Towards understanding oral health

Dysbiosis linking periodontal disease and oral squamous cell carcinoma-A brief narrative review

An association between periodontal disease and oral squamous cell carcinoma (OSCC) has been recognized. However, there is no causal relationship between the two. The polymicrobial etiology of periodontal disease is confirmed, and so are the proven etiological factors for OSCC. Inflammation lies at the core of periodontal pathogenesis induced by the putative microbes. OSCC has inflammatory overtures in its pathobiology. Bacterial species involved in periodontal disease have been extensively documented and validated. The microbial profile in OSCC has been explored with no specific conclusions. The scientific reasoning to link a common microbial signature that connects periodontal disease to OSCC has led to many studies but has not provided conclusive evidence. Therefore, it would be beneficial to know the status of any plausible microbiota having a similarity in periodontal disease and OSCC. This brief review attempted to clarify the existence of a dysbiotic "fingerprint" that may link these two diseases. The review examined the literature with a focused objective of identifying periodontal microbial profiles in OSCC that could provide insights into pathogen commonality. The review concluded that there is great diversity in microbial association, but important bacterial species that correlate with periodontal disease and OSCC are forthcoming.

Tissue Regeneration on Rise: Dental Hard Tissue Regeneration and Challenges-A Narrative Review

Background

As people live longer, there is an increasing need for hard tissue regeneration and whole-tooth regeneration. Despite the advancements in the field of medicine, the field of regenerative dentistry is still challenging due to the complexity of dental hard tissues. Cross-disciplinary collaboration among material scientists, cellular biologists, and odontologists aimed at developing strategies and uncovering solutions related to dental tissue regeneration. Methodology. A search of the literature was done for pertinent research. Consistent with the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) 2020 Statement, the electronic databases looked at were PubMed, Science Direct, Scopus, and Google Scholar, with the keyword search "hard dental tissue regeneration."

Results

Database analysis yielded a total of 476 articles. 222 duplicate articles have been removed in total. Articles that have no connection to the directed regeneration of hard dental tissue were disregarded. The review concluded with the inclusion of four studies that were relevant to our research objective.

Conclusion

Current molecular signaling network investigations and novel viewpoints on cellular heterogeneity have made advancements in understanding of the kinetics of dental hard tissue regeneration possible. Here, we outline the fundamentals of stem hard dental tissue maintenance, regeneration, and repair, as well as recent advancements in the field of hard tissue regeneration. These intriguing findings help establish a framework that will eventually enable basic research findings to be utilized towards oral health-improving medicines.

The oral microbial odyssey influencing chronic metabolic disease

INTRODUCTION

Since the oral cavity is the gateway to the gut, oral microbes likely hold the potential to influence metabolic disease by affecting the gut microbiota.

METHOD

A thorough review of literature has been performed to link the alterations in oral microbiota with chronic metabolic disease by influencing the gut microbiota.

RESULT

A strong correlation exists between abnormalities in oral microbiota and several systemic disorders, such as cardiovascular disease, diabetes, and obesity, which likely initially manifest as oral diseases. Ensuring adequate oral hygiene practices and cultivating diverse oral microflora are crucial for the preservation of general well-being. Oral bacteria have the ability to establish and endure in the gastrointestinal tract, leading to the development of prolonged inflammation and activation of the immune system. Oral microbe-associated prophylactic strategies could be beneficial in mitigating metabolic diseases.

CONCLUSION

Oral microbiota can have a profound impact on the gut microbiota and influence the pathogenesis of metabolic diseases.

Impact of Medical and Surgical Obesity Treatment on Dental Caries: A 2-Year Prospective Cohort Study

