SPring-8, the large synchrotron radiation facility

Release Date

16 Apr, 2009

Demonstration of recrystallization of hydroxyapatite crystals in early-stage dental caries using phosphoryl oligosaccharides of calcium - Restoration of hydroxyapatite crystals at remineralized areas with an ordered structure similar to that in healthy teeth.

Ezaki Glico Co., Ltd.
Japan Synchrotron Radiation Research Institute

In a joint research between Ezaki Glico Co., Ltd., and Japan Synchrotron Radiation Research Institute, the demineralization and remineralization^*1 of hydroxyapatite crystals in early-stage dental caries (subsurface lesion) were examined using X-ray microbeams at SPring-8 (on the order of approximately 6 μm, which is the size of a bacterial cell and a fog particle). The results revealed that at the remineralized area treated with phosphoryl oligosaccharides of calcium,^*2 not only the mineral content of calcium phosphate returned to normal but also the area was restored as hydroxyapatite crystals^*3 with an ordered orientation similar to that of healthy teeth.

This finding indicates that recrystallization occurs at the remineralized area in early-stage dental caries (subsurface lesion), and demonstrates that such dental caries can be restored to a level similar to that in healthy teeth.

This is the world's first report on crystalline changes associated with demineralization and remineralization analysed using X-ray microbeams of about 6 μm diameter in the field of food science. Ezaki Glico Co., Ltd., is planning to apply this finding in the research and development of oral-care foods and materials contributing to the promotion of dental health.

This research result on the recrystallization of hydroxyapatite crystals in early-stage dental caries using phosphoryl oligosaccharides of calcium was presented at the 55th European Organization for Caries Research (ORCA) Congress held on 25-28 June 2008 in Groningen, The Netherlands, and the Symposium of Japanese Society of Biomaterials held on 17-18 November 2008. The method of X-ray microbeam analysis of early-stage dental caries was published in the May 2009 edition of the Journal of Synchrotron Radiation, a British journal.

Publication:
"Evaluation of enamel crystallites in subsurface lesion by microbeam X-ray diffraction"
N. Yagi, N. Ohta, T. Matsuo, T. Tanaka, Y. Terada, H. Kamasaka, K. To-o, T. Kometani and T. Kuriki
Journal of Synchrotron Radiation 16 (3), 398-404 (2009), published online 17 March 2009.

<Glossary>

*1 Demineralization and remineralization
Demineralization is the elution of phosphoric acid (P) and calcium (Ca), the crystalline components of teeth, from the tooth occurring when the oral environment becomes acidic after taking meals or snacks. Remineralization is the restoration of such components onto the tooth.

*2 Phosphoryl oligosaccharides of calcium
A highly hydrosoluble calcium food material jointly developed by Ezaki Glico Co., Ltd., and Oji Cornstarch Co., Ltd.

*3 Hydroxyapatite crystals
Hydroxyapatite crystals are chemical crystalline materials composed of phosphoric acid and calcium, which are the most abundant inorganic components of teeth and bones. Here, crystalline material indicates a structure in which atoms are periodically arranged in a three-dimensional space.

<Figure>

Wide-angle X-ray diffraction and small-angle X-ray scattering