Black stain and dental caries: a review of the literature

Chromogenic bacterial staining of teeth: a scoping review

BACKGROUND

The purpose of this scoping review is to understand the etiological, clinical characteristics and treatment of chromogenic staining of teeth and the various management strategies reported in literature. This SR was performed in accordance with the PRISMA 2022 guidelines and was registered in the PROSPERO database (CRD42024565446).

METHODS

A systematic electronic search on databases like Scopus, Medline, EMBASE, CINAHL, ProQuest and Web of Science from inception to July 2024 was performed. Two independent reviewers ran the search strategy in the mentioned databases.

RESULTS

A total of 989 articles were obtained from various databases. 21 were included for data extraction of which 2 were case reports, 1 was case series and 18 were research articles. The prevalence of staining due to chromogenic bacteria reported from the included studies ranged from 3.1 to 18.5%. All these studies reported on the typical black color of staining of teeth.

CONCLUSION

This scoping review reveals sparsity in existing literature regarding the etiological, clinical characteristics and management of chromogenic staining of teeth. Though the role of peculiar oral microbiota is well established, evidence regarding the management strategies to combat these recalcitrant staining remains a strong research question.

Effects of Lacticaseibacillus paracasei L9 on Oral Microbiota and Cariogenic Factors in Streptococcus mutans-Infected Mice

In the pathogenesis of dental caries, Streptococcus mutans (S. mutans) plays a central role. S. mutans can produce extracellular polysaccharides, which can help the bacteria form biofilms on the tooth surface, create a stable living environment, and hinder the removal of bacteria by natural defense substances in the oral cavity such as saliva. Meanwhile, the oral microbiota and dietary habits exert long-term influences on its development. This study, employing the BALB/c mouse model, explored the effects of L. paracasei L9 on dental caries. In the experiment, mice underwent the S. mutans inoculation and were subsequently treated with L. paracasei L9 or S. salivarius K12 for 28 consecutive days. The results showed that L. paracasei L9 significantly ameliorated early enamel caries, and both L. paracasei L9 and S. salivarius K12 cooperatively downregulated the expressions of critical cariogenic factors, effectively suppressing the initial adhesion of S. mutans and the formation of dental plaques. L. paracasei L9 reshaped the oral microbiota of caries-affected mice, selectively reducing pathogens abundances and augmenting abundances of probiotics such as Lactobacillaceae and Streptococcus salivarius. This study offers a strategic approach for the management of dental caries, highlighting the potential of these probiotics in the field of oral health.

Dental Caries and Extrinsic Black Tooth Stain in Children With Primary, Mixed and Permanent Dentitions: A Cross-Sectional Study

BACKGROUND

Dental caries and extrinsic black tooth stain (EBS) are prevalent among children, with current evidence suggesting a negative correlation between them. It is unclear whether the factors contributing to developing or preventing dental caries and EBS are connected or aligned.

AIM

To investigate the prevalence and associated factors of caries and EBS among children with primary, mixed and permanent dentitions.

DESIGN

This was designed as a cross-sectional study. Probability proportionate to size sampling and simple random sampling methods were used to recruit children aged 5, 9 and 12. Three calibrated paediatric dentists conducted intra-oral examinations. Nutritional supplements, oral health-related behaviours and family background were collected. Bivariate analysis, negative binomial and binary logistic regression were performed.

RESULTS

Caries and EBS prevalence were 83.7% and 4.7%, respectively. A decreasing trend in caries and an increasing trend in EBS prevalence were observed across three dentitions. Caries were associated with EBS, oral hygiene, vitamin intake, gender, food-pocketing habits, toothbrushing duration, dental attendance and socioeconomic status. EBS was more likely to occur in caries-free children (OR = 4.42, 95% CI 2.97,6.58, p < 0.001) and children without vitamin consumption (OR = 1.59, 95% CI 1.07, 2.36, p = 0.021).

CONCLUSION

The occurrence of caries and EBS varied across different dentition stages. Their risk and protective factors were not significantly aligned.

Effect of A Fluoride Toothpaste Containing Enzymes and Salivary Proteins on Periodontal Pathogens in Subjects with Black Stain: A Pilot Study

OBJECTIVE

 Black stain (BS) is an extrinsic dental discoloration particularly difficult to treat. Although its etiology is not fully clear yet, chromogenic bacteria inside the oral cavity seem to be involved. In this pilot study, we evaluated whether a toothpaste containing enzymes and salivary proteins could improve oral health and reduce the presence of periodontal pathogens in subjects predisposed to BS discoloration.

