Caries-free Adults Research Articles

AMELX and ENAM Polymorphisms and Dental Caries.

The variety of the genetic factors playing role in development of dental caries calls for further research in this regard. The aim of the present study was to investigate the differences between caries-free adults and adults with dental caries in terms of polymorphism of caries-related genes (AMELX and ENAM). The present case-control study was performed on 81 adults aged 18-24 years, 41 caries free, and 40 with a DMFT ≥ 4. A questionnaire containing background and demographic information (such as age, gender, time and type of latest dental check-ups, parent's education, oral self-care, and the place of residence in the first 12 years of life) was completed by participants at the time of examination. The blood sample was taken from each participant in the EDTA tube, and PCR was performed. Gene diversity of AMELX and ENAM genes was compared between the two groups. Regarding AMELX gene, in the caries-free group 33 (80.5%) and in the group with DMFT ≥ 4, 33 (82.5%) students had TT genotype, but this difference was insignificant. For ENAM gene, in the caries-free group 34 (82.9%) and in the group with DMFT ≥ 4, 39 (97.5%) students had TT genotype, but this difference was insignificant (P value = 0.048, CI 95%:0.02-1.27, and OR = 0.145). There was no relationship between TT and TC genotypes of single nucleotide polymorphism of AMELX and ENAM gene and susceptibility to dental caries, but with increasing sample size, there may be a relationship between SNP of ENAM gene and being caries free.

Functional changes in the oral microbiome after use of fluoride and arginine containing dentifrices: a metagenomic and metatranscriptomic study

BackgroundTooth decay is one of the most prevalent diseases worldwide, and efficient tooth brushing with a fluoride-containing dentifrice is considered fundamental to caries prevention. Fluoride-containing dentifrices have been extensively studied in relation to enamel resistance to demineralization. Arginine (Arg) has also been proposed as a promising prebiotic to promote pH buffering through ammonia production. Here, we present the first metagenomic (DNA sequencing of the whole microbial community) and metatranscriptomic (RNAseq of the same community) analyses of human dental plaque to evaluate the effect of brushing with fluoride (Fl) and a Fl+Arg containing dentifrices on oral microbial composition and activity. Fifty-three patients were enrolled in a longitudinal clinical intervention study with two arms, including 26 caries-active and 27 caries-free adults. After a minimum 1-week washout period, dental plaque samples were collected at this post-washout baseline, 3 months after the use of a 1450-ppm fluoride dentifrice, and after 6 months of using a 1450-ppm fluoride with 1.5% arginine dentifrice.ResultsThere was a shift in both the composition and activity of the plaque microbiome after 3 months of brushing with the fluoride-containing toothpaste compared to the samples collected at the 1-week post-washout period, both for caries-active and caries-free sites. Although several caries-associated bacteria were reduced, there was also an increase in several health- and periodontitis-associated bacteria. Over 400 genes changed proportion in the metagenome, and between 180 and 300 genes changed their expression level depending on whether caries-free or caries-active sites were analyzed. The metagenome and metatranscriptome also changed after the subjects brushed with the Fl+Arg dentifrice. There was a further decrease of both caries- and periodontitis-associated organisms. In both caries-free and caries-active sites, a decrease of genes from the arginine biosynthesis pathway was also observed, in addition to an increase in the expression of genes associated with the arginine deiminase pathway, which catabolizes arginine into ammonia, thereby buffering acidic pH. Bacterial richness and diversity were not affected by either of the two treatments in the two arms of the study.ConclusionsOur data demonstrate that long-term use of both assayed dentifrices changes the bacterial composition and functional profiles of human dental plaque towards a healthier microbial community, both in caries-free and caries-active sites. This observation was especially apparent for the Fl+Arg dentifrice. Thus, we conclude that the preventive benefits of tooth brushing go beyond the physical removal of dental plaque and that the active ingredients formulated within dentifrices have a positive effect not only on enamel chemistry but also on the metabolism of oral microbial populations.-kQdKShqK4FxgvJNrxZQaCVideo

Oral Health Status among Adult Employees in Kuwait.

