September 13-16, 2009

Transcription

1 September 13-16, 2009 Waikoloa, HI September 13-16, 2009, Waokoloa, Waikoloa, HI

2 Biomimetic i Tooth Implants by Electron Beam Melting Mari Koike, DDS, PhD 1 ; Gilbert Chahine 2 ; Radovan Kovacevic, PhD 2 ; 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 2 Department of Mechanical Engineering, Southern Methodist University, 3101 Dyer Street, Dallas, Texas 75205, USA

3 Present Status of Dental Implants Research and development continues in dental sciences. Successful rehabilitation of many dental clinical situations ti is now a reality 69% of adults ages 35 to 44 have lost at least one permanent toothth 26% of adults have lost all of their permanent teeth by age 74

4 Present Status of Dental Implants (cont.) Option for patients t missing i permanent teeth: th Removable dentures and fixed bridges Dental implants (long-term replacements placed in the jawbone) In 2004, nearly 800,000 dental implants were done in the U.S. In 2002, $150 million of implants were sold to North American dentists

5 Present Status of Dental Implants Mostly ygeneric in form Fabricated by machining (cont.) 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 biomechanical i strength, th biocompatibility, and potential ti for relative motion

6 Generic Dental Implants Crown (C) Transmucosal Abutment (B) Implant Fixture (A)

7 Complications in Implant Components Fatigue failure of the screw due to Diameter of the screw (smaller than other components) Fracture Screw loosening Fatigue Screw loosening is reported in 38% of prostheses Some fracture by fatigue, in vivo, at the abutment screw and prosthesis screw

8 Radiograph of ITI implant with abutment screw fatigue fracture

9 One-piece Implants Fabricated in one piece, with the root-form implant and abutment together Benefit - potentially serve better intraorally. New, innovative technology of electron beam melting or EBM

10 Presentation Topics Electron beam melting (EBM) equipment Trial fabrication of biomimetic, root-form implants Mechanical properties Capability of the EBM process to produce lattice or mesh structures

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

12 CT Tomography/CAD Model (Powder) Thin Powder Layer Pre-Heating Melting (Powder) New Powder Layer (Repeating Process) 3D Object

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

14 Titanium Alloy Molars

15 Mechanical Properties of Ti-6Al-4V ELI Specimens Made by EBM Dumbbell pattern Gauge length: 20 mm Diameter: 3.0 mm Ti-6AL-4V ELI powder (Arcam AB ) Average particle size: 40 μm Yield strength, tensile strength and elongation

16 Strength (MPa) Mechanical properties Yield Strength 18 Tensile Strength 1000 Elongation Elongati ion (%) EBM cast wrought Ti-6Al-4V ELI 4 2 0

17 400 Vickers Hardness 350 Vic ckers Hard dness (VH) EBM cast wrought Ti-6Al-4V ELI

18 Tensile Strength: Polished vs. Non-Polished

19 Microstructures 50 μm Ti6Al4V ELI cast 50 μm Ti6Al4V ELI EBM CP Ti picture CP Ti cast 100 μm

20 Lattice Structures

21 Histopathological Results EBM implant 8 weeks Commercial implant (SLA implant) 1 week

22 Biomimetic Tooth Implant

23 CT Scanning Center Patient 1 Patient 1 Patient 1 Patient 2 Dentist A Patient 2 Dentist B Patient 3 Dentist C Patient 3 Patient 3 Patient 3 Center of Rapid Manufacturing of dental Implants Tooth A,1 Tooth A,2 Tooth A,3 Tooth B,1 Tooth B,2 Tooth B,3

24 Summary 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 surface Potential advantages: Reduce pre-insertion procedures Faster healing time Control stiffness and surface texture to promote healthier osseointegration

25 Summary (cont.) Tensile testing shows Polished specimens have mechanical properties comparable to those of wrought Ti-6Al-4V As-fabricated specimens have poor ductility and reduced strength Microstructural observation of specimens show Fine α- and β- microstructure (indicates fast cooling rate) Columnar growth parallel l to the direction of build up Challenges remaining Investigate fatigue behavior and corrosion resistance Find ways to improve surface characteristics Perform trials of implants in animals

26 Acknowledgement This project was partially supported by Army Research Grant No. W911NF