The effect of the combined use of silver diamine fluoride and potassium iodide in disrupting the plaque biofilm microbiome and alleviating tooth discoloration: A systematic review.

Silver diamine fluoride (SDF) is used in minimally invasive dentistry for arresting dental caries. However, discoloration of teeth is a significant side effect that has limited the use of SDF. Hence, the application of potassium iodide (KI) following SDF has been proposed to ameliorate the staining. Although antimicrobial activity is one of the major mechanisms of the caries-arresting effect of SDF, the antimicrobial potency of SDF/KI combination is unclear. Thus, the primary objective of this systematic review was to appraise the studies on the antimicrobial efficacy of SDF/KI combination on cariogenic microbes. The secondary objective was to summarize the evidence on the potential of KI in reducing the discoloration associated with the application of SDF. Electronic databases of Medline via PubMed, Cochrane Library, Web of Science, and EBSCO host were searched for English language manuscripts from January 2005 to 15th November 2020. The reference lists of these manuscripts were manually searched for additional studies. Twelve studies were included in the final analysis, seven of which have investigated the antimicrobial efficacy of SDF/KI, and the rest have examined the anti-staining potential of KI. The exploratory findings from the reviewed articles revealed the promising antimicrobial potential of SDF/KI on cariogenic microbes associated with dentine caries. There is, however, contradictory evidence on the effect of SDF/KI on tooth color. The reviewed in-vitro studies indicated significant effectiveness of KI in preventing staining. A clinical trial on primary dentition showed 25% reduction in the incidence of staining by SDF after applying KI, while a clinical study on root caries in adults showed no significant effect. Within the methodological limitations of this review, we conclude that for arresting dental caries, SDF could be combined with KI, as there may be a lower likelihood of staining. Further, well-designed clinical trials on the antimicrobial and anti-staining effect of SDF/KI are needed to obtain more robust evidence.

A colourimetric evaluation of the effect of bacterial contamination on teeth stained with blood in vitro: Evaluation of the efficacy of two different bleaching regimes.

BACKGROUND: Tooth discolouration could occur due to bacterial contamination in traumatized teeth. Hydrogen peroxide is the commonly used bleaching agent. However, due to concerns over safety, alternative bleaching regimes such as sodium perborate (S) and thiourea-hydrogen peroxide (T) have been investigated. METHODS: Apices resected and pulp extirpated 99 premolars were divided into two groups. Group 1 and 2 was injected with blood and blood/bacteria, stored anaerobically for 35 days. The two groups were treated by bleaching with water, S or T. Teeth were rebleached after 7 days. Colourimetric evaluation was assessed using digital imaging, CasMatch standardization and CIE L*a*b colour system preoperatively, 35 days of staining and 7 and 14 of bleaching. A linear mixed model with fixed effects of time, group and bleach was used to examine colour difference. RESULTS: Blood-stained teeth were significantly redder and darker on day 35 compared with blood/bacteria-stained teeth. After bleaching, blood-stained teeth retained significant redness compared with blood/bacteria-stained teeth using either S or T. T produced a significantly whiter shade in both the groups after 14 days. CONCLUSIONS: Blood-stained teeth were significantly darker and red compared with blood/bacteria-stained teeth. T bleaching regime was more effective than S.

A preliminary study on the relationship between iron and black extrinsic tooth stain in children.

