Abstract:
A denture attachment system ( 10 ) comprises an implant member ( 12 ) adapted to be secured in a mandible (B) such that a head ( 20 ) of the implant member ( 12 ) projects out of the mandible (B). A locking mechanism ( 14 ) is adapted to be received in a denture (A) so as to cooperate with the implant member ( 12 ) to releasably secure the denture (A) to the implant member ( 12 ). The locking mechanism ( 14 ) has a receptacle ( 50,51 ) for receiving the head ( 20 ) of the implant member ( 12 ). A locking member ( 60,61 ) is movable between a locking position in which the locking member blocks an access out of the receptacle ( 50,51 ) by opposing a surface complementary to the shape of the head ( 20 ) of the implant member ( 12 ) to hold the implant member ( 12 ) captive in the receptacle ( 50,51 ) with points of contact between the head ( 20 ) of the implant member ( 12 ) and the locking member ( 60 ) being diametrically opposed with respect to the head ( 20 ), and a release position in which the head ( 20 ) of the implant member ( 12 ) may enter/exit the receptacle ( 50,51 ).

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     The present patent application claims priority on U.S. Provisional Patent Application No. 60/580,699, filed on Jun. 21, 2004, by the present applicants. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates to dental prostheses, and more particularly, to a denture detachably mounted to permanent endosseous implants.  
       BACKGROUND OF THE INVENTION  
       [0003]     It is known to provide permanently fixed dentures which include implants anchored in the mandible or maxilla osseous portions and a denture including an artificial gum and teeth structure being fixed to the implants and/or existing teeth or roots.  
         [0004]     It is also known to provide a bridge or denture which includes a locking device adapted to lock onto the crown of a tooth. However, the torque which can be produced by the denture on the tooth or teeth by the function of the prosthesis can damage the crown of the tooth and render it useless.  
         [0005]     It is also known to have a denture which is removably detached from an implant structure, wherein the implant structure includes a metallic arch or bar formed to bridge individual roots or root substitutes, such as pins implanted directly into the osseous material of the mandible or maxilla. The denture includes an artificial gum structure adapted to fit snugly over the arch and locking device for locking the denture to the arch. An example of such a device is described in U.S. Pat. No. 4,085,506, issued Apr. 25, 1978 to Isaih Lew. Such an assembly requires the arch to accommodate the locking device.  
         [0006]     U.S. Pat. No. 5,716,214, granted on Feb. 10, 1998 to Lund et al., describes a dental prosthesis system in which a denture is removably secured to a mandible having permanent osseous implants. The interconnection between the denture and the implant is achieved by male/female members, that are releasable from one another when it is desired to remove the denture from the mandible. A single surface of interference is provided between the male and female members, so as to retain the denture onto the mandible. Moreover, the interference between male and female member is effected by a pair of arcuate surfaces, and maintained by a spring.  
         [0007]     Because of the pressures exerted during chewing (i.e., high magnitude, from any direction), it is believed that denture attachment systems having single surfaces of interference may be subjected to the undesired detachment of the denture from the mandible. Moreover, in the system of U.S. Pat. No. 5,716,214, the pressures exerted on the denture are potentially transmitted against the biasing action of the spring because of the contact between the arcuate surfaces of the male and female members. This may ultimately lead to the disconnection of the denture from the implant.  
       SUMMARY OF THE INVENTION  
       [0008]     It is therefore an aim of the present invention to provide a novel denture attachment system.  
         [0009]     It is a further aim of the present invention to provide a denture attachment system which overcomes the disadvantages of the prior art.  
         [0010]     Therefore, in accordance with the present invention, there is provided a denture attachment system comprising: an implant member adapted to be secured in a mandible such that a head of the implant member projects out of the mandible; and a locking mechanism adapted to be received in a denture so as to cooperate with the implant member to releasably secure the denture to the implant member, the locking mechanism having: a receptacle for receiving the head of the implant member; and a locking member being movable between a locking position in which the locking member blocks an access out of the receptacle by opposing a surface complementary to the shape of the head of the implant member to hold the implant member captive in the receptacle with points of contact between the head of the implant member and the locking member being diametrically opposed with respect to the head, and a release position in which the head of the implant member may enter/exit the receptacle.  
