instead it is also possible easily to pull the elastic band  20  into the middle region of the film  12 . 
     Although preferred embodiments have been depicted and described in detail herein, it will be apparent to those skilled in the relevant art that various modifications, additions, substitutions, and the like can be made without departing from the spirit of the invention and these are therefore considered to be within the scope of the invention as defined in the claims which follow.