Black extrinsic tooth stain, which has long troubled many people, is common among children and influences the aesthetics of teeth. The pigment was proposed to be a black insoluble ferric compound, but this is controversial. To determine whether iron exists in black stain, we collected 10 samples of black stain and 10 samples of plaque separately from children with and without black stain using sterile titanium implant curettes, and analysed the samples by inductively coupled plasma-mass spectrometry. Iron was present in both black stain and plaque, with concentrations ranging from 76·12 to 1116·88 µg g-1 . The contents of iron in black stain were significantly higher than in plaque. Because bacteria may be involved in the aetiology of black stain, we assessed the functional genes of bacteria in black stain based on 16S rRNA gene sequencing results obtained using Phylogenetic Investigation of Communities by Reconstruction of Unobserved States. Of 253 Kyoto Encyclopedia of Gene and Genomes (KEGG) pathways tested, 56 differed in abundance between samples from children with and without black stain. Genera altered in black stain were related to many of the pathways. Some KEGG Orthology groups showed differences between black stain and plaque of control group were found to be related to iron. SIGNIFICANCE AND IMPACT OF THE STUDY: In this study, we have confirmed the existence of iron in black extrinsic tooth stain by ICP-MS. It was the first time the functional genes of bacteria in black stain were accessed and the genes associated with iron were found. These findings provided clues on the research of aetiology of black stain, which troubled millions of children. It also revealed the association between metabolic pathway of microbiota and oral phenomenon.

Black Stains: a microbiological analysis and a view on familiarity and susceptibility to tooth decay of patients in childhood.

AIM: Assess prevalence, familial predisposition and susceptibility to caries of Black Stains (BS). Evaluate the microbiological composition of BS, saliva and subgingival plaque. MATERIALS AND METHODS: Sixty nine subjects with BS (test group) and 120 subjects without BS (control group) were analysed for oral status. For each BS-patient, a BS-deposit, 1 ml of saliva and subgingival plaque were collected and microbiologically analysed. Five deciduous teeth with BS were observed under SEM. RESULTS: This study showed a BS prevalence similar to that of the Mediterranean area and a familiality. The microbiological origin of BS was confirmed by SEM and culture method and the BS flora differ from that of supragingival plaque. CONCLUSIONS: Predominance in BS and saliva of Actinomycetes and the low salivary prevalence of S. mutans and L. acidophilus may be related with low caries incidence in BS patients. The high presence of Actinomyces spp can be a causative factor for BS.

Analysis of the Microbiota of Black Stain in the Primary Dentition.

Black tooth stain is a characteristic extrinsic discoloration commonly seen on the cervical enamel following the contour of the gingiva. To investigate the relationship between black tooth stain and the oral microbiota, we used 16S rRNA gene sequencing to compare the microbial composition of dental plaque and saliva among caries-free children with and without black stain. Dental plaque and saliva, as well as black stain, were sampled from 10 children with and 15 children without black stain. Data were analyzed using the pipeline tool MOTHUR. Student's t-test was used to compare alpha diversities and the Mann-Whitney U test to compare the relative abundances of the microbial taxa. A total of 10 phyla, 19 classes, 32 orders, 61 families and 102 genera were detected in these samples. Shannon and Simpson diversity were found to be significantly lower in saliva samples of children with black stain. Microbial diversity was reduced in the black stain compared to the plaque samples. Actinomyces, Cardiobacterium, Haemophilus, Corynebacterium, Tannerella and Treponema were more abundant and Campylobacter less abundant in plaque samples of children with black stain. Principal component analysis demonstrated clustering among the dental plaque samples from the control group, while the plaque samples from the black stain group were not and appeared to cluster into two subgroups. Alterations in oral microbiota may be associated with the formation of black stain.

Dental caries and microbiota in children with black stain and non-discoloured dental plaque.

