The Microbial Ecology of Dental Caries

Insights into medieval rural lives: A paleo-odontological investigation of two central European communities

OBJECTIVE

Oral status is an important indicator of past lifestyles. Determining the presence and extent of oral pathologies helps reconstruct average oral health, paramasticatory activities and diet of ancient and historical populations.

DESIGN

In this study, the dental remains from the early medieval cemetery of Früebergstrasse in Baar (Canton of Zug, Switzerland) and the high medieval Dalheim cemetery (North Rhine-Westphalia, Germany) were analyzed. Caries, periodontal condition, periapical lesions, antemortem tooth loss, and enamel hypoplasia were assessed in 654 teeth (993 observable loci) from 68 individuals (Baar: n = 36; Dalheim: n = 32).

RESULTS

The oral status of both populations was affected by age with higher values of tooth wear in advanced age individuals. High tooth wear values in both populations point towards the consumption of abrasive foods. Pronounced anterior tooth wear in Baar may also be due to non-masticatory tooth usage. Finally, possible nutritional deficiencies were hypothesized for the Baar population. A higher caries prevalence was observed in the Baar group, probably due to differences in carbohydrate intake. The oral conditions observed in the two studied populations exhibited several analogies, suggesting comparable lifestyles despite their separation in space and time. The only differences observed are related to the use of teeth as "tools" and are thus determined by behavioral choices rather than diverse socioeconomic factors.

CONCLUSIONS

Using multiple dental parameters to examine the oral health of premodern individuals can provide useful insights into the interactions between humans and their environment, from dietary patterns to paramasticatory activities.

ASSESSMENT OF DMFT INDEXES, SALIVARY FLOW RATE, PH, AND DETECTIONS OF S.MUTANS SALIVARY LEVELS BY A QUANTITATIVE REAL-TIME PCR IN POLYCYSTIC OVARY SYNDROME

Objectives: PCOS is an endocrine disorder that is common in women. However, PCOS effects on oral and dental health have not been stated clearly. The aim of this study is to examine the effects of Polycystic Ovary Syndrome (PCOS), which is common in women of reproductive age, on saliva and dental tissues in these women. Materials and Methods: One-hundred individuals who were / were not diagnosed with PCOS and insulin resistance were included in this study (n=100). Subsequently, individuals, with PCOS and insulin resistance (PCOSID +), with PCOS and non-insulin resistance (PCOSID-), without PCOS and insulin resistance (ControlID +) and without PCOS and non-insulin resistance (ControlID-) were divided into 4 groups (n=25). DMFT (Decayed, Missing, Filled Teeth) index was used for dental health evaluation, while pH meter was used for saliva pH measurement. Also, Streptococcus Mutans (S. Mutans) numbers were analyzed by the real-time Polymerase Chain Reaction (PCR) method. In statistical analysis p

Taste Perception in School Children: Is There an Association with Dental Caries?

Background/Aim: Individuals make food choices based on a number of physiological, nutritional, environmental and socioeconomic factors but sensory qualities of food namely the taste has priority as the determinant in food selection. The purpose of the study is to evaluate sweet, salty, sour and bitter taste perceptions of school children and compare them in term of caries experience.

Material and Methods: Two hundred children aged from 6-13 were included in the study. The dental examinations of children were performed using DMF(T), DMF(S), df(t) and df(s) indices. Questionnaires were presented to parents to record the socioeconomic and educational levels, oral health knowledge, child’s general health, oral health habits and fluoride exposure. Children rinsed sucrose (12g/L; 24g/L), sodium chloride (2g/L; 4g/L), citric acid (0,6g/L; 1,20g/L) and caffeine (0,27g/L; 0,54g/L) solutions randomly and the taste perception was recorded. Relationship between the taste perception and caries experience were evaluated.

Results: A significant correlation was found between 2 g/L of NaCl and age (p= 0,007, r= 0,178). When occlusal or approximal caries of the children aged from 6 to 9 were discriminated, the Spearman’s test found a weak positive correlation between occlusal caries and higher sweet taste (24 g/L sucrose) (r= 0,232; p= 0,021) and a weak negative correlation between approximal caries and higher salty taste (4 g/L NaCl) (r= –0,225; p= 0,025).

Conclusions: Age should be considered in the assessment of taste perception of children. Additionally, there is a weak relationship between taste perceptions and dental caries. These data suggest that further studies need to focus on the effect of taste preferences on dental caries.

Streptococcus salivarius MS-oral-D6 promotes gingival re-epithelialization in vitro through a secreted serine protease

Gingival re-epithelialization represents an essential phase of oral wound healing in which epithelial integrity is re-establish. We developed an automated high-throughput re-epithelialization kinetic model, using the gingival epithelial cell line Ca9–22. The model was employed to screen 39 lactic acid bacteria, predominantly including oral isolates, for their capacity to accelerate gingival re-epithelialization. This screen identified several strains of Streptococcus salivarius that stimulated re-epithelialization. Further analysis revealed that S. salivarius strain MS-oral-D6 significantly promoted re-epithelialization through a secreted proteinaceous compound and subsequent experiments identified a secreted serine protease as the most likely candidate to be involved in re-epithelialization stimulation. The identification of bacteria or their products that stimulate gingival wound repair may inspire novel strategies for the maintenance of oral health.