The objective was to study the long-term effects on oral health of bariatric surgery compared with medical treatment of obesity. Swedish females with morbid obesity (n = 66; 18-35 years at baseline) were followed prospectively from before obesity treatment until 2 years after treatment. The main response variable was dental caries registered according to the ICDAS-II system. Possible confounding factors, such as sociodemographic characteristics, general health, oral health habits, and oral hygiene, were controlled for. The statistical methods included χ2 tests, Student's t tests, one-way ANOVA, Wilcoxon's nonparametric tests, and linear regression models. In the surgically treated patients (n = 40), a significant increase over time in enamel caries (mean increase 4.13 tooth surfaces ICDAS1-2), dentine caries (mean increase 2.18 tooth surfaces ICDAS3-6), and total caries (mean increase 6.30 tooth surfaces ICDAS1-6) was registered (all p < 0.001), which was not seen in the medically treated patients (n = 26). However, the difference between the treatment groups (surgical or medical) was only statistically significant for enamel caries (crude β 4.89, p = 0.003) and total caries (crude β 6.53, p < 0.001). The relationships were stable and independent of differences in confounders as socioeconomy, general health, and oral health behaviors. In conclusion, 2 years after obesity treatment, a significant increase in dental caries was registered in the surgically treated but not in the medically treated women. The dental service should intensify its preventive efforts in individuals undergoing obesity treatment.

Repeatability of dental plaque quantitation by light induced fluorescence technology in current, former, and never smokers

BACKGROUND

The effects of smoking on the accumulation of dental plaque have not been studied in depth. We compared dental plaque quantitation obtained with a novel light induced fluorescence technology among current, former, and never smokers and verified measurements' repeatability.

METHODS

Dental plaque quantitation was objectively assessed by quantitative light induced fluorescence (QLF) technology on three separate study visits in current, former, and never smokers: baseline (day 0), day 7, day 30. Increase in the fluorescence intensity of at least 30% (ΔR30) and 120% (ΔR120) together with the simple oral hygiene (SOH) scoring were considered for analysis.

RESULTS

The QLF parameters were highly repeatable in each study group (p < 0.0001, by regression analyses). All QLF parameters showed a significant difference between never smokers and current smokers (p = 0.041 for ΔR30; p = 0.027 for ΔR120; p = 0.04 for SOH). No significant differences were observed between never and former smokers and between current and former smokers except for ΔR120 (p = 0.033).

CONCLUSION

Dental plaque measurements by QLF technology were highly reproducible and showed greater plaque formation among current smokers compared to non-smokers. Objective and reproducible quantitation of dental plaque can be a valuable clinical and regulatory science endpoint to investigate the effect of smoking cessation medications, combustion-free tobacco products, and consumer care products on oral health.

CLINICAL RELEVANCE

There is a need to objectively evaluate the relationship between smoking and plaque build-up as well as maturation. Current smokers demonstrated greater and more mature plaque buildup when compared to never and former smokers. Differences in plaque build-up and maturation between current, former and non-smokers may be utilized as an effective tool for patient motivation, identifying therapeutic end-points, translational research as well as prognostication.

TRIAL REGISTRATION

The study is a pilot study parts of a larger project with registration ID: NCT04649645. As preliminary study, the pilot study referred into this paper started before the larger study registered in ClinicalTrials.gov.

Is oral microbiota associated with overweight and obesity in children and adolescents? A systematic review

This article aims to verify the relationship between the composition and diversity of oral microbiota with overweight and obese children and adolescents. This systematic review was registered in PROSPERO, followed PRISMA 2020, and included an electronic search until March 2022, in PubMed/MEDLINE, Web of Science, Scopus, and The Cochrane Library databases. Studies were eligible if they compared the oral microbiota according to nutrition status among children and adolescents. Independent peers using JBI Critical Appraisal Checklists assessed the quality of studies. Eleven studies were eligible to be included in this review, with a total of 1,695 children and adolescents, 224 were obese, 190 were overweight, 1,154 were eutrophics and 127 were underweight. The most frequent phyla in overweight and obese children and adolescents, in comparison to their counterparts were Firmicutes, Bacteroidetes, Proteobacteria, Actinobacteria and Fusobacteria. It was identified that nine of the eleven articles selected showed an association between oral microbiota and overweight and obesity in children and adolescents. We observed that there is an important association between oral bacterial composition diversity and overweight and obesity. This finding indicates the relevance of the evaluation and surveillance in oral health to control cases of overweight and obesity in children and adolescents.

