Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61C—DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE
  • A61C8/00—Means to be fixed to the jaw-bone for consolidating natural teeth or for fixing dental prostheses thereon; Dental implants; Implanting tools
  • A61C8/0018—Means to be fixed to the jaw-bone for consolidating natural teeth or for fixing dental prostheses thereon; Dental implants; Implanting tools characterised by the shape
  • A61C8/0022—Self-screwing
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61C—DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE
  • A61C8/00—Means to be fixed to the jaw-bone for consolidating natural teeth or for fixing dental prostheses thereon; Dental implants; Implanting tools
  • A61C8/0018—Means to be fixed to the jaw-bone for consolidating natural teeth or for fixing dental prostheses thereon; Dental implants; Implanting tools characterised by the shape
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61C—DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE
  • A61C8/00—Means to be fixed to the jaw-bone for consolidating natural teeth or for fixing dental prostheses thereon; Dental implants; Implanting tools
  • A61C8/0048—Connecting the upper structure to the implant, e.g. bridging bars
  • A61C8/005—Connecting devices for joining an upper structure with an implant member, e.g. spacers
  • A61C8/006—Connecting devices for joining an upper structure with an implant member, e.g. spacers with polygonal positional means, e.g. hexagonal or octagonal
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61C—DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE
  • A61C8/00—Means to be fixed to the jaw-bone for consolidating natural teeth or for fixing dental prostheses thereon; Dental implants; Implanting tools
  • A61C8/0048—Connecting the upper structure to the implant, e.g. bridging bars
  • A61C8/005—Connecting devices for joining an upper structure with an implant member, e.g. spacers
  • A61C8/0062—Catch or snap type connection
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61C—DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE
  • A61C8/00—Means to be fixed to the jaw-bone for consolidating natural teeth or for fixing dental prostheses thereon; Dental implants; Implanting tools
  • A61C8/008—Healing caps or the like
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61C—DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE
  • A61C8/00—Means to be fixed to the jaw-bone for consolidating natural teeth or for fixing dental prostheses thereon; Dental implants; Implanting tools
  • A61C8/0089—Implanting tools or instruments

