WO2015135052A1

WO2015135052A1 - Biofunctional implant and abutment design

Info

Publication number: WO2015135052A1
Application number: PCT/CA2014/000201
Authority: WO
Inventors: Jayesh BHARADIA
Original assignee: Bharadia Jayesh
Priority date: 2014-03-11
Filing date: 2014-03-11
Publication date: 2015-09-17

Abstract

This particular dental implant-abutment design incorporates horizontal seating surfaces whose geometry is described by a radial portion of a spherical cap. Tolerances established for the fit of the internal conical sections will limit the range of movement that is available for any micro¬ motion. The spherical cap geometry and outer limits of the conical wall sections all share a common convergence or radial origin point. This shared origin point and spherical cap geometry directs axial loading to the centre of the implant and compress the outer walls of the dental. Compression of the outer walls of the implant offers better protection against deformation from the non-axial component of any loading forces. By allowing the implant-abutment interface to undergo non-destructive micro-movement the risk of screw loosening and breakage is reduced. An angled implant placement creates a micro-movement range that mimics physiological tooth movement.

Description

Biofunctional implant and abutment design

DESCRIPTION

Technical Field

A biofunctional dental implant and abutment design will assist in providing dental restorations that effectively mimic the behaviour of natural dentition in the alveolar process. Dental implants are currently being used to replace single or multiple missing teeth. In the case of a fully edentulous arch, dental implants are being used to facilitate full arch restorations utilizing fixed or removable treatment options with one or more dental implants.

Background Art

One of the more commonly used design concepts for dental implants includes a two part design, an implant body and an abutment that attaches to the implant body. This dental implant design raises concerns related to the observed micro-movement at the implant-abutment interface and its association with crestal bone loss and peri-implantitis. Dental implants with an internal conical connection designs offer an improvement over flat-top impiant-abutment interface designs, but are still prone to micro-motion related issues. Platform switching has also been used as a strategy to manage the effects of this micro-movement.

It has also been demonstrated that during loading of any dental implant leads to a deformation of the implant body which can results in the formation of micro-gaps that allow for microbial entry into the implant body and that some of these microbes may play a role in the development of peri-implantitis. One piece implants made of different materials like Zirconium and narrow diameter impiants are also being used as an alternative to the more traditional implant designs but have their own inherent limitations.

The use of dental implant that are tilted off the vertical axis have been associated with more frequent screw loosening and breakage, although implant survival rates are not necessarily altered. Use of a tilted implant placement is necessary in certain clinical treatment protocols; therefore an implant design that takes this treatment aspect into consideration must make allowances for the additional stress that result.

l Success of a dental implant depends not only on their ability to osseointegrate, but also on the ability to properly disperse loading forces without overloading the recipient bones physiological ability to model and remodel in response. The alveolar process flexes in response to loading of the natural dentition; the periodontal ligament system allows for physiological tooth movement during loading and the mandible itself exhibits a degree of flexure during function. With all these simultaneously occurring movements there are definite concerns related to having a rigid implant restoration design or fixed full arch restorations. The concerns include the possible impact on survival of the dental implant itself and/or the possible deleterious effect on the alveolar process and mandible itself that may result from restricting normal physiological movement.

Disclosure of invention

The biofunctional dental implant and abutment design being offered includes the incorporation of a spherical cap design geometry at the proximal end of the implant body whose radius of curvature is defined from the centre point created by the intersection of a perpendicular plane immediately above the threaded abutment screw access hole and the central long axis of the implant body to the widest diameter of the implant at its proximal end. The fitting surface of the abutment has an identical curvature to the proximal surface of the implant body. This feature allows for a control of the direction of micro-movement limited within a physiological range that can be predetermined by the manufacturing specifications of the implant-abutment interface. This controlled micro-movement along a path that forms a part of a spherical cap minimizes any elongation or stretching of the abutment screw, resulting in fewer screw breakages or loosening situations.

The spherical cap geometry also helps focus the axial component of any loading forces along to the central axis and creates a compressive force along the outer walls of the implant to offer more resistance to distortion against any non-axial component in the loading force. By limiting the amount of distortion in the outer walls of the dental implant, the formation of any micro-gaps between the implant-abutment interface is reduced. Additionally, this reduced distortion of the outer walls of the implant will result in less stress being transferred through to the cortical bone. Since the outer wall of the implant is in compression during non-axial loading the risk of fracturing is also reduced. Non-axial forces can cause greater deformation of the outer walls of the implant body and stretching of the screws in traditional flat-top and internal conical abutment designs.

The incorporation of an internal single or multi-tiered inverted conical sections in the abutment design with horizontal contact surfaces at their proximal bases that also follow a spherical cap geometry and the outer conical walls if extended would converge to the same point at the centre of the sphere that encompasses the spherical cap geometry of all these horizontal contact areas. This aspect of the abutment design helps by increasing the amount of horizontal surface area being used to create additional compressive force in the internal structure of the implant body which will better withstand any non-axial distortion during heavy loading by focusing the loads more centrally and axially. The use of one central point to define the spherical caps geometry and inverted conical sections at various heights ensure that there is a minimal elongation stress on the abutment screw, since there is only one point of rotation.

