Bacterial diversity in the saliva of patients with different oral hygiene indexes

Effect of implant abutment surface treatments on bacterial biofilm composition and structure

Background

For the long-term success of dental implants, implant abutment surface should promote the attachment of oral epithelial cells and reduce bacterial adhesion. Titanium nitride (TiN) coatings show antimicrobial properties. Nevertheless, there is a lack of clinical trials that assess the biofilm formation on TiN abutments in the context of clinical practice. Thus, the objective of this study was to evaluate the effect of different abutment surfaces (machined, TiN and TiN oxidized) on bacterial biofilm composition and structure.

Materials and methods

Implant abutments were connected to the dental implants. Bacterial communities were sampled at 1 and 60 days later. The relationship between surface, periodontal indices and bacterial community dynamics was assessed using 16S rRNA metagenomics. A total of 17 patients were involved in this study (14 included in final analyses: 15 machined, 16 TiN and 14 TiN oxidized abutments).

Results

No significant differences between surfaces were found considering taxa abundance, most alpha diversity metrics or community structure. Time showed a significant effect on diversity and also on the abundance of several bacterial taxa.

Conclusions

These results indicate that the effect of the three tested abutment surfaces on biofilm structure and composition was negligible, whereas patient and time exert strong influences on bacterial biofilm formation at different scales.

Prevalence of oral Capnocytophaga species and their association with dental plaque accumulation and periodontal inflammation in middle‑aged and older people

Capnocytophaga species are commonly found in human oral microbiome. The aim of the present study was to understand the association of the prevalence of oral Capnocytophaga species with oral hygiene and periodontal inflammation. A total of 136 patients (median age 72 years) who visited the Hiroshima University Hospital (Hiroshima, Japan) between April 2021 and June 2023 were enrolled. Swab samples were obtained from the tongue surface. DNA from Capnocytophaga species (C. ochracea and C. sputigena) was detected by real-time PCR analysis. Dental plaque accumulation was observed to assess the oral hygiene condition of participants. Additionally, clinical periodontal inflammation was assessed with periodontal inflamed surface area (PISA) scores. Clinical confounding factors such as age, sex, lifestyle-related disease, remaining teeth and denture wearing between Capnocytophaga species-positive and -negative groups were adjusted with a propensity score matching method. Mann-Whitney U and χ2 or Fisher's exact test were employed for statistical analysis. The prevalence rate was 67.6% for oral C. ochracea and 83.1% for C. sputigena. C. ochracea-positive participants showed significantly higher plaque control record scores (an indicator of dental plaque accumulation) than C. ochracea-negative participants (P=0.03). Additionally, C. ochracea/C. sputigena dual-positive participants exhibited significantly higher plaque control record and PISA scores than non-dual-positive participants (P=0.01 and P=0.04, respectively). Propensity score matching was conducted in the C. ochracea/C. sputigena dual-positive group and the non-dual-positive group for adjustment of clinical factors, resulting in 51 matched patient pairs. C. ochracea/C. sputigena dual-positive participants had significantly higher plaque control record scores than non-dual-positive participants (P=0.02). The present results suggest that the prevalence of both oral C. ochracea and C. sputigena is associated with poor oral hygiene in middle-aged and older people.

RNA Sequencing Analysis of Saliva exRNA

Next-generation sequencing (NGS) methodologies are rapidly developing. However, RNA Sequencing of saliva is challenging due to low abundance and integrity of extracellular RNA, as well as large amounts of bacterial RNAs that may be encountered in saliva. In addition, the literature about human salivary extracellular RNA is very scarce. Therefore, in our chapter, we present the most appropriate protocols for saliva collection, pre- and post-processing, including bioinformatic analysis of salivary RNA Sequencing data. However, the choice of the proper method for RNA extraction, cDNA library preparation, and computational pipeline can make a significant impact on the final quality of data and their interpretation.

Associations between PM2.5 exposure and infant growth: A mediation analysis of oral microbiota

BACKGROUND

Previous studies have linked growth retardation with ambient fine particulate matter (PM2.5) exposure. However, few studies explored such association from the perspective of microbiota, such as oral microbiota. We aimed to identify the potential role of oral microbiota in the links between PM2.5 exposure and infant growth.

