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Int Poster J Dent Oral Med 13 (2011), No. 4     15. Dec. 2011

Int Poster J Dent Oral Med 2011, Vol 13 No 4, Poster 560

A Complete Denture Strength Evaluation Based On Fracture Mechanics Concepts

Language: English
 

Authors:
Anghel Cernescu, PhD student eng., Nicolae Faur, Prof. eng.,
Politechnica University, Timisoara, Romania
Prof. Dr. Cristina Maria Bortun, Otilia Cornelia Gombos, Dr. Med. PhD student,
"Victor Babes" University of Medicine and Pharmacy, Timisoara, Romania

Date/Event/Venue:
July 14-17, 2010
IADR 88th General Session and Exhibition
Barcelona, Spain
 

Objectives

The aim of study was to evaluate the complete dentures strength and durability in case of some structural defects of complete dentures.
 

Material and Methods

For testing there were used samples of material and a upper complete denture, made by ECLIPSE RESIN SYSTEM (DENTSPLY International Inc. - DeguDent GmbH, Hanau Germany). Following an inspection on this denture, there were observed some defects. For strength evaluation of complete denture it was used finite element analysis and there were calculated the stress intensity factors in located points for material's mechanical parameters. There was obtained the geometric model of the complete denture by 3D scanning (Roland 3D laser scanner, model LPX-1200). This was imported into o finite element software - ABAQUS/CAE V6.6 and was determined the state of stress and the stress intensity factors for three located defects.

Fig. 1a: Zwick Roel equipment Fig. 1b: broken Eclipse samples
Fig. 1c: Roland 3D laser scanner LPX 1200 Fig. 1d: denture with structural defects
Fig. 1e: scanned denture image Fig. 1f: geometric model
Fig. 1g: forces loading Fig. 1h: denture's support areas on prosthetic field
 

Results

For Eclipse Base Plate there were obtained following mechanical properties: the tensile strength - σU=59.49 MPa, Young's modulus - E=2908.45 MPa and fracture toughness KC=24.93 MPa √ mm. tensile strength and deformation analysis of the denture is revealed through chromatic specters, to which warm colors indicated the risk zones for fracture. Defects located on palatal mid-line of upper complete denture, especially those at the junction between different support areas, generate tensile stress and deformation which can determine possible mid-line fractures.

Fig. 2a: Crack in denture Fig. 2b: Crack detail (K =4.32 MPa √mm)
Fig. 2c: Crack in denture Fig. 2d: Crack detail (K =22.8 MPa √mm)
 

Conclusions

Complete dentures' defects can initiate cracks that are responsible for failure of complete denture before the expected lifetime. Experimental study of prosthesis mechanical properties by finite element analysis is used for knowledge of risk zone for fracture.
 

Literature

  • D. L. Dixon, K. G. Ekstrand, L. C. Bredding, (1991). The transverse strengths of three denture base resins. J. Prosthet. Dent., 66: 510-513.
  • A. Mese, K. G. Guzel (2008 Feb): Effect of storage duration on the hardness and tensile bond strength of silicone- and acrylic resin-based resilient denture liners to a processed denture base acrylic resin. J Prosthet Dent.; 99(2):153-9.
  • G. L. Polyzois, PA Tarantili, MJ Frangou, AG Andreopoulos. (2001 Dec): Fracture force, deflection at fracture, and toughness of repaired denture resin subjected to microwave polymerization or reinforced with wire or glass fiber. J Prosthet Dent.; 86(6):613-9.
  • G. Uzun, N. Hersek. (2002 Jul): Comparison of the fracture resistance of six denture base acrylic resins. J Biomater. Appl.; 17(1):19-29.
     

Acknowledgements

This study was supported by Ideas grant CNCSIS-UEFISCSU, Project number PNII - IDEI code 1878/2008, contract no.1141/19.01.2009, from Ministry of Education and Research of Romania and also by Project PERFORM-ERA-ID 57649.
 

This Poster was submitted by Engineer PhD Anghel Cernescu.
 

Correspondence address:
Engineer PhD Anghel Cernescu
B-l Mihai Viteazu, no.1
Code 300222
Timisoara, Romania