         [0011]     Further in accordance with the present invention, there is provided a denture attachment system comprising: an implant member adapted to be secured in a mandible such that a head of the implant member projects out of the mandible; and a locking mechanism adapted to be received in a denture so as to cooperate with the implant member to releasably secure the denture to the implant member, the locking mechanism having: a receptacle for receiving the head of the implant member along an axis of insertion; and a locking member being movable in a plane of actuation between a locking position in which the locking member blocks an access to and out of the receptacle by opposing a surface complementary to the shape of the head of the implant member to hold the implant member captive in the receptacle, and a release position in which the head of the implant member may enter/exit the receptacle, the locking mechanism being configured such that the axis of insertion is generally normal to the plane of actuation. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]      FIG. 1  is an exploded view of a denture with respect to a mandible, for subsequent connection therebetween using a denture attachment system in accordance with a preferred embodiment of the present invention;  
         [0013]      FIG. 2  is an exploded view of a locking mechanism with respect to an endosseous implant abutment, both of the denture attachment system, in position for a subsequent connection therebetween;  
         [0014]      FIG. 3  is an exploded view of the locking mechanism of the denture attachment system of  FIG. 2 ;  
         [0015]      FIG. 4  is a perspective view of a seat member of the locking mechanism of  FIG. 2 ;  
         [0016]      FIG. 5  is a perspective view of a guillotine member of the locking mechanism of  FIG. 2 ;  
         [0017]      FIG. 6A  is an enlarged view illustrating an interrelation between the guillotine member and the seat-member with the guillotine member in a release position; and  
         [0018]      FIG. 6B  is an enlarged view illustrating an interrelation between the guillotine member and the seat member with the guillotine member in a locking position.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0019]     Referring to the drawings and, more particularly, to  FIG. 2 , a denture attachment system in accordance with a preferred embodiment is generally shown at  10 . The system  10  has an endosseous implant, partly illustrated at  12 , and a locking mechanism  14 . It is pointed out that the endosseous implant illustrated herein includes an implant portion (not shown) received in the osseous material, and an endosseous implant abutment illustrated at  12 , supported by the implant portion. One-piece implants could be used with the denture attachment system. As will be described hereinafter, the endosseous implant abutment  12  and the locking mechanism  14  cooperate so as to releasably secure a denture (i.e., a dental prosthesis) to a mandible (or maxillary) of a user person.  
         [0020]     Referring to  FIG. 1 , a denture A is shown placed above a mandible B. The denture A is secured to the mandible B by a pair of the denture attachment system  10  ( FIG. 2 ). Accordingly, two endosseous implants (the implant abutments being visible at  12 ) are anchored in the osseous material of the mandible B, and will be used as anchors for the denture A onto the mandible B. Two locking mechanisms  14  protrude out of the denture A, and will releasably lock the denture A onto the mandible B.  
         [0021]     Referring to  FIG. 2 , the endosseous implant abutment  12  is shown having a ball head  20  at an end of a stem  21 . According to a preferred embodiment, the ball head  20  has a spherical geometry.  
         [0022]     According to a preferred embodiment, the stem  21  has a cylindrical body, with threading  22  on the outer surface or any other suitable surface for anchoring the stem  21  in the mandible or maxillary. An abutment flange  23  is adjacent to the ball head  20 . In an embodiment, a hexagonal head  24  (with neck  24 B) is optionally positioned between the abutment flange  23  and the ball head  20 .  
         [0023]     When the implant abutment  12  is received in the mandible B as illustrated in  FIG. 1 , the stem  21  is screwed in the implant portion (not shown) implanted in the osseous material up to the abutment flange  23 , which protrudes from the soft tissue of the mandible B. Accordingly, when the implant abutment  12  is anchored in the mandible B, the ball head  20  is exposed, as illustrated in  FIG. 1 .  
         [0024]     The hexagonal head  24  provides grip (e.g., for tools such as a wrench) to affix or remove the implant abutment  12  from implant portion (not shown) in the mandible B.  
         [0025]     Referring to  FIG. 2 , the locking mechanism  14  is typically housed in the acrylic base of the denture A ( FIG. 1 ), such that a connection opening  40  thereof is exposed in a mandible receiving cavity of the denture A (i.e., at the underface of the denture A). Moreover, a detent end  41  faces outwardly from the base of the denture A, as shown in  FIG. 1 . The detent end  41 , constituted by a detent end portion  64  of the guillotine.  60   FIG. 5 , comes in different lengths. For instance, it is considered to provide the detent end  41  in three different sizes, to accommodate a lingual, normal or buccal position of the denture teeth depending on the three classical jaw relations (i.e., prognathic, normal, retrognathic).  
         [0026]     Referring to  FIG. 3 , the locking mechanism  14  is shown in an exploded view. The locking mechanism  14  has a hollow cylindrical casing  42 . The cylindrical casing  42  has an open end  42 A, through which a cavity of the casing  42  is accessed, and a closed end  42 B. An opening  43  is defined in the peripheral surface of the cylindrical casing  42 , which opening will be part of the connection opening  40  of the locking mechanism  14 . A tapped hole  44  is provided, so as to receive set screw  45  therein, or any suitable fastener.  