Incorporation of Nanomaterials in Glass Ionomer Cements-Recent Developments and Future Perspectives: A Narrative Review

Glass ionomer cements (GICs), restorative materials with commercial availability spanning over five decades, are widely applied due to their advantages (including bio-compatibility, fluoride release, or excellent bonding properties). However, GICs have shortcomings. Among the disadvantages limiting the application of GICs, the poor mechanical properties are the most significant. In order to enhance the mechanical or antimicrobial properties of these materials, the addition of nanomaterials represents a viable approach. The present paper aims to review the literature on the application of different types of nanomaterials for the enhancement of GICs' mechanical and antimicrobial properties, which could lead to several clinical benefits, including better physical properties and the prevention of tooth decay. After applying the described methodology, representative articles published in the time period 2011-present were selected and included in the final review, covering the modification of GICs with metallic nanoparticles (Cu, Ag), metallic and metalloid oxide nanoparticles (TiO₂, ZnO, MgO, Al₂O₃, ZrO₂, SiO₂), apatitic nanomaterials, and other nanomaterials or multi-component nanocomposites.

Temporal development of the infant oral microbiome

The human oral microbiome is becoming recognized as playing roles in health and disease well beyond the oral cavity over the lifetime of the individual. The oral microbiome is hypothesized to result from specific colonization events followed by a reproducible and ordered development of complex bacterial communities. Colonization events, proliferation, succession and subsequent community development are dependent on a range of host and environmental factors, most notably the neonate diet. It is now becoming apparent that early childhood and prenatal influences can have long term effects on the development of human oral microbiomes. In this review, the temporal development of the infant human oral microbiome is examined, with the effects of prenatal and postnatal influences and the roles of specific bacteria. Dietary and environmental factors, especially breastfeeding, have a significant influence on the development of the infant oral microbiome. The evidence available regarding the roles and functions of early colonizing bacteria is still limited, and gaps in knowledge where further research is needed to elucidate these specific roles in relation to health and disease still exist.

Antimicrobial Effect of Isotretinoin Therapy on Periodontal Pathogens: A Case-Control Study

Isotretinoin (INN), a drug used to treat severe acne, has anti-inflammatory and antibacterial properties. INN may affect periodontal pathogenic bacteria, so we aimed to study the effect of INN on intraoral microbial profiles of periodontal disease and healthy periodontium. Our case-control study divided 180 subjects into six groups according to periodontal health status and INN usage as follows: healthy periodontium receiving INN (HINN; n = 30); those with generalized plaque-induced gingivitis receiving INN (GINN; n = 30); and those with stage I generalized periodontitis receiving INN (PINN; n = 30). Subjects not taking INN, were categorized in the same manner: those with a healthy periodontium (HC; n = 30); those with generalized plaque-induced gingivitis (GC; n = 30); and those with generalized periodontitis stage I (PC; n = 30). Plaque samples were collected to determine the prevalence of four periodontal pathogens (Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola, and Fusobacterium nucleatum) in each study group using real-time polymerase chain reaction. Data were analyzed using IBM SPSS software, and multiple regression analysis was performed for each parameter tested in each group at a significance level of 0.05. All INN groups showed significantly lower levels of P. gingivalis, T. forsythia, and T. denticola and higher levels of F. nucleatum (p < 0.001). INN had an observable antimicrobial effect on the periodontal pathogen count in patients with plaque-induced gingivitis and chronic periodontitis. INN may have a potential additive antimicrobial value in the treatment of periodontal disease.

Bacteraemia of oral origin in children-A Systematic review and network meta-analysis

OBJECTIVES

To systematically review the prevalence of bacteraemia, triggered by dental intervention and home oral hygiene practices, in children. The network meta-analysis (NMA) quantitatively compared the risk of bacteraemia triggered by dental extractions and home and professional cleaning procedures.

MATERIALS AND METHODS

Clinical trials with the outcome "bacteraemia in children" were searched. The NMA was performed using the frequentist weighted least-squares approach comparing the odds ratios (OR) of different interventions.

RESULTS

Among 11 of 13 studies, dental treatment was performed under general anaesthesia. In 2,381 patients, bacteraemia occurred in 38.7%-56% patients following single-tooth extractions, in 22%-46% after manual toothbrushing (MTB), and in 26%-78% after power toothbrushing (PTB). When MTB was set as the reference (OR 1), rubber cup polishing showed a slightly higher risk (OR 1.26) of bacteraemia. PTB presented a higher risk (OR 1.79-2.27) than with single-tooth extractions (OR 1.55) but lower than that with multiple extractions (OR 2.55).

CONCLUSION

Daily use of MTB and routine professional cleaning were associated with the lowest risk of developing bacteraemia in children with gingivitis, almost as much as with a single-tooth extractions. Improved plaque control with PTB increased the risk of bacteraemia. There is limited evidence on gingivitis-free and systemically-diseased children.

