Background: Oral microbiome transplantation (OMT) is a novel concept of introducing health-associated oral microbiota into the oral cavity of a diseased patient. The premise is to reverse the state of oral dysbiosis, and restore the ecological balance to maintain a stable homeostasis with the host immune system. This study will assess the effectiveness, feasibility, and safety of OMT using an interdisciplinary approach. Methods/Design: To find donors suitable for microbial transplantation, supragingival plaque samples will be collected from 600 healthy participants. Each sample (200μL) will subsequently be examined in two ways: 1) 100μL of the sample will undergo high-throughput 16S rRNA gene amplicon sequencing and shotgun sequencing to identify the composition and characterisation of a healthy supragingival microbiome, 2) the remaining 100μL of the plaque sample will be mixed with 25% artificial saliva medium and inoculated into a specialised in-vitro flow cell model containing a hydroxyapatite disk. To obtain sufficient donor plaque, the samples would be grown for 14 days and further analysed microscopically and sequenced to examine and confirm the growth and survival of the microbiota. Samples with the healthiest microbiota would then be incorporated in a hydrogel delivery vehicle to enable transplantation of the donor oral microbiota. The third step would be to test the effectiveness of OMT in caries and periodontitis animal models for efficacy and safety for the treatment of oral diseases. Discussion: If OMTs are found to be successful, it can form a new treatment method for common oral diseases such as dental caries and periodontitis. OMTs may have the potential to modulate the oral microbiota and shift the ecological imbalances to a healthier state.

The aim of this systematic review and meta-analysis was to document the disparity in dental caries experiences among indigenous and nonindigenous populations globally by measuring dental caries prevalence and severity. An electronic database (MEDLINE) was initially searched using relevant keywords. This was followed by use of the search string in the following electronic databases: Scopus, EBSCOhost, Cochrane, and Open Grey. Two independent reviewers conducted the study search and screening, quality assessment, and data extraction, which was facilitated using JBI SUMARI software. The primary outcome was the decayed missing filled teeth (DMFT) score and dental caries prevalence. Subgroup analysis was done by country of publication to identify causes of heterogeneity. Forest plots were used with the standardized mean difference (SMD) and publication bias was assessed using the Egger test with funnel plot construction. For the final review, 43 articles were selected and 34 were meta-analyzed. The pooled mean DMFT for both the permanent dentition (SMD = 0.26; 95% CI 0.13–0.39) and deciduous dentition (SMD = 0.67; 95% CI 0.47–0.87) was higher for the Indigenous population than for the general population. Indigenous populations experienced more decayed teeth (SMD = 0.44; 95% CI 0.25–0.62), a slightly higher number of missing teeth (SMD = 0.11< 95% CI –0.05 to 0.26), and lesser filled teeth (SMD = –0.04; 95% CI –0.20 to 0.13) than their nonindigenous counterparts. The prevalence of dental caries (SMD = 0.27; 95% CI 0.13–0.41) was higher among indigenous people. Globally, indigenous populations have a higher caries prevalence and severity than nonindigenous populations. The factors which have led to such inequities need to be examined.

