Wavelength-independent microradiography used for quantification of mineral changes in thin enamel and dentin samples with natural surfaces, pseudo-thick tooth sections, and whole teeth.

Tests of the efficacy of therapeutic agents for caries repair or prevention in vitro or in situ should be performed as realistically as possible. This implies the non-destructive assessment of mineral changes in whole teeth. In this study, Wavelength-independent Microradiography (WIM), a non-destructive form of microradiography that uses polychromatic x-rays, was tested for its use in following mineral changes during demineralization of whole teeth. Since the method was, in a previous paper, only tested on flat samples of about 0.3 mm in thickness, the present study aimed to adapt and test WIM for use on thicker samples. This was done in three steps: In the first step, natural surfaces were introduced. The mineral content of enamel and dentin samples about 0.3 mm in thickness and with natural (curved) surfaces was determined by WIM, and the result was compared with mineral measurements performed with Longitudinal Microradiography (LMR). A correlation of 0.98 was found for both the enamel and the dentin samples. In the second step, the thickness of whole teeth was added. Thick tooth sections were simulated by addition of a 5-mm block of dentin to such thin enamel and dentin samples. Mineral measurements with WIM of the samples plus the dentin block were compared with mineral measurements of the thin samples (without block). A correlation of 0.97 was found for enamel, and one of 0.90 was found for dentin. Finally, in a third step, the demineralization of whole premolars was followed as a function of time.