Patent Publication Number: US-2006008773-A1

Title: Titanium-mesh umbrella device for bone grafting

Description:
BACKGROUND OF THE INVENTION  
      (1) Field of the Invention  
      This invention relates to a titanium-mesh umbrella deivce for alveoloplasty, especially to a structure of titanium-mesh umbrella for bone grafting, which can be positioned quickly during dental implant placement procedure to hold bone graft in proper position, and to maintain a bone graft space and the easy covering of a guide tissue membrane, and to shorten the operation duration.  
      (2) Description of the Related Art  
      In a method for treating a missing tooth in traditional dentistry, the outline of either tooth of its neighbors has to be grinded into smaller shape so as to form an abutment for consolidation of a crown bridge for fixing a prosthesis. However, there are many disadvantages in traditional method, such as the damage of enamel on healthy teeth of both neighbors, uneasiness for cleaning, bad looking of the metal clasp exposure, easiness of loosing of implant and bad masticatory capability etc. In recent years, the principle of osseointegration and dental implant is able to yield remarkable change in dentist clinical treatment. More clearly speaking, dental implant means that a titanium implant is implanted by surgical operation into the alveolar bone at the position where the tooth is missing, so as to form an artificial tooth root, i.e., implant which can provide a reliable consolidated base for the mounting of a prosthesis. After the implant is closely combined with alveolar bone, a denture can be mounted onto the base of the implant to function as a substitute for natural tooth. Due to the fact that the implant body is deeply inserted into the alveolar bone, it can load normal masticatory stress without any connection with adjacent natural dentition, and keep pace with natural dentition both in function as well as aesthetic.  
      As shown in  FIG. 1 , conventional dental implant placement procedure is of a two-steps type. In step one, dentist implants, by surgical operation, a cylindrical implant body ( 20 ) made by pure titanium into alveolar bone ( 10 ) at the alveolar ridge ( 1 ) of missing tooth. Then, bone graft ( 21 ) (e.g. hydroxyapatite or bone graft of various type) is filled into the alveolar bone ( 10 ) so as to consolidate the artificial tooth root. The bone graft ( 21 ) will be subjected to pressure during stitching process, which will result in deformation of the bone graft ( 21 ), before the bone graft ( 21 ) is cured and closely combined with the alveolar bone ( 10 ). Usually, dentist will first cut a piece of titanium mesh ( 22 ) with suitable size and put the titanium mesh ( 22 ) onto the surface of the alveolar bone ( 10 ) to hold the bone graft ( 21 ) in proper position. A biological barrier membrane ( 23 ) is laid on the surface of the titanium mesh ( 22 ) for healing and prevents the gingival soft tissue around the alveolar bone ( 10 ) from growing into the bone, as this will cause bone healing incomplete. In normal condition, the tooth hole within the alveolar bone ( 10 ) is filled with bone graft after a period of 4-6 months of healing, the implant has been under self osseointegration. Then, the second stage of implant placement is processed, wherein a firm abutment and prosthesis is securely mounted on the artificial tooth root.  
      In ideal case, the development of the principle of dental implant and its application in clinic, including implant material, healing principle of surgery, prosthesis designing and medicine control, has reached to a level of their maturity. However, the abovementioned conventional titanium mesh still has some defects, in other words, the conventional titanium mesh still has room for further improvements in clinic application. It is to be understood by those who are skillful in this field that titanium mesh is usually produced in large area configuration. A dentist has to carry out some pre-fabrication processes, such as cutting into suitable size, trimming delicately into desired size according to clinic condition, before it can be applied to the area to be treated. This pre-fabrication process not only extends operation duration, but also requires much efforts in the fixation of said titanium mesh, as there is no any structure in said titanium mesh for positioning, yet dentist has to take strenuous effort even in the fixation of using multiple mini-screws. In addition, the titanium mesh is easily displaced during stitching procedure, which will result in the shifting of the guide tissue membrane in healing process. Furthermore, the surface of titanium mesh is smooth so that a guide tissue membrane is not easy to adhere to the surface. Based on foregoing, there are troublesome procedures and increasing difficulties in using the conventional titanium mesh.  
     SUMMARY OF THE INVENTION  
      Therefore, the main object of this invention is to provide an titanium-mesh umbrella device for bone grafting, wherein the titanium-mesh can be positioned in place quickly during an implant placement procedure, so that, through the combination with the artificial tooth root, the deficiencies in conventional dental implant, such as requiring bone grafting and complicated procedure, can be significantly improved.  