Molecular Interactions between Saliva and Dental Composites Resins: A Way Forward

Dentin and enamel loss related to trauma or especially caries is one of the most common pathological issues in dentistry that requires restoration of the teeth by using materials with appropriate properties. The composite resins represent dental materials with significant importance in today’s dentistry, presenting important qualities, including their mechanical behavior and excellent aesthetics. This paper focuses on the saliva interactions with these materials and on their biocompatibility, which is continuously improved in the new generations of resin-based composites. Starting from the elements involved on the molecular landscape of the dental caries process, the paper presents certain strategies for obtaining more advanced new dental composite resins, as follows: suppression of oral biofilm acids formation, promotion of remineralization process, counteraction of the proteolytic attack, and avoidance of cytotoxic effects; the relation between dental composite resins and salivary oxidative stress biomarkers is also presented in this context.

Immunomodulatory streptococci that inhibit CXCL8 secretion and NFκB activation are common members of the oral microbiota

Introduction

Oral tissues are generally homeostatic despite exposure to many potential inflammatory agents including the resident microbiota. This requires the balancing of inflammation by regulatory mechanisms and/or anti-inflammatory commensal bacteria. Thus, the levels of anti-inflammatory commensal bacteria in resident populations may be critical in maintaining this homeostatic balance.

Hypothesis/Gap Statement

The incidence of immunosuppressive streptococci in the oral cavity is not well established. Determining the proportion of these organisms and the mechanisms involved may help to understand host-microbe homeostasis and inform development of probiotics or prebiotics in the maintenance of oral health.

Aim

To determine the incidence and potential modes of action of immunosuppressive capacity in resident oral streptococci.

Methodology

Supragingival plaque was collected from five healthy participants and supragingival and subgingival plaque from five with gingivitis. Twenty streptococci from each sample were co-cultured with epithelial cells±flagellin or LL-37. CXCL8 secretion was detected by ELISA, induction of cytotoxicity in human epithelial cells by lactate dehydrogenase release and NFκB-activation using a reporter cell line. Bacterial identification was achieved through partial 16S rRNA gene sequencing and next-generation sequencing.

Results

CXCL8 secretion was inhibited by 94/300 isolates. Immunosuppressive isolates were detected in supragingival plaque from healthy (4/5) and gingivitis (4/5) samples, and in 2/5 subgingival (gingivitis) plaque samples. Most were Streptococcus mitis/oralis. Seventeen representative immunosuppressive isolates all inhibited NFκB activation. The immunosuppressive mechanism was strain specific, often mediated by ultra-violet light-labile factors, whilst bacterial viability was essential in certain species.

Conclusion

Many streptococci isolated from plaque suppressed epithelial cell CXCL8 secretion, via inhibition of NFκB. This phenomenon may play an important role in oral host-microbe homeostasis.

Effect of Cariogenic Challenge on the Degradation of Adhesive-Dentin Interfaces

The aim was to evaluate, in vitro, the influence of pH cycling on microtensile bond strength (µTBS) and percentage of nanoleakage (%NL) in the dentin-adhesive interface. Flat dentin surfaces were obtained in 56 extracted third molars. The teeth were randomly divided into four groups (n=14): G1- Single Bond Universal (etch-and-rinse mode); G2- Single Bond Universal (self-etch mode); G3- Scotchbond Multi-Purpose; G4- Clearfil SE Bond. A block of composite was built on the adhesive area. Eight tooth/resin sets were cut parallel to the tooth's long axis to obtain 48 beams (0.8 mm2) for each group. Half of the beams were submitted to four cycles of pH cycling (demineralizing solution for 6 h and remineralizing solution for 18 h). The samples were submitted to µTBS test in a universal testing machine. Six tooth/resin sets were cut parallel to the tooth's long axis to obtain three slices of the central region (1.0 mm thickness). Half of the slices were submitted to pH cycling. The nanoleakage methodology was applied to obtain the %NL at the adhesive interfaces. According to two-way ANOVA, the interaction between factors (adhesive system x storage) was significant (p=0.0001) for µTBS and %NL. After pH cycling, there was a significant decrease in µTBS and a significant increase in %NL for all adhesives. The adhesives applied in the self-etch mode obtained lower %NL, differing significantly from the etch-and-rinse adhesives. It was concluded that the pH cycling negatively influenced the µTBS and %NL for all adhesives evaluated. However, self-etch adhesives allowed less %NL.