Salivary Distinctiveness and Modifications in Males with Diabetes and Behçet's Disease

Oral diseases associated with systematic diseases as metabolic and vasculitic have been included in this paper. This will enhance our understanding of the salivary function in promoting healthy oral condition. The study investigates the effects of type I and type II diabetes mellitus in well-controlled diabetic patients, in addition to Behçet disease (BD) on saliva flow rate (SFR), pH, the decay, missing, and filled tooth (DMFT) index, glucose, and major earth-alkaline ions (Ca2+ and Mg2+) compared to healthy males and age-matched controls. Saliva samples were collected from 1403 male human subjects, distributed on 7 levels including 3 control groups, and analyzed. The symptoms and clinical observations were enrolled. A preprandial salivary glucose has illustrated statistically strong significant and positive correlations with HbA1c and blood glucose levels. TIDM saliva showed lower pH, SFR, and Ca2+ but higher Mg2+, caries risk, and poor metabolic control. These led to dysfunction of secretory capacity of salivary glands. TIIDM proved higher SFR, DMFT, and glucose than TIDM patients. DM oral calcium has decreased by age while magnesium sharply slopes at seniority. BD oral fluid is associated with lower glucose and minerals but noticeably with both higher pH and DMFT.

The Oral Microbiota in Health and Disease: An Overview of Molecular Findings

Culture-independent nucleic acid technologies have been extensively applied to the analysis of oral bacterial communities associated with healthy and diseased conditions. These methods have confirmed and substantially expanded the findings from culture studies to reveal the oral microbial inhabitants and candidate pathogens associated with the major oral diseases. Over 1000 bacterial distinct species-level taxa have been identified in the oral cavity and studies using next-generation DNA sequencing approaches indicate that the breadth of bacterial diversity may be even much larger. Nucleic acid technologies have also been helpful in profiling bacterial communities and identifying disease-related patterns. This chapter provides an overview of the diversity and taxonomy of oral bacteria associated with health and disease.

Biosurfactants: promising bioactive molecules for oral-related health applications

Biosurfactants are naturally produced molecules that demonstrate potentially useful properties such as the ability to reduce surface tensions between different phases. Besides having similar properties to their artificial chemical counterparts, they are regarded as environmental friendly, biodegradable and less toxic, which make them desirable candidates for downstream applications. The structure-activity-related properties of the biosurfactants which are directly correlated with potency of the biosurfactants as antimicrobial agents, the ability of the biosurfactants to alter surface energies and their ability to increase bioavailability are particularly what attract researchers to exploit their potential use in the oral-related health applications. Current research into biosurfactant indicates significant future potential for use in cosmetic and therapeutic oral hygiene product formulations and related medical device treatments.

Antibacterial surface properties of various fluoride-releasing restorative materials in vitro

PURPOSE

The aim of this study was to investigate the antibacterial surface properties of high-viscosity glass ionomers (Fuji IX GP, Ketac Molar), a resin-modified nano-ionomer (Ketac N100), resin-modified glass ionomers (Fuji II LC, Vitremer), a compomer (Compoglass F) and a resin-based composite (Filtek Z250).

METHODS

ISO-standardized specimens 6 mm in diameter were prepared for each restorative material. The antibacterial properties of the materials were tested in an agar diffusion assay using Streptococcus mutans (ATCC 25175) for 24 and 48 hours. An inhibition zone greater than 6 mm was defined as diffuse inhibition, whereas zones ≤6 mm were described as contact inhibition.

RESULTS

All tested materials exhibited a contact antibacterial effect against S. mutans. Vitremer showed the most remarkable antibacterial diffuse inhibition.

CONCLUSIONS

These materials might cause antibacterial effects against S. mutans when placed on cavity surfaces in both enamel and dentine, thereby preventing secondary caries formation.

As-yet-uncultivated oral bacteria: breadth and association with oral and extra-oral diseases

It has been shown that 40–60% of the bacteria found in different healthy and diseased oral sites still remain to be grown in vitro, phenotypically characterized, and formally named as species. The possibility exists that these as-yet-uncultivated bacteria play important ecological roles in oral bacterial communities and may participate in the pathogenesis of several oral infectious diseases. There is also a potential for these as-yet-uncultivated oral bacteria to take part in extra-oral infections. For a comprehensive characterization of physiological and pathogenic properties as well as antimicrobial susceptibility of individual bacterial species, strains need to be grown in pure culture. Advances in culturing techniques have allowed the cultivation of several oral bacterial taxa only previously known by a 16S rRNA gene sequence signature, and novel species have been proposed. There is a growing need for developing improved methods to cultivate and characterize the as-yet-uncultivated portion of the oral microbiome so as to unravel its role in health and disease.

