Relating diffusion tensor imaging measurements to microstructural quantities in the cerebral cortex in multiple sclerosis

To investigate whether the observed anisotropic diffusion in cerebral cortex may reflect its columnar cytoarchitecture and myeloarchitecture, as a potential biomarker for disease‐related changes, we compared postmortem diffusion magnetic resonance imaging scans of nine multiple sclerosis brains with histology measures from the same regions. Histology measurements assessed the cortical minicolumnar structure based on cell bodies and associated axon bundles in dorsolateral prefrontal cortex (Area 9), Heschl's gyrus (Area 41), and primary visual cortex (V1). Diffusivity measures included mean diffusivity, fractional anisotropy of the cortex, and three specific measures that may relate to the radial minicolumn structure: the angle of the principal diffusion direction in the cortex, the component that was perpendicular to the radial direction, and the component that was parallel to the radial direction. The cellular minicolumn microcircuit features were correlated with diffusion angle in Areas 9 and 41, and the axon bundle features were correlated with angle in Area 9 and to the parallel component in V1 cortex. This may reflect the effect of minicolumn microcircuit organisation on diffusion in the cortex, due to the number of coherently arranged membranes and myelinated structures. Several of the cortical diffusion measures showed group differences between MS brains and control brains. Differences between brain regions were also found in histology and diffusivity measurements consistent with established regional variation in cytoarchitecture and myeloarchitecture. Therefore, these novel measures may provide a surrogate of cortical organisation as a potential biomarker, which is particularly relevant for detecting regional changes in neurological disorders.     

Discrimination or discretion? Exploring dentists' views on treating patients with hepatitis C

BACKGROUND: People with hepatitis C (over 259 000 Australians) experience stigma and discrimination, whether perceived or actual, in health care settings. They are less likely to access health care, presenting a major barrier to preventive care and treatment. This study aims to identify factors contributing to such discrimination, barriers to optimal care and strategies to overcome these. METHODS: A purposive sample of 25 Victorian dentists took part in semi-structured interviews to investigate their experiences and attitudes in providing care to people with hepatitis C. Interviews were taped, transcribed and coded for thematic analysis. RESULTS: All dentists interviewed were aware of Standard Precautions. However, there were some who changed practices when seeing a client with hepatitis C, suggesting that they lack confidence in Standard Precautions. When prompted, these dentists were concerned that patients may perceive these actions as discriminatory. All participants, including a small minority who expressed negative views about injecting drug users, felt a professional obligation to treat all patients. CONCLUSIONS: Most dentists have appropriate attitudes regarding patients with blood-borne viruses. However, it is important for dentists to understand how their actions may be interpreted by those who feel sensitive about their status. Dentists need to feel genuinely confident about Standard Precautions and have a realistic view of the infection risk posed by patients with blood-borne viruses.     

Effect of porcelain crown substructures on visually perceivable value.

Factors that will affect the potential color of ceramic restorations must be understood to control variables that exist. Clinical observations of porcelain restorations lead to the hypothesis that certain substructures tend to produce crowns with a lower than expected Value (brightness). This study was done to determine whether a visually perceivable difference could be detected between groups of ceramic crowns with different substructures. Two test groups of crown types with four different porcelain substructures were compared. In the first group, metal ceramic crowns made with either Galaxy or Rexillium III alloys were compared. In the second group, aluminous porcelain jacket crowns with and without a tin-plated, bonded platinum foil internally were compared. Visual analysis showed that (1) in the metal ceramic group, the crowns with the Rexillium III substructure were scored as more often having a lower significant Value, and (2) in the aluminous porcelain jacket group the crowns with the tin-plated, bonded platinum substructures were scored as more often having a lower significant Value.     

Effect of different metal ceramic alloys on the color of opaque and dentin porcelain

Certain metal ceramic alloys alter the final color of bonded porcelain. Contradicting results, inconsistent test designs, and incomplete alloy selections have led to some confusion. In this study, differential colorimetric analysis was done at the opaque and dentin porcelain stages with five major types of metal ceramic alloys. The color stability of the porcelain on the high-noble metal alloys was found to be excellent. The palladium-silver and nickel-chromium alloys resulted in significant color changes of the dentin porcelain only. The greatest changes in color were found with the palladium-silver alloy, which resulted in a higher yellow-green saturation. The nickel-chromium alloy also produced a color change, although not as severe, resulting in a porcelain shade with a reduced Value or lightness.     

Comprehensive molecular screening strategy of OCLN in band‐like calcification with simplified gyration and polymicrogyria

Occludin (OCLN) is an important component of the tight junction complex, providing apical intercellular connections between adjacent cells in endothelial and epithelial tissue. In 2010 O'Driscoll et al reported mutations in OCLN to cause band‐like calcification with simplified gyration and polymicrogyria (BLC‐PMG). BLC‐PMG is a rare autosomal recessive syndrome, characterized by early onset seizures, progressive microcephaly, severe developmental delay and deep cortical gray matter and basal ganglia calcification with symmetrical, predominantly fronto‐parietal, polymicrogyria. Here we report 4 additional cases of BLC‐PMG with novel OCLN mutations, and provide a summary of the published mutational spectrum. More generally, we describe a comprehensive molecular screening strategy taking into account the technical challenges associated with the genetic architecture of OCLN, which include the presence of a pseudo‐gene and copy number variants.     

Is there a need for orthodontic plaque indices?—diagnostic accuracy of four plaque indices

Objectives

The aim of this study was to assess the diagnostic performance and accuracy of four plaque indices for orthodontic patients.

Materials and methods

The plaque accumulation of 140 maxillary incisors with bonded brackets was recorded using intra-oral photographs and assessed using four different plaque indices: the orthodontic plaque (OP) index, the modified orthodontic plaque (MOP) index, the Quigley and Hein (QHP) index and the modified Navy plaque (MNP) index. The assessment was performed twice within a time interval of 4 weeks by four different examiner groups: orthodontists, dentists, students and orthodontic assistants.

Results

No significant differences were detected for the OP and MOP indices among the examiner groups. A significant difference was found for the QHP and MNP indices. The inter- and intra-examiner reliability of the OP and MOP indices was good. In contrast, the reliability for the QHP and MNP indices was moderate to poor with few exceptions. The discrimination performance of the OP and MOP indices was excellent. The sum of the sensitivity and specificity was generally lower for the QHP and MNP indices compared with the OP and MOP indices.

Conclusion

OP and MOP indices showed good performance. The QHP and MNP indices are not appropriate for orthodontic purposes.

Clinical relevance

Traditional plaque indices reflect the typical pattern of plaque accumulation for patients without multi-bracket appliances. The performance of these indices for orthodontic patients has never been investigated. Orthodontic plaque indices that focus on the surface along the gingival margin and areas around the bracket exhibit higher diagnostic performance and accuracy compared with traditional indices.     

Innocent until proven guilty: mechanisms and roles of Streptococcus–Candida interactions in oral health and disease

Candida albicans and streptococci of the mitis group colonize the oral cavities of the majority of healthy humans. While C. albicans is considered an opportunistic pathogen, streptococci of this group are broadly considered avirulent or even beneficial organisms. However, recent evidence suggests that multi‐species biofilms with these organisms may play detrimental roles in host homeostasis and may promote infection. In this review we summarize the literature on molecular interactions between members of this streptococcal group and C. albicans, with emphasis on their potential role in the pathogenesis of opportunistic oral mucosal infections.