The abutment can incorporate one or more internal inverted conical sections depending upon the diameter of the implant to be manufactured. The outer limits of these conical sections are confined within the space created by extending the outer wall of the cone to its apex which is located at the centre point of the abutment screw access hole located along the central long axis of the implant body that was previously described. The proximal and distal ends of the cone will continue till its intersection with the spherical cap geometry of the horizontal abutment fitting surfaces located at various heights along the central axis whose number and position will depend upon the diameter of the dental implant. Therefore any additional inverted conical section will be narrower than the more proximal conical section. The distal most conical section on the abutment will terminate at the level where it intersects the opening for the abutment screw along the central axis of the body of the implant, and also incorporate 3 lobes located at 0,120 and 240 degrees on the outer edge formed by the circle at the distal most end. These lobes will provide the alignment and anti-rotational features for the dental implant-abutment interface. Since the 3 lobes do not physically seat against a distal contact surface during axial loading, there would not be any peak stress point being created during heavy load. A central access hole with a defined diameter is situated in the abutment along the central long axis to allow for the passage of the abutment screw. A wider diameter hole is created at the proximal end of the abutment and will terminates at a defined point above the most proximal spherical cap geometry to receive the flat fitting surface of the wider abutment screw head. From the central axis at the proximal end of the implant body an identical contoured surface is prepared to receive and integrate with the above described abutment such that the fit is intimate for all horizontal contact surfaces defined by a spherical cap and all conical wall sections will have specific established manufacturing tolerances to allow for a specified amount of micro- movement. The central access hole for the body of the abutment screw is finished to a level where the fiare at the distal end of the abutment screw will contact at a defined torque. Along the same central axis a smaller diameter threaded screw access hole is found that wilt receive the threaded portion of the abutment screw.

The flare in the abutment screw will assist in minimizing movement at the level of the threads within the screw hole by absorbing the tension being created during any micro-movement. Secondly the tension created in the flare during any non-axial loading will create a rebound effect that will ensure that the abutment returns to its centre position when the load is removed.

Therefore by allowing for a controlled range of micro-motion in the dental implant-abutment interface, several things are accomplished. First, there is a reduction in the amount of stress being transmitted through to the bone. Second, in axialiy positioned implants this controlled movement mimics physiological tooth movement in the XY plane and to a lesser degree in the Z plane. However in tilted implants a similar level of movement will be exhibited in the X, Y and Z planes. This controlled and non-destructive micro-movement that emulates physiological tooth movement will minimize clinical concerns related with fixed full arch implant restoration and its restriction of normal mandibular flexure. With single tooth dental implant restorations or combination dental implant and natural dentition bridges the clinical concerns with overloading of the implant will be reduced. Rigid implant-restoration not allowing for this type of micro- movement could potentially overload the bone's physiological ability to model and remodel leading to bone loss and implant failure.

Screw threads along the body of the implant are not continuous to facilitate an increase in the surface area available for osseointegration and thereby create more bone support for a given diameter of implant. The effect of varying between continuous and non-continuous threads will allow for ensuring initial implant placement stability is good and with the increased available surface area for more bone support after osseointegration will prove useful when implants are placed in an off-axial position. Micro threads at the neck level of the dental implant will ensure that maximum thickness is available for strength and stability of the outer implant walls at a given diameter. Brief Description of Drawings

The illustrations are designed to provide a visual reference frame for the design concepts previous described and not a limitations on the variation possible within this design concept.

Figure 1A shows an assembled implant body-abutment complex with micro threads along the slightly flared proximal end and standards screw threads along the reminder of the dental implant outer body.

Figure 18 illustrates a type of non-continuous design for the screw threads along the outer body of the implant.

Figure 2 illustrates the cross section of the implant body with the abutment and abutment screw. Point 5 defines the common centre point for all spherical caps geometry at the various heights and is also the apex for all the inverted conical walls section forming the various tiers.. Point 6 is the alignment lobe on outer surface of the distal most conical surface. Point 18 is the flat fitting surface for the flare (point 15) on the abutment screw.

Figure 3 illustrates the abutment with the flat seating surface at point 24 for the abutment screw head. Point 20, 12 and 22 are the portion of the spherical cap geometry on the abutment that will contact the same seat geometry in points 9, 11 and 13 in the implant body respectively. Points 17, 25, 9 act as the lateral stops for the micro-motion of the abutment when they simultaneously contact with points 8, 10 and 12 respectively in the implant body.

Figure 4 illustrates a top view of the implant, where point 29 accepts the lobes (point 6) on the abutment. Point 18 represents the flat surface where the flare of the abutment screw point 15 would seat.