MATERIALS AND METHODS

 Twenty-six subjects were enrolled in the study: 10 subjects without BS; 16 subjects with BS, randomly assigned in two groups: test (n = 8) and control (n = 8). The test group used a toothpaste containing sodium fluoride, enzymes, and salivary proteins. The control group used a toothpaste with amine fluoride. At enrollment and after 14 weeks, participants were subjected to professional oral hygiene, evaluation of BS (through Shourie index) and oral health status, collection of saliva and dental plaque samples. The presence of periodontal pathogens in plaque and saliva of all subjects was investigated by molecular analysis (PCR).

STATISTICAL ANALYSIS

 The prevalence of investigated microbial species in patients with/without BS was performed by Chi-squared test. The variation in the prevalence of the investigated species after treatment in test and control group was analyzed by t-test.

RESULTS

 Clinical evaluation showed that 86% of participants with BS had a reduction in the Shourie index, independently from the toothpaste used. In particular, a greater reduction in the Shourie index was observed in subjects using an electric toothbrush. We did not observe an effect of the fluoride toothpaste containing enzymes and salivary proteins on the composition of the oral microbiota of the test subjects in comparison with controls. When comparing all subjects with BS (n = 16) and without BS (n = 10), P. gingivalis detection was significantly higher in saliva samples collected from subjects with BS (p = 0.0129).

CONCLUSION

 We verified that the use of an enzyme-containing toothpaste alone is not sufficient to prevent the formation of BS dental pigmentation in subjects predisposed to this discoloration. Mechanical cleaning, especially using electrical toothbrushes, seems to be useful to counteract BS formation. Moreover, our results suggest a possible association between BS and the presence of P. gingivalis at the salivary level.

[Prevalence of exogenous pigmentations and caries by intake of ferric supplements in primary dentition]

Objective

The aim of this study was to determine the prevalence of extrinsic black pigmentation in primary dentition and its relationship with dental caries in children aged 3 to 5 years.

Materials and methods

The study design was descriptive, prospective, cross-sectional and observational; The sample of the present study consisted of 79 children who were receiving treatment with ferrous sulfate, who underwent a clinical examination and odontogram. To determine the presence of extrinsic black pigmentation, the Shourie classification was used.

Results

A low prevalence of extrinsic pigmentation of 7.6% was found, and children with extrinsic pigmentation had a Ceod of 9.83+-3.601, while those children without the presence of pigmentations had a Ceod of 4.60+-3.248.

Conclusions

A significant relationship was found between the Ceod index and extrinsic black pigmentation (p<0.001).

The effect of antibacterial photodynamic therapy with diode laser on chromogenic bacteria associated with dental black staining: An in-vitro study

BACKGROUND

Aggregatibacter actinomycetemcomitan (A.a) and Actinomyces naeslundii (A.n) are two gram-negative chromogenic bacteria involved in the formation of dental black stainings. Our study aimed to investigate the antibacterial effect of photodynamic therapy (aPDT) using two photosensitizers, Methylene Blue (MB) and Indocyanine Green (ICG).

MATERIALS AND METHODS

In this in-vitro study, two isolates of each selected bacterium were cultured and treated as follows; Negative control with no treatment; CHX as a positive control; ICG; MB; ICG with 808 nm laser activation; and MB with 660 nm laser activation. The number of colonies (CFU/mL) was determined to compare the groups. The qualitative evaluation of biofilm formation was done by scanning electron microscopy of treated enamel pieces. The logarithmic values of the colony counts were compared using One-way ANOVA and the Welch test Tukey HSD and Games-Howell tests were used for multiple comparisons. P-values of less than 0.05 were considered statistically significant.

RESULTS

The use of ICG alone or along with laser irradiation at the wavelength of 808 nm significantly reduced the number of colonies of A.a and A.n bacteria. Comparing the colony counts in the MB group with the positive control showed no significant decrease in bacterial load. On the contrary, activation of MB with 660 nm radiation of diode laser showed a significant antibacterial effect. The density of bacterial biofilm was significantly lower in the groups treated with MB and ICG without laser activation than in the control group; however, the reduction in bacteria biofilm density was more robust using photodynamic therapy with ICG.

CONCLUSION

aPDT using MB with 660 nm laser and ICG with 808 nm laser significantly reduced the number of chromogenic A.a and A.n bacteria, and photodynamic therapy with ICG was proven to be significantly more effective than MB with or without laser radiation.

Aesthetic management of discoloured incisors in children

Children can often present with discolouration of their teeth, commonly affecting their permanent maxillary central incisors. These opacities can often cause children to suffer with psychosocial and confidence related issues. With long waiting lists in secondary care, many children may face increased waiting times to receive aesthetic dental treatment. It is important that the dental professional is aware of the different causes of discolouration, the possible treatment options and when to consider a referral to secondary care.

