Radiopaque zones in the dentine beneath amalgam and silicate fillings

Interpretation of base-metal dentinal radiopacities: survey results

A survey was conducted to determine the familiarity with base metal dentinal radiopacity. The results show that although 91% of the respondents had observed this phenomenon, only 6% could correctly identify its cause. Despite the general misunderstanding concerning its cause, 48% of the respondents considered this radiopacity when making a diagnosis and providing treatment. To limit confusion, a standard term is suggested so this feature can be more consistently identified and properly considered in making diagnoses and in formulating treatment plans.

Visualization of stannous fluoride treatment of carious lesions by subtraction radiography

To determine whether treatment with SnF2 results in changes in radiographic density, eight extracted teeth with lesions confined to the enamel and five with lesions extending into the dentin were radiographed before and after treatment with a 10% SnF2 solution. Although visual comparison of pretreatment and post-treatment radiographs showed increased density in some areas where the pretreatment radiographs had shown demineralization and unchanged conditions in other instances, subtraction images of these radiographs revealed density increase in all the demineralized areas. Even in cases with white spot lesion not visible on radiographs, the subtraction images disclosed an increase in radiographic density.

Radiopaque zones in the dentin beneath silicate fillings analyzed by electron microprobe

Seven teeth which showed radiopaque zones beneath silicate fillings were sectioned and studied by microradiography and electron microprobe analysis in order to elucidate which elements were responsible for the increased absorption of X-rays and whether the presence of carious lesions could be masked by foreign elements in the tissue. The Ca concentration was frequently found to be either slightly increased or reduced compared with radiographically unaltered dentin. Increased concentrations of F and Zn occurred in the radiopaque zones. The highest F concentrations (0.4--1%) were recorded in zones with an increased Ca content. The highest Zn concentrations (5--8%) were found in the three specimens having a reduced Ca content. The possible conditions responsible for the increased Ca, F and Zn concentrations are discussed. The results indicate that both Ca and Zn may contribute to the increased absorption of X-rays. The hypothesis that carious dentin may be obscured in intraoral radiographs by the presence of foreign elements in the tissue, was not substantiated.