Micro and nanostructural analysis of a human tooth using correlated focused ion beam (FIB) and transmission Electron microscopy (TEM) investigations.

In this study, natural molar human tooth specimens were investigated for determining their micro- and nanoscale structural morphology, chemistry and crystallinity. The differences were tracked comparatively for both enamel and dentin layers and at their interfaces. Although dental material structures are hard and tough and the cross-sectioning of these materials using mechanical methods is challenging, FIB-SEM dual-beam instruments serve for preparing ultra-thin homogenous lamella sections. In this work, both FIB-SEM and TEM based advanced characterization methods were applied to reveal different morphological characteristics of dental tissue via complementary imaging and diffraction analysis. In addition, SEM-EDS and Raman spectroscopy techniques provided additional information about the elemental distribution and the chemical composition differences of the dental tissues. According to electron microscopy examinations at the intersection between the enamel and the dentin layers, it was shown that the enamel was denser and polycrystalline, while the dentin layer was porous, fibrillar and of negligible long-range order, due to its tubular structure and organic components. In particular, EDS mapping and linescan analyses showed almost no differences in the elemental distribution. Raman results confirmed that both tissues had similar chemical composition except dentin showed spectral background effects in the spectrum due to its tubular structure and organic components.

Apical Sealing Ability of a Novel Material: Analysis by Fluid Filtration Technique.

AIM: The aim of this study is to evaluate the sealing ability of Biodentine(TM), which is new calcium-silicate based dental cement and has endodontic indications similar to those of MTA. METHODS: The study sample consists of 21extracted human mandibular anterior teeth. The teeth were submitted to root-end preparation and instrumented up to file #40 by step back technique and randomly divided into 3 study groups (n=7): White MTA Angelus(TM) (Angelus, Angelus Odontológica, Londrina, PR, Brazil), Biodentine(TM) (Septodont, SeptodontSpecialités, Saint-MaurdesFosses, France) and the controls. The length of dye penetration between the filling material and tooth structure was measured in millimetres, using a calibrated stereo microscope (Leica MZ75, Germany) at 20× magnification under the same conditions. One-way Analysis of Variance (ANOVA) was used to indicate differences between the experimental groups and the controls. In addition, Tukey Multiple Comparisons Test was used to indicate differences within each group. RESULTS: The results showed that none of the groups were completely sealed. The mean and standard deviation for dye penetration in Biodentine(TM) group was 0.63±0.20 and in MTA Angelus(TM) group, it was 0.26±0.25. Regarding the comparisons between each group, significant differences were not observed (P=0.0193). The comparison between materials only found a significant difference only between MTA Angelus(TM) and Biodentine(TM) (P<0.05). CONCLUSIONS: This study evaluated the possibility of Biodentine(TM)'s sealing ability and marginal adaptation, since no studies are available on Biodentine. However, further in vitro and in vivo investigations should be conducted to determine the suitability of Biodentine(TM) for clinical application.