         [0027]     Referring to  FIG. 3 , a biasing member  46  is received at the closed end  42 B of the cavity of the casing  42 . The biasing member  46  is typically a cushion of resilient material, or a spring.  
         [0028]     Referring concurrently to  FIGS. 3, 4  and  5 , a seat member  50  and a guillotine member  60  are received one on another within the cylindrical cavity of the casing  42 . Accordingly, the superposition of the seat member  50  and the guillotine member  60  defines a cylindrical body, sized so as to snugly fit within the cylindrical cavity of the casing  42 .  
         [0029]     The seat member  50  is a semi-cylinder having a hemispherical receptacle  51  on a flat surface thereof. A throughbore  52  is adjacent to the hemispherical receptacle  51 . When assembled as illustrated in  FIG. 2 , the set screw  45  passes through the throughbore  52  of the seat member  50 . The throughbore  52  is sized such that the seat member  50  is immovable when retained in the casing  42  by the set screw  45 . In this position, the seat member  50  has the hemispherical receptacle  51  aligned with and facing toward the opening  43  in the casing  42 .  
         [0030]     Referring to  FIGS. 3 and 5 , the guillotine member  60  has a semi-cylinder portion  60 A between a circular end  63  and a detent end portion  64 , such that the seat member  50  and the guillotine member  60  form a cylindrical portion when the semi-cylinder position  60 A and the seat member  50  are against one another. The semi-cylinder portion  60 A has a greater length than the seat member  50 , such that a translational degree of freedom is provided between the seat member  50  and the guillotine member  60  when the seat member  50  is abutted against the semi-cylinder position  60 A, as shown in  FIG. 3  by direction C.  
         [0031]     The guillotine member  60  has an obround-shaped slot  61  (i.e., hockey-rink shape), as well as a generally pear-shaped slot  62  (e.g., with a circular portion and a throat portion). The guillotine member  60  is the movable member of the locking mechanism  14 . More specifically, when the guillotine member  60  is received in the casing  42 , the set screw  45  passes through the obround-shaped slot  61 . The elongated shape of the obround-shaped slot  61  enables the translation of the guillotine member  60  along the directions illustrated by C in  FIG. 2 , between a locking position, and a release position.  
         [0032]     The guillotine member  60  is sized such that the detent end portion  64  thereof extends out of the open end  42 A of the casing  42 , which end  64  is visible in  FIG. 2 . Moreover, the guillotine member  60  is configured such that the biasing member  46  biases the guillotine member  60  away from the closed end  42 B through contact with the circular end  63 , such that the guillotine member  60  has its end  64  extending out of the open end  42 A of the casing  42 . The detent end portion  64  of the guillotine member  60  will serve as detent to release the locking mechanism  14  from the implant abutment  12 .  
         [0033]     Referring to  FIGS. 6A and 6B , enlarged views illustrate the relative positions between the pear-shaped slot  62  of the guillotine member  60 , and the hemispherical receptacle  51  of the seat member  50 , when the seat member  50  and the guillotine member  60  are superposed in the casing  42 , as illustrated in  FIG. 2 . These relative positions are the opposed limits associated with the translation of the guillotine member  60  with respect to the seat member  50 .  
         [0034]     In  FIG. 6A , the guillotine member  60  is in its release position with respect to the seat member  50 , whereby the larger end of the pear-shaped slot  62  is in register with the hemispherical receptacle  51 . In the release position, the ball head  20  of the implant abutment  12  may access the hemispherical receptacle  51 , so as to be lodged therein. In order for the guillotine member  60  to reach the release position of  FIG. 6A , pressure must be exerted on the detent end portion  64  of the guillotine member  60 , against the biasing action of the biasing member  46 . When the pressure on the detent end portion  64  of the guillotine member  60  is released, the guillotine member  60  returns to its locking position, illustrated in  FIG. 6B .  
