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Cardiff MediCentre, 29th March 2007

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Presentation on theme: "Cardiff MediCentre, 29th March 2007"— Presentation transcript:

1 Cardiff MediCentre, 29th March 2007
Meditech Meeting on: “Innovations in Materials and Manufacturing of Dental Devices” Thermal-mechanical reliability of Ti/HAp-based endosseous dental implant in severe conditions of Bruxism Giuseppe Cevola

2 Outline Introduction 3D FEM Modelling mandibular bone
FGMs (Functionally Graded Materials) endosseous dental implant Mechanical loading conditions occlusive loading bruxism loading FGMs composition’s parametric studying Thermal-mechanical Studying & Bruxism conditions Conclusions and future developments

3 Introduction Bruxism is a disorder of the masticatory
system characterized by teeth grinding and clenching Bruxism is considered aetiological factor for temporomandibular disorders (TMD) tooth wear (attrition) loss of periodontal support failure of dental restorations

4 Introduction The most common current dental implants are: ENDOSSEOUS
Sub-PERIOSTEAL

5 Introduction Endosseous dental implant performance requirements:
biocompatibility: osteointegration thermal/mechanical reliability: residual stress due to production (Hot Isostatic Pressing, Spark Sintering)

6 Introduction The success of the endosseous dental implant integration is due to: Lack of clinical signs and symptoms of pathology Lack of mobility Radiographically stable interface Radiographically stable interface Dynamic Modeling process Remodeling process Adaptive capacity: load-bearing biological structures that bond with bone Clark M. Stanford Biomechanical and functional behavior of implants Adv Dent Res 13:88-92, June, 1999

7 Introduction Used Materials Titanium and its alloys
Bioceramics : Hydroxyapatite (HAp) as coating, Zirconia Groundbreaking dental implants are designed using Functionally Graded Materials (FGM’s) made of Ti/HAp – Graduality along vertical direction: Titanium: upper part (occlusive loading) HAp: lower part (bone contact)

8 Outline Introduction 3D FEM Modelling mandibular bone
FGMs (Functionally Graded Materials) endosseous dental implant Mechanical loading conditions occlusive loading bruxism loading FGMs composition’s parametric studying Thermal-mechanical studying & Bruxism conditions Conclusions and future developments

9 3D FEM models obtained by Modelling Mandibular bone segment (35.25 mm)
FGM’s endosseous dental implant (first lower molar) obtained by Computed Tomography (CT) images of Human mandibular bone Computed Tomography (CT) images of Titanium dental implant (Bioform®)

10 Modelling Mandible Computed Tomography image

11 Completed Model Modelling The materials are supposed
isotropic with linear-elastic behaviour Toparli M, Sasaki S. Finite element analysis of the temperature and thermal stress in a postrestored tooth. J Oral Rehabil 2003;30:921–926.

12 Modelling Mesial-Distal section Buccal-Lingual section Higher peri-implant tensile and compressive stresses would imply: implant-bone bond failure bone absorption S.C.Huang, C.F.Tsai Finite element analysis of a dental implant Biomedical Engineering-Applications, Basis & communications Vol.15 No.2 April 2003 Implant mechanical performances are evaluated by means peri-implant-bone stresses: von Mises stress First principal stress Third principal stress

13 Outline Introduction 3D FEM Modelling mandibular bone
FGMs (Functionally Graded Materials) endosseous dental implant Mechanical loading conditions occlusive loading bruxism loading FGMs composition’s parametric studying Thermal-mechanical Studying & Bruxism conditions Conclusions and future developments

14 Mechanical loading conditions: Experimental data
Normal bilateral occlusive loading: Molar region : N Premolar region : N Canine region : N Incisive region : N K.J. Anusavice, Phillips Science of Dental Materials, W.B.Saunders Co., New York, (1996) Molar region unilateral occlusive loading : 30% smaller than one obtained during bilateral loading TWENTY-SECOND BIENNIAL MEETING 7–10 June 2001, Lugano, Switzerland Journal of Oral Rehabilitation ; 872–889 Upper and lower dental appliances containing miniaturestrain-gauge transducers.

15 Mechanical loading conditions: Experimental data
Bruxist bilateral clenching loading molar region : 790 N transversal force: 50 N First lower molar Journal of Oral Rehabilitation ; K. Nishigawa Department of Fixed Prosthodontics, The University of Tokushima School of Dentistry, Tokushima, Japan

16 Outline Introduction 3D FEM Modelling mandibular bone
FGMs (Functionally Graded Materials) endosseous dental implant Mechanical loading conditions occlusive loading bruxism loading FGMs composition’s parametric studying Thermal-mechanical Studying & Bruxism conditions Conclusions and future developments

17 FGMs composition’s parametric studying
Exponential law between composition and longitudinal coordinate h = hydroxyapatite t = titanium Increasing value of Ti along the implant lenght

18 Outline Introduction 3D FEM Modelling mandibular bone
FGMs (Functionally Graded Materials) endosseous dental implant Mechanical loading conditions occlusive loading bruxism loading FGMs composition’s parametric studying Thermal-mechanical Studying & Bruxism conditions Conclusions and future developments

19 Thermal-mechanical Studying
Changing temperature implant performances: ΔT = 0°C m=0.1 m=0.2 m=0.5 m=1 m=2 m=5 m=10 Ti

20 Thermal-mechanical Studying
Changing temperature implant performances: ΔT = 0°C m=0.1 m=0.2 m=0.5 m=1 m=2 m=5 m=10 Ti

21 Thermal-mechanical Studying
Changing temperature implant performances: ΔT= + 20°C and -20°C

22 Thermal-mechanical Studying
Changing temperature implant performances: ΔT= + 20°C and -20°C

23 Thermal-mechanical Studying
Bruxism Conditions: Clenching load & grinding force

24 Outline Introduction 3D FEM Modelling mandibular bone
FGMs (Functionally Graded Materials) endosseous dental implant Mechanical loading conditions occlusive loading bruxism loading FGMs composition’s parametric studying Thermal-mechanical Studying & Bruxism conditions Conclusions and future developments

25 Conclusions and future developments
So far m = 2 composition withstands the highest von Mises and first principal stresses in all the implants, with temperature reduction of 20°C In progress On the basis of provided experimental data (K. NISHIGAWA School of Dentistry, Tokushima, Japan ) the bruxism behaviour is in progress Future works Would be desirable to carry-out fatigue analysis for the implant-bone bond The residual stresses due to the technological processes can neglect the hosting oral changing temperature effect?

26 Acknowledgment Dr. WANG Fang, PhD. Institute of High Performance Computing Singapore, External Advisor Prof. Estevam Barbosa de Las Casas, Universidade Federal de Minas Gerais, Belo Horizonte, BRASIL Prof. K. Nishigawa, School of Dentistry, Tokushima, Japan Prof. F. Lobbezoo, Department of Oral function, Academic Centre for Dentistry Amsterdam (ACTA), Amsterdam, The Netherlands Are gratefully acknowledged for their assistance and contributions Prof. Roberto Contro, Prof. of Biomechanics, Politecnico di Milano, Italy Prof. Pasquale Vena, Assoc. of Biomechanics, Politecnico di Milano, Italy Dr. Dario Gastaldi, PhD. of Material Engineering, Politecnico di Milano, Italy Are also acknowledged for their kind assistance and useful discussions

27 Thank you!


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