Figure 5 illustrates the abutment screw where point 28 represents the space for receiving the driver to tighten the screw. Point 26 represents the portion of the screw that fits to the abutment screw access hole. Point 17 is the section extending beyond the abutment which tapers to a narrower diameter. Point 7 represent the screw shaft the extends through the implant body and point 15 represents the flared portion of the screw that fits onto point 18 on implant screw access hole. Point 16 is the threaded portion of the abutment screw of a narrower diameter that fits into the threaded screw hole at the distal end of the central axis in the dental implant body.

Figure 5 also illustrates where point 30 on the abutment screw intimately contacts point 24 on the abutment screw access hole in the abutment. Best Mode of Carrying out Invention

The biofunctional dental Implant-abutment design can be fabricated with metal, non-metal, inorganic or organic biocompatible materials that have osseoinductive properties either naturally occurring or by virtue of chemical treatment or nano technology processes.

Fabrication of a bio-functional implant-abutment can be achieved by CAD/CAM processes using milling, casting or any other manufacturing technology that would ensure that fit tolerances are accurate and reproducible

Claims

CLAIMS IMPLANT BODY

1. Elongated cylindrical implant body shape with slight flare of the body at the proximal end and slight inward taper of the body at the distal end. The proximal fitting surface has geometry that is defined by the outer portion of a spherical cap whose radius length measures from the intersection point starting at the plane immediately above threaded abutment screw access hole and its intersection with the central longitudinal axis through the centre of the threaded screw access hole located towards the distal end of the implant to the proximal most outer edge of the implant.

2. Inverted conical section whose space is defined by an inverted cone whose apex shares the same distal origin point along the central axis of the implant body as defined in claim 1 but whose diameter is narrower than the diameter of the implant in claim 1. The outer proximal base that intersects with the inverted conical sectional space is the defined by the spherical cap of the implant in Claim 1.

3. The second inverted conical section whose space is defined by an inverted cone whose apex shares the same distal origin point along the central axis of the implant body as defined in claim 1 but whose diameter at its proximal end is narrower than the narrowest diameter of the inverted conical section in claim 2. The outer proximal base connecting to the cone defined in claim 2 is the defined by a spherical cap geometry of a radius defined from the same origin point as the apex of the inverted cone in Claim 2 and measured to the distal most outer edge of the cone in Claim 2.

4. The proximal base of the distal most inverted conical section has a spherical cap

geometry with a radius is defined by the same origin point in Claim 1 and extending to the distal most edge of the inverted conical space described in Claim 3 when two tiers are used or claim 2 when one tier is being used and connects to the widest diameter this cone which is narrower than the narrowest diameter of the conical section immediately above it. The distal portion of the conical section terminates at the intersection point of the central abutment screw access hole

5. Alignment grooves coincide with dimensions of alignment lobes on abutment and are located at positions 0, 120 and 240 degrees on the outer end of the distal circle described in claim 4..

6. A central abutment screw access hole is located along the central long axis of the

implant to the depth of the origin point described in Claim 1.

7. A narrower diameter hole is located below the origin point described in Claim 1 along the central axis of the implant body which is threaded and mates with the abutment screw.

8. The outer proximal flared portion of the implant described in Claim 1 will have shallow micro-threads

9. The outer portion of the implant described in Claim 1 and in the region not encompassed by claim 8 will have deeper threads and greater pitch than the threads described in claim 8 and will also be non-continuous in its configuration.

ABUTMENT

10. The proximal most surface of the abutment has a seat prepared that is wider than the screw access hole to accommodate the width of the abutment screw head and terminates at a specified height above the spherical cap geometry that defines the most proximal seating surface designed to fit the top of the dental impiant described in claim 1.

11. The horizontal and vertical fitting surfaces of the abutment that fit the implant described in Claim 1 are shaped to match the specifications described in Claims 1 , 2, 3, 4 and 5.

12. The distal most aspect of the abutment has alignment lobes placed a 0, 120 and 240 to coincide and fit with anti-rotationai grooves identified in Claim 5.

13. The central axis of the abutment has a hole that extends through the entire abutment with a diameter that compliments and fits the diameter of the central abutment screw access hole described in Claim 6.

ABUTMENT SCREW . The proximal head of the screw has a diameter that compliments the width of the seat preparation described in Claim 10.

15. The body of the screw has a diameter that compliments and fits the diameter of the central abutment screw access hole described in Claim 13.

16. The body of the abutment screw as it emerges from abutment, will taper to a narrower diameter.

17. The body of the abutment screw will flare outward slightly to fit intimately with the plane located at the proximal most portion of the thread screw hole described in claim 6.

18. The distal most threaded aspect of the abutment screw will mate intimately with the threaded hole described in Claim 7.

19. The length of the screw body will be such that screw head in Claim 14 and the flare in Claim 17 will be in intimate and simultaneous contact with the abutment and implant body respectively when appropriately torqued.

TREATMENT

20. Fitting surface of abutment described in Claims 1 and 12 to be plated with gold.

21. Implant body with outer thread pattern described in Claims 8 and 9 to be electro- chemically treated or etched for enhancing osseintergration.