Search

Understanding the behaviour of light propagation in biological materials is essential for biomedical engineering and applications, and even more so when dealing with incoming biomaterials. Many methods for determining optical parameters from biological media assume that scattered light is isotropically distributed over all angles. However, an angular dependence of light scattering may exist and affect the optical behaviour of biological media. The present work seeks to experimentally analyze the scattering anisotropy in different dental tissues (enamel and dentine) and their potential substitute biomaterials (hybrid dental-resin, nano-filled composite, and zirconia ceramic) and comparatively study them. Goniometric measurements were made for four wavelengths in the visible range, allowing a spectral characterization of the materials studied. Previously, for each material, measurements were made with two different sample thicknesses at the same wavelength, checking the behaviour of the angular scattering profile. The asymmetry of experimental phase functions was considered in the recovery of the scattering anisotropy factor. The results demonstrate that the thicker sample yielded a less forward-directed scattering profile than did the thinner sample. The biomaterials analysed show angular scattering comparable to those of the tissues that they may replace. Comparisons can be made by virtue of the low uncertainties found.

ABSTRACT Objective Materials and Methods Results Conclusions Clinical Significance To provide guidelines and means for optimal coverage and distribution of computer models with 1–10 clusters, designed based on an in vivo extensive dental colorimetric database and compare the findings with some reputable shade guides.The Fuzzy C‐Means (FCM) algorithm was used to optimize the tab position in the CIELAB color space, while MATLAB Fuzzy Logic was used to implement the codes. A minimization process was performed to fine‐tune the cluster centers, minimizing Coverage Error (CE00) and Maximum Error (ME00). Spectral reconstruction was performed, and the results were compared with the corresponding data for VITA classical A1–D4 (VC), Linearguide 3D‐Master (LG), and Bleachedguide 3D‐Master (BG) shade guide. Paired t‐test was employed to assess the significance of CE00 differences.CE00 and ME00 ranges for 1‐to‐10‐tab models were 3.8 (14.2) to 1.7 (4.3), while the corresponding values for shade guides were 3.1 (9.1) for VC, 2.3 (6.0) for LG, and 2.9 (9.3) for BG. Hence, the 4‐tab‐model with CE00 of 2.2 and ME00 of 7.1, outperformed CE00 of LG (the lowest/best CE00 among shade guides), while the 6‐tab‐model, with CE00 of 2.0 and ME00 of 5.6, outperformed its ME00. A paired t‐test confirmed that increasing the number of tabs models resulted in significant CE improvement in all cases (p ≤ 0.05).Shade guide models with only 4 to 6 tabs, optimized using computational techniques, outperformed physical dental shade guides tested, exhibiting significantly lower (better) Coverage Error and Maximum Error.Given that the spectral modeling was performed on an extensive in vivo database of natural teeth, this approach was validated as a biomimetic guide for shade guides and corresponding materials of the future, offering a possibility for better shade matching with fewer shades/shade tabs. [ABSTRACT FROM AUTHOR]

Copyright of Ceramica is the property of Associacao Brasileira de Ceramica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Data are presented on 24 patients with epilepsy and psychosis whose clinical presentation was rated using the Present State Examination (PSE). Seventeen had complex partial seizures and a diagnosis of temporal lobe epilepsy, seven had generalised epilepsy. An association between a CATEGO category of nuclear schizophrenia (NS) and a lesion of the left side was noted. No clear link between depressive symptoms and a right-sided focus was discovered. Affective disorders were noted in both groups of epileptic patients, although paranoid psychoses were commoner in the temporal lobe group. There was also a tendency for the latter to have more delusions of persecution, ideas of reference, and special features of depression. The group rated as NS appear less likely to show evidence of intellectual deterioration than the other psychotic patients; in addition, the interval between the onset of their epilepsy and the onset of their psychosis is shorter. Radiological assessment by CAT reveals few differences between groups, but the psychotic samples do show higher than expected values on a number of variables, in particular the bilateral septum-caudate distance and the size of the third and fourth ventricle. [ABSTRACT FROM AUTHOR]

The mental states of 23 epileptic psychotic patients and 10 patients with process schizophrenia were compared, using the Present State Examination. The epileptics displayed marked heterogeneity of psychiatric diagnoses. Disturbances of affect underlying the psychosis or presenting as manic-depressive psychosis were frequent and independent of the type of epilepsy. Schizophrenic psychosis, classified with psychopathological criteria similar to those used in the non-epileptic schizophrenic group, was significantly associated with temporal lobe epilepsy. Psychoses other than schizophrenia, however, were present in 5 out of 16 patients with temporal lobe epilepsy. These results support a relationship between schizophrenic symptoms and temporal lobe pathology and emphasize the need to use reproducible methods of diagnosis in psychiatric research. [ABSTRACT FROM AUTHOR]

Surgical procedures carried out in the oral and maxillofacial region can result in large tissue defects. Accounting for the shortage of oral mucosa to replace the excised tissues, different models of an organotypic substitute of the oral mucosa generated by tissue engineering have recently been proposed. In this work, the propagation of light radiation through artificial human oral mucosa substitutes based on fibrin-agarose scaffolds (fibrin, fibrin-0.1% agarose, fibrin-0.2%agarose) is investigated, and their optical properties are determined using the inverse adding-doubling (IAD) method based on integrating-sphere measurements. Similar values for the absorption and scattering coefficients between the fibrin and fibrin-0.1% agarose bioengineered tissues and the native oral mucosa were found. These results suggest the adequacy of these biomaterials for potential clinical use in human oral mucosa applications. These optical properties represent useful references and data for applications requiring the knowledge of the light transport through this type of tissues, applications used in clinical practice. It also provides a new method of information analysis for the quality control of the development of the artificial nanostructured oral mucosa substitutes and its comparison with native oral mucosa tissues.

The physical understanding of the optical properties of dental biomaterials is mandatory for their final success in restorative applications. Light propagation in biological media is characterized by the absorption coefficient, the scattering coefficient, the scattering phase function, the refractive index, and the surface conditions (roughness). We have employed the inverse adding-doubling (IAD) method to combine transmittance and reflectance measurements performed using an integrating-sphere setup with the results of the previous scattering-anisotropy goniometric measurements. This has led to the determination of the absorption and the scattering coefficients. The aim was to optically characterize two different dental-resin composites (nanocomposite and hybrid) and one type of zirconia ceramic, and comparatively study them. The experimental procedure was conducted under repeatability conditions of measurement in order to determine the uncertainty associated to the optical properties of the biomaterials. Spectral variations of the refraction index and the scattering anisotropy factor were also considered. The whole experimental procedure fulfilled all the necessary requirements to provide optical-property values with lower associated uncertainties. The effective transport coefficient presented a similar spectral behavior for the two composites but completely different for the zirconia ceramic. The results demonstrated that the scattering anisotropy exerted a clearly distinct impact on the optical properties of the zirconia ceramic compared with those of the dental-resin composites.