To determine the oral health status among adult employees in Kuwait. This cross-sectional study was performed on a convenience sample (n = 1294) of adult employees. Their ages ranged from 19 to 77 years (mean 36.2). Six trained and calibrated dentists examined them using a mouth mirror and a WHO ball-tip probe. Caries was scored using WHO diagnostic criteria. The debris index simplified (DI-S) score was used to assess oral hygiene status. Overall, the mean DMFT in the adults was 10.3. The DMFT increased from 7.8 for the age group 19-24 years to 10.7 at 35-44 years and 18.9 at 65-77 years (p < 0.001). Females had slightly higher caries experience (DMFT) (11.0) than did males (10.1) (p = 0.021), and Kuwaitis (11.1) more than non-Kuwaitis (8.9) (p < 0.001). The proportion of caries-free adults was 28%. In multivariate analysis, adults with poor oral hygiene (OR=1.5; 95% CI=1.2-2.1), those with an intermediate-school (grades 6 to 9) or lower level of education (OR=2.6; 95% CI=1.4-4.7), Kuwaitis (OR=1.3; 95% CI=1.0-1.7), those with oral pain (OR=1.4; 95% CI=1.0-1.8), and those needing urgent dental care (OR=4.6; 95% CI=2.6-8.0) were statistically significantly associated with caries risk. About 19.6% of these adults had good, 36.1% fair and 44.4% had poor oral hygiene. Nearly one-third (32.9%) of adults had perceived oral pain at the time of examination. Implementing oral health programs is needed and efforts should be made to promote oral hygiene practices in workplaces among adults in Kuwait.

Quantification of carious pathogens in the interdental microbiota of young caries-free adults.

BackgroundThe majority of caries lesions in adults occur on the proximal tooth surfaces of the posterior teeth. A comprehensive study of the composition of the oral microbiota is fundamental for a better understanding of the etiology of interdental caries.MethodsTwenty-five caries-free subjects (20–35 years old) were enrolled in the study. The interdental biofilm of four interdental sites were collected. The real-time polymerase chain reaction (PCR) methodology were used to quantify (i) the following bacteria: Streptococcus spp., Streptococcus mutans, Lactobacillus spp., Enterococcus spp., and Enterococcus faecalis; (ii) the fungus Candida albicans; and (iii) total bacteria.ResultsStreptococcus spp. was the most abundant species, followed by Lactobacillus spp. and Enterococcus spp. Streptococcus spp. and Lactobacillus spp. were detected at all tested sites and Enterococcus spp. at 99% of sites. S. mutans was detected at only 28% of the tested sites and C. albicans was detected at 11% of sites. E. faecalis was never detected. In 54.5% of the biofilm inhabited by C. albicans, S. mutans was present. Moreover, 28% of the ID sites co-expressed S. mutans and Lactobacillus spp. The studied pathogens were organized into two correlated groups of species. Strikingly, the fungus C. albicans and the bacteria Enterococcus spp. cluster together, whereas Streptococcus spp., S. mutans and Lactobacillus spp. form one distinct cluster.ConclusionThe interdental biofilm of young caries-free adults is comprised of pathogens that are able to induce interproximal caries. That several of these pathogens are implicated in heart disease or other systemic diseases is an argument for the disruption of interdental biofilms using daily oral hygiene.

Effect of the Biofilm Age and Starvation on Acid Tolerance of Biofilm Formed by Streptococcus mutans Isolated from Caries-Active and Caries-Free Adults.

Streptococcus mutans (S. mutans) is considered a leading cause of dental caries. The capability of S. mutans to tolerate low pH is essential for its cariogenicity. Aciduricity of S. mutans is linked to its adaptation to environmental stress in oral cavity. This study aimed to investigate the effect of biofilm age and starvation condition on acid tolerance of biofilm formed by S. mutans clinical isolates. S. mutans clinical strains isolated from caries-active (SM593) and caries-free (SM18) adults and a reference strain (ATCC25175) were used for biofilm formation. (1) Both young and mature biofilms were formed and then exposed to pH 3.0 for 30 min with (acid-adapted group) or without (non-adapted group) pre-exposure to pH 5.5 for three hours. (2) The mature biofilms were cultured with phosphate-buffered saline (PBS) (starved group) or TPY (polypeptone-yeast extract) medium (non-starved group) at pH 7.0 for 24 h and then immersed in medium of pH 3.0 for 30 min. Biofilms were analyzed through viability staining and confocal laser scanning microscopy. In all three strains, mature, acid-adapted and starved biofilms showed significantly less destructive structure and more viable bacteria after acid shock than young, non-adapted and non-starved biofilms, respectively (all p < 0.05). Furthermore, in each condition, SM593 biofilm was denser, with a significantly larger number of viable bacteria than that of SM18 and ATCC25175 (all p < 0.05). Findings demonstrated that mature, acid-adapted and starvation might protect biofilms of all three S. mutans strains against acid shock. Additionally, SM593 exhibited greater aciduricity compared to SM18 and ATCC25175, which indicated that the colonization of high cariogenicity of clinical strains may lead to high caries risk in individuals.

The clinical performance of chairside caries risk assessment kits.