Characterization of the oral microbiome and gut microbiome of dental caries and extrinsic black stain in preschool children

Introduction

A lower prevalence of dental caries (hereafter termed “caries”) has been observed in children with dental extrinsic black stain (EBS).

Methods

We investigated the epidemiologic characterization of EBS and explored the possible role of the oral microbiome (OM) and gut microbiome (GM) in EBS formation and caries prevention. In an epidemiologic survey, 2,675 children aged 3–6 years were included. Thirty-eight of these children (7 children had both caries and EBS, 10 had EBS only, 11 had caries only, and 10 were healthy children) were recruited for 16S rRNA sequencing and collection of samples of supragingival plaque and feces. Collected plaque samples were divided into four groups: BCP (EBS+, caries+), BP (EBS+, caries−), CP (EBS−, caries+), and P (EBS−, caries−). Fecal samples were also divided into four groups: BCF (EBS+, caries+), BF (EBS+, caries−), CF (EBS−, caries+), and F (EBS−, caries−).

Results

EBS was observed in 12.10% of this population. Children with EBS had a significantly reduced prevalence of caries and a lower mean value of decayed–missing–filled teeth (dmft; p &lt; 0.01). According to analyses of dental plaque, the P group had the most complex microbiome. The BCP group exhibited greater operational taxonomic unit (OTU) richness but a reduced evenness compared with the BP group, and the CP group showed greater OTU richness than the BP group. At the genus level, higher abundance of Actinomyces and Cardiobacterium species was observed in the BCP group. Higher abundance of Lautropia and Pesudopropionibacteriumin species was observed in the BP group compared with P and CP groups, respectively (p &lt; 0.05). Veillonella species were significantly more common in P and CP groups than in BP groups, whereas Porphyromonas and Fusobacterium species were more common in the CP group (p &lt; 0.05). With regard to the GM, the CF group exhibited greater OTU diversity than the BF group. The GM in the BCF group exhibited the most complex relationships across all fecal groups. GM groups could be distinguished by various unique biomarkers, such as Escherichia and Shigella species in the BCF group, Agathobacter and Ruminococcus species in the CF group, Lactobacillus species in the BF group, and Roseburia species in the F group. Our results suggest that EBS is a possible protective factor against early-childhood caries. Dental plaque and the GM may be relevant to EBS in primary dentition.

Diet and stomach characteristics of feral piglets (Sus scrofa): Implications for farmed piglets

Evaluation of the diet of the pig (Sus scrofa) in natural settings may provide new views on diet optimization for growth and development of commercially raised piglets under farm conditions. A field study was conducted to gain insight in the diet and stomach characteristics of feral piglets. Forty animals (body weight: 4.6 ± 1.37 kg) were collected from the Bahía Samborombón (Buenos Aires, Argentina). Stomachs were weighed after storage in formalin and the particle size distribution of their contents was determined by wet sieving. Diet items present in their stomachs were classified and their proportional weight and relative abundance was calculated. Based on their dentition, 5, 16 and 19 piglets were approximately 1, 3-6 and 6-16 weeks of age respectively. Vegetable matter (mainly 'leaves and stems') was predominantly present in 39 animals. It represented on average 83 ± 36.4% of total stomach contents by weight. The stomachs of 12 piglets contained curd and represented on average 16 ± 35.1% by weight. Other diet items were less abundant or absent. The proportion of stomach particles retained were 24%, 13%, 22%, 13% and 28% for sieves with mesh sizes of 2000, 1000, 420, 210 and <210 µm respectively. For comparison, we used data of farmed piglets of similar age and fed a nutrient-dense, finely ground diet. Feral piglets' relative empty stomach weights increased with age (p < 0.050), whereas this was not the case for farmed piglets. Relative stomach contents weight increased significantly with age only for farmed piglets (p < 0.050). We infer from our data that feral suckling piglets consumed a variety of non-milk items, mainly consisting of vegetable material with a coarse particle size from their first week in life onwards. Their diet is associated with an enhanced stomach development compared to those of farmed piglets.