         [0035]     In  FIG. 6B , the guillotine member  60  is in its locking position with respect to the seat member  50 , whereby the narrower end of the pear-shaped slot  62  is in register with the hemispherical receptacle  51 . In the locking position, the ball head  20  (not shown in  FIG. 6B ) is held captive in the hemispherical receptacle  51  by the periphery of the narrower end of the pear-shaped slot  62 . More precisely, the width of the narrower end of the pear-shaped slot  62  is less than the diameter of the ball head  20  ( FIG. 2 ), such that the ball head  20  lodged in the hemispherical receptacle  51  is held captive therein with the neck  24 B passing through the narrower end of the pair-shaped slot  62 . The surface of the guillotine member  60  (within the pear-shaped slot  62 ) that contacts the ball head  20  may be carved so as to match the surface of the ball head  20 , to ensure the integrity of the fit between the ball head  20  as retained by the guillotine member  60 . Alternatively, the pear-shaped slot  62  could oppose a pair of flat surfaces to the ball head  20 , thereby providing two points of interference between the ball head  20  and the periphery of the pear-shaped slot  62 , so as to enhance the integrity of the connection between the implant abutment  12  and the locking mechanism  14 .  
         [0036]     As the biasing member  46  biases the guillotine member  60  to the locking position of  FIG. 6B , the ball head  20  will be held captive within the hemispherical receptacle  51 , until the detent end portion  64  of the guillotine member  60  is pressed.  
         [0037]     The ball head  20  will access the hemispherical receptacle  51  through the connection opening  40  illustrated in  FIG. 2 , and oriented in the denture toward the mandible supporting the implant abutment  12 .  
         [0038]     Therefore, in order to install the denture A onto the mandible B, the denture A is positioned above the mandible B as illustrated in  FIG. 1 , with the implant abutments  12  in the mandible B and the locking mechanisms  14  in the denture A having been relatively positioned with respect to one another in view of their cooperation.  
         [0039]     Thereafter, the denture A is brought down onto the mandible B, such that the ball heads  20 ′ of the implant abutments  12  are received in the connection openings  40  in the locking mechanisms  14  ( FIG. 2 ).  
         [0040]     The detent end portion  64  of the guillotine member  60  is pressed inwardly, so as to bring the guillotine member  60  to its release position ( FIG. 6A ), such that the ball head  20  of the implant abutment  12  may be lodged in the hemispherical receptacle  51  of the seat member  50 . It is contemplated to provide the locking mechanism  14  with a quick connect configuration. For instance, the periphery of the pear-shaped slot  62  may be bevelled in order to momentarily force the guillotine member  60  toward the release position as a function of pressure exerted thereon by the ball head  20 . In such an embodiment, the user person would not need to press the detent end  41  of the guillotine member  60  to install the denture A.  
         [0041]     Once the ball head  20  of the implant abutment  12  is lodged in the hemispherical receptacle  51  of the seat member  50 , the guillotine member  60  returns to its locking position through the action of the biasing member  46 , whereby the implant abutment  12  is connected to the locking mechanism  14 , and the denture A is releasably secured to the mandible B ( FIG. 1 ).  
         [0042]     In order to remove the denture A from the mandible B ( FIG. 1 ), the detent end portion  64  of the guillotine member  60  is pressed such that the guillotine member  60  reaches its release position ( FIG. 6A ). The denture A may thus be lifted away from the mandible B, with the ball head  20  of the implant abutment  12  exiting through the connection opening  40  of the locking mechanism  14 .  
         [0043]     Advantageously, the two diametrically opposed points of interference (i.e., contact) between the ball head  20  and the guillotine member  60  reduce the risk of the unwanted disconnection of the locking mechanism  14  from the endosseous implant abutment  12 .  
         [0044]     It is contemplated to provide the denture attachment system  10  in various configurations. For instance, the use of a ball head  20  is described for implant abutment  12 , but other geometries (e.g., conical, frusto-conical, cubic, and the like) could be used. Circular sections are preferred in that they often do not require to be in a given orientation for cooperation with a locking mechanism.  
         [0045]     The biasing member  46  ( FIG. 3 ) may be of various types. For instance, a resilient cushion member is preferably used, but it is contemplated to use a spring or the like. In the preferred embodiment, in order to enhance the biasing action of the resilient cushion, the latter may have given geometries, such as a hollow hourglass-shaped cylinder. All components of the denture attachment system  10  of the present invention are made of materials well suitable to the oral environment.  
         [0046]     It is pointed out that the degree of freedom of the guillotine member  60  is generally transverse to the lockable degree of freedom between the locking mechanism  14  and the implant abutment  12 . More specifically, the axis of insertion of the implant abutment  12  in the locking mechanism  14  is generally normal to a plane in which the guillotine member  60  is displaceable (i.e., actuation plane).  
         [0047]     Although two denture attachment systems  10  of the present invention are illustrated in  FIG. 1 , it is pointed out that a denture could be connected to a mandible with one of more of the denture attachment system  10  of the present invention. The denture attachment system  10  of the present invention may be used for both the mandible and the maxillary.