A MicroCT Study on Mineral Change over Time Associated with Demineralisation in Primary Teeth.

OBJECTIVE To evaluate the change in demineralisation depth (DD)and mineral density (MD) over time in primary teeth exposed to a demineralisation protocol with microcomputed tomography (microCT). METHODS Caries lesions were artificially induced on the labial surfaces of 9 primary incisors by way of a demineralisation protocol using 0.1 M lactic acid with 10% methylcellulose gel for 7 and 14 days. The specimens were scanned with microCT and CTAn software (Bruker, Billerica, MA, USA) was used to analyse the changes in DD and MD. Statistical analyses were performed using SPSS software (IBM, Armonk, NY, USA). Repeated analysis of variance (ANOVA) test and Pearson bivariate correlation were used and the level of significance was set at P < 0.05. RESULTS The DD ranged from 0.00 to 0.99 μm (mean ± standard deviation [SD] 0.70 ± 0.43 μm) at baseline, 11.18 to 29.5 μm (18.15 ± 5.23 μm) at 7 days and 18.00 to 55.30 μm (34.20 ± 8.70 μm) at 14 days. The MD for all specimens (n = 9) ranged from 1.48 to 1.76 g/cm3 (1.65 ± 0.08 g/cm3) at baseline, from 1.47 to 1.74 g/cm3 (1.62 ± 0.08 g/cm3) at 7 days demineralisation and 1.33 to 1.72 g/cm3 (1.54 ± 0.13 g/cm3) at 14 days. There were statistically significant differences in DD (P < 0.001) and MD (P = 0.016) between different durations of demineralisation. CONCLUSION DD and MD change with time after being exposed to demineralising solution. MicroCT is a nondestructive method that allows repeated MD evaluations of the same sample.