September 13-16, 2009

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September 13-16, 2009

Waikoloa, HI

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Bi

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Biomimetic Tooth Implants by

Electron Beam Melting

Mari Koike, DDS, PhD1_{; Gilbert Chahine}2_{; Radovan}

Kovacevic, PhD2_{; Toru Okabe, PhD}1

1 _{Department of Biomaterials Science, Baylor College of Dentistry, Texas A&M}

Health Science Center 3302 Gaston Avenue Dallas Texas 75246 USA Health Science Center, 3302 Gaston Avenue, Dallas, Texas 75246, USA

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Present Status of Dental Implants

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• Research and development continues in dental sciences.

• Successful rehabilitation of many dental clinical

it ti i lit

situations is now a reality

• 69% of adults ages 35 to 44 have lost at least one t t th

permanent tooth

• 26% of adults have lost all of their permanent teeth by age 74

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Present Status of Dental Implants

(cont.)

O ti f ti t i i t t th

• Option for patients missing permanent teeth:

– Removable dentures and fixed bridges

– Dental implants (long-term replacements placed in the jawbone) – Dental implants (long-term replacements placed in the jawbone)

• In 2004, nearly 800,000 dental implants were done in the U.S.

U.S.

• In 2002, $150 million of implants were sold to North American dentists

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Present Status of Dental Implants

(cont.)

• Mostly generic in formy g • Fabricated by machining

• Extra-low interstitial Ti-6Al-4V is used when enhanced ductility and toughness are required • Require enhanced ductility and toughness

• Titanium alloys successfully used

– They represent the best compromise between

bi h i l t th bi tibilit d t ti l f biomechanical strength, biocompatibility, and potential for relative motion

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Generic Dental Implants

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Crown (C)

( )

Transmucosal

Abutment (B)

( )

Implant

Fixture (A)

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Complications in Implant Components

• Fatigue failure of the screw due to

Di t f th ( ll th th t )

– Diameter of the screw (smaller than other components) – Fracture

Screw loosening – Screw loosening – Fatigue

• Screw loosening is reported in 38% of prostheses • Screw loosening is reported in 38% of prostheses

• Some fracture by fatigue, in vivo, at the abutment screw and prosthesis screw

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Radiograph of ITI implant with

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abutment screw fatigue fracture

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One-piece Implants

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• Fabricated in one piece, with the root-form

implant and abutment together

• Benefit - potentially serve better intraorally

Benefit potentially serve better intraorally.

• New, innovative technology of electron

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Presentation Topics

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• Electron beam melting (EBM) equipment

• Trial fabrication of biomimetic, root-form

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l

t

implants

• Mechanical properties

• Capability of the EBM process to produce

lattice or mesh structures

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Filament Coils Coils Electron Focus coils Electron beam Gun Chamber Deflection coil Electron beam Powder Specimen Fabrication Rake Hopper •Powder Tooth implant Chamber Building Table

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CT Tomography/CAD Model

(Powder)

Thin Powder Layer

M lti

Pre-Heating

New Powder Layer

(Powder)

Melting

New Powder Layer

(Powder)

(Repeating Process)

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Sequence of manufacturing customized dental implant Preparation MRI or CT scanning for insertion Patient C t i d 3D Data Converting to CAD Customized Implant 3D Data Rapid f t i Customized Dental manufacturing Dental implant designing Electron Beam Melting (EBM)

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Mechanical Properties of Ti-6Al-4V ELI

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Specimens Made by EBM

D bb ll tt

• Dumbbell pattern

– Gauge length: 20 mm Diameter: 3 0 mm

– Diameter: 3.0 mm

• Ti-6AL-4V ELI powder (Arcam AB®₎

A ti l i 40

– Average particle size: 40 μm

• Yield strength, tensile strength and elongation

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1200 20 Yi ld S h

Mechanical properties

1000 16 18 Yield Strength Tensile Strength Elongation 600 800 h (MPa ) 10 12 14 ion ( % ) 400 600 St re n g th 6 8 10 E longat i 200 2 4 6

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Vickers Hardness

400 350 400 ) 250 300 d n e ss ( V H ) 150 200 c ke rs Ha rd 50 100 Vi c 0

EBM cast wrought

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Tensile Strength:

Polished vs Non Polished

Polished vs. Non-Polished

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Microstructures

Ti6Al4V ELI cast

50 μm

•CP Ti picture

Ti6Al4V ELI cast

50 μm

•CP Ti picture

Ti6Al4V ELI EBM

CP Ti cast

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Histopathological Results

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Commercial implant

EBM implant Commercial implant

(SLA implant) 1 week

EBM implant 8 weeks

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CT Scanning Center

Dentist A

Patient 1 Patient 1 Patient 1

Patient 3 Patient 2

Patient 2 Dentist B Dentist C

Patient 3 Patient 3 Patient 3

Center of Rapid Manufacturing of dental Implants Center of Rapid Manufacturing of dental Implants

Tooth A 1 Tooth B,1 Tooth B,2 Tooth B,3 Tooth A,1 Tooth A,2 Tooth A,3 ,

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Summary

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• The EBM process is capable of manufacturing a new design of dental implants:

– Made of one component – Mimics the patient’s tooth

Can have a lattice structure implemented on its – Can have a lattice structure implemented on its

surface

• Potential advantages:

– Reduce pre-insertion procedures – Faster healing time

Control stiffness and surface texture to promote – Control stiffness and surface texture to promote

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Summary (cont.)

• Tensile testing shows

– Polished specimens have mechanical properties

bl t th f ht Ti 6Al 4V

comparable to those of wrought Ti-6Al-4V

– As-fabricated specimens have poor ductility and reduced strengthg

• Microstructural observation of specimens show

– Fine α- and β- microstructure (indicates fast cooling rate)

C l th ll l t th di ti f b ild

– Columnar growth parallel to the direction of build up • Challenges remaining

– Investigate fatigue behavior and corrosion resistanceInvestigate fatigue behavior and corrosion resistance – Find ways to improve surface characteristics

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Acknowledgement

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This project was partially supported by Army Research Grant No. W911NF-07-2-0056.