BackgroundAccumulating evidence suggests that tobacco smoking affects the susceptibility to and severity of chronic periodontitis. Epigenetics may explain the role of smoking in the development and progress of periodontal disease. In this study, we performed transcriptomic and methylomic analyses of non-periodontitis and periodontitis-affected gingival tissues according to smoking status.MethodsHuman gingival tissues were obtained from 20 patients, including non-smokers with and without periodontitis (n = 5 per group) and smokers with and without periodontitis (n = 5 per group). Total RNA and genomic DNA were isolated, and their quality was validated according to strict standards. The Illumina NextSeq500 sequencing system was used to generate transcriptome and methylome datasets.ResultsComprehensive analysis, including between-group correlation, differential gene expression, DNA methylation, gene set enrichment, and protein-protein interaction, indicated that smoking may change the transcription and methylation states of extracellular matrix (ECM) organization-related genes, which exacerbated the periodontal condition.ConclusionsOur results suggest that smoking-related changes in DNA methylation patterns and subsequent alterations in the expression of genes coding for ECM components may be causally related to the increased susceptibility to periodontitis in smokers as they could influence ECM organization, which in turn may have an effect on disease characteristics.Electronic supplementary materialThe online version of this article (doi:10.1186/s13148-017-0381-z) contains supplementary material, which is available to authorized users.

Nitrous oxide, the least potent inhalation anesthetic, is widely used for conscious sedation. Recently, it has been reported that the occurrence of anesthetic-induced loss of consciousness decreases the interconnection between brain regions, resulting in brain network changes. However, few studies have investigated these changes in conscious sedation using nitrous oxide. Therefore, the present study aimed to use graph theory to analyze changes in brain networks during nitrous oxide sedation. Participants were 20 healthy volunteers (10 men and 10 women, 20-40 years old) with no history of systemic disease. We acquired electroencephalogram (EEG) recordings of 32 channels during baseline, nitrous oxide inhalation sedation, and recovery. EEG epochs from the baseline and the sedation state (50% nitrous oxide) were extracted and analyzed with the network connection parameters of graph theory. Analysis of 1/f dynamics, revealed a steeper slope while in the sedation state than during the baseline. Network connectivity parameters showed significant differences between the baseline and sedation state, in delta, alpha1, alpha2, and beta2 frequency bands. The most pronounced differences in functional distance during nitrous oxide sedation were observed in the alpha1 and alpha2 frequency bands. Change in 1/f dynamics indicates that changes in brain network systems occur during nitrous oxide administration. Changes in network parameters imply that nitrous oxide interferes with the efficiency of information integration in the frequency bands important for cognitive processes and attention tasks. Alteration of brain network during nitrous oxide administration may be associated to the sedative mechanism of nitrous oxide.Behavior management required for children with severe anxiety and fear can lead to difficulties in obtaining high quality dental care. In adults, pain or anxiety may cause reluctance to receiving dental treatment. In particular, in patients with a history of syncope due to severe stress, dentists should attempt to minimize stress, ensure that patients are comfortable with the treatment, and consider the use of sedation during dental treatment.Nitrous oxide is a sedative, widely used in medicine and dentistry 1 due to its sedative and analgesic effects, fast onset and recovery, and lack of serious side effects. Sedation refers to the intermediate state between consciousness and total loss of consciousness, in which consciousness is suppressed. Nitrous oxide is the least potent inhalation anesthetic, and induces a minimally conscious sedation state allowing patients to respond appropriately to physical stimuli or verbal commands 2 .The brain is a complex network, and recently using the graph theoretical approach, the structural and functional network of the brain has been shown to have similar properties as those of other complex network systems 3 . Graph theory is a mathematical field that attempts to understand and analyze social phenomena, nature, and network structure, by simplifying them to graphs, defined as a...

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