Effects of black tea tooth staining previously to 35% hydrogen peroxide bleaching

Aim: To determine if the artificial staining with black tea (BT) influences the enamel microhardness before in-office bleaching and if BT staining is necessary to evaluate the efficacy of bleaching with 35% hydrogen peroxide Methods: Enamel/dentin blocks were randomized into groups according to the staining protocol (n=5/group): (CO) control – maintained in artificial saliva solution (AS); (BT4) immersed in black tea solution for 4 h; (BT24) immersed in black tea solution for 24 h. After the staining protocols, all specimens were kept in AS for one week, followed by bleaching (three sessions of HP application for 40 min). Knoop surface microhardness (kgF/mm2) was determined at baseline (T0), after staining (T1), after 7 days of storage in AS (T2), and after bleaching (T3). The color (ΔE00) and coordinate changes (ΔL, Δa, Δb) were measured using a digital spectrophotometer at T0 and T3. Data were submitted to one-way (ΔE00, ΔL, Δa, Δb) or two-way ANOVA repeated measures (kgF/mm2) and Tukey’s test (a=5%). Results: The staining protocols (BT4 and BT24) promoted significantly lower microhardness (T1 and T2, p<0.05) than CO, whereas CO was the only group to maintain microhardness values over time. Bleaching promoted perceptible ΔE00 without a significant difference among the groups regardless of the staining protocol (p=0.122). CO and BT4 showed no differences in terms of ΔL and Δa (p>0.05), but BT4 displayed a higher Δb than CO. Conclusion: The artificial staining with BT negatively affected the enamel surface microhardness and was not essential to evaluate the efficacy of 35% hydrogen peroxide bleaching.

The association between black stain and lower risk of dental caries in children: a systematic review and meta-analysis

BACKGROUND

Previous literature shows that children with dental black stain might be less susceptible to dental caries. The aim of this study was to systematically review the available literature to determine whether black stain presence could influence the prevalence or severity of dental caries in primary dentition.

METHODS

A systematic search of PubMed, Web of Science, Scopus, Google Scholar, OpenGrey, and Egyptian Universities Libraries Consortium was conducted up to December 2020. Quality assessment was done using a modified version of Down's and Black checklist. Meta-analyses were performed to assess the association between dental black stain and: (i) Likelihood of developing dental caries/being caries-free (ii) Number of teeth affected by dental caries (iii) Number of tooth surfaces affected.

RESULTS

The database search yielded 2164 results, 14 of which matched the eligibility criteria. The meta-analysis showed that the likelihood of developing caries (Fixed effect model: OR [95% CI]: 0.67 [0.54; 0.82]; I²=37%; τ²=0.05), number of teeth affected (Random effects model: MD [95% CI]: -0.98 [-1.54; -0.42]; I²=79%; τ² =0.44), and number of surfaces affected (Random-effects model: MD [95% CI]: -2.34 [-4.23; -0.44]; I²=85%; τ² =2.93), were all lower in children with black stain.

CONCLUSIONS

It is suggested that dental black stain is associated with lower dental caries experience in children with primary dentition. However, it is questionable whether black stain has a protective effect against dental caries, or whether children at low risk of dental caries are more likely to develop BS because their oral microbiome favors BS-forming organisms.

Black staining: an overview for the general dental practitioner

'Black stain' is a form of extrinsic staining affecting the buccal and palatal surfaces of primary and permanent teeth. It presents as an incomplete line of dark dots formed at the cervical third of the tooth, typically following the gingival margin and not extending to the proximal areas. There is no consensus on its prevalence, though it appears to vary between 2-20%, with an equal male and female distribution. Although the aetiology is not completely understood, its microflora is dominated by chromogenic bacteria, such as actinomyces and prevotella melaninogenica, and there appears to be a low incidence of caries in the presence of the stain. The cause of the dark pigmentation seems to be from iron deposits such as ferric sulphate, present due to a reaction with the products of bacterial metabolism. This paper aims to provide information on the diagnosis, aetiology and treatment considerations for black stain. A patient case report is also explored.

'Black stain' is a poorly understood form of tooth discolouration by dental professionals.

Its aetiology is not completely understood, although the black pigmentation is likely to be an insoluble ferric salt precipitate, produced by chromogenic bacteria.

Treatment should involve a combination of reassurance to the patient/parents, with a minimally invasive approach to remove staining, while avoiding iatrogenic damage.

Deciphering Black Extrinsic Tooth Stain Composition in Children Using Metaproteomics

The present study focuses on the use of a metaproteomic approach to analyze Black Extrinsic Tooth Stains, a specific type of pigmented extrinsic substance. Metaproteomics is a powerful emerging technology that successfully enabled human protein and bacterial identification of this specific dental biofilm using high-resolution tandem mass spectrometry. A total of 1600 bacterial proteins were identified in black stain (BS) samples and 2058 proteins in dental plaque (DP) samples, whereas 607 and 582 human proteins were identified in BS and DP samples, respectively. A large diversity of bacteria genera (142) in BS and DP was identified, showing a high prevalence of Rothia, Kingella, Neisseria, and Pseudopropionibacterium in black stain samples. In this work, the high diversity of the dental microbiota and its proteome is highlighted, including significant differences between black stain and dental plaque samples.

