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Objective: The purpose of this study was to use scanning electron microscopy (SEM) in order to compare the surfaces of cavities prepared using laser with those prepared conventionally, and to measure the degree of leakage through both enamel and cementum., Materials and Methods: We prepared 135 class V cavities and divided them randomly into three groups: laser-treated (group A), laser-treated, and acid-etched (group B) and rotary instrumented (group C)., Results: On analyzing the tooth enamel, the amount of leakage was found to be similar in groups A and B, whilst the samples in the group C were more prone to leakage. On analyzing the cementum, the group C samples appeared to display surfaces that were more conducive to the adhesion of the materials used in obturation (although this difference was not strictly significant), and this might have provoked the relatively low levels of leakage., Conclusion: The use of acid etching in conjunction with both conventional and laser cavity preparation improves the adhesion of the materials used in obturation to enamel surfaces.

We have undertaken a scanning electron microscope study of the enamel surface of the third molar in adult patients. The enamel surface are partially covered by a thin cuticle. The arrangement of the enamel prisms was clearly observed in the basal region of the cusps.

Abstract: Introduction: This in vitro study compared the tooth color and the ultrastructure of internal dental tissues before and after internal bleaching. Methods: Sodium perborate was placed in the pulp chamber of endodontically treated molars and sealed with intermediate restorative material. The test samples were stored in a physiologic solution, and the bleaching agent was replaced every 7 days. A control group was used. After 1 month, the colors of the test and control samples were measured with a colorimeter, and the internal surfaces were observed under field emission scanning electron microscopy (FESEM). Results: Statistically significant differences were found between the test and control sample colors. The FESEM ultrastructure analysis of the internal enamel and dentin surfaces did not show any changes after the internal bleaching. Conclusions: The results of the present study show that sodium perborate is effective in bleaching nonvital teeth and does not produce ultrastructural changes in the dental tissues. [Copyright &y& Elsevier]