Self-rated oral health (SROH) is a valid, comprehensive indicator of oral health status. The purpose of this cross-sectional study was to analyze how oral health behaviors and clinical oral status were associated with SROH and how they had changed over the course of nine years in Japanese university students. Data were obtained from 17,996 students who underwent oral examinations and completed self-questionnaires from 2011 to 2019. Oral status was assessed using the decayed and filled teeth scores, bleeding on probing (BOP), probing pocket depth, the Oral Hygiene Index-Simplified (OHI-S), oral health behaviors, and related factors. SROH improved from 2011 to 2019. The logistic regression model showed that university students who were female and had a high daily frequency of tooth brushing, no BOP, no decayed teeth, no filled teeth, and a low OHI-S score and were significantly more likely to report very good, good, or fair SROH. An interaction effect was observed between survey year and regular dental check-ups (year × regular dental check-ups). The improvement trend in SROH might be associated with changes in oral health behaviors and oral health status.

Oral health behaviors, risk aversion, and the health belief model are associated with health behaviors. However, there have been few studies that investigated the association between these factors and the willingness to undergo regular dental check-ups. The purpose of this cross-sectional study was to investigate the associations between the willingness of Japanese university students to undergo regular dental check-ups and oral health behaviors, the health belief model, and absolute risk aversion. An analysis was conducted with the cooperation of questionnaire respondents (n = 748) who underwent dental check-ups at Okayama University. The students answered questionnaires on oral health behaviors, the health belief model, absolute risk aversion, and willingness to undergo regular dental check-ups. The logistic regression analysis showed significant positive associations (p < 0.05) between oral health behaviors (use of the inter-dental brush and the dental floss) and the health belief model with the willingness to undergo regular dental check-ups. However, there was no significant association with absolute risk aversion (p > 0.05). These results suggest that willingness to undergo regular dental check-ups was associated with oral health behaviors and the health belief model, but not with absolute risk aversion.

Although some studies showed that lifestyle was associated with oral health behavior, few studies investigated the association between household type and oral health behavior. The aim of this prospective cohort study was to investigate the association between household type, oral health behavior, and periodontal status among Japanese university students. Data were obtained from 377 students who received oral examinations and self-questionnaires in 2016 and 2019. We assessed periodontal status using the percentage of bleeding on probing (%BOP), probing pocket depth, oral hygiene status, oral health behaviors, and related factors. We used structural equation modeling to determine the association between household type, oral health behaviors, gingivitis, and periodontitis. At follow-up, 252 students did not live with their families. The mean ± standard deviation of %BOP was 35.5 ± 24.7 at baseline and 32.1 ± 25.3 at follow-up. In the final model, students living with their families were significantly more likely to receive regular dental checkup than those living alone. Regular checkup affected the decrease in calculus. The decrease in calculus affected the decrease in %BOP over 3 years. Living with family was directly associated with regular dental checkups and indirectly contributed to gingival status among Japanese university students.

The long-term effects of secondhand smoke (SHS) on dental caries among Japanese young adults remain unclear. The purpose of this cross-sectional study was to evaluate whether household exposure to SHS is associated with dental caries in permanent dentition among Japanese young adults. The study sample included 1905 first-year university students (age range: 18–19 years) who answered a questionnaire and participated in oral examinations. The degree of household exposure to SHS was categorized into four levels according to the SHS duration: no experience (−), past, current SHS < 10 years, and current SHS ≥ 10 years. Dental caries are expressed as the total number of decayed, missing, and filled teeth (DMFT) score. The relationships between SHS and dental caries were determined by logistic regression analysis. DMFT scores (median (25th percentile, 75th percentile)) were significantly higher in the current SHS ≥ 10 years (median: 1.0 (0.0, 3.0)) than in the SHS—(median: 0.0 (0.0, 2.0)); p = 0.001). DMFT ≥ 1 was significantly associated with SHS ≥ 10 years (adjusted odds ratio: 1.50, 95% confidence interval: 1.20–1.87, p < 0.001). Long-term exposure to SHS (≥10 years) was associated with dental caries in permanent dentition among Japanese young adults.

Background/Objectives: Halitosis is a condition characterized by an unpleasant malodor. Intra-oral halitosis is caused by volatile sulfur compounds (VSCs) and can be associated with oral dryness. Trehalose is one of the materials used to relieve oral dryness. The aim of the present study was to investigate the effect of trehalose on halitosis. Methods: This prospective, double-blinded, placebo-controlled, cross-over study enrolled volunteers from Okayama University Hospital. The participants were randomly divided into two groups, with one group receiving trehalose (a 10% trehalose solution) and the other receiving a placebo (distilled water) in a 1:1 allocation. The primary study outcome was the subjective organoleptic test. The secondary outcomes were the concentrations of the VSCs, which were measured using a portable gas chromatography device, and the oral moisture status, which was measured using an oral moisture meter. The planned sample size was 10 participants based on the previous study. Results: The final intention-to-treat analysis was performed using the data from 9 participants. After applying 10% trehalose as an oral spray, the organoleptic score decreased in a time-dependent manner. However, no significant differences were seen between the trehalose and placebo groups. In terms of secondary outcomes, the oral moisture levels increased immediately after the trehalose spray application, and significant differences in the amount of change from the baseline were seen between the trehalose and placebo groups (p = 0.047). No significant differences were seen in any of the other variables (p > 0.05). Conclusions: We could not identify any positive effects on halitosis from a one-time 10% trehalose application as an oral spray in this prospective, double-blinded, placebo-controlled, cross-over study. However, the trehalose application immediately improved the oral moisture levels and was useful for treating oral dryness.

Objectives: The study aim was to investigate the effects of extracellular vesicles (EVs) derived miR-128-3p on renal inflammation using a rat periodontitis model. Methods: Ten-week-old male Wistar rats were divided into two groups: a control (n = 8) and a lipopolysaccharides (LPS) group (n = 8). The LPS group received LPS (Porphyromonas gingivalis) injection in the gingiva for 7 days. At the end of the experiment, plasma, gingival tissue, and kidney samples were collected. Hematoxylin and eosin staining was performed to evaluate the glomerular tissue injury score. Bioinformatic analysis was conducted to identify potential target genes of miR-128-3p. The reverse transcription-quantitative polymerase chain reaction was performed to evaluate miR-128-3p, inflammatory, pro-inflammatory cytokine, chemokine and predicting gene’s expression. The control and LPS groups were compared using Welch’s t-test. p-values < 0.05 were considered to indicate statistical significance. Results: The kidney glomerular tissue injury score was significantly higher in the LPS than in the control group. miR-128-3p expression in the LPS group was significantly higher in the gingival tissue and plasma. mRNAs (interleukin [IL]-1β, tumor necrosis factor [TNF]-α, C-X3-C motif chemokine ligand 1 [CX3CL1], and C-X-C motif chemokine ligand 7 [CXCL7]) expression was higher in the kidney of the LPS group. The potential target genes of activin A receptor type I (Acvr1), ribosomal protein S6 kinase B1 (Rps6kb1), and transforming growth factor beta receptor type 1 (Tgfbr1) were significantly lower in the kidneys of the LPS group. Conclusions: EVs-derived miR-128-3p in LPS induced periodontitis may cause kidney inflammation which may be mediated by, Rps6kb1, Tgfbr1, and Acvr1.