Objectives: The hard tissues structure-function relationship may be diminished via aging processes. The purpose of this study was to investigate the deterioration of the biomolecular structure and time-dependent change of mechanical properties of human dentin and their relationship through the mimetic aging process inducing by x-ray irradiation. Materials and Methods: Extracted human teeth were sectioned perpendicular to the long axis of the teeth at the middle of the crown by using a low-speed diamond saw and following embedded into a cold-cure epoxy resin. 30 KGy X-ray irradiation was carried out on the sample surfaces. The surface of the sample was finalized with 0.05 μm alumina polishing paste. Raman spectra on the sample surfaces were acquired using confocal Raman microspectroscopy. The relative ratio of X-ray induced advanced glycation end products (AGEs) to hydroxyapatite was quantified. Nanoindentation testing was used to assess elastic moduli, viscoelasticity and time-dependent creep/recovery. Measurement of Raman spectra and nanoindentation testing were conducted to same specimens before and after X-ray irradiation. Results: The relative ratio of AGEs was increased in the sample irradiated to 30 KGy when compared with those in the sample without irradiation. Nanoindentation test showed the irradiated sample tended to be lower elastic moduli, decrease in viscoelasticity, and be lesser creep/recovery than the sample without irradiation. Conclusions: It was suggested that there is a relationship between biomolecular structure and mechanical properties. The deteriorated dentin associated with AGEs increase may decrease their mechanical properties.
DDS,Graduate student in PhD course
Takuma Tobe, D.D.S, is Ph. D. candidate in Showa University. I received my Doctor of Dental Surgery degree from Showa University in 2014.My main research project is "biomechanical analysis of dentin related to Aging processes".
Thursday, April 26
10:00 AM – 1:00 PM
Yo Shibata, D.D.S, Ph. D. He received his Doctor of Dental Surgery degree from Showa University and his Ph.D degree from Showa University. He is currently serve as an assistant professor, Division of Biomaterials and Engineering, Department of Conservative Dentistry, Showa University School of Dentistry.
Takashi Miyazaki, D.D.S, Ph. D. He received his Doctor of Dental Surgery degree from Tokyo Medical and Dental University and his Ph.D degree from Tokyo Medical and Dental University. He is currently serve as a professor, Division of Biomaterials and Engineering, Department of Conservative Dentistry, Showa University School of Dentistry.