METHODS

Baseline information of 335 recruited mother-child pairs was collected by structured questionnaires. Growth indicators (weight, length) of one-year-old infants were abstracted from medical records when they had physical examination and corresponding z scores were calculated. 16S rRNA gene amplicon sequencing was performed to assess oral microbiota of infants and co-abundance groups (CAGs) were further calculated. We assessed PM2.5 levels by inverse distance weighting (IDW). Generalized linear regression and mediation analysis were performed to determine associations between PM2.5 exposure, oral microbiota and growth indicators.

RESULTS

Per 10 μg m-3 increment of PM2.5 in the period of 10th month-examination was associated with decreased length z score (β = -1.97, 95%CI: -3.83, -0.11). Oral microbiota correlated with weight z score and body mass index (BMI) z score was identified by Spearman correlation analysis. CAG4 was statistically associated with increased weight z score (β = 3.40, 95%CI: 0.29, 6.51) and BMI z score (β = 5.44, 95%CI: 1.00, 9.87). Several bacteria in the level of genus and CAG associated with PM2.5 exposure were additionally identified (P < 0.05). Mediation analysis revealed that PM2.5 in the period of birth-3rd month impacted the z scores of weight and BMI by altering relative abundance of Megasphaera (P < 0.05).

CONCLUSION

PM2.5 exposure from 10th to 12th month after birth could retard infant linear growth. PM2.5 might impact oral microbiota of one-year-old infants. Growth-related bacteria and CAGs were identified. Megasphaera might function as mediator between PM2.5 exposure during birth-3rd month and infant z scores of weight and BMI.

Screening for prevalence and abundance of Capnocytophaga spp by analyzing NGS data: A scoping review

BACKGROUND

Capnocytophaga spp. are commensal bacteria of the oral cavity and constitute a genus of the core microbiome.

OBJECTIVE

This genus is responsible for many local and systemic conditions in both the immunocompetent and immunocompromised patients, but its beneficial or deleterious role in the microbiota has been little explored.

DESIGN

Online databases were used to identify papers published from 1999 to 2019 based on next-generation sequencing (NGS) data to study comparative trials. Work using other identification methods, case reports, reviews, and non-comparative clinical trials was excluded.

RESULTS AND CONCLUSION

We selected 42 papers from among 668 publications. They showed a link between the abundance of Capnocytophaga spp. in the oral microbiota and various local pathologies (higher for gingivitis and halitosis; lower in active smokers, etc.) or systemic diseases (higher for cancer and carcinomas, IgA nephropathy, etc.). After discussing the limits inherent to the NGS techniques, we present several technical and biological hypotheses to explain the diversity of results observed between studies, as well as the links between the higher or lower abundance of Capnocytophaga spp and the appearance of local or systemic conditions and diseases.

High-throughput sequencing identifies salivary microbiota in Chinese caries-free preschool children with primary dentition

OBJECTIVES

The study aimed at identifying salivary microbiota in caries-free Chinese preschool children using high-throughput sequencing.

METHODS

Saliva samples were obtained from 35 caries-free preschool children (18 boys and 17 girls) with primary dentition, and 16S ribosomal DNA (rDNA) V3-V4 hypervariable regions of the microorganisms were analyzed using Illumina MiSeq.

RESULTS

At 97% similarity level, all of these reads were clustered into 334 operational taxonomic units (OTUs). Among these, five phyla (Firmicutes, Proteobacteria, Actinobacteria, Bacteroidetes, and Candidate division TM7) and 13 genera (Streptococcus, Rothia, Granulicatella, Prevotella, Enterobacter, Veillonella, Neisseria, Staphylococcus, Janthinobacterium, Pseudomonas, Brevundimonas, Devosia, and Gemella) were the most dominant, constituting 99.4% and 89.9% of the salivary microbiota, respectively. The core salivary microbiome comprised nine genera (Actinomyces, Capnocytophaga, Gemella, Granulicatella, Lachnoanaerobaculum, Neisseria, Porphyromonas, Rothia,and Streptococcus). Analysis of microbial diversity and community structure revealed a similar pattern between male and female subjects. The difference in microbial community composition between them was mainly attributed to Neisseria (P=0.023). Furthermore, functional prediction revealed that the most abundant genes were related to amino acid transport and metabolism.