AIM: We aimed to assess caries experience and microbiota in systemically healthy children with black stain (BS) and non-discoloured plaque. METHODS: Forty-six children with BS and 47 counterparts with non-discoloured plaque aged 7.9 ± 1.3 years were clinically examined. Dental caries was scored using WHO criteria. Samples of BS and non-discoloured dental plaque were collected from tooth surfaces. The DNA of the samples was extracted and real-time PCR was performed to determine the total number of bacteria and the species Streptococcus mutans, S. sobrinus, Lactobacillus sp., Actinomyces naeslundii, Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia and Fusobacterium nucleatum. RESULTS: Children with BS had lower DMFT (p = 0.013), lower DT values (p = 0.005) and a tendency to lower caries prevalence (p = 0.061) than children with non-discoloured plaque. Plaque samples of the BS group contained higher numbers of A. naeslundii (p = 0.005) and lower numbers of F. nucleatum (p = 0.001) and Lactobacillus sp. (p = 0.001) compared to the non-discoloured plaque samples of the control group. Comparing the children with BS and non-discoloured plaque, higher counts for A. naeslundii (p = 0.013) were observed in caries-free children with BS while in caries-affected children with BS, lower counts of F. nucleatum (p = 0.007) were found. Counts of Lactobacillus sp. were higher in non-discoloured plaque samples than in BS of caries-free and caries-affected children. CONCLUSION: Results suggest that the different microbial composition of BS might be associated with the lower caries experience in affected subjects. The role of black-pigmented bacteria associated with periodontitis needs further studies.

Biofilms of black tooth stains: PCR analysis reveals presence of Streptococcus mutans

This study investigated the presence of the black-pigmented bacteria Prevotella nigrescens and Prevotella intermedia, the non-black-pigmented bacteria Actinomyces spp and particularly the cariogenic pathogen Streptococcus mutans in the dental biofilms of patients with or without black extrinsic tooth stains, using the multiplex polymerase chain reaction (PCR) technique. Analysis of the dental biofilms of patients with (n=26) or without (n=26) black tooth stains was performed using duplex PCR for the 16S ribosomal RNA gene (P. nigrescens, P. intermedia, Actinomyces spp) and glucosyltransferase-I gene for S. mutans. P. nigrescens and S. mutans were the most frequent bacteria detected in both groups. The least frequently detected were P. intermedia and Actinomyces spp. The similar bacterial composition of dental biofilms of black tooth stains and healthy tooth surfaces indicates that black tooth stains are not free of cariogenic bacteria.

O objetivo deste estudo foi investigar a presença das bactérias pigmentadoras de negro Prevotella nigrescens e Prevotella intermedia, da não pigmentadora de negro Actinomyces spp e particularmente a bactéria cariogênica Streptococcus mutans, no biofilme dentário de pacientes com ou sem manchas dentárias extrínsecas negras, utilizando a técnica multiplex PCR (reação em cadeia da polimerase). Análises do biofilme dentário de pacientes com manchas (n=26) e sem manchas (n=26) foram realizadas utilizando a multiplex PCR para o gene 16S RNA ribosomal (P. nigrescens, P. intermedia, Actinomyces spp) e o gene glucosiltransferase-I para S. mutans. P. nigrescens e S. mutans foram as bactérias mais frequentemente detectadas em ambos os grupos. As menos frequentemente detectadas foram P. intermedia e Actinomyces spp. A similaridade entre a composição bacteriana dos biofilmes dentários das manchas dentárias extrínsecas negras e das superfícies dentárias sem manchas indicam que as manchas dentárias extrínsecas negras não estão livres de bactérias cariogênicas.

Laboratory evaluation of extrinsic stain removal by a specially engineered sonic powered toothbrush with unique sensing and control technologies.