Caries risk assessment is an important component of clinical practice. The goal of this project was to evaluate the diagnostic performance of two commercially available kits (the Saliva-Check mutans and the Plaque-Check pH kit; GC-America) in distinguishing caries-active from caries-free individuals. The effect of following instructions not to eat, drink, or perform oral hygiene, prior to testing, was also investigated on the effectiveness of these kits. The subjects included 26 caries-affected children and 20 caries-free adults. Plaque and saliva samples were collected for analysis by the two kits following the manufacturer's instructions. For 63 additional subjects, instructions not to eat, drink, or practice oral hygiene were omitted prior to sample collection. The sensitivity and specificity in distinguishing caries-free from caries-active subjects was calculated for both kits. The sensitivity (88%) and specificity (90%) of the Saliva-Check mutans kits were satisfactory in the subjects refraining from eating etc. In contrast, both the sensitivity and the specificity of this kit were reduced when subjects were tested without use instructions. When tested in subjects that followed instructions, the pH kit's sensitivity and specificity were 72% and 55% respectively. This modest diagnostic performance was reduced when pH values were measured in subjects not following use instructions. These kits, particularly the Saliva-Check mutans kits, can contribute to patient education by documenting microbial caries risk factors. Though difficult to implement in practice, subjects should refrain from eating or other activities that disturb the oral environment prior to sample collection.

Caries-related factors and bacterial composition of supragingival plaques in caries free and caries active Algerian adults

ObjectiveTo compare oral hygiene practices, education and social background, food intake and oral malodor of Algerian adults suffering from dental caries with normal controls, and to determine and compare the bacterial composition of the supragingival plaques from the above-mentioned groups. MethodsParticipants completed a questionnaire and were clinically examined for dental caries using decayed, missing and filled teeth index according to the criteria laid down by the World Health Organization. Supragingival plaque samples were collected from 50 caries-free adults (CF) and 50 caries-active adults (CA). Standard procedures of culture and identification of aerobic and anaerobic bacteria were used. Data were analyzed using Chi-square test. ResultsA total of 117 bacterial strains were isolated from supragingival plaques in CF group subjects, 76 (64.96%) of them belonged to 9 aerobic genera, and 41 (35.04%) to 9 anaerobic genera (P<0.05). While in the second group, 199 strains were isolated, 119 (59.80%) of the strains belonged to 10 aerobic genera and 80 (40.20%) to 10 anaerobic bacteria (P<0.05). Streptococcus mutans, Enterococcus faecium, Aerococcus viridans, Actinomyces meyeri, Lactobacillus acidophilus and Eubacterium limosum showed a significantly higher prevalence in the CA group (P<0.05). The findings revealed that CA group had a high sugar intake (80%). A significantly higher frequency of tooth brushing (P<0.000) and a significantly less self-reported oral malodor (P<0.000) and tooth pain (P<0.000) were found in CF group, while there was no association of socioeconomic levels and intake of meal snacks with dental caries. ConclusionsThis study confirms the association of some aciduric bacteria with caries formation, and a direct association of sugar intake and cultural level with dental caries. Furthermore, oral hygiene practices minimize the prevalence of tooth decay.

Morphological and proteomic analyses of the biofilms generated by Streptococcus mutans isolated from caries-active and caries-free adults

Background/purposeBiofilm formation by Streptococcus mutans is a prerequisite for the development of caries. Different strains of S. mutans may differ in their capacity in biofilm formation and protein expression. The objective of this study was to investigate the morphological features and proteomes of biofilms of S. mutans clinical isolates. Materials and methodsClinical strains isolated from caries-active (SM 593) and caries-free (SM 18) adults were cultured on polystyrene sheets in tryptone–polypeptone–yeast extract medium. Biofilm formation and structure were assessed by confocal laser scanning microscopy and scanning electron microscopy. Proteins were extracted from SM 593 and SM 18 presented in biofilms and separated with two-dimensional gel electrophoresis, followed by peptide mass fingerprinting using matrix-assisted laser desorption time-of-flight mass spectrometry analysis. ResultsInitially detected 2 hours after incubation, biofilm formation reached its maximum level at 20 hours. The biofilm formed by SM 593 was thicker with a higher percentage of viable bacteria compared with that formed by SM 18. Hydrolase and pantothenate kinase were detected in the SM 593 biofilm only, whereas 6-pyruvoyl tetrahydropterin synthase and phosphoribosylglycinamide formyltransferase were expressed exclusively in the SM 18 biofilm. Expressions of D-alanyl-D-alanine carboxypeptidase and response regulator homolog of RumR were most greatly enhanced in the SM 593 and SM 18 biofilms, respectively. ConclusionSM 593 exhibited greater biofilm-forming capacity compared to SM 18. SM 593 and SM 18 biofilms expressed specific proteins involved in nucleic acid metabolism and intermediary metabolism, respectively, which may account for the differences in their biofilm-forming abilities.