Definitions

• the present invention relates generally to the field of endosseous dental implants and more specifically to the field of endosseous screw type dental implants.
• Screw type implants are implants having threaded outer surfaces and used as anchoring members for different prostheses, such as dental and orthopedic prostheses.
• This type of implant is screwed into a borehole arranged in the bone tissue of a bone tissue structure at a site where a prosthesis is required.
• the borehole may be formed into a shape generally corresponding to the shape of the implant, although slightly smaller in size.
• These implants may be provided with self-cutting edges to cut one or more internal threads in the inner wall of the borehole during the screwing in of the implant. If there are no self-cutting edges, the bore must be internally threaded before insertion of the implant.
• Bone tissue has two components, cancellous bone tissue and cortical bone tissue.
• the major part of a bone usually is built up with the cancellous bone tissue, which is a relatively soft tissue in the interior of the bone.
• the cortical bone tissue is harder and normally forms a relatively thin layer surrounding the cancellous bone.
• screw implants of the type described would typically be in contact with cancellous bone tissue along a larger part of its length, and with cortical bone tissue only at a shorter portion at one end of the implant.
• a superstructure for carrying a prosthetic part may be secured to the implant.
• the superstructure will typically comprise an abutment or transmucosal component, which engages the implant to bridge the gingiva overlaying the maxilla or mandible at the implant site.
• the prosthetic part e.g. a crown, a bridge or a denture is then secured to the abutment.
• the implant could also be formed integrally with a superstructure, such as a transgingival component, on which for example a crown is directly secured.
• a problem occurring when using many prior art screw type implants is referred to as the bone resorption problem.
• Bone resorption is a term used for a process in which, once an implant is installed in the bone tissue, the bone surrounding the implant tends to degenerate. This is highly undesired, since a diminished amount of bone surrounding the implant will lead to diminished stability and sometimes result in failure of the prosthesis. This is particularly the case because bone resorption primarily occurs in the cortical bone, which, as mentioned above, is the hardest part of the bone. Once bone resorption exists, secondary problems may also appear. Such secondary problems, particularly related to dental implants, are for example deposition of plaque, resulting in inflammation in the gingival tissue surrounding the implant, or down-growth of gingival tissue along the exposed end of the implant. Also, the aesthetic appeal of the implant is undermined by bone tissue resorption, which is an important drawback in particular when the implant is intended for dental applications since dental prosthesis form part of the field of cosmetic surgery.
• the objective of the invention is to provide a well-functioning implant in a number of important aspects, such as providing stable primary fixation, initial stability and proper loading of the bone tissue.
• a modular implant for insertion into a borehole arranged in bone tissue.
• Said implant having a cancellous portion, and a cortical portion having an axial length such that, when installed in the borehole, the engagement of said cortical portion with the bone tissue will generally be confined to the cortical bone tissue layer.
• Said cortical portion comprise one or more removable segments and presents an outer surface that is threaded for accomplishing said engagement, and has an outer design such that, when being screwed into said borehole under the action of a screwing torque, said cortical portion acts to increase the compression of the cortical bone tissue only.
• a modular implant comprises an implant body and one or more removable implant segments, wherein said removable segments are adapted to be engaged or coupled with the implant body and with each other, by a snap lock mechanism.
• This modular implant has been previously unknown in the art and its manufacturing was not technically feasible up to date.
• the removable implant segment is removed, thus leaving a shorter implant inside the bone, without any exposed portions.
• cortical bone engagement portion is used to define a portion of the implant that, in an implanted state, would mainly be engaged with the cortical bone tissue layer.
• cortical portion the term will hereinafter in the description and in the claims be referred to as “cortical portion”.
• cancellous bone engagement portion will be referred to as “cancellous portion” and refers to a portion of the implant that is engaged mainly with cancellous bone tissue.
• the cortical portion is provided with a threaded outer surface.
• threaded is meant a surface allowing the portion to function as a screw.
• any surface having a helical arrangement fulfilling this purpose would be confined in the term “threaded”, for example a surface having a series of discontinuous protrusions, subsequently following ribs or a conventional thread.
• a surface presenting a conventional thread seems to be the most advantageous alternative.