OBJECTIVE: The purpose of this laboratory study was to evaluate extrinsic stain removal from teeth by a specially engineered sonic powered toothbrush with unique sensing and control technologies, using the Triple Clean and the Sensitive refill brush heads, in comparison to a manual flat-trim toothbrush. METHODS: Twelve (12) artificially stained bovine teeth were tested with each product. The percentage of stain removed by each product was calculated by taking the ratio of the amount of stain removed by brushing for 800 strokes to the total amount of stain removed by subsequent application of a dental prophylaxis. The stain was quantified by measuring the light reflected by the stained teeth with a spectrophotometer. Data were reported as L*, lightness of the stain, and as W*, a whiteness index comprising the lightness, hue, and chroma of reflected light. Statistical analyses were performed separately for the AL* and AW* scores. Comparisons of the toothbrushes with respect to baseline-adjusted deltaL* and deltaW* scores were performed using an analysis of covariance (ANCOVA). Post-ANCOVA pair-wise comparisons of the study toothbrushes were performed using Tukey's test for multiple comparisons. All statistical tests of hypotheses were two-sided, and employed a minimum level of significance of 0.05. RESULTS: The percentage of stain removed by the sonic powered toothbrush, using either the Triple Clean brush head or the Sensitive brush head under laboratory test conditions, is superior (p < 0.05) to the percentage of stain removed by the manual flat-trim toothbrush when analyzed for both the deltaL* and deltaW* scores. The mean percentage of stain removed was 62.10 for the power toothbrush with the Triple Clean brush head, 49.01 for the power toothbrush with the Sensitive brush head, and 30.56 for the manual flat-trim toothbrush when calculated using deltaL* scores. The mean percentage of stain removed was 59.89 for the power toothbrush with the Triple Clean brush head, 46.83 for the power toothbrush with the Sensitive brush head, and 29.25 for the manual flat-trim toothbrush when calculated using deltaW* scores. CONCLUSIONS: This new specially engineered sonic powered toothbrush with unique sensing and control technologies effectively removes extrinsic stains from the surface of teeth under laboratory test conditions with both the Triple Clean and the Sensitive brush heads. The effectiveness of stain removal with either brush head is significantly greater than the effectiveness of stain removal of a manual flat-trim toothbrush under these conditions.

Biofilms of black tooth stains: PCR analysis reveals presence of Streptococcus mutans.

This study investigated the presence of the black-pigmented bacteria Prevotella nigrescens and Prevotella intermedia, the non-black-pigmented bacteria Actinomyces spp and particularly the cariogenic pathogen Streptococcus mutans in the dental biofilms of patients with or without black extrinsic tooth stains, using the multiplex polymerase chain reaction (PCR) technique. Analysis of the dental biofilms of patients with (n=26) or without (n=26) black tooth stains was performed using duplex PCR for the 16S ribosomal RNA gene (P. nigrescens, P. intermedia, Actinomyces spp) and glucosyltransferase-I gene for S. mutans. P. nigrescens and S. mutans were the most frequent bacteria detected in both groups. The least frequently detected were P. intermedia and Actinomyces spp. The similar bacterial composition of dental biofilms of black tooth stains and healthy tooth surfaces indicates that black tooth stains are not free of cariogenic bacteria.

Un enfoque actual sobre la relevancia de las pigmentaciones extrínsecas / Current approach to the relevance of extrinsic stains

Las manchas extrínsecas negras son consideradas un tipo especial de placa calcificada y pueden aparecer en dientes temporarios alrededor de los 2 ó 3 años de edad. Se extienden en forma paralela al margen gingival y pueden presentarse como puntos aislados o líneas continuas, principalmente sobre las caras libres.De acuerdo a investigaciones recientes, en la formación de estos depósitos estaría involucrado el ActinobacillusActinomycetemcomitans; mientras que desde el punto de vista bioquímico se encontró una elevada concentración de iones calcio y fosfato que disminuirían la solubilidad del esmalte.La presente revisión tuvo por objetivo recopilar y exponer los estudios publicados acerca las pigmentaciones extrínsecas negras, su etiología, prevalencia y relación con la baja incidencia de caries.

Black tooth stains are considered a specific type of calculus formation that may appear in deciduous dentition between the age of 2 to 3 years old. Characterized by dark dots or lines localized parallel to the gingival margin, mainly on clean tooth surfaces.Recent research studies suggest that Actinobacillus Actinomycetemcomitans plays an important role in the formation of these deposits; from a biochemical point of view it was found that high calcium and phosphate ion concentrations in saliva reducesenamel solubility. The aim of this review was to collect and analyze published studies on extrinsic tooth discoloration, its etiology, prevalence andrelation to low caries incidence.

[Exogenous tooth discoloration in children: black stains]. / Les colorations dentaires noires exogènes chez l'enfant : Black-stains.

