PSI - Issue 79

Mays H. Udah et al. / Procedia Structural Integrity 79 (2026) 53–64

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Consequently, a higher SIF leads to a lower number of fatigue cycles required to reach final failure. Nevertheless, this work compares the results with literature that used a fatigue load of 25 MPa. Fatigue life diagrams for the dentin beams and the critical cyclic stress range to failure are shown in Fig. 12. The stress capacity decreases as fatigue life increases. Fatigue life, measured in cycles, refers to the number of loading cycles a material can endure before failure. Generally, the curve indicates that as the number of cycles increases, the material's capacity to withstand stress without failure decreases. A comparison with the literature is shown in Fig. 12.

Fig. 12. Comparison of dentin fatigue life with Ref. [26]

4. Conclusions After conducting stress analyses using ANSYS, the maximum stress points (hotspots) were identified, followed by fracture analysis. The conclusions drawn from this research indicate that: 1. The analysis showed stress distribution across the tooth, with the highest stress concentration at the top and at the base near the middle projection, identified as the crack origin point. The loading type significantly influences crack development, with loading at a 45 ᵒ angle producing crack growth patterns more aligned with actual conditions than vertical loading. The load magnitude also plays a critical role, exhibiting notable variability in impact. 2. The crack length increases non-linearly with applied force, showing a direct proportionality higher forces lead to longer cracks, and vice versa. 3. Crack formation and growth are directly dependent on dentin properties. 4.Individuals with higher dentin properties can withstand greater forces without crack development compared to those with lower dentin quality. 5. SIF values are influenced by both the applied load and crack length. 6. Dentin behaves similarly to other materials under fatigue loading, as its capacity to endure stress without failure diminishes over time. Acknowledgements The authors gratefully acknowledge Mechanical Engineering Department, College of Engineering, Baghdad University, for conducting the current research. References 1. Rivera, E. M., & Walton, R. E. (2007). Longitudinal tooth fractures: findings that contribute to complex endodontic diagnoses. Endodontic Topics , 16 (1), 82-111. 2. Kang, S. H., Kim, B. S., & Kim, Y. (2016). Cracked teeth: distribution, characteristics, and survival after root canal treatment. Journal of endodontics , 42 (4), 557-562. 3. Loomba, K., Loomba, A., Bains, R., & Bains, V. K. (2010). A proposal for classification of tooth fractures based on treatment need. Journal of oral science , 52 (4), 517-529. 4. Al-Mukhtar, A. M., & Könke, C. (2011, August). Fracture mechanics and micro crack detection in bone: A short communication. In Conference Medical Device Materials V. Novelty: ASM International (p. 27776).