Time relevance, citation of reporting guidelines, and breadth of literature search in systematic reviews in orthodontics

INTRODUCTION As the importance of systematic review (SR) conclusions relies upon the scientific rigor of methods and the currency of evidence, we aimed to investigate the currency of orthodontic SRs using as proxy the time from the initial search to publication. Additionally, SR information regarding reporting guidelines, registration, and literature searches were recorded when available. MATERIALS AND METHODS A systematic PubMed search was carried out using the Clinical Queries page to identify orthodontic SRs cited between 1 January 2008 and 7 November 2013. Data related to reporting guidelines, review registration, dates of review processing, literature search, and abstract reporting were retrieved and classified by journal type. Survival analysis was used to assess the time to reach predefined manuscript stages for orthodontic and non-orthodontic journals. RESULTS One hundred twenty seven of the originally identified 585 SRs were considered eligible. The median interval from search until publication was 13.2 months (interquartile range: IQR = 9.7 months) irrespective of the journal type. There was evidence (P = 0.05) that SRs published by non-orthodontic journals appeared in PubMed faster than in orthodontic journals (non-orthodontic: median = 6.5 months; IQR = 5.7 months; orthodontic: median = 10.2 months; IQR = 5.6 months) from submission to publication and from acceptance to publication (non-orthodontic: median = 1.5 months; IQR = 2.4 months; orthodontic: median = 6.0 months; IQR = 6.2 months; P < 0.001). More than half of these SRs did not cite adherence to any reporting guidelines, whereas all but five studies were not prospectively registered. Search of unpublished research was undertaken in approximately 21 per cent and 29 per cent of the SRs published in non-orthodontic and orthodontic periodicals, respectively. CONCLUSIONS This study indicates that SR users should be aware that median time for orthodontic SRs from search to publication is 13.2 months. SRs published in non-orthodontic journals are likely to be more current in terms of submission until time to publication and acceptance until time to publication compared with those published in orthodontic journals.

The outer mucus layer hosts a distinct intestinal microbial niche

The overall composition of the mammalian intestinal microbiota varies between individuals: within each individual there are differences along the length of the intestinal tract related to host nutrition, intestinal motility and secretions. Mucus is a highly regenerative protective lubricant glycoprotein sheet secreted by host intestinal goblet cells; the inner mucus layer is nearly sterile. Here we show that the outer mucus of the large intestine forms a unique microbial niche with distinct communities, including bacteria without specialized mucolytic capability. Bacterial species present in the mucus show differential proliferation and resource utilization compared with the same species in the intestinal lumen, with high recovery of bioavailable iron and consumption of epithelial-derived carbon sources according to their genome-encoded metabolic repertoire. Functional competition for existence in this intimate layer is likely to be a major determinant of microbiota composition and microbial molecular exchange with the host.