CONCLUSIONS

Our results revealed the diversity and composition of salivary microbiota in caries-free preschool children, with little difference between male and female subjects. Identity of the core microbiome, coupled with prediction of gene function, deepens our understanding of oral microbiota in caries-free populations and provides basic information for associating salivary microecology and oral health.

Аnalysis of the exposure of the medical-preventive toothpaste containing bicarbonate and sodium fluoride on the status of oral cavity in inflammatory diseases of fabric of parоdontium in young patients (clinical and laboratory research)

Relevance of the research topic. Evaluation of changes in the index characteristics of oral hygiene, physicochemical parameters of mixed saliva (pH, buffer capacity of saliva, redox potential, osmolality and others) allows to determine the quality of the effect of toothpaste «Рarodontax ultra clean» on the state of the oral cavity. The use of mixed saliva as a biological fluid of the body as an object of study is confrmed by its high information content and availability of diagnostic material. Studies of changes in mixed saliva, whose components affect the composition, accumulation of microbial plaque and the process of its calcifcation are appropriate.

Purpose. То evaluate the clinical effcacy of toothpaste «Рarodontax ultra clean», the complex effect of its components on the tissues of the teeth and of fabric of parоdontium, to determine the possible mechanism of anti-inflammatory action.

Materials and methods. The experiment involved 58 people. The clinical examination included: Green-Vermillion hygiene indices; bleeding, gingivitis, parоdontium indices. Laboratory studies of unstimulated mixed saliva included parameters: qualitative analysis of the secret, a number of physico-chemical parameters; crystallographic characteristics. For an integrated assessment of nonspecific resistance of the oral cavity, the reaction of adsorption of microorganisms by epithelial cells was used.

Results. In the course of use by patients of toothpaste «Рarodontax ultra clean», an improvement in the oral hygiene condition was noted, a decrease in the rate of plaque formation was diagnosed in 100% of cases, which is clinically confrmed by positive dynamics of hygiene indices (p < 0.05). With regular use of toothpaste, the inflammation of the gums decreases: after 7 days the bleeding of the gums decreases twice, after 14 days - 4.5 times. Summary. The use of toothpaste «Рarodontax ultra clean» leads to a qualitative transformation of the structure of mixed saliva in patients: an improvement in microcrystallization, an increase in salivation, an increase in pH values and bringing it into the range of normal values, an increase in buffer capacity and osmolality. Ingredients such as sodium bicarbonate, silicon dioxide and sodium fluoride contribute to the improvement of metabolic processes in the oral cavity and the adsorption properties of the epithelium after exposure to the investigated toothpaste.

Novel approaches for bioinformatic analysis of salivary RNA sequencing data for development

Motivation

Analysis of RNA sequencing (RNA-Seq) data in human saliva is challenging. Lack of standardization and unification of the bioinformatic procedures undermines saliva's diagnostic potential. Thus, it motivated us to perform this study.

Results

We applied principal pipelines for bioinformatic analysis of small RNA-Seq data of saliva of 98 healthy Korean volunteers including either direct or indirect mapping of the reads to the human genome using Bowtie1. Analysis of alignments to exogenous genomes by another pipeline revealed that almost all of the reads map to bacterial genomes. Thus, salivary exRNA has fundamental properties that warrant the design of unique additional steps while performing the bioinformatic analysis. Our pipelines can serve as potential guidelines for processing of RNA-Seq data of human saliva.

Availability and implementation

Processing and analysis results of the experimental data generated by the exceRpt (v4.6.3) small RNA-seq pipeline (github.gersteinlab.org/exceRpt) are available from exRNA atlas (exrna-atlas.org). Alignment to exogenous genomes and their quantification results were used in this paper for the analyses of small RNAs of exogenous origin.