      The present invention will be accomplished by an titanium-mesh umbrella device for bone grafting. The present invention comprises a metal shank which has one end part as an implant end and the opposite end part has an aperture at the center of its end surface to form as a mounting portion; a titanium-mesh with its surface having a number of meshes, wherein said titanium-mesh defines an area with a diameter in horizontal direction and forms a convex umbrella surface with a curvature in the perpendicular direction, a rough surface being formed on said convex umbrella surface, and a leg being formed on the bottom surface and extending in downward direction, said metal leg being mounted at the underside of said titanium-mesh to form an umbrella configuration, to the effect that said mounting portion of the shank is securely cannulated in said leg. Thus, said titanium-mesh umbrella is able to insert into the mounting portion of the implant metal insert quickly so as to be able to provide a pressureless space for the bone graft to cure and avoid distortion, to shorten the surgery duration, to ensure that the bone graft will not loss in healing, and to ensure that the guide tissue membrane will not slip or shift from original place.  
      According to the present invention, the surface of the titanium-mesh umbrella is provided with a plurality of projections to form a rough surface which can be formed either by etching or by casting work, for enhancing attachment capability, so that the guide tissue membrane will securely attach to said surface without any slipping or displacement happened. Therefore, the surgical process can be simplified and the fixation by mini-screw can be eliminated, which is another object of present invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      For the purpose of illustrating the invention, there are shown in the drawings several forms which are presently preferred, it being understood, however, that the invention is not limited to the precise arrangement and instrumentalities shown.  
       FIG. 1  is a conventional dental implant technology wherein an embodiment of artificial implant is shown;  
       FIG. 2  is a schematic front view showing the first embodiment of the titanium-mesh umbrella device for bone grafting of present invention;  
       FIG. 2   a  is a schematic plane view of  FIG. 2 ;  
       FIG. 2   b  is a schematic sectional view taken along line  2   b - 2   b  of  FIG. 2   a;    
       FIG. 3  is view showing a demonstration example of the application of the titanium-mesh umbrella device for bone grafting of present invention in dental implant;  
       FIG. 4  is a schematic front view showing the second embodiment of the titanium-mesh umbrella device for bone grafting of present invention;  
       FIG. 4   a  is a schematic plane view of  FIG. 4 ;  
       FIG. 4   b  is a schematic sectional view taken along line  4   b - 4   b  of  FIG. 4   a;    
       FIG. 5  is a derivative variation of the first embodiment of present invention;  
       FIG. 6  is s a derivative variation of the second embodiment of present invention 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
      In view of the biocompatibility of the titanium, i.e.,the ability not to be rejected to combine with the bone cell within bone, the titanium metal implant can be closely integrated with the alveolar ridge to be secured within the jaw bone. The implant body concerned with present invention utilizes titanium as the primary material. While above objects and advantages of present invention will be further described with preferred embodiments of this invention, said embodiments is for illustrative purpose only and should not be considered as limitative. This invention will become more apparent with the following detailed description of preferred embodiments by reference to the accompanied drawings.  
       FIG. 2  is the first embodiment of the titanium-mesh umbrella device for bone grafting of present invention, wherein  FIG. 2   a  is a top view,  FIG. 2   b  is sectional view taken along the line  2   b - 2   b  in  FIG. 2   a.  As shown in  FIG. 2 ˜ 2   b,  the titanium-mesh umbrella device  100  for bone grafting of present invention comprises a metal shank  110 , which is a tooth root-shaped cylindrical body made by titanium, the first end  110   a  of which is a end for implant. Usually, the first end  110   a  of the metal shank  110  has a thread to enhance anchored capability for deeply implanted into the alveolar bone. The second end  110   b  has an axial pin hole at its center to form a mounting portion  111  used to fix a denture. A titanium-mesh  120  is made by titanium into sheet form, the surface of which is provided with a plurality of screen meshes  121  for air-permeable purpose and for activating the implant and bone graft area. Said titanium-mesh  120  encircles an area with a diameter D in horizontal direction, which can be adjusted according to the location of treated tooth, and forms a umbrella surface  122 , projecting with a height H, with a curvature in perpendicular direction, a rough surface  123  being formed with dense granule-shaped projections on said projecting umbrella surface  122  for the purpose of enhancing the surface attachment capability. In addition, a leg  125  is formed in the bottom  124  and extending in vertical direction. According to present invention, the mounting portion  111  of the metal shank  110  is provided with a plastic block  112 , the center of which contains a pin hole  112   a.  The leg  125  of the titanium-mesh  120  can be inserted into the pin hole  112   a  of the plastic block  112  of the mounting portion  111  of the metal shank  110 , so that it can be positioned in place quickly to form an umbrella configuration.  