Disparities in Access to Oral Health Care

In the United States, people are more likely to have poor oral health if they are low-income, uninsured, and/or members of racial/ethnic minority, immigrant, or rural populations who have suboptimal access to quality oral health care. As a result, poor oral health serves as the national symbol of social inequality. There is increasing recognition among those in public health that oral diseases such as dental caries and periodontal disease and general health conditions such as obesity and diabetes are closely linked by sharing common risk factors, including excess sugar consumption and tobacco use, as well as underlying infection and inflammatory pathways. Hence, efforts to integrate oral health and primary health care, incorporate interventions at multiple levels to improve access to and quality of services, and create health care teams that provide patient-centered care in both safety net clinics and community settings may narrow the gaps in access to oral health care across the life course.

Shifts in the bacterial community of saliva give insights on the relationship between obesity and oral microbiota in adolescents

The current study aimed at the determination of the impact of obesity on the salivary microbiome in adolescents. Sixty subjects ranging 14-17 years old were enrolled (obese: n = 30-50% females, and normal weight: n = 30-50% females). Stimulated saliva was collected for denaturing gradient gel electrophoresis (DGGE) band patterns and massive 16S rRNA gene sequencing using the Ion Torrent platform. Overall, data analysis revealed that male subjects harbored a higher diverse salivary microbiome, defined by a significant higher richness (32.48 versus 26.74) and diversity (3.36 versus 3.20), higher Simpson values (0.96 versus 0.95) and distinct bacterial community structure considering either sex or condition (p < 0.05). Bacterial community fingerprinting analysis in human saliva showed a positive correlation with increased body mass index (BMI) in adolescents. Veillonella, Haemophilus and Prevotella occurrence was found to be affected by BMI, whereas Neisseria and Rothia occurrence was significantly impacted by sex in obese subjects. Our findings suggest that male and female adolescents may harbor a naturally distinct salivary microbiota and that obesity may specifically have an impact on their oral bacterial community. The potential dysbiotic oral microbiome in obese adolescents raises new insights on the etiology and prevention of future conditions in these populations.

Getting ahead of the oral health game: it starts before we're born?

Dental caries is one of the most common chronic diseases affecting individuals of all ages. Caries in the primary dentition is one of the main risk factors for caries in the permanent dentition. Preventing the development of the first carious lesion is fundamental not only to long term health and wellbeing but to reducing the burden of this disease on individuals, families and the community. Described as the developmental origins of health and disease, events from the prenatal period are increasingly recognised as having a significant impact on later health outcomes. While social and behavioural factors from this period have long been linked with oral health, emerging evidence of the influence of epigenetics and early life programming of microbiome and host response suggests that the prenatal period provides a timely opportunity for preventive interventions. Pregnancy is an ideal time to focus on health promoting activities as most women have regular interaction with health care professionals who can target risk factors before the onset of disease. This paper summarizes contemporary understanding of the role of pre- and perinatal factors on child oral health and describes how this evidence might be used by all health professionals to ensure infants start life ahead in the oral health game.

Salivary total Immunoglobulin G as a surrogate marker of oral immune activity in salivary bioscience research

The integration of salivary biomeasures in biobehavioral, psychophysiological, and clinical research has greatly expanded our ability to study the biopsychosocial processes underlying health. Much of this research, however, has failed to adequately assess and adjust for the impact of oral immune activity on salivary biomeasure concentrations and associations with serum levels. Aiming to improve the validity and reliability of salivary biomeasure data, we examine salivary total Immunoglobulin G (IgG) as a potential surrogate marker of oral inflammation and immune activity. During a single study visit in Baltimore, Maryland, healthy young adult participants provided matched blood and saliva samples (N=99; age 18-37 years, 42% female) and completed an oral health questionnaire. Biospecimens were assayed for total IgG and immune markers related to inflammation (cytokines), blood in saliva (transferrin), and tissue remodeling (matrix metalloproteinase-8). Total IgG (μg/mL) concentrations were higher in serum than saliva. Salivary total IgG was associated with some self-reported oral health measures, and strongly positively associated with all salivary immune markers. Controlling for salivary total IgG may be a feasible, affordable approach to adjusting salivary biomeasure findings for the influence of the oral immune environment when it is not possible or practical to obtain clinical oral health data.

