Hertzian contact response of dentin with loading rate and orientation

• Published in: Archives of oral biology Vol. 53; no. 8; pp. 729 - 735
• Main Authors: Silva, Nelson Renato Franca Alves da, Lalani, F, Coelho, Paulo G, Clark, Elizabeth A, Fernandes, Carlos Augusto de Oliveira, Thompson, Van P
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01-08-2008
• Subjects: Advanced Basic Science; Dental Stress Analysis - methods; Dentin; Dentin - ultrastructure; Dentistry; Hertzian contact; Humans; Imaging, Three-Dimensional; Loading rate; Orientation; Stress, Mechanical; Tubule orientation; Dentin; Hertzian contact; Tubule orientation; Loading rate
• ISSN: 0003-9969; 1879-1506
• DOI: 10.1016/j.archoralbio.2008.02.013

Abstract Objective To test the hypothesis that dentin Hertzian contact response varies with loading rate and tubule orientation. Design Sound teeth ( n = 12) were cut either parallel or perpendicular to the axial direction to expose dentin ( n = 6 each). The cut specimens were embedded (poly-methyl-methacrylate (PMMA) and divided into two groups: (GL) load applied parallel to dentin tubule direction and (GP) load applied perpendicular to tubule direction. A 1.5 mm diameter tungsten-carbide ball was used for Hertzian contact testing with a maximum load of 150 N load and loading rates of 0.1, 1, 100, and 1000 N/s on each specimen. Indented specimens were observed microscopically and photomicrographs acquired. Hertzian contact diameter and modulus were analysed ( p < 0.05) by one-way ANOVA and Tukey test. Results There were significant differences ( p < 0.05) in Hertzian response with respect to loading rate for GL (0.1 N/s versus 1000 N/s, 0.1 N/s versus 100 N/s, 1 N/s versus 1000 N/s, and 1 N/s versus 100 N/s), and GP (0.1 N/s versus 1000 N/s, 0.1 N/s versus 100 N/s, and 1 N/s versus 1000 N/s). Contact modulus was higher for GL compared to GP at all loading rates ( p < 0.05). Conclusion The results suggest that dentin contact modulus is loading rate dependent. Tubule orientation of dentin did not influence contact modulus values ( p > 0.05).