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Increased Youngs Modulus and Hardness of Col1a2oim Dentin
1 Endocrinology Section, Department of Medicine, University of Wisconsin, H4/556 CSC (5148), 600 Highland Ave., Madison, WI 53792, USA; Correspondence: * corresponding author, rdb{at}medicine.wisc.edu
Mice harboring the Col1a2oim mutation (oim) express dentinogenesis imperfecta. To determine the effect of Col1a2 genotype on tissue mechanical properties, we compared Youngs modulus and hardness of dentin in the 3 Col1a2 genotypes. Upper incisors were tested by nanoindentation. Genotype had a significant effect on Youngs modulus, but there was not a simple mutant allele dosage relationship. The effect of genotype on hardness did not reach significance. Hardness and Youngs modulus were greater near the dento-enamel junction than near the pulp chamber. Greater hardness and Youngs modulus values near the dento-enamel junction reflected continued mineralization of the dentin following its initial synthesis. Analysis showed the mechanical data to be consistent with Fourier transform infrared and backscattered electron microscopy studies that revealed increased mineralization in oim bone. Analysis of the data suggests that clinical fragility of teeth in oim mice is not due to deficiencies of hardness or Youngs modulus, but may be due to defects in post-yield behavior or resistance to fatigue damage.
Key Words: collagen type I dentinogenesis imperfecta osteogenesis imperfecta biomechanics tooth calcification
Journal of Dental Research, Vol. 85, No. 11,
1032-1036 (2006) |
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