# US 4,270,905 A · Replacement system for dental and other bone implants

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- Number: US 4,270,905 A
- Document ID: US4270905A
- Status: Granted
- Kind: A
- Application number: 06/013,064
- Filed: 1979-02-21
- Granted: 1981-06-02
- Earliest claimed: 1979-02-21
- Inventors: M. Hamdi A. Mohammed
- Web page: https://patentgrep.com/patent/US4270905A

## CPC

- A61C 8/0086: {with shock absorbing means}
- A61C 8/005: {Connecting devices for joining an upper structure with an implant member, e.g. spacers}
- A61C 8/0065: {with expandable or compressible means}
- A61C 8/0069: {tapered or conical connection}
- A61F 2/30907: {Nets or sleeves applied to surface of prostheses or in cement}
- A61C 8/0054: {having a cylindrical implant connecting part}
- A61C 8/0057: {with elastic means}
- A61C 8/0063: {with an internal sleeve}
- A61F 2002/30014: {differing in elasticity, stiffness or compressibility}
- A61F 2002/30235: {tubular, e.g. sleeves}
- A61F 2002/30372: {with additional means for limiting said translation}
- A61F 2002/30405: {made by screwing complementary threads machined on the parts themselves}
- A61F 2002/30929: {having at least two superposed coatings}
- A61F 2002/30968: {Sintering}
- A61F 2220/0025: Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
- A61F 2220/0033: made by longitudinally pushing a protrusion into a complementary-shaped recess, e.g. held by friction fit
- A61F 2230/0069: cylindrical
- A61F 2250/0018: differing in elasticity, stiffness or compressibility
- A61F 2310/00011: Metals or alloys
- A61F 2310/00017: Iron- or Fe-based alloys, e.g. stainless steel
- A61F 2310/00023: Titanium or titanium-based alloys, e.g. Ti-Ni alloys
- A61F 2310/00029: Cobalt-based alloys, e.g. Co-Cr alloys or Vitallium
- A61F 2310/00161: Carbon; Graphite
- A61F 2310/00173: Graphite
- A61F 2310/00179: Ceramics or ceramic-like structures
- A61F 2310/00353: Bone cement, e.g. polymethylmethacrylate or PMMA
- A61F 2310/00407: Coating made of titanium or of Ti-based alloys
- A61F 2310/00574: Coating or prosthesis-covering structure made of carbon, e.g. of pyrocarbon
- A61F 2310/00586: Coating made of graphite
- A61F 2310/00592: Coating or prosthesis-covering structure made of ceramics or of ceramic-like compounds
- A61F 2310/00928: Coating or prosthesis-covering structure made of glass or of glass-containing compounds, e.g. of bioglass
- A61F 2310/00952: Coating, pre-coating or prosthesis-covering structure made of bone cement, e.g. pre-applied PMMA cement mantle
- A61C: DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE (non-driven toothbrushes A46B; {tongue scrapers A61B17/24;} preparations for dentistry A61K6/00; preparations for cleaning the teeth or mouth A61K8/00, A61Q11/00)
- A61F: FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS (dental prosthetics A61C)

## Abstract

A dental implant system to provide a mechanically self-sufficient artificial tooth possessing a functional pseudo peridontal ligament that does not cause resorption of the supporting bone and ultimate loss is disclosed. The implant includes a core component that withstands the masticatory load and transmits such load to the root system. The root system comprises an outer component that adheres to the jawbone and possesses a similar modulus of elasticity thus capable of transmitting masticatory stresses along its interface with the bone without excessive stress concentrations and an intermediate component adhering tightly to both the core component and the outer component and having a much lower modulus of elasticity than either the core component and the outer component. The longitudinal movement of the core component causes the oblique or diagonal stretching of the intermediate component which pulls or applies a force on the outer component which tends to contract it and creates tensile stresses in the portions of the supporting jawbone which interface with the outer component. Such tensile stresses cause bone deposition and stabilize the implant further.

## Claims

### Claim 1

A tooth replacement system comprising a dental implant having a core providing a central shaft having a lower end, an outer component adapted to be positioned in a socket in the jawbone surrounding the central shaft and spaced therefrom to define a gap therewith, an intermediate component disposed in the gap, and means securing the intermediate component both to the central shaft and to the surrounding wall of the outer component, the intermediate component having a lower modulus of elasticity than either the central shaft or the outer component to permit axial movement of the central shaft relative to the outer component, said outer component having a modulus of elasticity which approximates that of bone, said central shaft being non-convergent toward its lower end so that axial movement of the central shaft relative to the outer component imparts tensile stresses in said intermediate component which tend to contract said outer component thereby to impart tensile stresses in the surrounding portions of the supporting jawbone.

### Claim 2 (depends on 1)

The tooth replacement system of claim 1 wherein the modulus of elasticity of the intermediate layer is no more than about one-fifth as much as that of either the central shaft of the outer layer.

### Claim 3 (depends on 1)

The tooth replacement system of claim 1 wherein the central shaft has a porous surface layer adjacent the gap and the intermediate component is engaged in the voids thereof.

### Claim 4 (depends on 3)

The tooth replacement system of claim 3 wherein the outer component has a porous surface layer adjacent the gap and the intermediate component is engaged in the voids thereof.

### Claim 5 (depends on 1)

The tooth replacement system of claim 1 wherein the outer component has an outer surface which is porous to permit bone growth therein.

### Claim 6 (depends on 1)

The tooth replacement system of claim 1 wherein the modulus of elasticity of the outer component is in the range of about 0.5-2 times that of bone.

### Claim 7

A bone implant having a core providing a central shaft having a lower end, an outer component adapted to be positioned in a socket formed in a bone surrounding the central shaft and spaced therefrom to define a gap therewith, an intermediate component disposed in the gap, and means securing the intermediate component both to the central shaft and to the surrounding wall of the outer component, the outer component having a modulus of elasticity approximately that of bone, the intermediate component having a lower modulus of elasticity than either the central shaft or the outer component to permit axial movement of the central shaft relative to the outer component, said central shaft being non-convergent toward its lower end so that axial movement of the central shaft relative to the outer component imparts tensile stresses in said intermediate component which tend to contract said outer component thereby to impart tensile stresses in the surrounding portions of the supporting bone.

### Claim 8 (depends on 7)

The bone implant of claim 7 wherein the modulus of elasticity of the outer component is in the range of about 0.5-2 times that of bone.

### Claim 9 (depends on 7)

The bone implant of claim 7 wherein the outer component is porous to permit bone growth therein.