Epidemiological and Microbiome Characterization of Black Tooth Stain in Preschool Children

OBJECTIVE

To assess the epidemiologic attributes and microbial variations associated with extrinsic black tooth stain (BTS) among Chinese preschool children.

METHODS

This cross-sectional study included 250 preschool children (3-4 years) from three kindergartens in Shanghai, China. Following clinical examination, and using a case-control design, saliva and dental plaque specimens were collected from caries-free participants with (n = 21, BTS group) and without (n = 48, control group) BTS. The chi-square test and logistic regression model were used to evaluate factors associated with BTS. 16S rRNA sequencing were used to characterize the associated microbial communities.

RESULTS

BTS was detected in 12.4% of participants, with a mean of 13.7 black-stained teeth. Participants with BTS had a lower caries burden and better oral hygiene (P = 0.003). Children with less frequent intake of marmalade or honey (P = 0.033) and regular application of fluoride (P = 0.007) had a lower likelihood of having BTS. Microbiota analysis revealed 14 phyla, 35 classes, 63 orders, 113 families, 221 genera, 452 species, and 1,771 operational taxonomic units (OTUs). In terms of microbial diversity, no significant differences were observed in the saliva of the two groups (P > 0.05). Dental plaque from the BTS group exhibited higher OTU richness but lower evenness than that from the control group (Chao P = 0.006, Shannon P = 0.007, respectively) and showed a significant difference in β diversity (P = 0.002). The microbiome in the two groups was characterized by various microbial biomarkers, such as Pseudomonas fluorescens, Leptotrichia sp._HMT_212, Actinomyces sp._HMT_169, and Aggregatibacter sp._HMT_898 in plaques from the BTS group. Functional analysis of the microbial species suggested the existence of a hyperactive metabolic state on teeth surfaces with BTS plaques and revealed that ferric iron, the iron complex transport system, and the iron (III) transport system were more abundant in BTS plaque samples.

CONCLUSIONS

This study provides insights into the epidemiologic and microbial features of BTS in preschool children. The microbiome in BTS is characterized by various microbial biomarkers, which can serve as indicators for BTS diagnosis and prognosis.

Comparative Microbial Profiles of Caries and Black Extrinsic Tooth Stain in Primary Dentition

Extrinsic black tooth stain (BS) is a common oral disease associated with lower caries experience in preschool children, although the microbiotic features contributing to the low risk of caries in this group remain elusive. In this study, we aimed at identifying the dominant bacteria in dental plaque to indicate the incidence of caries in the primary dentition. Subjects were divided into 3 groups based on the clinical examination: group CF, children without pigment who had no caries lesions or restorations (n = 18); group CS, children who were diagnosed with severe early childhood caries (n = 17); and group BS, children with pigment (black extrinsic stain) without caries or restorations (n = 15). The total microbial genomic DNA was extracted and subjected to bacterial 16S ribosomal RNA gene sequencing using an Illumina HiSeq platform. The differential dominant bacteria were determined using Wilcoxon rank-sum testing and linear discriminant analysis effect size (LEfSe). Co-occurrence network analysis was performed using sparse correlations for compositional data, calculation and functional features were predicted using PICRUSt. Interestingly, our results showed that the relative abundance of Pseudopropionibacterium, Actinomyces, Rothia, and Cardiobacterium was from high to low and that of Porphyromonas was low to high in the BS, CF, and CS groups, consistent with the clinical incidence of caries in the 3 groups. Moreover, an increased level of Selenomonas_3, Fusobacterium, and Leptotrichia was associated with high caries prevalence. We found that the interactions among genera in the BS and CS plaque communities are less complex than those in the CF communities at the taxon level. Functional features, including cofactor and vitamin metabolism, glycan biosynthesis and metabolism, and translation, significantly increased in caries plaque samples. These bacterial competition- and commensalism-induced changes in microbiota would result in a change of their symbiotic function, finally affecting the balance of oral microflora.

Metagenomic analysis of black-stained plaques in permanent dentition

OBJECTIVES

We aimed to determine the aetiologic agent responsible for black staining of permanent dentition using next-generation sequencing and determine the relationship between caries and black stains.

MATERIALS AND METHODS

A total of 52 systemically healthy patients with black-stained and caries-free (n = 13), black-stained and carious (n = 13), black stain-free and caries-free (n = 13), and black stain-free and carious (n = 13) teeth were enrolled in the study. The International Caries Detection and Assessment System (ICDAS II) was used for caries classification. Between 08:00 and 10:00, supragingival plaque samples were collected after a minimum of 8-12 h of accumulation and DNA samples were isolated. The samples were processed using the ZymoBIOMICS™ Service. Bioinformatics analysis was performed using mothur at usegalaxy.org. Data were analysed statistically using the Pearson chi-square and Fisher tests.