Bacterial salivary microbiome associates with asthma among african american children and young adults

Several studies have shown that the airways of asthma patients contain higher diversity of bacteria and are enriched in pathogenic species. However, sampling the airways in children is challenging. Here we aimed to identify differences in the salivary bacterial composition between African Americans children with and without asthma. Saliva samples from 57 asthma cases and 57 healthy controls were analyzed by means of 16S ribosomal RNA amplicon profiling. Measurements of bacterial diversity and genus relative abundance were compared between cases and controls using the nonparametric Wilcoxon test and multivariate regression models. A total of five phyla and a mean of 56 genera were identified. Among them, 15 genera had a relative abundance greater than 1%, being Prevotella, Haemophilus, Streptococcus, and Veillonella the most abundant genera. Differences between cases and controls were found in terms of diversity, as well as in relative abundance for Streptococcus genus (13.0% in cases vs 18.3% in controls; P = .003) and Veillonella genus (11.1% in cases vs 8.0% in controls; P = .002). These differences remained significant after correction for multiple comparisons and when potential confounders were taken into account in logistic regression models. In conclusion, we identified changes in the salivary microbiota associated with asthma among African Americans.

Periodontal health

OBJECTIVES

To date there is a paucity of documentation regarding definitions of periodontal health. This review considers the histological and clinical determinants of periodontal health for both intact and reduced periodontium and seeks to propose appropriate definitions according to treatment outcomes.

IMPORTANCE

Defining periodontal health is can serve as a vital common reference point for assessing disease and determining meaningful treatment outcomes.

FINDINGS

The multifactorial nature of periodontitis is accepted, and it is recognized that restoration of periodontal health will be defined by an individual's response to treatment, taking into account allostatic conditions.

CONCLUSIONS

It is proposed that there are 4 levels of periodontal health, depending on the state of the periodontium (structurally and clinically sound or reduced) and the relative treatment outcomes: (1) pristine periodontal health, with a structurally sound and uninflamed periodontium; (2) well-maintained clinical periodontal health, with a structurally and clinically sound (intact) periodontium; (3) periodontal disease stability, with a reduced periodontium, and (4) periodontal disease remission/control, with a reduced periodontium.

Apical Periodontitis Is Associated with Elevated Concentrations of Inflammatory Mediators in Peripheral Blood: A Systematic Review and Meta-analysis

INTRODUCTION

Apical periodontitis (AP), except for the local known consequences, may also be a systemic burden. Circulating inflammatory mediators that are released to sustain the AP lesion can in theory harm other bodily tissues. The aim of this systematic review was to summarize the existing evidence on the influence of AP on the peripheral blood levels of inflammatory mediators and markers of systemic stress.

METHODS

A search of MEDLINE-PubMed, Embase, and Cochrane was conducted up to and including February 2019 to identify studies in 5 different languages. The Newcastle-Ottawa Scale was used for quality assessment of the included studies.

RESULTS

Twelve of the 20 included studies were case-control studies, and 8 were intervention studies. The data of all the included studies were analyzed descriptively, whereas the data of 11 studies were available for meta-analyses. The study designs were heterogeneous. Nevertheless, the meta-analyses revealed statistically significant differences in C-reactive protein, interleukin 6, and asymmetric dimethylarginine levels between AP subjects and controls in peripheral blood. In addition, the concentration of C3 complement fragment in peripheral blood was significantly lower after the treatment and resolution of AP than before.

CONCLUSIONS

The existing literature indicates that AP adds on to systemic inflammation by elevating C-reactive protein, interleukin 6, asymmetric dimethylarginine, and C3 levels. In order to overcome the issue of large variation between study designs, future studies should have clear inclusion criteria, preferably larger cohorts, adequate follow-up of all subjects, and a thorough presentation of the data to enable further exploration of the possible burden of AP on general human health. Nevertheless, there is now stronger evidence that AP contributes to low-grade systemic inflammation.