The oral microbiota: general overview, taxonomy, and nucleic acid techniques

Application of nucleic acid technology to the analysis of the bacterial diversity in the oral cavity in conditions of health and disease has not only confirmed the findings from early culture studies but also significantly expanded the list of oral inhabitants and candidate pathogens associated with the major oral diseases. Over 800 bacterial distinct species-level taxa have been detected in the oral cavity and recent studies using high-throughput technology suggest that the breadth of bacterial diversity can be much larger. This chapter provides an overview of the diversity and taxonomy of oral bacteria. Emphasis is also given on nucleic acid technologies that have been widely used for the study of the oral microbiota.

In vitro growth and acid production by mutans streptococci on traditional African foods

The growth rate and production of acids by mutans streptococci (MS) are influenced by their ability to ferment different dietary carbohydrates. This suggests that the nutrient environment in the oral cavity affects bacterial virulence. The aim of this study was to investigate the effect of maize, samp and brown bread on the growth and acidogenicity of this species. Six laboratory references and five clinical strains isolated from the dental plaque of South African black and 'colored' (historical race classification) children were studied in batch culture on maize, samp (coarsely ground maize), brown bread and compared against a 3% sucrose control. The doubling time of bacterial strains was prolonged in maize (1.9-17.5 h) and samp (2.4-18.4 h), and the number of cell divisions was low. Staple foods accounted for 25% (F=5.98; P=0.0007) and MS strains 30.78% (F=2.84; P=0.009) of the total variance. The fermentation of samp and maize showed the least drop in pH of the culture medium, ranging between 0.54 and 1.06 and 0.69 and 2.28 pH units respectively, with variation between strains most significant in maize (F=33.62; P<0.0001). The total mean concentration of acids produced was highest in bread (25.13 mM/mL) and samp (17.00 mM/mL) which was comparable to Brain Heart Infusion broth (16.49 mM/mL) and a basal synthetic medium (17.96 mM/mL) containing 3% sucrose, but the yield of lactate, acetate and formate was low during the fermentation of samp (0.50 mM/mL), BHI+3% sucrose (4.12 mM/mL) and brown bread (0.06 mM/mL) respectively. Results indicated that maize and samp do not optimally support the growth or acid production by MS, and the varying response of test strains demonstrates the strain variability of this species to different carbohydrate sources in the diet.

The effect of traditional African food mixtures on growth, pH and extracellular polysaccharide production by mutans streptococci in vitro

Four, traditional African food mixtures (maize plus milk and sugar, maize plus gravy, samp plus beans, brown bread plus margarine and peanut butter) were evaluated for their ability to sustain the growth of mutans streptococci in batch culture. A synthetic complex medium, brain heart infusion with 3% sucrose was used as an experimental control. Six NCTC laboratory reference strains and five clinical isolates collected from the plaque of children were investigated. The doubling time of bacterial strains was prolonged in maize plus gravy (2.5-6.0 h) and samp plus beans (1.3-9.9h), and the number of cell divisions was low, compared with bread plus margarine plus peanut butter (0.7-5.1h). The least amount of acid was produced in maize plus milk plus sugar (3.92+/-8.15 mmole/mL), and the average pH during the fermentation of maize plus milk plus sugar, maize plus gravy and samp plus beans did not drop below the critical point for enamel demineralisation, pH 5.7. Bacterial growth in samp plus beans produced a small quantity of lactic acid (0.46+/-1.10 mmole/mL) compared to bread plus margarine and peanut butter (2.64+/-3.30 mmole/mL) and BHI plus 3% sucrose (12.23+/-10.72 mmole/mL). Extracellular polysaccharide (ECP) produced was lowest in maize plus milk and sugar (0.22+/-0.33 mg/mL), compared with the remaining food mixtures (0.47-1.75 mg/mL). Statistical analysis showed that the influence of the mixed-foods on doubling time (F=3.01, P=0.03), pH (F=14.41, P<0.0001) and ECP (F=135.32, P<0.0001) was greater than the significant variance found between mutans streptococci strains. Results suggest that the level of mutans streptococci activity in samp plus beans, maize plus milk and sugar and maize plus gravy contributes little towards the formation of dental caries, and that significant differences exist between mutans streptococci laboratory reference and clinical strains in response to traditional African food mixtures.

Mutans streptococci and lactobacilli in carious dentine before and after Atraumatic Restorative Treatment

OBJECTIVES

This study was performed to examine the cultivable flora in dentine after manual excavation of caries lesions using the Atraumatic Restorative Treatment (ART) technique and to examine for associations between the microbiological results and cavity size, dentine colour and consistency.

METHODS

Dentine samples from 40 caries lesions were collected before and after treatment and cultured for total viable counts (TVC), mutans streptococci (MS) and lactobacilli.

RESULTS

The bacterial bioburden between the two samples showed a significant reduction in the frequency and proportions of TVC and MS but not lactobacilli.

CONCLUSION

Cavity preparation produced a clinical change in dentine colour and consistency from dark shades and soft dentine at enamel dentine junction to light shades and hard dentine at the cavity floor. The results show that cavity size, dentine colour and consistency are not absolute indicators of the microbiological bioburden in an ART cavity.