Racially minoritized children often bear a greater burden of dental caries, but the overall magnitude of racial gaps in oral health and their underlying factors are unknown. A systematic review and meta-analysis were conducted to fill these knowledge gaps. We compared racially minoritized (E) children aged 5–11 years (P) with same-age privileged groups (C) to determine the magnitude and correlates of racial inequities in dental caries (O) in observational studies (S). Using the PICOS selection criteria, a targeted search was performed from inception to December 1, 2021, in nine major electronic databases and an online web search for additional grey literature. The primary outcome measures were caries severity, as assessed by mean decayed, missing, and filled teeth (dmft) among children and untreated dental caries prevalence (d > 0%). The meta-analysis used the random-effects model to calculate standardized mean differences (SMD) and 95% confidence intervals (95% CI). Subgroup analysis, tests for heterogeneity (I2, Galbraith plot), leave-one-out sensitivity analysis, cumulative analysis, and publication bias (Egger’s test and funnel plots) tests were carried out. The New Castle Ottawa scale was used to assess risk of bias. This review was registered with PROSPERO, CRD42021282771. A total of 75 publications were included in the descriptive analysis. The SMD of dmft score was higher by 2.30 (95% CI: 0.45, 4.15), and the prevalence of untreated dental caries was 23% (95% CI: 16, 31) higher among racially minoritized children, compared to privileged groups. Cumulative analysis showed worsening caries outcomes for racially marginalized children over time and larger inequities in dmft among high-income countries. Our study highlights the high caries burden among minoritized children globally by estimating overall trends and comparing against factors including time, country, and world income. The large magnitude of these inequities, combined with empirical evidence on the oral health impacts of racism and other forms of oppression, reinforce that oral health equity can only be achieved with social and political changes at a global level.

Oral microbiome transplantation (OMT) has the potential to serve as a therapeutic approach for managing dental caries; however, it is essential to identify suitable donors. The aim of this study was to analyse the relationship between dietary (i.e., energy, water, carbohydrate and sugar intake), saliva quality (i.e., saliva flow rate and salivary pH), and clinical factors (i.e., past caries experience and fluoride exposure) on the oral microbiome composition of potential OMT donors. For this cross-sectional study, a comprehensive dental examination was conducted for 93 healthy, caries-free adults (aged 18–85 years) without systemic or oral disease. All participants completed questionnaires on food frequency and socio-economic, lifestyle, and behavioural factors. Supragingival plaque samples were collected, and bacterial 16S rRNA genes were amplified, sequenced, and assigned to bacterial taxa. Stimulated saliva samples were collected for salivary flow rate and pH measurements. Constrained partial ordination analysis revealed that dietary factors, such as carbohydrate and sugar intake, had strong directional influences on microbial composition, while salivary factors like flow rate and pH showed opposing effects. Correlation analysis linked high sugar intake and reduced salivary pH to increased Streptococcus abundance. Differential abundance analysis identified significantly higher abundance of Streptococcus species among low water and high carbohydrate and sugar consumers. In mediation analysis, sugar consumption was directly and indirectly linked to reduced salivary pH, with Streptococcus showing a significant negative mediation effect (mean: -0.198; 95% CI: -0.387 to -0.010). High carbohydrate and sugar intake significantly influenced alpha diversity metrics (p < 0.05). Beta diversity permutational multivariate ANOVA revealed that covariates explained 11.45–12.52% of microbial variation (p < 0.05). This study emphasises that OMT donors with diverse oral microbiomes, low sugar and carbohydrate intake, and reduced levels of acidogenic taxa, such as Streptococcus, which significantly mediate salivary pH reduction, may be preferred for caries prevention.

Our systematic review aimed to evaluate the effect of periodontal interventions on the diversity and composition of periodontal microbiota assessed by high throughput sequencing (HTS) metagenomics analysis. An electronic search was conducted from database inception to November 2021. All clinical trials that evaluated the effect of periodontal interventions on the gingival microbiota through HTS were selected. The measures of alpha diversity, richness, Shannon diversity index, and the Chao1 index, were used as the primary outcome, whereas relative abundances of bacterial genera were considered as the secondary outcome. Overall, 24 studies were eligible for the systematic review, of which 13 studies were included in the meta-analysis. Periodontal intervention for the test group decreased Shannon diversity, richness, and Chao1 index (alpha diversity), as observed from baseline to post-treatment. The most common genera that increased after periodontal therapy were Rothia, Actinomyces, Streptococcus, Veillonella, and Hemophilus, whilst Porphyromonas, Tannerella, Fusobacterium, and Treponema decreased after periodontal therapy. Periodontal interventions may decrease the bacterial diversity and richness and alter the composition of oral microbiota in the short term. Periodontal microbiota signatures could potentially be used for the assessment of periodontal disease development, progression, and success of the intervention.