High-resolution micro-CT scanning as an innovative tool for evaluating dental hard tissue development

Microcomputerized tomography (micro-CT) allows discriminating very small changes in dental hard tissue volumes. The aim of the present study was to create a new method for obtaining high-resolution, three-dimensional images of dental hard tissue development using micro-CT, and to observe the changes in dental hard tissue development and composition in growing rat pups. Tooth germs from rats at the end of the 20-day embryonic period (E20) and during the neonatal period (D1-14) were subjected to micro-CT. Three-dimensional reconstructions were analyzed to compare dental hard tissue formation and mineralization during the different development periods. Scanning electron microscopy and energy dispersive spectroscopy were used to confirm mineral density (MD). Dental hard tissue began to form during the E20, but the process was slow and resulted in minimal deposition. Hard tissue volume increased by approximately 0.040 mm(3)/day from E20 to D3, and by 0.12-0.42 mm(3)/day after D3, peaking at 0.42 mm(3)/day at D12. This increase in hard tissue volume resulted in continuous increases in hard tissue thickness, from 90.0 +/- 20.7 mu m at E20 to 545.2 +/- 14.1 mu m by D14. MD was 298 +/- 3.1 mg HA/cm at E20 and increased to 678.2 +/- 6.1 mg HA/cm by D14. The degree of calcification also progressively increased during the first 14 days of development. Dental MD was strongly associated with calcification. This study indicates that micro-CT is a nondestructive, high-resolution, reliable, and innovative tool for the evaluation of volume and MD of dental hard tissues during development. Micro-CT minimizes artifacts caused by sample preparation.