RESULTS

The number of caries-free teeth (ICDAS 0, 1, and 2) was significantly higher in patients with black stains (p = 0.007).Capnocytophaga (4.8 %), Corynebacterium (3.9 %), and Neisseria (5.4 %) species were the most abundant among all black-stained plaques (carious and caries-free) (p < 0.05). Capnocytophaga (10.8 %), Cardiobacterium (3.6 %), and Rothia (1.72 %) species were detected in the black-stained plaques of caries-free patients (p < 0.05).

CONCLUSION

This study is one of the first studies examining the microbial composition of dental plaques with black staining in carious and caries-free adult patients using next generation sequencing technology. In the presence of black staining, plaques have an ultimate complex microbial structure. A lower caries burden was noted in the presence of black staining.

Missing and decayed teeth, oral hygiene and dental staining in relation to esophageal cancer risk: ESCCAPE case-control study in Kilimanjaro, Tanzania

In the African esophageal squamous cell carcinoma (ESCC) corridor, recent work from Kenya found increased ESCC risk associated with poor oral health, including an ill-understood association with dental fluorosis. We examined these associations in a Tanzanian study, which included examination of potential biases influencing the latter association. This age and sex frequency-matched case-control study included 310 ESCC cases and 313 hospital visitor/patient controls. Exposures included self-reported oral hygiene and nondental observer assessed decayed+missing+filled tooth count (DMFT index) and the Thylstrup-Fejerskov dental fluorosis index (TFI). Blind to this nondental observer TFI, a dentist independently assessed fluorosis on photographs of 75 participants. Odds ratios (ORs) are adjusted for demographic factors, alcohol and tobacco. ESCC risk was associated with using a chewed stick to brush teeth (OR 2.3 [95% CI: 1.3-4.1]), using charcoal to whiten teeth (OR 2.13 [95% CI: 1.3, 4.1]) and linearly with the DMFT index (OR 3.3 95% CI: [1.8, 6.0] for ≥10 vs 0). Nondental observer-assessed fluorosis was strongly associated with ESCC risk (OR 13.5 [95% CI: 5.7-31.9] for TFI 5+ v 0). However, the professional dentist's assessment indicated that only 43% (10/23) of participants assessed as TFI 5+ actually had fluorosis. In summary, using oral charcoal, brushing with a chewed stick and missing/decayed teeth may be risk factors for ESCC in Tanzania, for which dose-response and mechanistic research is needed. Links of ESCC with "dental fluorosis" suffered from severe exposure misclassification, rendering it impossible to disentangle any effects of fluorosis, extrinsic staining or reverse causality.

Salivary Microbiome Variation in Early Childhood Caries of Children 3-6 Years of Age and Its Association With Iron Deficiency Anemia and Extrinsic Black Stain

ECC is a common clinical manifestation of the oral cavity in childhood and Iron deficiency-anemia (IDA) is a high-risk factor but extrinsic black stain on the tooth surface is a protective factor for caries. There is limited information about oral microecological change in early children who suffer from ECC with IDA and extrinsic black stain (BS). This study enrolled 136 children aged 3-6 years. Dental caries and teeth BS were examined. Saliva was collected for 16S rRNA gene and fingertip blood were for Hemoglobin test. There are 93 ECC including 13 with IDA (IDA ECC) and 80 without IDA (NIDA ECC) and 43 caries free (CF) including 17 with BS (BSCF) and 26 without BS (NBS CF). Statistical analysis of microbiota data showed differences of the oral flora in different groups. The oral flora of the IDA ECC group had a high diversity, while the BSCF group had a low diversity. The bacterial genera Bacillus, Moraxella, and Rhodococcus were enriched in the IDA ECC while Neisseria was enriched in the NIDA ECC. Neisseria only exhibited high abundance in the BSCF, and the remaining genera exhibited high abundance in the NBSCF. Interestingly, the BSCF had the same trend as the NIDA ECC, and the opposite trend was observed with IDA ECC. We established random forest classifier using these biomarkers to predict disease outcomes. The random forest classifier achieved the best accuracy in predicting the outcome of caries, anemia and black stain using seven, one and eight biomarkers, respectively; and the accuracies of the classifiers were 93.35%, 94.62% and 95.23%, respectively. Our selected biomarkers can achieve good prediction, suggesting their potential clinical implications.