Contact

dtww@ucla.edu.

CLINICAL AND LABORATORY SUBSTANTIATION OF APPLICATION OF TREATMENT-AND-PROPHYLACTIC GEL REDUCING TOOTHPASTE WITH SODIUM FLUORIDE IN YOUNG PATIENTS

Object. The paper analyzes the change in the physical and chemical properties of mixed saliva in patients with the course of use of toothpaste "Sensodyne® Recovery and protection" containing NovaMin and sodium fluoride. The analysis of the survey of organoleptic properties of toothpaste, clinical examination of patients with hyperesthesia and laboratory parameters of mixed saliva in dynamics was carried out. Purpose. Rationale for the use of therapeutic and prophylactic toothpaste "Sensodyne® Recovery and protection" with sodium fluoride for sensitive teeth in young patients. Methodology. A clinical examination of the oral cavity of young patients (50 men, mean age of 22.50±2.59 years), index estimation of a condition of the teeth (CPUs, municipal production unitary enterprise), oral hygiene (J. R. Green, J. R. Vermillion, 1964), the determination of "teeth sensitivity" (method L. Y. Nut–Litovskogo S. B.); the study of mixed saliva (qualitative analysis, salumeria; concentration of fluorine ions and sodium, pH, redox potential, total zhestkost) exchange rate before and after application of toothpaste. Results. A pronounced clinical effect was obtained, which manifests itself in the cleansing qualities (p≤0.05), and in the elimination of hyperesthesia (p≤0.05) in all patients. The increase of pH values (p≤0.05) was revealed. After cleaning in the sample of mixed saliva, the concentration of fluoride ions increases by 22%, the content of sodium ions decreases by 35.4%, the content of calcium and magnesium ions decreases. This contributes to the formation of stable fluorapatite Ca5(PO4)3F in the surface layers of enamel. calcium ions from phosphosilicate calcium-sodium (NovaMin) go directly from the toothpaste "Sensodyne® repair and protect" with the sodium fluoride in the construction of the hydroxyapatite of tooth enamel. Summary. Thus, the analysis of the results of the survey evaluation of the organoleptic properties of toothpaste "Sensodyne® Recovery and protection" containing sodium fluoride, which are estimated to be highly valued, clinical examination of patients with hyperesthesia and laboratory parameters of mixed saliva in dynamics, showed a significant clinical effect: improving the cleaning ability of toothpaste, reducing the sensitivity of teeth in 100% of patients.

Exploring the salivary microbiome of children stratified by the oral hygiene index

Poor oral hygiene often leads to chronic diseases such as periodontitis and dental caries resulting in substantial economic costs and diminished quality of life in not only adults but also in children. In this study, the salivary microbiome was characterized in a group of children stratified by the Simplified Oral Hygiene Index (OHI-S). Illumina MiSeq high-throughput sequencing based on the 16S rRNA was utilized to analyze 90 salivary samples (24 Good, 31 Moderate and 35 Poor oral hygiene) from a cohort of Thai children. A total of 38,521 OTUs (Operational Taxonomic Units) with a 97% similarity were characterized in all of the salivary samples. Twenty taxonomic groups (Seventeen genera, two families and one class; Streptococcus, Veillonella, Gemellaceae, Prevotella, Rothia, Porphyromonas, Granulicatella, Actinomyces, TM-7-3, Leptotrichia, Haemophilus, Selenomonas, Neisseria, Megasphaera, Capnocytophaga, Oribacterium, Abiotrophia, Lachnospiraceae, Peptostreptococcus, and Atopobium) were found in all subjects and constituted 94.5-96.5% of the microbiome. Of these twenty genera, the proportion of Streptococcus decreased while Veillonella increased with poor oral hygiene status (P < 0.05). Furthermore, an unassigned species of Veillonella, Veillonella dispar and Veillonella parvula tended to be elevated in the Poor oral hygiene group. This is the first study demonstrating an important association between increase of Veillonella and poor oral hygiene status in children. However, further studies are required to identify the majority of Veillonella at species level in salivary microbiome of the Poor oral hygiene group.