• the threaded surface is useful in that its engagement with the cortical bone tissue will increase the friction between the cortical bone and the implant, thus contributing to the distinct rise in screwing torque needed when the cortical portion is screwed into the borehole. Owing to this effect, the compression of cortical bone tissue can be held smaller than what would be necessary if a smooth surface was used, which is advantageous as discussed above. Furthermore, during screwing in of the implant, the threaded surface urges the cortical portion down into the borehole, compressing the cortical tissue in essentially radial directions. Without the threaded surface, there might be an increased risk that forces from the bone tissue that counteract the screwing in of the cortical portion overcoming the forces urging the cortical portion downwardly. In that case, the screwing torque applied to the implant would act only to rotate the implant, but not to advance it in a longitudinal direction, whereby internal threads cut in the borehole may be damaged.
• threaded surfaces have been shown to be beneficial to bone tissue ingrowth and are useful to enable proper load distribution to the surrounding bone tissue. Due to the load distribution function, they are useful to stimulate bone growth and inhibit marginal bone resorption. Also, the threaded outer surface of the cortical portion will contribute to the primary fixation and initial stability of the implant.
• an implanted screw implant is in contact with both cancellous bone tissue and cortical bone tissue.
• the cortical bone tissue constitutes a relatively thin layer around the bone, the major part of the length of a screw implant is in contact with the cancellous bone.
• the length of the cortical portion of an implant is relatively short in relation to the implant length, as it should largely correspond to the thickness of the cortical bone tissue layer. Said thickness varies with the type of bone, the implantation site, and individually from patient to patient. A normal thickness would be around 0.5-1 mm. to 3 mm.
• the coronal end of the implant and "down" meaning towards the insertion end, i. e. the apical end of the implant.
• the "lower part” of the implant would refer to the part that would first be introduced into a borehole. Obviously, this does not constitute any restriction regarding in what actual directions the implant may be implanted and used.
• cortical portion of an implant according to the invention would be positioned at the uppermost end of the implant, so to be in engagement with the cortical bone tissue when the implant is in its final position.
• FIG. 1A is a perspective view of an embodiment of the modular dental implant of the invention.
• FIG. IB is an exploded view of an embodiment of the modular dental implant of the invention.
• FIG. 1C is a cross-sectional view of an embodiment of the modular dental implant of the invention.
• FIG. 2A is a perspective view of an implant segment of an embodiment of the modular dental implant of the invention.
• FIG. 2B is a cross-sectional view of an implant segment of an embodiment of the modular dental implant of the invention.
• FIG. 2C is a cross-sectional view of an embodiment of the modular dental implant of the invention.
• FIG. 2D is a cross-sectional view of a snap lock latching mechanism of the modular dental implant of the invention.
• FIG. 3 A is a cross-sectional exploded view of another embodiment of the modular dental implant of the invention.
• FIG. 3B is an exploded view of another embodiment of the modular dental implant of the invention.
• FIG. 4 is a flowchart illustrating a method for adjusting the length of the modular dental implant according to some embodiments of the invention.
• FIG. 1 A is a perspective view of a modular dental implant 100, according to an embodiment of the invention.
• the modular dental implant 100 includes an implant body 120 and one or more implant segments 130 connected to the cortical portion of the implant body 120.
• the multiple implant segments 130 can be connected to each other in a coaxial manner wherein an upper portion of one segment is located above an upper portion of the other.
• the modular dental implant 100 has a generally tapered or conic like shape. It may include a plurality of cutting recesses or grooves 103 circumferentially distributed about the circumference of the apical end of the modular dental implant 100 for self-tapping of the modular dental implant 100 when being screwed into the borehole drilled in the bone tissue of a maxilla or mandible. If the modular dental implant 100 is not provided with cutting recesses 103, the borehole may be internally threaded before the implant is inserted.
• the modular dental implant 100 also contains a threaded cancellous portion 101 having an axial length such that, when installed in the borehole, the engagement of the threaded cancellous portion 101 with the bone tissue will generally be confined to the cancellous bone tissue layer. It also has a threaded cortical portion 102 having an axial length such that, when installed in the borehole, the engagement of the threaded cortical portion 102 with the bone tissue will generally be confined to the cortical bone tissue layer.
• the threaded portions 101 and 102 may comprise a single thread or preferably multiple threads, for example double, triple or quadruple threads.
• Threads 105 are sometimes called "micro- threads" and have been shown to be particularly advantageous when provided on the upper part of dental implants, where their presence inhibits marginal bone resorption.
• the external threads 104 and 105 include a progressively changing profile.
• the thread 104 is sharp and narrow in order to facilitate cutting and self-tapping into the bone.
• the thread 105 is sharp and narrow in order to facilitate cutting and self- tapping into cortical bone.