Dental black plaque: metagenomic characterization and comparative analysis with white-plaque

Extrinsic black dental staining is an external dental discoloration of bacterial origin, considered a special form of dental plaque. Currently, there is no definitive therapeutic option for eliminating black stain. This study employed 16S rRNA metagenomics to analyze black stain and white-plaque samples from 27 adult volunteers. Study objectives were to: describe the microbial diversity of adult black stain samples; characterize their taxonomic profile; compare the microbiomes of black stain versus white-plaque from adult volunteers and propose a functional map of the black stain microbiome using PICRUSt2. The black stain microbiome was poorer in species diversity as compared to white-plaque. The five most abundant genera in black stain were Capnocytophaga, Leptotrichia, Fusobacterium, Corynebacterium and Streptococcus. Functional analysis of microbial species revealed conserved and consistent clustering of functional pathways within and between black stain and white-plaque microbiomes. We describe enrichment of heme biosynthetic pathways in black stain. Our results suggest that the dysbiosis in black stain resembles "orally healthy" communities. The increased abundance of heme biosynthetic pathways suggests that heme-dependent iron sequestration and subsequent metabolism are key for black stain formation. Further research should decipher the regulation of heme biosynthetic genes and characterize the temporal sequence leading to colonization and dysbiosis.

Black stain and dental caries in primary teeth of Tunisian preschool children

AIM

To assess the prevalence of black tooth stains and to investigate its correlation with caries experience in the primary dentition of 3-5-year-old children in the region of Monastir, Tunisia.

METHODS

It was a descriptive cross-sectional study involving children in preschool establishments in Monastir, Tunisia. It consisted of an oral examination of 393 children and data collection through a questionnaire completed by parents. ANOVA test and Pearson Chi-square test were used to assess the prevalence of black stains and its association with dental caries.

RESULTS

The overall mean decayed, missing, and filled teeth (dmft) index was 1.42 ± 0.1. Caries prevalence was 49.9%. Of all the children involved, 6.1% had black stains. A statistically significant relationship was found between black stain and the prevalence of early childhood caries (p = 0.047). However, the association with the dmft index was not statistically significant (p = 0.08).

CONCLUSION

Preschool children with black tooth stain had lower dental caries experience. The results of the present study suggest that black stains are a protective factor for early childhood caries. More studies are needed to explore the risk factors of black stains.

Lactoferrin and oral pathologies: a therapeutic treatment

The oral cavity is a non-uniform, extraordinary environment characterized by mucosal, epithelial, abiotic surfaces and secretions as saliva. Aerobic and anaerobic commensal and pathogenic microorganisms colonize the tongue, teeth, jowl, gingiva, and periodontium. Commensals exert an important role in host defenses, while pathogenic microorganisms can nullify this protective function causing oral and systemic diseases. Every day, 750-1000 mL of saliva, containing several host defense constituents including lactoferrin (Lf), are secreted and swallowed. Lf is a multifunctional iron-chelating cationic glycoprotein of innate immunity. Depending on, or regardless of its iron-binding ability, Lf exerts bacteriostatic, bactericidal, antibiofilm, antioxidant, antiadhesive, anti-invasive, and anti-inflammatory activities. Here, we report the protective role of Lf in different oral pathologies, such as xerostomia, halitosis, alveolar or maxillary bone damage, gingivitis, periodontitis, and black stain. Unlike antibiotic therapy, which is ineffective against bacteria that are within a biofilm, adherent, or intracellular, the topical administration of Lf, through its simultaneous activity against microbial replication, biofilms, adhesion, and invasiveness, as well as inflammation, has been proven to be efficient in the treatment of all known oral pathologies without any adverse effects.

Comparing dental plaque microbiome diversity of extrinsic black stain in the primary dentition using Illumina MiSeq sequencing technique

Background

Extrinsic black stain (EBS) is characterized by discrete dark dots or lines on the tooth surface. The relationship between EBS and oral microbiota in children remains elusive. The aim of this study was to compare dental plaque microbiome in EBS children with that in EBS-free children in the primary dentition.

Methods

The Illumina MiSeq sequencing technique was utilized in the cross-sectional pilot study to investigate the diversity and composition of the supragingival plaque microbiota from 10 EBS-positive and 10 EBS-free children. The results were analysed with nonparametric Mann-Whitney U test, Pearson Chi-Square test, Fisher’s Exact test and one-way ANOVA tests.

Results

We identified 13 different phyla, 22 classes, 33 orders, 54 families, 105 genera, and 227 species from a total of 52,646 high-quality sequences. Between two groups, no statistical differences were observed in the estimators of community richness and diversity at 97% similarity, as well as in the Unweighted Unifrac principal co-ordinates analysis (PCoA). At the species level, higher level of relative abundance of Actinomyces naeslundii and lower level of relative abundance of a species belonging to Candidate_division_TM7 was observed in dental plaque of EBS-positive subjects, compared to dental plaque of EBS-free subjects (P < 0.05). This indicated that some species might be involved in the EBS process.