       FIG. 3  is an example for demonstration showing the application of the titanium-mesh umbrella device of the present invention during the dental implant placement process. In step one, dentist implants, by surgical process, a metal shank  110  into alveolar bone  201  at the edentulous ridge  200 , and then, bone graft  202  (e.g. hydroxyapatite or bone graft of various animals) is filled into the alveolar bone  201  so as to consolidate the metal shank  10 . At the same time, the leg  125  of the titanium-mesh  120  is inserted and fixed into the pin hole  112   a  of the plastic block  112  of the mounting portion  111  of the metal shank  110 , so that the titanium-mesh  120  is laid onto the surface of the alveolar bone  201  to hold the bone graft  202  in proper position. Then, after a biological barrier membrane  210  is laid onto the rough surface  123  of the umbrella type titanium-mesh  120 , stitching process is undergone for the healing of the surface.  
      According to this invention, the leg  125  at the bottom  124  of the umbrella type titanium-mesh  120  is inserted and fixed quickly into the mounting portion  111  of the implant metal shank  110  during the implant placement process, so that the bone graft  202  is not distorted and compressed during stitching process. Thereby, the time required for surgery operation can be reduced, and the shift of the guide tissue membrane caused by the umbrella type titanium-mesh  120  can be avoided. Simultaneously, because the guide tissue membrane  210  is securely attached to the rough surface  123  of the titanium-mesh  120  without any slipping or shift happened, the stitching during surgery operation can be undergone easily. After a period of 4-6 months for healing, the tooth hole within the alveolar bone  201  is filled with artificial tooth root, then step two can be undergone. In other words, a rigid prosthesis is mounted on the mounting portion  111  based on the metal shank  110 .  
       FIG. 4  is the second embodiment of the titanium-mesh umbrella device for bone grafting of present invention, wherein  FIG. 4   a  is a top view,  FIG. 4   b  being a sectional view taken along a line  4   b - 4   b  of  FIG. 4   a.  Basically, this embodiment has the same structure as that of the above first embodiment, therefore, detailed description is omitted. The difference between this embodiment and the first embodiment lies on the method of combination between the titanium-mesh  120  and the metal shank  110 . As shown in  FIG. 4 ˜ 4   b,  a locating hole  126  is formed at the center of the surface  122  of the titanium-mesh  120 , which is used to combine with the metal shank  110  to form an umbrella configuration. A peripheral groove  113  is formed along the periphery of the end portion of the second end  110   b  of the metal shank  110 . After the locating hole  126  of the titanium-mesh  120  is inserted through the second end  110   b,  a U-shaped retainer ring  114  is inserted into the peripheral groove  113  for the fixation of the titanium-mesh  120  on the metal shank  110 . Therefore, both of titanium-mesh  120  and the metal shank  110  can be positioned easily and combined with each other quickly.  
      With the same concept, it is noted here to those who are skillful in this field, that the tooth hole in the alveolar bone, after the extraction of a decayed tooth, is not necessarily a symmetrical shape. Dentist might set the dental implant eccentrically depending on the requirement of each case.  FIG. 5  and  FIG. 6  are examples of variations derivated from this invention. As shown in  FIG. 5 , the leg  125  can be placed at a location outside of the center in the bottom  124  of the titanium-mesh  120 , so as to combine with the metal shank  110  to form an eccentric umbrella structure. Similarly, in  FIG. 6 , the locating hole  126  can be provided at a predetermined point outside the center of the titanium-mesh  120 , so as to combine with the metal shank  110  to form an eccentric umbrella structure. In addition, in abovementioned embodiments, the surface of the umbrella titanium-mesh  120  is provided with a rough surface  123  in the form of granule-like projections, or which can be formed either by etching or by casting work.  
      The abovementioned are merely preferred embodiments of present invention, which is not considered as a limitation to the range of this invention. It will be understood by those who are skillful in this field that titanium material can be substituted by any other biocompatible materials. In other words, all equivalent modifications and variations made without departing from the scope defined by the appended claims of present invention should be considered within the coverage of present invention.  
      In summary, the titanium-mesh umbrella device for bone grafting of present invention can be inserted and fixed, during dental implant placement process, into the mounting portion of the implant metal shank quickly for the consolidation of bone graft, so that the guide tissue membrane can be securely attached to the surface of the umbrella without any slipping happened. Therefore, stitching during surgery process can be undergone very easily, the operation duration being reduced, the shift of the guide tissue membrane caused by the umbrella type titanium-mesh  120  being avoided, and the growing space for bone graft being provided. Thus, this invention is a novel invention with inventive steps and industrial availability.  
     LIST OF NUMERALS FOR MAJOR COMPONENTS  
     
         
           100  titanium-mesh umbrella device for bone grafting of this invention  
           110  metal shank  
           110   a  first end  
           110   b  second end  
           111  mounting portion  
           112  plastic block  
           113  peripheral groove  
           114  U-shaped retainer ring  
           120  titanium-mesh  
           121  pin hole  
           122  surface of the umbrella  
           123  rough surface  
           124  bottom  
           125  leg  
           126  locating hole  
           200  alveolar ridge  
           201  alveolar bone  
           202  bone graft  
           210  guide tissue membrane