Susceptibility to Dental Caries and the Salivary Proline-Rich Proteins

Early childhood caries affects 28% of children aged 2–6 in the US and is not decreasing. There is a well-recognized need to identify susceptible children at birth. Caries-free adults neutralize bacterial acids in dental biofilms better than adults with severe caries. Saliva contains acidic and basic proline-rich proteins (PRPs) which attach to oral streptococci. The PRPs are encoded within a small region of chromosome 12. An acidic PRP allele (Db) protects Caucasian children from caries but is more common in African Americans. Some basic PRP allelic phenotypes have a three-fold greater frequency in caries-free adults than in those with severe caries. Early childhood caries may associate with an absence of certain basic PRP alleles which bind oral streptococci, neutralize biofilm acids, and are in linkage disequilibrium with Db in Caucasians. The encoding of basic PRP alleles is updated and a new technology for genotyping them is described.

The Isolation of Bifidobacteria from Occlusal Carious Lesions in Children and Adults

The aim of this study was to enumerate and identify bifidobacteria from occlusal carious lesions in permanent and deciduous teeth. Samples of infected dentine were obtained from 24 active occlusal lesions in deciduous teeth and from 15 occlusal lesions in permanent teeth. Plaque samples from sound occlusal surfaces of 12 caries-free adults and 12 children were also obtained. The bifidobacterial strains were isolated in mupirocin-containing selective media, Gram-stained and subcultured for identification. Total bacterial counts were determined using fastidious anaerobic agar, and isolates were identified using genus-specific PCR primers and were confirmed by 16S rRNA sequencing. Bifidobacteria were isolated from 13 of the 15 occlusal lesions in the adults and formed 5.09 ± 2.11% of the total cultivable flora. In the children, bifidobacteria were isolated from 16 of the 24 occlusal lesions and formed 7.4 ± 2.6% of the total flora. No bifidobacteria were isolated from the occlusal surfaces of caries-free adults or children. A total of 424 bifidobacteria were identified and these were Bifidobacteriumdentium, Parascardovia denticolens, Scardoviainopicata, Bifidobacterium longum,Scardovia genomosp. C1 and Bifidobacterium breve. B. dentium was present in 14 out of the 16 bifidobacteria-positive samples from the lesions on the deciduous teeth and in 7 out of the 13 positive lesions in adults (p = 0.04). The present data suggest that bifidobacteria may play a role in the progression of occlusal caries lesions in both children and adults.

Cariogenic Virulence Characteristics of Mutans Streptococci Isolated from Caries-active and Caries-free Adults

The objective of the study was to compare aciduricity (ability, to live in acid), acidogenicity (ability to produce acid), and intracellular polysaccharide production of mutans streptococci (MS) strains isolated from caries-active (CA, with one or more cavitated lesions) and caries-free (CF, with no clinically observable new caries in the last five years) adults. Forty-three MS strains from 17 of 17 CA adults, and 14 strains from eight of 12 CF adults were investigated. MS isolates' growth, survival, and pH reduction in pH 3.5-7.0 broths were evaluated to compare their acidogenicity and aciduricity. Extracellular water-soluble polysaccharide (WSP) and water-insoluble polysaccharide (WISP) was extracted from MS culture in BHI broth with 5 percent sucrose and assessed by a colorimetric anthrone-sulfuric acid microassay. No significant differences in mean aciduricity were found between CA and CF MS isolates (P>0.05, t test). However, significantly more CA subjects (29 percent) were colonized by MS strains with aciduricity above the average than CF subjects (13 percent, Fisher's exact test, P<0.05). Furthermore, CA MS strains produced significantly more acid at pH<5 (Mann-Whitney, P<0.05) and significantly more CA subjects were colonized with more acidogenic MS at pH<4.5 (Fisher's exact test, P<0.01). Similarly, CA MS isolates produced significantly more WISP than CF (Mann-Whitney test, P<0.01) while no statistical difference was found in WSP between the two groups. More CA subjects were colonized by multiple strains with aciduricity, acidogenicity, and polysaccharide synthesis ability above average. The study indicated that differences in acidogenicity, aciduricity, and polysaccharide synthesis in strains of MS may partially contribute to increased caries activity.

CLONAL DIVERSITY OF STREPTOCOCCUS MUTANS CLARKE (1924) IN CARIES-FREE ADULTS

Very few information about the clonal profile of Streptococcus mutans in caries-free adults is available. Microbial samples of saliva, tongue dorsum, and dental biofilm were taken from eight caries-free volunteers (DMFT = 0). Presumptive colonies of mutans streptococci were identified until species level. After confirmation, S. mutans strains were grown in liquid culture media and harvested for whole-cell protein extraction. Multilocus Enzyme Electrophoresis (MLEE) separated protein extracts and the bands’ patterns were assessed for six enzymes. Results showed that two or more distinct clonal types (avg = 4.75) were found cocolonizing all the enrolled subjects, confirming the premise that caries-free subjects are prone to be colonized by more than one strain of S. mutans.