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Age, dehydration and fatigue crack growth in dentin
Devendra Bajaj1, Naryana Sundaram, Ahmad Nazari
1Department of Mechanical Engineering, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA.
Biomaterials
|December 13, 2005
Summary
Human dentin
Area of Science:
- Biomaterials Science
- Dental Materials
- Biomechanics
Background:
- Dentin's mechanical properties are crucial for tooth integrity.
- Age and dehydration are potential factors influencing dentin's fatigue resistance.
Purpose of the Study:
- To investigate the impact of aging and dehydration on fatigue crack growth in human dentin.
- To quantify differences in fatigue crack growth rates and exponents between young, old, hydrated, and dehydrated dentin.
Main Methods:
- Compact tension (CT) fatigue specimens were prepared from extracted human molars.
- Specimens were subjected to high cycle fatigue (10^5 to 10^6 cycles) under Mode I loading.
- Fatigue crack growth rates were analyzed using the Paris Law, determining the crack growth exponent (m) and coefficient (C).
Main Results:
- Young hydrated dentin exhibited a significantly lower fatigue crack growth exponent (m=13.3) compared to old hydrated (m=21.6) and young dehydrated dentin (m=18.8).
- Fatigue cracks initiated at lower stress intensity ranges and propagated over 100x faster in old dentin than in young dentin.
- Microscopic analysis revealed differences in fracture surface features, suggesting altered energy dissipation mechanisms in older dentin.
Conclusions:
- Dentin's fatigue crack growth resistance diminishes with both age and dehydration.
- Aging appears to compromise mechanisms essential for dentin's crack growth resistance.
- These findings have implications for understanding tooth durability and failure under cyclic loading.
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