Conclusion

Changes in dental plaque microbiota is possibly relevant to the process of EBS in the primary dentition.

Do Patients with Extrinsic Black Tooth Stains Have a Lower Dental Caries Experience? A Systematic Review and Meta-Analysis

Studies have suggested that individuals affected by extrinsic black tooth stains have less dental caries experience in comparison to those without this condition. The aim of the present study was to perform a systematic review and meta-analysis to determine whether there is scientific evidence demonstrating that extrinsic black stains are a protective factor for the occurrence of dental caries. This systematic review was developed in accordance with the PRISMA statement and the research question was determined using the PECO strategy. Electronic searches were conducted in the PubMed, Science Direct, Virtual Health Library, Cochrane, Web of Science, and Google Scholar databases for relevant articles published up to September 2018. All articles included were submitted to an appraisal of methodological quality using the Newcastle-Ottawa Scale and the data were extracted for meta-analysis. The search strategy resulted in the retrieval of 9,108 publications. After the application of the eligibility criteria, 18 articles were selected for analysis, 13 of which were included in the meta-analysis. The meta-analysis demonstrated that individuals with extrinsic black stains involving primary (median, MD: -0.78 [-1.09; -0.48]; I2 = 44%) and permanent (MD: -0.50 [-0.93; -0.08]; I2 = 86%) teeth have a lower dental caries experience in comparison to those without this condition. Patients with extrinsic black tooth stains have a lower dental caries experience in cross-sectional studies.

Risk factors for the presence of dental black plaque

In order to evaluate risk factors related to the presence of extrinsic dental black stain, a total of 94 orally healthy volunteers (47 individuals with dental black stain and 47 individuals without dental black stain) were recruited from ten different dental clinics in Valencia and Castellón (Spain). Data regarding their oral hygiene, dietary habits, and oral health status were gathered by questionnaire. Samples of dental plaque, saliva and drinking water were collected for chemical analysis. Three factors were found to be statistically significantly associated with dental black stain, (i) consuming water with high iron content, (ii) consuming water with high pH, and (iii) having a high salivary pH. Other factors such as smoking, taking iron supplements or consuming caffeinated drinks were not found to be risk factors for the presence of black stain. A multivariate logistic regression analysis showed that drinking tap or osmosis-purified water and lower levels of salivary iron increase the risk of having dental black stain. Overall, several risk factors for the presence of dental black stain have been identified. The main modifiable risk factor identified in this study was the consumption of tap or osmosis drinking water.

Mobile Apps for Oral Health Promotion: Content Review and Heuristic Usability Analysis

BACKGROUND

There has been an increase in consumer-facing mobile health (mHealth) apps in recent years. Prior reviews have characterized the availability, usability, or quality of popular mHealth apps targeting a range of health behaviors, but none has examined apps that promote better oral health care. Oral disease affects billions of people worldwide and mobile phone use is on the rise, so the market for well-designed and effective oral health apps is substantial.

OBJECTIVE

We examined the content and usability of popular oral health promotion apps to better understand the current state of these self-help interventions and inform the need and opportunity for future app development.

METHODS

Between February and March 2018, we identified oral health-focused apps that were designed for Android or iOS, available in English, and targeted adult consumers (as opposed to children or dental health professionals). The sample was limited to the most popular and highly rated apps on each platform. For each app reviewed, we assessed its basic descriptive characteristics (eg, platform, cost), evidence of a theoretical basis or empirical validation, key program functionality, and the extent to which the app addressed diet and tobacco and alcohol use as risk factors for oral disease. We characterized the framing (ie, gain vs loss) of all persuasive messaging and conducted a heuristic analysis to assess each app's usability as a persuasive health technology.

RESULTS

Thirty-three apps were eligible for review based on the selection criteria. Two-thirds (22/33, 67%) were geared toward the general public as opposed to dental clinic patients, insurance plan members, or owners of specific electric toothbrushes. Most (31/33, 94%) were free to download, and a majority (19/33, 58%) were sponsored by software developers as opposed to oral health experts. None offered any theoretical basis for the content or had been empirically validated. Common program features included tools for tracking or reminding one to brush their teeth and assistance scheduling dental appointments. Nineteen apps (58%) included educational or persuasive content intended to influence oral health behavior. Only 32% (6/19) of these included a larger proportion of gain-framed than loss-framed messaging. Most of the apps did not mention diet, alcohol or tobacco-important risk factors for oral disease. Overall, the apps performed poorly on standard usability heuristics recommended for persuasive health technologies.

CONCLUSIONS

The quality of the reviewed apps was generally poor. Important opportunities exist to develop oral health promotion apps that have theoretically grounded content, are empirically validated, and adhere to good design principles for persuasive health technologies.