This systematic review aims to investigate the role of the oral microbiome in the pathophysiology of mental health disorders and to appraise the methodological quality of research of the oral–brain axis which is a growing interest area. The PRISMA guideline was adopted, to carry out an electronic search through the MEDLINE database, to identify studies that have explored the role of the oral microbiome in the pathophysiology of mental health disorders published from 2000 up to June 2020. The search resulted in 140 records; after exclusions, a total of 22 papers were included in the present review. In accordance with the role of the oral microbiome in the pathophysiology of mental disorders, four mental disorders were identified: Alzheimer’s disease, dementia, and cognitive disorders; autism spectrum disorder; Down’s syndrome and mental retardation; and Bipolar disorders. Studies argue for correlations between oral microbiota and Alzheimer’s disease, autism spectrum disorders, Down’s syndrome, and bipolar disorders. This field is still under-studied, and studies are needed to clarify the biological links and interconnections between the oral microbiota and the pathophysiology of all mental health disorders. Researchers should focus their efforts to develop research on the oral–brain axis in the future.

This review aims to clarify the nature of the link between Alzheimer’s disease and the oral microbiome on an epidemiological and pathophysiological level, as well as to highlight new therapeutic perspectives that contribute to the management of this disease. We performed a systematic review, following the Preferred Reporting Items for Systematic Reviews checklist, from January 2000 to July 2021. The terms “plaque,” “saliva,” and “mouth” were associated with the search term “oral diseases” and used in combination with the Boolean operator “AND”/“OR”. We included experimental or clinical studies and excluded conferences, abstracts, reviews, and editorials. A total of 27 articles were selected. Evidence for the impact of the oral microbiome on the pathophysiological and immunoinflammatory mechanisms of Alzheimer’s disease is accumulating. The impact of the oral microbiome on the development of AD opens the door to complementary therapies such as phototherapy and/or the use of prebiotic compounds and probiotic strains for global or targeted modulation of the oral microbiome in order to have a favourable influence on the evolution of this pathology in the future.

This systematic review aims to identify probiotics and prebiotics for modulating oral bacterial species associated with mental disorders. Using the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guideline, we search the electronic MEDLINE database published till January 2021 to identify the studies on probiotics and/or prebiotics for preventing and treating major oral dysbiosis that provokes mental disorders. The outcome of the search produces 374 records. After excluding non-relevant studies, 38 papers were included in the present review. While many studies suggest the potential effects of the oral microbiota on the biochemical signalling events between the oral microbiota and central nervous system, our review highlights the limited development concerning the use of prebiotics and/or probiotics in modulating oral dysbiosis potentially involved in the development of mental disorders. However, the collected studies confirm prebiotics and/or probiotics interest for a global or targeted modulation of the oral microbiome in preventing or treating mental disorders. These outcomes also offer exciting prospects for improving the oral health of people with mental disorders in the future.

The first aim of this study was to investigate the recreational use of nitrous oxide (N₂O) among health profession students at Montpellier University (France). The second aim was to identify the factors associated with N₂O use. All students in medicine, dentistry, pharmacy and midwifery of the Montpellier University were contacted by email to participate in the survey. The students answered directly online by filling out anonymously a questionnaire including demographic information and questions about N₂O, illicit drugs and alcohol use. Ethical approval was granted by the ethics committee of the Montpellier University. The sample comprised 593 students (mean age = 22.3 ± 2.6 yr), with 68.6% of females. Lifetime N₂O use was reported by 76.6% and frequent alcohol use by 30.5% of the respondents. The lifetime use of cannabis, ‘poppers’, cocaine, ecstasy and LSD was 26.8%, 54.6%, 9.6%, 10.1% and 2.0% respectively. In multivariate analysis, the substances significantly associated with lifetime N₂O were alcohol drinking and ‘poppers’ use. With respect to this self-nominated sample, our results indicate that respondents who were alcohol drinkers, were poppers users, follow longer studies, divert medical products for recreational use or were members of a students’ corporation had higher odds of lifetime N₂O use.

Background: Despite extensive prevention programs, dental hygiene remains inadequate, particularly among children under the age of six, and early childhood caries (ECC) are still a concern. Oral hygiene behavior and preventive practices seem difficult to change at a family level. Aim. The present study aimed to better understand the reasons behind this behavior and to identify the different barriers to the implementation of adequate preventive measures. Methods: A qualitative study was conducted in the pediatric dentistry service of the Montpellier University Hospital (France) in 2019. A thematic analysis concerning three domains was performed: family environment, dental literacy, and oral hygiene. Results. The main barriers encountered by the parents were, respectively, (1) a weakness in the organization of familial life, together with a low-medium family income and a lack of authority, (2) ignorance of the necessity of treating carious primary teeth, and (3) a lack of time for brushing or supervising their children’s teeth. Conclusion: These results showed that oral hygiene and primary teeth care could not be easily achieved in the family environment of the participants, and oral health strategies should be focused not only on children but also on their parents.

In many countries, periodontal surgery is mainly provided by periodontists. This specialty is not recognised in France, where periodontal care and treatment are principally the responsibility of general dentists (GDs). The objective of this study was to investigate the periodontal care provided and factors associated with the treatment of periodontal diseases, including periodontal surgery, by GDs in France. A national cross-sectional survey of GDs practicing in the French metropolitan area was conducted in 2019. A self-administered questionnaire was sent by mail to the GDs selected by stratified simple random sampling. It included questions on respondents’ sociodemographic characteristics and their periodontal practice. A multivariate logistic regression model was employed to identify the factors associated with the practice of periodontal surgery by GDs. Three hundred eighty-five GDs responded (response rate, 23.4%). Their mean age was 45.2 years; 51.2% were male and 83.6% were in private practice. They reported performing selective periodontal examinations such as pocket probing on average for 34.2% of their patients, but only 5.5% of them performed them systematically. Several variables were significantly associated with the provision of periodontal surgical procedures such as the gender of the GDs, full mouth periodontal probing, implantology practice, insufficient fees, or uncertainty about treatment procedure. This survey confirmed the referral of patients for periodontal surgery by a minority of practitioners. It also highlighted insufficient screening and diagnostic procedures for periodontal diseases by GDs. There is a need to improve French GDs’ periodontal skills and knowledge and to address other barriers that currently limit their ability to deliver comprehensive periodontal care.