Hexagonal Disk-Shaped Crystals Observed in Early and Old Dental Calculi and Caries-Arrested Enamel

Abstract

Hexagonal disk-shaped crystals were found in caries-arrested enamel as well as in early and old dental calculi with scanning electron microscopy. The crystals which were constructed with wafer-like laminations linked together, formed rosette-like structures, or aggregated with each other. The main components were calcium phosphate with a small amount of Mg under energy-dispersive X-ray microanalysis. The crystals were frequently coexistent with Mg-containing whitlockite (WH) while no WH crystals were observed in the early calculus; thereby, the pH range of the formation sites might be lower than that of WH crystals.