Bacterial biofilm composition in healthy subjects with and without caries experience

Objective:The composition of the oral microbiome differs distinctively between subjects with and without active caries. Still, caries research has mainly been focused on states of disease; aspects about how biofilm composition and structure maintain oral health still remain widely unclear. Therefore, the aim of the study was to compare the healthy oral microbiome of caries-free adult subjects with and without former caries experience using next generation sequencing methods. Methods: 46 samples were collected from subjects without any signs of untreated active caries. Samples of pooled supragingival plaque from 19 subjects without caries experience (NH; DMFT = 0) and 27 subjects with 'caries experience' ( CE; DMFT > 0 [F(T)> 0; D(T)= 0]) were analyzed by 16S ribosomal RNA amplicon sequencing. Results: Subjects with caries experience did not exhibit a dramatically modified supragingival plaque microbiome. However, we observed a slight and significant modification between the two groups, validated by PERMANOVA ( NH vs. CE: R2 0.04; p= 0.039). The composition of the microbiome of subjects with caries experience indicates a tendency to lower α-diversity and richness. Subjects without caries experience showed a significant higher evenness compared to patients with previous caries. LDA effect size (LEfSe) analysis demonstrated that the genus Haemophilus is significantly more frequent in patients with caries experience. For the group without caries experience LefSe analysis showed a set of 11 genera being significantly more frequent, including Corynebacterium, Fusobacterium, Capnocytophaga, Porphyromonas, Prevotella,and Leptotrichia. Conclusion: The analysis of the oral microbiome of subjects with and without caries experience indicates specific differences. With the presence of Corynebacterium and Fusobacterium subjects without caries experience exhibited more frequently organisms that are considered to be main actors in structural plaque formation and integration. The abundance of Corynebacterium might be interpreted as a signature for dental health.

Gender-Specific Associations Between Saliva Microbiota and Body Size

OBJECTIVE

The human intestinal microbiota likely play an important role in the development of overweight and obesity. However, the associations between saliva microbiota and body mass index (BMI) have been sparsely studied. The aim of this study was to identify the associations between saliva microbiota and body size in Finnish children.

METHODS

The saliva microbiota of 900 Finnish children, aged 11-14 years with measured height and weight, was characterized using 16S rRNA (V3-V4) sequencing.

RESULTS

The core saliva microbiota consisted of 14 genera that were present in more than 95% of the Finnish children. The saliva microbiota profiles were gender-specific with higher alpha-diversity in boys than girls and significant differences between the genders in community composition and abundances. Alpha-diversity differed between normal weight and overweight girls and between normal weight and obese boys. The composition was dissimilar between normal weight and obese girls, but not in boys. The relative abundance profiles differed according to body size. Decrease in commensal saliva bacteria were observed in all the body sizes when compared to normal weight children. Notably, the relative abundance of bacteria related to, Veillonella, Prevotella, Selenomonas, and Streptococcus was reduced in obese children.

CONCLUSION

Saliva microbiota diversity and composition were significantly associated with body size and gender in Finnish children. Body size-specific saliva microbiota profiles open new avenues for studying the potential roles of microbiota in weight development and management.

Advanced smart biomaterials and constructs for hard tissue engineering and regeneration

Hard tissue repair and regeneration cost hundreds of billions of dollars annually worldwide, and the need has substantially increased as the population has aged. Hard tissues include bone and tooth structures that contain calcium phosphate minerals. Smart biomaterial-based tissue engineering and regenerative medicine methods have the exciting potential to meet this urgent need. Smart biomaterials and constructs refer to biomaterials and constructs that possess instructive/inductive or triggering/stimulating effects on cells and tissues by engineering the material's responsiveness to internal or external stimuli or have intelligently tailored properties and functions that can promote tissue repair and regeneration. The smart material-based approaches include smart scaffolds and stem cell constructs for bone tissue engineering; smart drug delivery systems to enhance bone regeneration; smart dental resins that respond to pH to protect tooth structures; smart pH-sensitive dental materials to selectively inhibit acid-producing bacteria; smart polymers to modulate biofilm species away from a pathogenic composition and shift towards a healthy composition; and smart materials to suppress biofilms and avoid drug resistance. These smart biomaterials can not only deliver and guide stem cells to improve tissue regeneration and deliver drugs and bioactive agents with spatially and temporarily controlled releases but can also modulate/suppress biofilms and combat infections in wound sites. The new generation of smart biomaterials provides exciting potential and is a promising opportunity to substantially enhance hard tissue engineering and regenerative medicine efficacy.

