Background: This follow‐up study evaluated microbiome changes in periodontal recall patients after consuming a nitrate‐rich diet that led to a marked decrease of gingival inflammation.Methods: Subgingival microbial samples of 37 patients suffering from gingival inflammation with reduced periodontium were taken before professional mechanical plaque removal (baseline) and subsequently after 2 weeks of regularly consuming a lettuce juice beverage (day 14) containing a daily dosage of 200 mg of nitrate (test group, n = 18) or being void of nitrate (placebo group, n = 19). Three hundred base pairs paired‐end sequencing of the V3‒V4 hypervariable region of the 16S rDNA was performed.Results: At baseline, there were no significant differences about the bacterial diversity parameters between the groups (Mann‐Whitney U test). After intervention in the test group, Rothia and Neisseria, including species reducing nitrate, increased significantly (negative binomial regression model). Alpha diversity decreased significantly from 115.69 ± 24.30 to 96.42 ± 24.82 aRSVs/sample (P = 0.04, Wilcoxon signed‐rank test), accompanied by a significant change in beta diversity (P < 0.001, PERMANOVA). In the control group, however, no genus changed significantly, and alpha‐, as well as beta‐diversity did not change significantly.Conclusions: The decrease of gingival inflammation in periodontal recall patients induced by a nitrate‐rich diet is accompanied by significant compositional changes within the subgingival microbiome.

Background: The objective of this trial was to evaluate whether the regular consumption of probiotics may improve the known deterioration of periodontal health in navy sailors during deployments at sea.Methods: 72 healthy sailors of a naval ship on a practicing mission at sea were recruited and randomly provided with a blinded supply of lozenges to be consumed twice daily for the following 42 days containing either the probiotic strains Lactobacillus reuteri (DSM 17938 and L. reuteri (ATTC PTA 5289) (test n = 36) or no probiotics (placebo n = 36). At baseline, at day 14 and day 42 bleeding on probing (primary outcome), gingival index, plaque control record, probing attachment level, and probing pocket depth were assessed at the Ramfjord teeth.Results: At baseline there were no significant differences between the groups. At day 14 and day 42 test group scores of all assessed parameters were significantly improved (P < 0.001) compared to baseline and to the placebo group which by contrast showed a significant (P < 0.001) deterioration of all parameters at the end of the study.Conclusions: The consumption of probiotic L. reuteri‐lozenges is an efficacious measure to improve and maintain periodontal health in situations with waning efficacy of personal oral hygiene.

Aim: To assess the prevalence and severity of periodontitis in patients with moderate chronic kidney disease (CKD) and comparing the results with the self‐reported periodontitis awareness of the study subjects.Material and methods: The periodontal status of 270 patients with moderate CKD randomly selected from a cohort of 5,217 subjects participating in the prospective observational German Chronic Kidney Disease (GCKD) project was analysed by recording bleeding on probing (BOP), probing pocket depth (PPD) and clinical attachment level (CAL). Furthermore, the awareness of the study subjects of their periodontal conditions was evaluated by a self‐reported questionnaire.Results: 24.4% of the CKD study patients showed no or only mild signs of periodontal disease, 47.6% displayed moderate and 27% severe periodontitis. Questionnaire data revealed that 62.3% of the study subjects with severe periodontitis were not aware of the presence of the disease, 44.4% denied having received any systematic periodontal therapy so far, although 50% of them indicated to visit their dentist regularly for professional tooth cleanings.Conclusion: While the clinical study data confirm an increased prevalence of periodontitis in CKD patients, their self‐reported awareness of periodontitis was low.

The oral mucosa has an important role in maintaining barrier integrity at the gateway to the gastrointestinal and respiratory tracts. Smoking is a strong environmental risk factor for the common oral inflammatory disease periodontitis and oral cancer. Cigarette smoke affects gene methylation and expression in various tissues. This is the first epigenome-wide association study (EWAS) that aimed to identify biologically active methylation marks of the oral masticatory mucosa that are associated with smoking. Ex vivo biopsies of 18 current smokers and 21 never smokers were analysed with the Infinium Methylation EPICBeadChip and combined with whole transcriptome RNA sequencing (RNA-Seq; 16 mio reads per sample) of the same samples. We analysed the associations of CpG methylation values with cigarette smoking and smoke pack year (SPY) levels in an analysis of covariance (ANCOVA). Nine CpGs were significantly associated with smoking status, with three CpGs mapping to the genetic region of CYP1B1 (cytochrome P450 family 1 subfamily B member 1; best p = 5.5 × 10−8) and two mapping to AHRR (aryl-hydrocarbon receptor repressor; best p = 5.9 × 10−9). In the SPY analysis, 61 CpG sites at 52 loci showed significant associations of the quantity of smoking with changes in methylation values. Here, the most significant association located to the gene CYP1B1, with p = 4.0 × 10−10. RNA-Seq data showed significantly increased expression of CYP1B1 in smokers compared to non-smokers (p = 2.2 × 10−14), together with 13 significantly upregulated transcripts. Six transcripts were significantly downregulated. No differential expression was observed for AHRR. In vitro studies with gingival fibroblasts showed that cigarette smoke extract directly upregulated the expression of CYP1B1. This study validated the established role of CYP1B1 and AHRR in xenobiotic metabolism of tobacco smoke and highlights the importance of epigenetic regulation for these genes. For the first time, we give evidence of this role for the oral masticatory mucosa.

Aims: Various studies have reported that young European women are more likely to develop early‐onset periodontitis compared to men. A potential explanation for the observed variations in sex and age of disease onset is the natural genetic variation within the autosomal genomes. We hypothesized that genotype‐by‐sex (G × S) interactions contribute to the increased prevalence and severity.Materials and methods: Using the case‐only design, we tested for differences in genetic effects between men and women in 896 North‐West European early‐onset cases, using imputed genotypes from the OmniExpress genotyping array. Population‐representative 6823 controls were used to verify that the interacting variables G and S were uncorrelated in the general population.Results: In total, 20 loci indicated G × S associations (P < 0.0005), 3 of which were previously suggested as risk genes for periodontitis (ABLIM2, CDH13, and NELL1). We also found independent G × S interactions of the related gene paralogs MACROD1/FLRT1 (chr11) and MACROD2/FLRT3 (chr20). G × S‐associated SNPs at CPEB4, CDH13, MACROD1, and MECOM were genome‐wide‐associated with heel bone mineral density (CPEB4, MECOM), waist‐to‐hip ratio (CPEB4, MACROD1), and blood pressure (CPEB4, CDH13).Conclusions: Our results indicate that natural genetic variation affects the different heritability of periodontitis among sexes and suggest genes that contribute to inter‐sex phenotypic variation in early‐onset periodontitis.