Volumetric assessment and quantitative element analysis of the effect of fluoridated milk on enamel demineralization.

OBJECTIVES: It was the purpose of this study to investigate the effect of milk and fluoridated milk on experimentally induced caries-like-lesions. MATERIALS AND METHODS: Twelve extracted impacted human molars were covered with wax leaving two 3 mm x 3 mm windows on the buccal and lingual surfaces and incubated alternating in demineralizing solution at pH 4.85 and in milk, F-milk, saline, and remineralizing solution, respectively. Afterwards serial ground sections were cut and investigated by polarization-light-microscopy (PLM) and SEM using EDX element analysis. RESULTS: The results showed increased thickness of the superficial layer in the F-milk samples. Quantitative element analysis revealed a significant increase in the fluoride content of the superficial layer and of the body of the lesion of the F-milk group. The body of the lesion of the F-milk group was less demineralized than in the other groups. CONCLUSION: From the results we conclude, that the parallel investigation by PLM, SEM combined with EDX quantitative element analysis is a powerful method to assess caries-like-lesion formation and that fluoridated milk has protective properties in inhibiting demineralization.

Qualitative and quantitative assessment of intratubular dentin formation in human natural carious lesions.

It was the aim of this study to investigate the scanning electron microscopy (SEM) features and the element content of calcium (Ca) phosphorus (P), magnesium (Mg), oxygen (O), and carbon (C) of sound dentin, demineralized dentin, secondary dentin, intratubular and peritubular de novo dentin formation due to caries progression and to compare the element content with chemically pure hydroxyapatite. Eighteen extracted teeth with deep dentin carious lesions were embedded in Technovit 9100 (Kulzer), and serial sections of 80 microm thickness were made. These sections were then investigated with polarized light microscopy to identify the lesions. Two sections of each lesion were then coated with carbon and studied with a scanning electron microscope. Of the 18 teeth, 8 showed intratubular dentin formation. The element content was measured using energy dispersive X-ray analysis (EDX). About 75% of all involved dentin tubules showed intratubular de novo dentin formation. The Ca/P ratio in sound dentin, demineralized dentin, peritubular dentin, and secondary dentin was within the range of hydroxyapatite, whereas in intratubular dentin the Ca/P ratio was different than that of hydroxyapatite. The element content for Ca was statistically highly significantly different (P < 0.01) among sound dentin/intratubular dentin, sound dentin/peritubular dentin, and sound dentin/ secondary dentin, but not between sound dentin/ demineralized dentin and sound dentin/hydroxyapatite. For the other measured elements varying statistical differences were found. Our results indicate that intratubular dentin does not occlude the dentin tubules completely and mineralizes different than that of sound dentin and may therefore not be true hydroxyapatite.

Distribution and volumetric assessment of initial approximal caries lesions in human premolars and permanent molars using computer-aided three-dimensional reconstruction.

Serial sections from 21 extracted premolars and permanent molars, divided into three age groups (group 1, 10-19 years; group 2, 20-39 years; group 3, 50-69 years.), were viewed by polarized light microscopy for reconstruction of the caries lesions. The volumes of the lesional body and the transparent zone, and the volumes of early dentinal lesions were calculated; and an enamel demineralization index (EDI) and an enamel-dentine demineralization index (EDDI), representing the volumetric ratio of the body of the lesion to the translucent zone, and the body of the lesion to the volume of the early dentinal lesion, respectively, were determined. The method showed that there are three typical sites of individual initial caries lesions at the approximal surface: within the contact area, in the subcontact area, and in the cervical area. Volumetric assessment demonstrated a larger volume of the body of the lesion in older teeth with a smaller volume of the translucent zone relative to the lesional body. From these results it can be concluded that there are usually more than one individual initial caries lesions at the approximal tooth surface. Calculation of demineralization indices demonstrated different features for small lesions with pronounced transparent zones and for large lesions with small transparent zones. The computer-assisted three-dimensional reconstruction technique and the volumetric assessment are of value in investigations of the micromorphology and progression of natural caries lesions in permanent teeth.