Black-stains are a coloring frequently met in pediatric dentistry. They can be medically diagnosed as 1-mm borders or unfinished lines formed by a dark exogenous substance which follows the gingival festoon of bet coronary (in cervical third of the crown) temporary teeth and permanent, or they can appear in like points or dark spots. They are caused by bacteria anaerobic chromogenous. The dominant responsible species are actinomyces. Blacks-stains are ferrous depots, formed following a chemical interaction on the surface of the tooth between sulphide of hydrogen (under the effect of the anaerobic bacteria which are producing hydrogen) and the iron contained in the saliva (by a healthy diet) or that released by red blood corpuscles (in case of bloody gums). Black-stains are a shape of characteristic dental plaque by its flora with trend to calcify. It contains an insoluble iron salt with a content raised in calcium and in inorganic phosphor. The coloring Black-stain is a mild pathology and has no incidence on the vitality of the tooth. Certainly these spots are unsightly. The dental surgeon in current practice can deprive them. The pediatrician plays a leading role in the diagnosis and advice to parents and patients affected by these stains.

Black stain - a review.

The purpose of this review was to summarise the fundamentals about black stain, its diagnosis and possible differential diagnoses as well as its microbiology and therapy. In addition, various studies investigating the relationship between black stain and dental caries are examined. Many studies report lower caries prevalence in children with black stain, but this finding could not be confirmed by all authors. Also, a negative relation between degree of staining and caries severity has been described. Reasons for these results are not yet clear but it was speculated that they are related to the specific oral microflora described in black stain-affected individuals.

Case report: Blue chromogenic dental staining in child with West syndrome.

BACKGROUND: Tooth discolouration can be caused by a variety of local and systemic factors. Extrinsic dental stains may be caused by predisposing factors, and other factors such as dental plaque, foods and beverages, chromogenic bacteria, metallic compounds and medications. Studies have reported a correlation between the colour of extrinsic staining and caries risk. CASE REPORT: A 4-year-old boy with West syndrome, characterised by epileptic seizures and severe muscle spasm, was referred to the paediatric dentistry clinic at School of Clinical Dentistry, Sheffield. He had a percutaneous endoscopic gastrostomy (PEG) tube and had no oral food or fluid intake. The presenting complaint was his parent's concern of trauma to the oral tissues from epileptic fits. An examination revealed an unusual navy-blue staining to his teeth that appeared extrinsic in nature. There was evidence of tooth-wear of his primary dentition, and marked calculus deposits. No caries was detected. TREATMENT: A further dental examination and treatment was carried out under general anaesthesia. The mandibular central incisors were extracted, due to imminent pulp exposure from bruxism, and were sent for histopathology to determine the nature of the staining. A moderate growth of Pseudomonas aeruginosa, a blue pigment-producing bacteria usually implicated in chronic pulmonary infections, was recovered from a swab sample. FOLLOW-UP: The patient was reviewed at 4 months at which time the staining had returned. CONCLUSION: The patient had no oral intake of food or drink, which placed him in a low caries risk category despite limited oral hygiene practice. His extensive lists of medications were not found to have extrinsic dental staining as a possible side effect. However, these may have altered the oral flora such that growth of pigmented bacteria, normally absent from the oral cavity, was favoured, causing generalised extrinsic staining.

Microbiological and microscopic analysis of the pulp of non-vital traumatized teeth with intact crowns.