• the thread 105 progresses toward the implant's coronal end, it becomes increasingly broader or wider in its cross-sectional profile.
• the increasing breadth of threads 104 and 105 facilitates compression of cortical and cancellous bone that was previously tapped by the sharp coronal thread profiles. Bone compression increases the stability of the implant.
• the implant segment 130 includes a polygonal (which may be a hexagonal) connector 131, positioned on the base 140 of the implant segment 130.
• the polygonal connector 131 tightly fits into a corresponding polygonal socket 121 of the implant body 120, the socket 121 has the same cross-section as the connector 131.
• the connector 131 and the socket 121 however may have a shape other than a polygonal shape.
• the polygonal connector 131 is comprised of a plurality of bendable sections 133, separated from each other by a slot 138. The sections 133 create the polygonal shape of the connector 131.
• the implant segment 130 Upon the insertion of the connector 131 into the socket 121, the implant segment 130 is secured to the implant body 120 by a snap lock mechanism activated between the socket 121 and the connector 131.
• the snap lock mechanism comprises an annular protrusion 123 located inside the implant body bore 122 and below the socket 121, and an annular groove 134 located on the outer surface of the connector 131, near its end.
• the annular protrusion 123 is configured to be fitted into the annular groove 134 of the connector 131.
• the snap lock mechanism is also used to connect the implant segments 130 to each other.
• a snap connection is made between an annular groove 134 of the polygonal connector 131 and an annular protrusion 136 located below a threaded socket 139, upon insertion of the polygonal connector 131 into the corresponding threaded polygonal socket 139 of another implant segment 130.
• the implant segment 130 also includes a threaded bore 135 located below the threaded polygonal socket 139.
• the threaded bore 135 is used for connecting a healing screw 140 to the implant 100.
• the threaded polygonal socket 139 is used for insertion of a driver key 110.
• the driver key 110 is used for extraction of the implant segment 130 from the implant body 120.
• the rotation of the threaded portion 112 of the driver key 110 inside the socket thread 137 forces the driver key shaft against the bottom surface of the implant body bore 122, thus creating an opposite force acting upon the implant segment 130 and causing its extraction from the implant body 120.
• FIG. 3B is a perspective view of a modular dental implant 300 comprising an implant body 310 and an implant segment 320, according to another embodiment of the invention.
• the implant 300 comprises an annular seal 330 (for example O- ring) which could be manufactured from biocompatible material, such as (but not limited to) biocompatible polymer, medical silicone rubber or fluoropolymer.
• the seal 330 is positioned in an annular depression 321 of the implant segment 320.
• the seal 330 is compressed against a sealing surface 311 of the implant body 310, thus creating a sealing between the implant body 310 and the implant segment 320.
• the seal 330 is compressed against a sealing surface 322 of the implant segment 320, thus creating a sealing between the first and the second implant segments 320.
• the seal 330 prevents entry of foreign matter into the interior of the implant 300.
• the present invention also comprises a method 400 for adjusting the length of the modular dental implant, when it already positioned in the bone tissue.
• the method 400 starts with a stage 410 of conducting visual/X-ray/CT examination of the implant site.
• Stage 410 is followed by stage 420 of detecting a bone resorption. If bone resorption is detected, the stage 420 is followed by stage 430 of removing the prosthesis and the abutment from the examined implant. If bone resorption is not detected, the stage 420 is followed by stage 460 of moving to the next implant site for conducting an examination. Stage 430 is followed by stage 440 of removing one or more implant segments until the most of the remaining implant length is covered with a bone tissue. Stage 440 is followed by stage 450 of fitting an abutment and a prosthesis to the remaining implant.
• the implants 100, 300 may be manufactured from commercially pure titanium, a titanium alloy, another biocompatible metal or metal alloy, or a ceramic to promote osseointegration of the implants with the bone tissue of the boundary walls of the borehole.
• the length of the implants 100, 300 is preferably between 6-16 mm. and the width is preferably between 3-6 mm.
• the distance between each thread of the cancellous portion is 0.6-1.6 mm.
• the distance between each thread of the micro-thread is 0.3 mm. or lower.

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• Health & Medical Sciences (AREA)
• Oral & Maxillofacial Surgery (AREA)
• Orthopedic Medicine & Surgery (AREA)
• Dentistry (AREA)
• Epidemiology (AREA)
• Life Sciences & Earth Sciences (AREA)
• Animal Behavior & Ethology (AREA)
• General Health & Medical Sciences (AREA)
• Public Health (AREA)
• Veterinary Medicine (AREA)
• Dental Prosthetics (AREA)

Priority Applications (1)

Applications Claiming Priority (1)

Publications (1)

Family

ID=49757664

Family Applications (1)

Country Status (1)

Cited By (7)

Citations (5)

• 2012
  • 2012-06-10 WO PCT/IL2012/000227 patent/WO2013186765A1/fr not_active Ceased

Patent Citations (5)

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