ABSTRACT
Dental fluorosis is a very prevalent endemic disease. Although oral microbiome has been reported to correlate with different oral diseases, there appears to be an absence of research recognizing any relationship between the severity of dental fluorosis and the oral microbiome. To this end, we investigated the changes in oral microbial community structure and identified bacterial species associated with moderate and severe dental fluorosis. Salivary samples of 42 individuals, assigned into Healthy (N = 9), Mild (N = 14) and Moderate/Severe (M&S, N = 19), were investigated using the V4 region of 16S rRNA gene. The oral microbial community structure based on Bray Curtis and Weighted Unifrac were significantly changed in the M&S group compared with both of Healthy and Mild. As the predominant phyla, Firmicutes and Bacteroidetes showed variation in the relative abundance among groups. The Firmicutes/Bacteroidetes (F/B) ratio was significantly higher in the M&S group. LEfSe analysis was used to identify differentially represented taxa at the species level. Several genera such as Streptococcus mitis, Gemella parahaemolysans, Lactococcus lactis, and Fusobacterium nucleatum, were significantly more abundant in patients with moderate/severe dental fluorosis, while Prevotella melaninogenica and Schaalia odontolytica were enriched in the Healthy group. In conclusion, our study indicates oral microbiome shift in patients with moderate/severe dental fluorosis. We identified several differentially represented bacterial species enriched in moderate and severe fluorosis. Findings from this study suggests that the roles of these bacteria in oral health and related diseases warrant more consideration in patients with moderate and severe fluorosis.
Subject(s)
Fluorosis, Dental/microbiology , Microbiota , Mouth Mucosa/microbiology , Adolescent , DNA, Bacterial/isolation & purification , Female , Fluorosis, Dental/diagnosis , High-Throughput Nucleotide Sequencing , Humans , Male , Oral Health , RNA, Ribosomal, 16S/genetics , Saliva/microbiology , Severity of Illness IndexABSTRACT
OBJECTIVES: The aim of this in vitro study was to evaluate the surface properties of moderately to severely fluorotic enamel and the adhesion of Streptococcus mutans and Streptococcus sanguinis to enamel, exploring the relationship between dental fluorosis and dental caries from a microbiology perspective. METHODS: We examined the basic surface properties of moderately to severely fluorotic enamel by surface microhardness test, scanning electron microscopy (SEM) and atomic force microscopy. Then S. mutans single-species biofilms and S. mutans - S. sanguinis dual-species biofilms were cultured on fluorotic enamel surface. The morphology of biofilms, the volume of bacteria and expolysaccharides (EPS) and the number of bacteria were respectively tested by SEM, confocal laser scanning microscopy and colony-forming units (CFU) counting. RESULTS: Fluorotic enamel displayed lower average microhardness and greater surface roughness than sound enamel, and it also showed structure defects like pores or pits. The biofilm thickness, volume of bacteria and EPS, and CFU counts of bacteria in both single-species and dual-species biofilms on fluorotic enamel were all significantly higher than those on sound enamel. The volume of bacteria and EPS in dual-species biofilms are both less than those of single-species biofilms. CONCLUSIONS: The higher surface roughness and the structure defects of teeth with moderate to severe dental fluorosis contributed to the adhesion of S. mutans and S. sanguinis, and the increased adhesion of S. mutans may increase the susceptibility of dental caries. However, S. sanguinis would play a role as a "designer bacteria" which reduce the cariogenicity of the biofilms on fluorotic enamel surface.
Subject(s)
Bacterial Adhesion , Dental Enamel/microbiology , Fluorosis, Dental/microbiology , Streptococcus mutans/physiology , Streptococcus sanguis/physiology , Biofilms , Dental Caries , Dental Enamel/ultrastructure , Humans , Microscopy, Atomic Force , Microscopy, Confocal , Microscopy, Electron, Scanning , Surface PropertiesABSTRACT
BACKGROUND: High fluorine concentrations in drinking water are associated with a decrease in the amount of salivary S mutants. Taking into account that clinical dental fluorosis can appear with 1.5 ppm of fluorine in the drinking water, fluorine concentrations in Mamiña is 2.4 ppm. AIM: To quantify salivary S mutans in school age children from Mamiña, a zone with a high fluorine content in the drinking water, during one year. MATERIAL AND METHODS: During 1997 and 1998, dental health was assessed and salivary samples were obtained from 51 children (27 male) aged 10 +/- 2 years to quantify S mutans. RESULTS: Most children studied had more than 10(5) salivary S mutans colony forming units. No changes in the rates of infection or dental health characteristics were observed during the observation year. CONCLUSIONS: High fluorine content in the drinking water did not have an effect on salivary S mutans infection in this population.