OBJECTIVE: This study evaluated the presence of microorganisms and analyzed microscopically the pulp of 20 traumatized human teeth with intact crowns and clinical diagnosis of pulp necrosis, based on the association of at least three of the clinical criteria: crown discoloration, negative response to thermal and electric pulp vitality tests, positive response to vertical and horizontal percussion, pain on palpation or mobility. MATERIAL AND METHODS: Microbiological collection was performed from the root canals to evaluate the presence of microorganisms. The pulp samples were stained with hematoxylin and eosin (H.E.) for histological evaluation of possible morphological alterations. RESULTS: Analysis of results was performed by statistical tests (linear regression test and diagnostic analysis) and subjective analysis of the sections stained with H.E. and revealed that only 15% of the sample did not exhibit microbial development. The time elapsed between dental trauma and onset of endodontic intervention ranged from 15 days to 31 months; the percussion test presented high sensitivity (80%) for detection of microorganisms in the root canal of traumatized teeth; 3 teeth (15%) did not present pulp tissue, being characterized as complete autolysis; analysis of pulp samples was performed on the other 17 cases, among which 3 (15%) exhibited partial necrosis without possibility of repair and 14 presented complete necrosis; none of the clinical criteria employed for the diagnosis of pulp necrosis in traumatized teeth was pathognomonic. CONCLUSIONS: The present results allowed the following conclusions: with regard to microbiological findings, 85% of teeth presented microorganisms in the root canal, despite the presence of an intact crown. Concerning the microscopic findings, 100% of traumatized teeth presented pulp necrosis; the pulp vitality tests based on pulp response to heat, cold and vertical percussion were the most reliable to diagnose pulp necrosis in traumatized teeth.

Microbiological and microscopic analysis of the pulp of non-vital traumatized teeth with intact crowns

OBJECTIVE: This study evaluated the presence of microorganisms and analyzed microscopically the pulp of 20 traumatized human teeth with intact crowns and clinical diagnosis of pulp necrosis, based on the association of at least three of the clinical criteria: crown discoloration, negative response to thermal and electric pulp vitality tests, positive response to vertical and horizontal percussion, pain on palpation or mobility. MATERIAL AND METHODS: Microbiological collection was performed from the root canals to evaluate the presence of microorganisms. The pulp samples were stained with hematoxylin and eosin (H.E.) for histological evaluation of possible morphological alterations. RESULTS: Analysis of results was performed by statistical tests (linear regression test and diagnostic analysis) and subjective analysis of the sections stained with H.E. and revealed that only 15 percent of the sample did not exhibit microbial development. The time elapsed between dental trauma and onset of endodontic intervention ranged from 15 days to 31 months; the percussion test presented high sensitivity (80 percent) for detection of microorganisms in the root canal of traumatized teeth; 3 teeth (15 percent) did not present pulp tissue, being characterized as complete autolysis; analysis of pulp samples was performed on the other 17 cases, among which 3 (15 percent) exhibited partial necrosis without possibility of repair and 14 presented complete necrosis; none of the clinical criteria employed for the diagnosis of pulp necrosis in traumatized teeth was pathognomonic. CONCLUSIONS: The present results allowed the following conclusions: with regard to microbiological findings, 85 percent of teeth presented microorganisms in the root canal, despite the presence of an intact crown. Concerning the microscopic findings, 100 percent of traumatized teeth presented pulp necrosis; the pulp vitality tests based on pulp response to heat, cold and vertical percussion ...

Black stains in the mixed dentition: a PCR microbiological study of the etiopathogenic bacteria.

The aim of this work is to emphasize that particular stains on the third cervical of the buccal and lingual surfaces in mixed dentition, called "black stain." Previous research showed the microbiological etiology of this discoloration by chromogen bacterias. Our study shows bacteria spp involved in stains by means of PCR process and electrophoresis gel on the agarose medium. Sample was formed by 100 subject with black stain and 100 control subjects stain-free. A statistical analysis (SPSS 10.0) using X2 was performed in this study. Porphyromonas gingivalis and Prevotella melaninogenica, were not involved in both in black stain subjects and in the control. On the contrary, Actinomyces could be involved in the pigmentation process.

Development of clinical and radiographic signs associated with dark discolored primary incisors following traumatic injuries: a prospective controlled study.