Live and let die: Hydrogen peroxide production by the commensal flora and its role in maintaining a symbiotic microbiome

The majority of commensal oral streptococci are able to generate hydrogen peroxide (H₂ O₂ ) during aerobic growth, which can diffuse through the cell membrane and inhibit competing species in close proximity. Competing H₂ O₂ production is mainly dependent upon the pyruvate oxidase SpxB, and to a lesser extent the lactate oxidase LctO, both of which are important for energy generation in aerobic environments. Several studies point to a broad impact of H₂ O₂ production in the oral environment, including a potential role in biofilm homeostasis, signaling, and interspecies interactions. Here, we summarize the current research regarding oral streptococcal H₂ O₂ generation, resistance mechanisms, and the ecological impact of H₂ O₂ production. We also discuss the potential therapeutic utility of H₂ O₂ for the prevention/treatment of dysbiotic diseases as well as its potential role as a biomarker of oral health.

The oral microbiome - an update for oral healthcare professionals

For millions of years, our resident microbes have coevolved and coexisted with us in a mostly harmonious symbiotic relationship. We are not distinct entities from our microbiome, but together we form a 'superorganism' or holobiont, with the microbiome playing a significant role in our physiology and health. The mouth houses the second most diverse microbial community in the body, harbouring over 700 species of bacteria that colonise the hard surfaces of teeth and the soft tissues of the oral mucosa. Through recent advances in technology, we have started to unravel the complexities of the oral microbiome and gained new insights into its role during both health and disease. Perturbations of the oral microbiome through modern-day lifestyles can have detrimental consequences for our general and oral health. In dysbiosis, the finely-tuned equilibrium of the oral ecosystem is disrupted, allowing disease-promoting bacteria to manifest and cause conditions such as caries, gingivitis and periodontitis. For practitioners and patients alike, promoting a balanced microbiome is therefore important to effectively maintain or restore oral health. This article aims to give an update on our current knowledge of the oral microbiome in health and disease and to discuss implications for modern-day oral healthcare.

Dysbiosis as a determinant factor of systemic and oral pathology: importance of microbiome

Advances in genetic and epigenetic studies modified some concepts of health and disease that had been kept intact for decades. In this respect, in the last few years, microorganisms that have evolved with superior life forms for millions of years have taken an increased prominence. The genes of organisms and their microbiota constitute a microbiome that intervenes in health maintenance. The oral cavity is inhabited by a variety of microorganisms, their control aids in stabilising oral and systemic disease. The objective of this article is to update some concepts related to oral microbiome and its correlation with general and oral health.

Developing a New Generation of Antimicrobial and Bioactive Dental Resins

Dental caries is prevalent, and secondary caries causes restoration failures. This article reviews recent studies on developing a new generation of bioactive resins with anticaries properties. Extensive effects were made to develop new antimicrobial composites, bonding agents, and other resins containing quaternary ammonium methacrylates to suppress plaque buildup and bacterial acid production. The effects of alkyl chain length and charge density and the antimicrobial mechanisms for chlorhexidine, nano-silver, quaternary ammonium methacrylates, and protein-repellent agents were discussed. Synergistic effects of contact-killing and protein-repellent properties were shown to yield the greatest biofilm-inhibition effects. The combination of antimicrobial, protein-repellent, and calcium phosphate nanoparticle remineralization was suggested to provide maximal anticaries effects. In addition, for use orally, cytotoxicity and biocompatibility were important considerations for the new bioactive materials. Furthermore, rather than kill all bacteria, it would be more desirable to modulate the oral biofilm compositions via bioactive resins to suppress cariogenic/pathogenic species and promote benign species. For widespread clinical use of the new antimicrobial and therapeutic materials, whether they would induce bacterial drug resistance needs to be determined, which requires further study. Nonetheless, the new generation of bioactive anticaries resins with therapeutic and biofilm acid-inhibiting properties has the potential to substantially benefit oral health.

What are We Learning and What Can We Learn from the Human Oral Microbiome Project?

Extraordinary technological advances have greatly accelerated our ability to identify bacteria, at the species level, present in clinical samples taken from the human mouth. In addition, technologies are evolving such that the oral samples can be analyzed for their protein and metabolic products. As a result, pictures are the advent of personalized dental medicine is becoming closer to reality.