The purpose was to evaluate late complications of asymptomatic traumatized primary incisors with dark coronal discoloration. The clinical and radiographic signs of 97 teeth of the study group were recorded along a follow-up period that ranged between 12 and 75 months (mean >36 months). Children's age at time of injury ranged between 18 and 72 months (mean 40). The control group consisted of 102 non-discolored maxillary primary central incisors in 51 children older than 54 months with no history of dental trauma. In 50 teeth (52%) the color faded or became yellowish and in 47 (48%) it remained dark. Clinical signs of infection, that were diagnosed 5-58 months after the injury, were associated significantly more with dark than yellowish hues (83 and 17%, respectively). Teeth that had changed their color to become yellow presented more PCO than teeth with black/gray/brown coronal discoloration (78 and 6%, respectively). Arrest of dentine apposition was found in 15 teeth, one had yellow coronal discoloration and the remaining 14 had a dark shade. Eleven teeth showed inflammatory root resorption all with dark discoloration. Two atypical types of root resorption were observed: a surface resorption restricted to the lateral aspects of the apical half of the root while the root length remained unchanged and in the other expansion of the follicle of the permanent successor was observed. Expansion of the dental follicle was observed in 72% of all teeth with no significant difference between the various types of coronal discoloration but only half of the cases were associated with resorption of the root of the primary incisor. The various pathologic findings observed in the study group were either absent or rarely seen in the control group. It can be concluded that more than 50% of the primary incisors that retain their dark coronal discoloration acquired after dental injuries remain clinically asymptomatic till the eruption of the permanent successor even if they present accelerated root resorption. Asymptomatic traumatized primary incisors that retain their dark coronal discoloration may develop a sinus tract and inflammatory root resorption years after the injury. There is still a dilemma: which treatment is better for dark discolored primary incisors: early endodontic treatment or follow-up with the risk of development of infection and root resorption that may require extraction?

Relating visual and radiographic ranked scoring systems for occlusal caries detection to histological and microbiological evidence.

This study compared a visual ranked scoring system and a radiographic ranked scoring system for occlusal caries detection with the level of infection of dentin. Seventy-five third-molars, designated for extraction, were professionally cleaned. Caries was scored according to a visual ranked scoring system at a selected site in the groove-fossa system. Radiographs of the teeth were available and caries was recorded along a five-point ranked scoring system. Each tooth was extracted and hemi-sectioned through the investigation site under aseptic conditions. A burful of dentin was removed from the EDJ of one of the section faces and these samples were processed to establish the level of dentin infection. The depth of the lesion was assessed on the other section face using a five-point ranked histological scoring system. A strong relationship was observed between the histological lesion depth and visual score (r(s)=0.93) while a moderate relationship was seen between lesion depth and radiographic scores (r(s)=0.77). The dentin from teeth with cavities exposing dentin was heavily infected. The dentin from teeth with microcavities or grey discoloration of the dentin was less infected than the lesions with frank cavitation (score 4) (p<0.05, t-test), but more infected than the initial lesions (p<0.05, t-test). The latter lesions showed minimal infection. A similar tendency was seen with respect to increasing radiographic scores and the level of infection of the dentin.

Association of salivary mutans streptococci with discoloured pits and fissures.

Experimental studies have demonstrated that mutans streptococci play a major role in caries etiology. Several previous epidemiologic studies found a positive association of salivary mutans streptococci with caries prevalence. The present epidemiologic study aimed at detecting a possible association of salivary mutans streptococci with brown discoloured pits and fissures, supposing that discolouration indicates caries. In the Canton of Zurich 1035 schoolchildren, aged 6.5-12.5, were examined with regard to caries prevalence and presence of discolourations in pits and fissures. A commercially available, semi-quantitative test was used to estimate the salivary level of mutans streptococci in each child. The salivary level (low/high) of mutans streptococci was significantly associated with the presence of slightly brown discoloured (C1), clearly brown discoloured (C2) and cavitated (C3) pits and fissures. The odds ratios were 1.5 (P<0.01) for C1, 2.5 (P<0.001) for C2 and 5.0 (P<0.001) for C3 pits and fissures. The findings are consistent with the hypothesis that brown discolouration indicates caries. Furthermore, the findings suggest that this type of discolouration at elementary school age indicates increased caries activity.